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Cadmium hyperaccumulation and genetic differentiation of Thlaspi caerulescens populations
Cadmium hyperaccumulation and genetic differentiation of Thlaspi caerulescens populations Nevena hyperaccumulation mechanisms is increasing, the genetic basis of cadmium (Cd) hyperaccumulation remains fragment length polymorphism (AFLP); Cadmium (Cd); Genetic differentiation; Hyperaccumulation; Outlier loci
Alvarez, Nadir
Plant species capable of hyperaccumulating heavy metals are of considerable interest for phytoreme- diation and phytomining. This work aims to identify the role of antioxidative metabolism in heavy metal toler- ance in the Cd hyperaccumulator, Thlaspi caerulescens. Hairy roots of T. caerulescens and the non-hyperaccumu- lator, Nicotiana tabacum (tobacco), were used to test the effects of high Cd environments. In
Rengasamy Boominathan; Pauline M. Doran
Worldwide more than 400 plant species are now known that hyperaccumulate various trace metals (Cd, Co, Cu, Mn, Ni, and Zn), metalloids (As) and nonmetals (Se) in their shoots. Of these, almost one-quarter are Brassicaceae family members, including numerous Thlaspi species that hyperaccumulate Ni up to 3% of there shoot dry weight. We observed that concentrations of glutathione, Cys, and O-acetyl-l-serine (OAS), in shoot tissue, are strongly correlated with the ability to hyperaccumulate Ni in various Thlaspi hyperaccumulators collected from serpentine soils, including Thlaspi goesingense, T. oxyceras, and T. rosulare, and nonaccumulator relatives, including T. perfoliatum, T. arvense, and Arabidopsis thaliana. Further analysis of the Austrian Ni hyperaccumulator T. goesingense revealed that the high concentrations of OAS, Cys, and GSH observed in this hyperaccumulator coincide with constitutively high activity of both serine acetyltransferase (SAT) and glutathione reductase. SAT catalyzes the acetylation of l-Ser to produce OAS, which acts as both a key positive regulator of sulfur assimilation and forms the carbon skeleton for Cys biosynthesis. These changes in Cys and GSH metabolism also coincide with the ability of T. goesingense to both hyperaccumulate Ni and resist its damaging oxidative effects. Overproduction of T. goesingense SAT in the nonaccumulator Brassicaceae family member Arabidopsis was found to cause accumulation of OAS, Cys, and glutathione, mimicking the biochemical changes observed in the Ni hyperaccumulators. In these transgenic Arabidopsis, glutathione concentrations strongly correlate with increased resistance to both the growth inhibitory and oxidative stress induced effects of Ni. Taken together, such evidence supports our conclusion that elevated GSH concentrations, driven by constitutively elevated SAT activity, are involved in conferring tolerance to Ni-induced oxidative stress in Thlaspi Ni hyperaccumulators. PMID:15269333
Freeman, John L.; Persans, Michael W.; Nieman, Ken; Albrecht, Carrie; Peer, Wendy; Pickering, Ingrid J.; Salt, David E.
Investigating Heavy-metal Hyperaccumulation using Thlaspi caerulescens as a Model System
Background Metal-hyperaccumulating plant species are plants that are endemic to metalliferous soils and are able to tolerate and accumulate metals in their above-ground tissues to very high concentrations. One such hyperaccumulator, Thlaspi caerulescens, has been widely studied for its remarkable properties to tolerate toxic levels of zinc (Zn), cadmium (Cd) and sometimes nickel (Ni) in the soil, and accumulate these metals to very high levels in the shoot. The increased awareness regarding metal-hyperaccumulating plants by the plant biology community has helped spur interest in the possible use of plants to remove heavy metals from contaminated soils, a process known as phytoremediation. Hence, there has been a focus on understanding the mechanisms that metal-hyperaccumulator plant species such as Thlaspi caerulescens employ to absorb, detoxify and store metals in order to use this information to develop plants better suited for the phytoremediation of metal-contaminated soils. Scope In this review, an overview of the findings from recent research aimed at better understanding the physiological mechanisms of Thlaspi caerulescens heavy-metal hyperaccumulation as well as the underlying molecular and genetic determinants for this trait will be discussed. Progress has been made in understanding some of the fundamental Zn and Cd transport physiology in T. caerulescens. Furthermore, some interesting metal-related genes have been identified and characterized in this plant species, and regulation of the expression of some of these genes may be important for hyperaccumulation. Conclusions Thlaspi caerulescens is a fascinating and useful model system not only for studying metal hyperaccumulation, but also for better understanding micronutrient homeostasis and nutrition. Considerable future research is still needed to elucidate the molecular, genetic and physiological bases for the extreme metal tolerance and hyperaccumulation exhibited by plant species such as T. caerulescens. PMID:18440996
Milner, Matthew J.; Kochian, Leon V.
The use of heavy metal hyperaccumulating plants has the poten- tial to become a promising new technique to remediate contaminated sites. We investigated the role of metal mobilization in the Cd hyper- accumulation of Thlaspi caerulescens (J. & C. Presl, 'Ganges'). In a micro-lysimeter experiment we investigated the dynamics of Cd con- centration of leachate as well as Cd removal
Joachim Ingwersen; Barbara Bucherl; Gunter Neumann; Thilo Streck
American Journal of Botany 85(2): 259265. 1998. NICKEL HYPERACCUMULATION BY THLASPI MONTANUM
growing on non- serpentine soil. This adaptive value may be a consequence of metal-based plant defense259 American Journal of Botany 85(2): 259┬Ł265. 1998. NICKEL HYPERACCUMULATION BY THLASPI MONTANUM of Botany and Microbiology and Alabama Agricultural Experiment Station, Auburn University, Alabama 36849
Boyd, Robert S.
The ability of Thlaspi goesingense Hßlßcsy to hyperaccumulate Ni appears to be governed by its extraordinary degree of Ni tolerance. However, the physiological basis of this tolerance mechanism is unknown. We have investigated the role of vacuolar compartmentalization and chelation in this Ni tolerance. A direct comparison of Ni contents of vacuoles from leaves of T. goesingense and from the non-tolerant non-accumulator Thlaspi arvense L. showed that the hyperaccumulator accumulates approximately 2-fold more Ni in the vacuole than the non-accumulator under Ni exposure conditions that were non-toxic to both species. Using x-ray absorption spectroscopy we have been able to determine the likely identity of the compounds involved in chelating Ni within the leaf tissues of the hyperaccumulator and non-accumulator. This revealed that the majority of leaf Ni in the hyperaccumulator was associated with the cell wall, with the remaining Ni being associated with citrate and His, which we interpret as being localized primarily in the vacuolar and cytoplasm, respectively. This distribution of Ni was remarkably similar to that obtained by cell fractionation, supporting the hypothesis that in the hyperaccumulator, intracellular Ni is predominantly localized in the vacuole as a Ni-organic acid complex. PMID:10759531
Kramer, Ute; Pickering, Ingrid J.; Prince, Roger C.; Raskin, Ilya; Salt, David E.
We investigated bacterial populations associated with the Zn hyperaccumulator Thlaspi caerulescens subsp. calaminaria grown in a soil collected from an abandoned Zn-Pb mine and smelter in PlombiĶres, Belgium. The bacterial population of the nonrhizospheric soil consisted of typical soil bacteria, some exhibiting multiple heavy-metal resistance characteristics that often are associated with polluted substrates: 7.8% and 4% of the population survived
C. Lodewyckx; M. Mergeay; J. Vangronsveld; H. Clijsters; D. Van Der Lelie
Uptake of Cd and Zn by intact seedlings of two contrasting ecotypes of the hyperaccumulatorThlaspi caerulescens was characterized using radioactive tracers. Uptake of Cd and Zn at 2 8C was assumed to represent mainly apoplastic binding in the roots, whereas the difference in uptake between 22 8C and 2 8C represented metabolically dependent influx. There was no significant difference between
Fang-Jie Zhao; Rebecca E. Hamon; Enzo Lombi; Mike J. McLaughlin; Steve P. McGrath
Thlaspi goesingense is able to hyperaccumulate extremely high concentrations of Ni when grown in ultramafic soils. Recently it has been shown that rhizosphere bacteria may increase the heavy metal concentrations in hyperaccumulator plants significantly, whereas the role of endophytes has not been investigated yet. In this study the rhizosphere and shoot-associated (endophytic) bacteria colonizing T. goesingense were characterized in detail by using both cultivation and cultivation-independent techniques. Bacteria were identified by 16S rRNA sequence analysis, and isolates were further characterized regarding characteristics that may be relevant for a beneficial plant-microbe interactionŚNi tolerance, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and siderophore production. In the rhizosphere a high percentage of bacteria belonging to the Holophaga/Acidobacterium division and ?-Proteobacteria were found. In addition, high-G+C gram-positive bacteria, Verrucomicrobia, and microbes of the Cytophaga/Flexibacter/Bacteroides division colonized the rhizosphere. The community structure of shoot-associated bacteria was highly different. The majority of clones affiliated with the Proteobacteria, but also bacteria belonging to the Cytophaga/Flexibacter/Bacteroides division, the Holophaga/Acidobacterium division, and the low-G+C gram-positive bacteria, were frequently found. A high number of highly related Sphingomonas 16S rRNA gene sequences were detected, which were also obtained by the cultivation of endophytes. Rhizosphere isolates belonged mainly to the genera Methylobacterium, Rhodococcus, and Okibacterium, whereas the majority of endophytes showed high levels of similarity to Methylobacterium mesophilicum. Additionally, Sphingomonas spp. were abundant. Isolates were resistant to Ni concentrations between 5 and 12 mM; however, endophytes generally tolerated higher Ni levels than rhizosphere bacteria. Almost all bacteria were able to produce siderophores. Various strains, particularly endophytes, were able to grow on ACC as the sole nitrogen source. PMID:15128517
Idris, Rughia; Trifonova, Radoslava; Puschenreiter, Markus; Wenzel, Walter W.; Sessitsch, Angela
Cellular Compartmentation of Zinc in Leaves of the Hyperaccumulator Thlaspi caerulescens1
Cellular compartmentation of Zn in the leaves of the hyperaccumulator Thlaspi caerulescens was investigated using energy-dispersive x-ray microanalysis and single-cell sap extraction. Energy-dispersive x-ray microanalysis of frozen, hydrated leaf tissues showed greatly enhanced Zn accumulation in the epidermis compared with the mesophyll cells. The relative Zn concentration in the epidermal cells correlated linearly with cell length in both young and mature leaves, suggesting that vacuolation of epidermal cells may promote the preferential Zn accumulation. The results from single-cell sap sampling showed that the Zn concentrations in the epidermal vacuolar sap were 5 to 6.5 times higher than those in the mesophyll sap and reached an average of 385 mm in plants with 20,000 ?g Zn g?1 dry weight of shoots. Even when the growth medium contained no elevated Zn, preferential Zn accumulation in the epidermal vacuoles was still evident. The concentrations of K, Cl, P, and Ca in the epidermal sap generally decreased with increasing Zn. There was no evidence of association of Zn with either P or S. The present study demonstrates that Zn is sequestered in a soluble form predominantly in the epidermal vacuoles in T. caerulescens leaves and that mesophyll cells are able to tolerate up to at least 60 mm Zn in their sap. PMID:9880373
Kupper, Hendrik; Jie Zhao, Fang; McGrath, Steve P.
BackgroundThlaspi caerulescens is a natural selected heavy metal hyperaccumulator that can not only tolerate but also accumulate extremely high levels of heavy metals in the shoots. Thus, to identify the transportors involved in metal long-distance transportation is very important for understanding the mechanism of heavy metal accumulation in this hyperaccumulator.Methodology\\/Principal FindingsWe cloned and characterized a novel gene TcOPT3 of OPT
Yi Ting Hu; Feng Ming; Wei Wei Chen; Jing Ying Yan; Zheng Yu Xu; Gui Xin Li; Chun Yan Xu; Jian Li Yang; Shao Jian Zheng
To understand the role of free histidine (His) in Ni hyperaccumulation in Thlaspi goesingense, we investigated the regulation of His biosynthesis at both the molecular and biochemical levels. Three T. goesingense cDNAs encoding the following His biosynthetic enzymes, ATP phosphoribosyltransferase (THG1, GenBank accession no. AF003347), imidazoleglycerol phosphate dehydratase (THB1, GenBank accession no. AF023140), and histidinol dehydrogenase (THD1, GenBank accession no. AF023141) were isolated by functional complementation of Escherichia coli His auxotrophs. Northern analysis of THG1, THD1, and THB1 gene expression revealed that each gene is expressed in both roots and shoots, but at the concentrations and dosage times of Ni treatment used in this study, these genes failed to show any regulation by Ni. We were also unable to observe any increases in the concentration of free His in root, shoot, or xylem sap of T. goesingense in response to Ni exposure. X-ray absorption spectroscopy of root and shoot tissue from T. goesingense and the non-accumulator species Thlaspi arvense revealed no major differences in the coordination of Ni by His in these tissues. We therefore conclude that the Ni hyperaccumulation phenotype in T. goesingense is not determined by the overproduction of His in response to Ni. PMID:10594099
Persans, Michael W.; Yan, Xiange; Patnoe, Jean-Marc M.L.; Kramer, Ute; Salt, David E.
We investigated changes in mineral nutrient uptake and cellular expression levels for metal transporter genes in the cadmium (Cd)/zinc (Zn) hyperaccumulator, Thlaspi caerulescens during whole plant and leaf ontogenesis under different long-term treatments with Zn and Cd. Quantitative mRNA in situ hybridization (QISH) revealed that transporter gene expression changes not only dependent on metal nutrition/toxicity, but even more so during plant and leaf development. The main mRNA abundances found were: ZNT1, mature leaves of young plants; ZNT5, young leaves of young plants; MTP1 (= ZTP1 = ZAT), young leaves of both young and mature plants. Surprisingly different cellular expression patterns were found for ZNT1 and ZNT5, both belonging to the ZIP family of transition metal transporters: ZNT1, photosynthetic mesophyll and bundle sheath cells; ZNT5, nonphotosynthetic epidermal metal storage cells and bundle sheath cells. Thus, ZNT1 may function in micronutrient nutrition while ZNT5 may be involved in metal storage associated with hyperaccumulation. Cadmium inhibited the uptake of Zn, iron (Fe) and manganese (Mn), probably by competing for transporters or by interfering with the regulation of transporter gene expression. Cadmium-induced changes in cellular expression for ZNT1, ZNT5 and MTP1 could also be part of plant acclimatization to Cd toxicity. Defence against Cd toxicity involved enhanced uptake of magnesium (Mg), calcium (Ca) and sulphur (S). PMID:19843304
K³pper, Hendrik; Kochian, Leon V
Background Thlaspi caerulescens is a natural selected heavy metal hyperaccumulator that can not only tolerate but also accumulate extremely high levels of heavy metals in the shoots. Thus, to identify the transportors involved in metal long-distance transportation is very important for understanding the mechanism of heavy metal accumulation in this hyperaccumulator. Methodology/Principal Findings We cloned and characterized a novel gene TcOPT3 of OPT family from T. caerulescens. TcOPT3 was pronouncedly expressed in aerial parts, including stem and leaf. Moreover, in situ hybridization analyses showed that TcOPT3 expressed in the plant vascular systems, especially in the pericycle cells that may be involved in the long-distance transportation. The expression of TcOPT3 was highly induced by iron (Fe) and zinc (Zn) deficiency, especially in the stem and leaf. Sub-cellular localization showed that TcOPT3 was a plasma membrane-localized protein. Furthermore, heterogonous expression of TcOPT3 by mutant yeast (Saccharomyces cerevisiae) complementation experiments demonstrated that TcOPT3 could transport Fe2+ and Zn2+. Moreover, expression of TcOPT3 in yeast increased metal (Fe, Zn, Cu and Cd) accumulation and resulted in an increased sensitivity to cadmium (Cd) and copper (Cu). Conclusions Our data demonstrated that TcOPT3 might encode an Fe/Zn/Cd/Cu influx transporter with broad-substrate. This is the first report showing that TcOPT3 may be involved in metal long-distance transportation and contribute to the heavy metal hyperaccumulation. PMID:22761683
Hu, Yi Ting; Ming, Feng; Chen, Wei Wei; Yan, Jing Ying; Xu, Zheng Yu; Li, Gui Xin; Xu, Chun Yan; Yang, Jian Li; Zheng, Shao Jian
Cadmium (Cd) is a widespread, naturally occurring element present in soil, rock, water, plants and animals. Cd is a non-essential element for plants and is toxic at higher concentrations. Transcript profiles of roots of Arabidopsis thaliana (Arabidopsis) and Thlaspi caerulescens plants exposed to Cd and zinc (Zn) are examined, with the main aim to determine the differences in gene expression
Mortel van de J. E; HENK SCHAT; PERRY D. MOERLAND; EMIEL VER LOREN VAN THEMAAT; SJOERD VAN DER ENT; M. H. C. Blankestijn-de Vries; A. Ghandylian; STYLIANI TSIATSIANI; MARK G. M. AARTS
Potential use of metal hyperaccumulators
Experiments involving biological accumulation of metal contaminants are summarized in the article. The focus is on identification of hyperaccumulating plant species for cadmium and zinc. Two of the studies examined Thlaspi caerulescens (alpine pennycress) as a bioadsorbent; the third study compared different species of Thlaspi. The T. caerulescens accumulated both metals, but with low yields. Other plant species were identified which adsorbed cadmium or zinc, but not both metals.
Chaney, R.; Li, Yin-Ming; Green, C. [Environmental Chemistry Lab., Beltsville, MD (United States)] [and others
. ┬Ę Selenium hyperaccumulators Astragalus bisulcatus and Stanleya pinnata were monitored over two growing: Astragalus bisulcatus, Astragalus sericoleucus, hyperaccumulation, Oxytropis sericea, selenium (Se), Stanleya pinnata, sulfur (S), Thlaspi montanum. New Phytologist (2007) 173: 517┬Ł525 ┬® The Authors (2006). Journal
Response of Thlaspi caerulescens to Nitrogen, Phosphorus and Sulfur Fertilisation
The main limiting factor for cleaning-up contaminated soils with hyperaccumulator plants is the low production of aerial biomass and the number of successive crops needed to reach the objective of remediation. The aim of this study was to contribute to the determination of a fertilisation strategy to optimise soil metal phytoextraction by Thlaspi caerulescens. A pot experiment was conducted on
Sirguey Catherine; Schwartz Christophe; Morel Jean Louis
The potential of Thlaspi caerulescens for phytoremediation of contaminated soils
Uptake of Cd, Zn, Pb and Mn by the hyperaccumulator Thlaspi caerulescens was studied by pot trials in plant growth units and in populations of wild plants growing over Pb\\/Zn base-metal mine wastes at Les Malines in the south of France. The pot trials utilised metal-contaminated soils from Auby in the Lille area. Zinc and Cd concentrations in wild plants
Brett H. Robinson; Marc Leblanc; Daniel Petit; Robert R. Brooks; John H. Kirkman; Paul E. H. Gregg
Evaluation of the remediation ability of zinc\\/cadmium in hyper- and non-hyperaccumulator plant species through greenhouse studies is limited. To bridge the gap between greenhouse studies and field applications for phytoextraction, we used published data to examine the partitioning of heavy metals between plants and soil (defined as the bioconcentration factor). We compared the remediation ability of the Zn\\/Cd hyperaccumulators Thlaspi
Hong-Ming Liang; Ting-Hsiang Lin; Jeng-Min Chiou; Kuo-Chen Yeh
Facultative hyperaccumulation of heavy metals and metalloids.
Approximately 500 species of plants are known to hyperaccumulate heavy metals and metalloids. The majority are obligate metallophytes, species that are restricted to metalliferous soils. However, a smaller but increasing list of plants are "facultative hyperaccumulators" that hyperaccumulate heavy metals when occurring on metalliferous soils, yet also occur commonly on normal, non-metalliferous soils. This paper reviews the biology of facultative hyperaccumulators and the opportunities they provide for ecological and evolutionary research. The existence of facultative hyperaccumulator populations across a wide edaphic range allows intraspecific comparisons of tolerance and uptake physiology. This approach has been used to study zinc and cadmium hyperaccumulation by Noccaea (Thlaspi) caerulescens and Arabidopsis halleri, and it will be instructive to make similar comparisons on species that are distributed even more abundantly on normal soil. Over 90% of known hyperaccumulators occur on serpentine (ultramafic) soil and accumulate nickel, yet there have paradoxically been few experimental studies of facultative nickel hyperaccumulation. Several hypotheses suggested to explain the evolution of hyperaccumulation seem unlikely when most populations of a species occur on normal soil, where plants cannot hyperaccumulate due to low metal availability. In such species, it may be that hyperaccumulation is an ancestral phylogenetic trait or an anomalous manifestation of physiological mechanisms evolved on normal soils, and may or may not have direct adaptive benefits. PMID:24467891
Pollard, A Joseph; Reeves, Roger D; Baker, Alan J M
Summary Ģ Genetic variation structure and breeding system were investigated in metalli- colous (MET) and nonmetallicolous (NONMET) populations of the heavy-metal hyperaccumulator Thlaspi caerulescens from Belgium, Luxembourg and the French Mediterranean region. Ģ Allozyme variation showed a clear differentiation between the two ecotypes in Belgium and Luxembourg but not in southern France, in line with the lower degree of geographical
S. Dubois; P.-O. Cheptou; C. Petit; P. Meerts; M. Poncelet; X. Vekemans; C. Lefebvre; J. Escarre
Metal hyperaccumulation in plants: mechanisms of defence against insect herbivores
Summary 1. To determine the mechanisms by which metal hyperaccumulation in plants could provide a chemical defence against insect herbivores, the feeding behaviour and per- formance of the desert locust, Schistocerca gregaria (ForskÕl), was investigated on plants of Thlaspi caerulescens J. & C. Presl containing different zinc concentrations, as well as on artificial food differing only in Zn content. 2.
A hydroponics experiment using hyperaccumulator Thlaspi caerulescens (alpine pennycress) and non-specific accumulator Raphanus sativus (common radish) was conducted to investigate the short-term effect of increasing Cd concentrations (0, 25, 50, 75, 100 ?M) on metal uptake, chlorophyll content, antioxidative enzymes, and apoplastic bypass flow. As expected, T. caerulescens generally showed better resistance to metal stress, which was reflected by higher
Saoussen Benzarti; Helmi Hamdi; Shino Mohri; Yoshiro Ono
BACKGROUND: The Ni hyperaccumulator Thlaspi goesingense is tolerant to Ni ? Zn, ? Co and slightly resistant to > Cd. We previously observed that elevated glutathione, driven by constitutive activation of serine acetyltransferase (SAT), plays a role in the Ni tolerance of T. goesingense. RESULTS: Here we show that the elevated shoot concentration of glutathione, previously shown to cause elevated
John L Freeman; David E Salt
Evaluation of the remediation ability of zinc/cadmium in hyper- and non-hyperaccumulator plant species through greenhouse studies is limited. To bridge the gap between greenhouse studies and field applications for phytoextraction, we used published data to examine the partitioning of heavy metals between plants and soil (defined as the bioconcentration factor). We compared the remediation ability of the Zn/Cd hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri and the non-hyperaccumulators Nicotiana tabacum and Brassica juncea using a hierarchical linear model (HLM). A recursive algorithm was then used to evaluate how many harvest cycles were required to clean a contaminated site to meet Taiwan Environmental Protection Agency regulations. Despite the high bioconcentration factor of both hyperaccumulators, metal removal was still limited because of the plants' small biomass. Simulation with N. tabacum and the Cadmium model suggests further study and development of plants with high biomass and improved phytoextraction potential for use in environmental cleanup. PMID:19268408
Liang, Hong-Ming; Lin, Ting-Hsiang; Chiou, Jeng-Min; Yeh, Kuo-Chen
To assess the potential of the Cd hyperaccumulator Thlaspi caerulescens (Ganges ecotype) for Cd phytoremediation in Japan, we compared the changes in the soil Cd concentration between a Fluvisol and an Andosol and the efficiency of Cd removal under different planting frequencies in a pot experiment. The soils were artificially contaminated with Cd(NO3)2 to the level of about 5 mg
Yuko Nishiyama; Junta Yanai; Takashi Kosaki
Metal Hyperaccumulation Armors Plants against Disease
Metal hyperaccumulation, in which plants store exceptional concentrations of metals in their shoots, is an unusual trait whose evolutionary and ecological significance has prompted extensive debate. Hyperaccumulator plants are usually found on metalliferous soils, and it has been proposed that hyperaccumulation provides a defense against herbivores and pathogens, an idea termed the æelemental defenseÆ hypothesis. We have investigated this hypothesis using the crucifer Thlaspi caerulescens, a hyperaccumulator of zinc, nickel, and cadmium, and the bacterial pathogen Pseudomonas syringae pv. maculicola (Psm). Using leaf inoculation assays, we have shown that hyperaccumulation of any of the three metals inhibits growth of Psm in planta. Metal concentrations in the bulk leaf and in the apoplast, through which the pathogen invades the leaf, were shown to be sufficient to account for the defensive effect by comparison with in vitro dose¢response curves. Further, mutants of Psm with increased and decreased zinc tolerance created by transposon insertion had either enhanced or reduced ability, respectively, to grow in high-zinc plants, indicating that the metal affects the pathogen directly. Finally, we have shown that bacteria naturally colonizing T. caerulescens leaves at the site of a former lead¢zinc mine have high zinc tolerance compared with bacteria isolated from non-accumulating plants, suggesting local adaptation to high metal. These results demonstrate that the disease resistance observed in metal-exposed T. caerulescens can be attributed to a direct effect of metal hyperaccumulation, which may thus be functionally analogous to the resistance conferred by antimicrobial metabolites in non-accumulating plants. PMID:20838462
Fones, Helen; Davis, Calum A. R.; Rico, Arantza; Fang, Fang; Smith, J. Andrew C.; Preston, Gail M.
Molecular Dissection of the Cellular Mechanisms Involved in Nickel Hyperaccumulation in Plants
Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1-2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determines metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. Our long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, our strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information we propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumulation in Thlaspi goesingense, a Ni hyperaccumulator species. We will clone key genes involved in histidine biosynthesis. We will characterize their transcriptional and post transcriptional regulation by histidine, Ni. We will determine if any of these genes are essential and sufficient for Ni hyperaccumulation by their expression in the non-hyperaccumulator Arabidopsis thaliana.
Salt, David E.
Some plants hyperaccumulate selenium (Se) up to 1% of dry weight. This study was performed to obtain insight into whole-plant Se fluxes in hyperaccumulators. Selenium hyperaccumulators Astragalus bisulcatus and Stanleya pinnata were monitored over two growing seasons for seasonal fluctuations in concentrations of Se and the chemically similar element sulfur (S). The related nonhyperaccumulators Astragalus sericoleucus, Oxytropis sericea and Thlaspi montanum were included for comparison. In both hyperaccumulators leaf Se decreased from April to October, coinciding with Se hyperaccumulation in flowers and seeds. Root Se levels were lowest in summer. Selenium concentration decreased with leaf age in both hyperaccumulators. Leaf S levels peaked in summer in all plant species, as did Se levels in nonhyperaccumulators. Selenium and S levels tended to be negatively correlated in hyperaccumulators, and positively correlated in nonhyperaccumulators. These results suggest a specific flow of Se in hyperaccumulator plants over the growing season, from root to young leaves in spring, followed by remobilization from aging leaves to reproductive tissues in summer, and back to roots in the autumn. PMID:17244046
Galeas, Miriam L; Zhang, Li Hong; Freeman, John L; Wegner, Mellissa; Pilon-Smits, Elizabeth A H
The role of rhizosphere processes in metal hyperaccumulation is largely unexplored and a matter of debate, related field data are virtually not available. We conducted a field survey of rhizosphere characteristics beneath the Ni hyperaccumulator Thlaspi goesingense Hßlßcsy and the metal-excluder species Silene vulgaris L. and Rumex acetosella L. growing natively on the same serpentine site. Relative to bulk soil and to the rhizosphere of the excluder species, we found significantly increased DOC and Ni concentrations in water extracts of T. goesingense rhizosphere, whereas exchangeable Ni was depleted due to excessive uptake of Ni. Chemical speciation analysis using the MINTEQA2 software package revealed that enhanced Ni solubility in Thlaspi rhizosphere is driven by the formation of Ni-organic complexes. Moreover, ligand-induced dissolution of Ni-bearing minerals is likely to contribute to enhanced Ni solubility. Increased Mg and Ca concentrations and pH in Thlaspi rhizosphere are consistent with ligand-induced dissolution of orthosilicates such as forsterite (Mg(2)SiO(4). Our field data reinforce the hypothesis that exudation of organic ligands may contribute to enhanced solubility and replenishment of metals in the rhizosphere of hyperaccumulating species. PMID:12663213
Wenzel, W W; Bunkowski, M; Puschenreiter, M; Horak, O
Background, Aims and ScopeĀĀPhytoremediation is a promising means for the treatment of heavy metal contamination. Although several species have been identified\\u000a as hyperaccumulators, most studies have been conducted with only one metal. Experiments were conducted to investigate the\\u000a ability of Helianthus annuus and Thlaspi caerulescens to simultaneously uptake Cd, Cr and Ni.\\u000a \\u000a \\u000a \\u000a Materials and MethodsĀĀThe efficiency of plants grown in
Jeffrey Munn; Mary January; Teresa J. Cutright
Nickel and zinc isotope fractionation in hyperaccumulating and nonaccumulating plants.
Until now, there has been little data on the isotope fractionation of nickel (Ni) in higher plants and how this can be affected by plant Ni and zinc (Zn) homeostasis. A hydroponic cultivation was conducted to investigate the isotope fractionation of Ni and Zn during plant uptake and translocation processes. The nonaccumulator Thlaspi arvense, the Ni hyperaccumulator Alyssum murale and the Ni and Zn hyperaccumulator Noccaea caerulescens were grown in low (2 ?M) and high (50 ?M) Ni and Zn solutions. Results showed that plants were inclined to absorb light Ni isotopes, presumably due to the functioning of low-affinity transport systems across root cell membrane. The Ni isotope fractionation between plant and solution was greater in the hyperaccumulators grown in low Zn treatments (?(60)Niplant-solution = -0.90 to -0.63ē) than that in the nonaccumulator T. arvense (?(60)Niplant-solution = -0.21ē), thus indicating a greater permeability of the low-affinity transport system in hyperaccumulators. Light isotope enrichment of Zn was observed in most of the plants (?(66)Znplant-solution = -0.23 to -0.10ē), but to a lesser extent than for Ni. The rapid uptake of Zn on the root surfaces caused concentration gradients, which induced ion diffusion in the rhizosphere and could result in light Zn isotope enrichment in the hyperaccumulator N. caerulescens. In high Zn treatment, Zn could compete with Ni during the uptake process, which reduced Ni concentration in plants and decreased the extent of Ni isotope fractionation (?(60)Niplant-solution = -0.11 to -0.07ē), indicating that plants might take up Ni through a low-affinity transport system of Zn. We propose that isotope composition analysis for transition elements could become an empirical tool to study plant physiological processes. PMID:25222693
Deng, Teng-Hao-Bo; Cloquet, Christophe; Tang, Ye-Tao; Sterckeman, Thibault; Echevarria, Guillaume; Estrade, Nicolas; Morel, Jean-Louis; Qiu, Rong-Liang
Comparative transcriptome analysis of the metal hyperaccumulator Noccaea caerulescens
The metal hyperaccumulator Noccaea caerulescens is an established model to study the adaptation of plants to metalliferous soils. Various comparators have been used in these studies. The choice of suitable comparators is important and depends on the hypothesis to be tested and methods to be used. In high-throughput analyses such as microarray, N. caerulescens has been compared to non-tolerant, non-accumulator plants like Arabidopsis thaliana or Thlaspi arvense rather than to the related hypertolerant or hyperaccumulator plants. An underutilized source is N. caerulescens populations with considerable variation in their capacity to accumulate and tolerate metals. Whole transcriptome sequencing (RNA-Seq) is revealing interesting variation in their gene expression profiles. Combining physiological characteristics of N. caerulescens accessions with their RNA-Seq has a great potential to provide detailed insight into the underlying molecular mechanisms, including entirely new gene products. In this review we will critically consider comparative transcriptome analyses carried out to explore metal hyperaccumulation and hypertolerance of N. caerulescens, and demonstrate the potential of RNA-Seq analysis as a tool in evolutionary genomics. PMID:24904610
Halimaa, Pauliina; Blande, Daniel; Aarts, Mark G. M.; Tuomainen, Marjo; Tervahauta, Arja; Karenlampi, Sirpa
Thlaspi caerulescens (J. and C. Presl) and Thlaspi ochroleucum (Boiss. ex Heldr) were grown in three different soils containing moderate to high amounts of heavy metals in a pot experiment, using a rhizobag technique. T. caerulescens accumulated significantly more Zn in the shoots than T. ochroleucum. The concentrations of Zn in the shoots of T. caerulescens ranged from 3100 to
S. P. McGrath; Z. G. Shen; F. J. Zhao
Evolutionary aspects of elemental hyperaccumulation.
Hyperaccumulation is the uptake of one or more metal/metalloids to concentrations greater than 50-100ū those of the surrounding vegetation or 100-10,000Āmg/kg dry weight depending on the element. Hyperaccumulation has been documented in at least 515 taxa of angiosperms. By mapping the occurrence of hyperaccumulators onto the angiosperm phylogeny, we show hyperaccumulation has had multiple origins across the angiosperms. Even within a given order, family or genus, there are typically multiple origins of hyperaccumulation, either for the same or different elements. We address which selective pressures may have led to the evolution of hyperaccumulation and whether there is evidence for co-evolution with ecological partners. Considerable evidence supports the elemental-defense hypothesis, which states that hyperaccumulated elements protect the plants from herbivores and pathogens. There is also evidence that hyperaccumulation can result in drought stress protection, allelopathic effects or physiological benefits. In many instances, ecological partners of hyperaccumulators have evolved resistance to the hyperaccumulated element, indicating co-evolution. Studies on the molecular evolution of hyperaccumulation have pinpointed gene duplication as a common cause of increased metal transporter abundance. Hypertolerance to the hyperaccumulated element often relies upon chelating agents, such as organic acids (e.g., malate, citrate) or peptide/protein chelators that can facilitate transport and sequestration. We conclude the review with a summary and suggested future directions for hyperaccumulator research. PMID:24463931
Cappa, Jennifer J; Pilon-Smits, Elizabeth A H
Impact of Metal Pollution and Thlaspi caerulescens Growth on Soil Microbial Communities?
Soil microorganisms drive critical functions in plant-soil systems. As such, various microbial properties have been proposed as indicators of soil functioning, making them potentially useful in evaluating the recovery of polluted soils via phytoremediation strategies. To evaluate microbial responses to metal phytoextraction using hyperaccumulators, a microcosm experiment was carried out to study the impacts of Zn and/or Cd pollution and Thlaspi caerulescens growth on key soil microbial properties: basal respiration; substrate-induced respiration (SIR); bacterial community structure as assessed by PCR-denaturing gradient gel electrophoresis (DGGE); community sizes of total bacteria, ammonia-oxidizing bacteria, and chitin-degrading bacteria as assessed by quantitative PCR (Q-PCR); and functional gene distributions as determined by functional gene arrays (GeoChip). T. caerulescens proved to be suitable for Zn and Cd phytoextraction: shoots accumulated up to 8,211 and 1,763 mg kg?1 (dry weight [DW]) of Zn and Cd, respectively. In general, Zn pollution led to decreased levels of basal respiration and ammonia-oxidizing bacteria, while T. caerulescens growth increased the values of substrate-induced respiration (SIR) and total bacteria. In soils polluted with 1,000 mg Zn kg?1 and 250 mg Cd kg?1 (DW), soil bacterial community profiles and the distribution of microbial functional genes were most affected by the presence of metals. Metal-polluted and planted soils had the highest percentage of unique genes detected via the GeoChip (35%). It was possible to track microbial responses to planting with T. caerulescens and to gain insight into the effects of metal pollution on soilborne microbial communities. PMID:20935131
Epelde, Lur; Becerril, Jose M.; Kowalchuk, George A.; Deng, Ye; Zhou, Jizhong; Garbisu, Carlos
BIOFUMIGANT COMPOUNDS RELEASED BY FIELD PENNYCRESS ( Thlaspi arvense ) SEEDMEAL
Defatted field pennycress (Thlaspi arvense L.) seedmeal was found to completely inhibit seedling germination\\/emergence when added to a sandy loam soil containing wheat (Triticum aestivum L.) and arugula [Eruca vesicaria (L.) Cav. subsp. sativa (Mill.) Thell.] seeds at levels of 1.0% w\\/w or higher. Covering the pots with Petri dishes containing the soil-seedmeal mixture decreased germination of both species at
Using hyperaccumulator plants to phytoextract soil Ni and Cd.
Two strategies of phytoextraction have been shown to have promise for practical soil remediation: domestication of natural hyperaccumulators and bioengineering plants with the genes that allow natural hyperaccumulators to achieve useful phytoextraction. Because different elements have different value, some can be phytomined for profit and others can be phytoremediated at lower cost than soil removal and replacement. Ni phytoextraction from contaminated or mineralized soils offers economic return greater than producing most crops, especially when considering the low fertility or phytotoxicity of Ni rich soils. Only soils that require remediation based on risk assessment will comprise the market for phytoremediation. Improved risk assessment has indicated that most Zn + Cd contaminated soils will not require Cd phytoextraction because the Zn limits practical risk from soil Cd. But rice and tobacco, and foods grown on soils with Cd contamination without corresponding 100-fold greater Zn contamination, allow Cd to readily enter food plants and diets. Clear evidence of human renal tubular dysfunction from soil Cd has only been obtained for subsistence rice farm families in Asia. Because of historic metal mining and smelting, Zn + Cd contaminated rice soils have been found in Japan, China, Korea, Vietnam and Thailand. Phytoextraction using southern France populations of Thlaspi caerulescens appears to be the only practical method to alleviate Cd risk without soil removal and replacement. The southern France plants accumulate 10-20-fold higher Cd in shoots than most T. caerulescens populations such as those from Belgium and the UK. Addition of fertilizers to maximize yield does not reduce Cd concentration in shoots; and soil management promotes annual Cd removal. The value of Cd in the plants is low, so the remediation service must pay the costs of Cd phytoextraction plus profits to the parties who conduct phytoextraction. Some other plants have been studied for Cd phytoextraction, but annual removals are much lower than the best T. caerulescens. Improved cultivars with higher yields and retaining this remarkable Cd phytoextraction potential are being bred using normal plant breeding techniques. PMID:15948583
Chaney, Rufus L; Angle, J Scott; McIntosh, Marla S; Reeves, Roger D; Li, Yin-Ming; Brewer, Eric P; Chen, Kuang-Yu; Roseberg, Richard J; Perner, Henrike; Synkowski, Eva Claire; Broadhurst, C Leigh; Wang, S; Baker, Alan J M
Stress tolerance is currently one of the major research topics in plant biology because of the challenges posed by changing\\u000a climate and increasing demand to grow crop plants in marginal soils. Increased Zn tolerance and accumulation has been reported\\u000a in tobacco expressing the glyoxalase 1-encoding gene from Brassica juncea. Previous studies in our laboratory showed some Zn tolerance-correlated differences in
Marjo Tuomainen; Viivi Ahonen; Sirpa O. Kõrenlampi; Henk Schat; Tanja Paasela; Algirdas Ŗvanys; Saara Tuohimetsõ; Sirpa Perõniemi; Arja Tervahauta
Thermoinductive regulation of gibberellin metabolism in Thlaspi arvense L
Field pennycress (Thlaspi arvense L.) is a winter annual crucifer with a cold requirement for stem elongation and flowering. In the present study, the metabolism of exogenous ({sup 2}H)-ent-kaurenoic acid (KA) and ({sup 14}C)-gibberellin A{sub 12}-aldehyde (GA{sub 12}-aldehyde) was compared in thermo- and noninduced plants. Thermoinduction greatly altered both quantitative and qualitative aspects of ({sup 2}H)-KA metabolism in the shoot tips. The rate of disappearance of the parent compound was much greater in thermoinduced shoot tips. These results are consistent with the suggestion that the conversion of KA in to GAs is under thermoinductive control only in the shoot tip, the site of perception for thermoinductive temperatures in field pennycress. There were essentially no differences in the qualitative or quantitative distribution of metabolites formed following the application of ({sup 14}C)GA{sub 12}-aldehyde to the shoot tips of thermo- or noninduced plants. Thus, the apparent thermoinductive regulation of the KA metabolism into GAs is probably limited to the two metabolic steps involved in converting KA to GA{sub 12}-aldehyde.
Hazebroek, J.P.; Metzger, J.D. (Department of Agriculture, Fargo, ND (USA))
Compartmentation and complexation of metals in hyperaccumulator plants
Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their ōstrangeö behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs. PMID:24065978
Leitenmaier, Barbara; Kupper, Hendrik
REGULAR ARTICLE Enhanced decomposition of selenium hyperaccumulator litter
REGULAR ARTICLE Enhanced decomposition of selenium hyperaccumulator litter in a seleniferous-Smits # Springer Science+Business Media B.V. 2010 Abstract Selenium (Se) hyperaccumulation, when plant species
Biofumigant compounds released by field pennycress (Thlaspi arvense) seedmeal.
Defatted field pennycress (Thlaspi arvense L.) seedmeal was found to completely inhibit seedling germination/emergence when added to a sandy loam soil containing wheat (Triticum aestivum L.) and arugula [Eruca vesicaria (L.) Cav. subsp. sativa (Mill.) Thell.] seeds at levels of 1.0% w/w or higher. Covering the pots with Petri dishes containing the soil-seedmeal mixture decreased germination of both species at the lowest application rate (0.5% w/w), suggesting that the some of the phytotoxins were volatile. CH2Cl2, MeOH, and water extracts of the wetted seedmeal were bioassayed against wheat and sicklepod (Senna obtusifolia (L.) H. S. Irwin & Barneby) radicle elongation. Only the CH2Cl2 extract was strongly inhibitory to both species. Fractionation of the CH2Cl2 extract yielded two major phytotoxins, identified by gas chromatography-mass spectrometry and NMR as 2-propen-1-yl (allyl) isothiocyanate (AITC) and allyl thiocyanate (ATC), which constituted 80.9 and 18.8%, respectively, of the active fraction. When seeds of wheat, arugula and sicklepod were exposed to volatilized AITC and ATC, germination of all three species was completely inhibited by both compounds at concentrations of 5 ppm or less. In field studies, where seedmeal was applied at 0.50, 1.25, and 2.50 kg/m2 and tarped with black plastic mulch, all of the treatments significantly reduced dry weight of bioassay plants compared to the tarped control, with the highest seedmeal rate decreasing dry matter to less than 10% of the control 30 d after seedmeal application. Field pennycress seedmeal appears to offer excellent potential as a biofumigant for high-value horticultural crops for both conventional and organic growers. PMID:15839488
Vaughn, Steven F; Isbell, Terry A; Weisleder, David; Berhow, Mark A
Selenium hyperaccumulation offers protection from cell disruptor herbivores
BACKGROUND: Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se) hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating
Colin F Quinn; John L Freeman; Ray JB Reynolds; Jennifer J Cappa; Sirine C Fakra; Matthew A Marcus; Stormy D Lindblom; Erin K Quinn; Lindsay E Bennett; Elizabeth AH Pilon-Smits
Selenium hyperaccumulation reduces plant arthropod loads in the field
Summary Ģ The elemental defense hypothesis proposes that some plants hyperaccumulate toxic elements as a defense mechanism. In this study the effectiveness of selenium (Se) as an arthropod deterrent was investigated under field conditions. ü Arthropod loads were measured over two growing seasons in Se hyperaccumulator habitats in Colorado, USA, comparing Se hyperaccumulator species (Astragalus bisulca- tus and Stanleya pinnata)
Miriam L. Galeas; Erin M. Klamper; Lindsay E. Bennett; John L. Freeman; Boris C. Kondratieff; Colin F. Quinn; Elizabeth A. H. Pilon-Smits
Summary. Tissues of most plant species contain ?1 but Ni hyperaccumulators contain more than 1000Ā?g NiĀg?1 . Hyperaccumulated Ni can defend plants from some herbivores but the defensive role of lesser Ni concentrations is little explored. We raised five species of Streptanthus (Brassicaceae) native to ultramafic soils, one of which (S. polygaloides) is a Ni hyperaccumulator whereas the others are
Robert S. Boyd; Edward M. Jhee
Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non Arsenic reduced the activity of nitrate and nitrite reductase more in Pteris ensiformis than Pteris March 2009 Accepted 26 March 2009 Keywords: Arsenic Nitrate metabolism Pteris vittata Arsenic
Ma, Lena
The weedy crucifer species Thlaspi arvense has the ability to acclimate to lower temperatures than Arabidopsis thaliana and the related crop species, Brassica napus. As a step towards understanding the genetic basis for this enhanced low temperature response, we isolated and sequenced\\u000a 8.7Ākb of genomic DNA encompassing the T.Āarvense CBF locus. CBF is a transcription factor believed to play a
Ning Zhou; Stephen J. Robinson; Terry Huebert; Nicholas J. Bate; Isobel A. P. Parkin
The ecological significance of nickel hyperaccumulation: a plant chemical defense
Nickel hyperaccumulating plants have more than 1000 mg Ni kg-1 dry weight when grown on nickel-bearing soils. We hypothesized that Ni hyperaccumulation could serve as a chemical defense against herbivores In feeding experiments with potential insect herbivores and Ni hyperaccumulating plants, only those inseets fed leaves from plants grown on non-nickel-bearing soil survived or showed a weight gain. Among chemical
Scott N. Martens; Robert S. Boyd
XAS Speciation of Arsenic in a Hyper-Accumulating Fern
XAS Speciation of Arsenic in a Hyper-Accumulating Fern S A M U E L M . W E B B , J E A N - F R A N environment and the redox speciation of arsenic in a newly discovered arsenic hyper-accumulating fern (Pteris high As concentrations (ca. 1% As per dry weight) arsenic in the fern leaves is coordinated
Ma, Lena
The flavonoid profiles of 22 accessions of Camelina sativa and five other crucifer species, Crambe abyssinica, Crambe hispanica, Thlaspi arvense, Brassica napus, and Sinapis alba, were studied by a combination of liquid, paper and thin layer chromatography. Flavonoids were confirmed by comparison of their characteristics, including colour under UV light, changes to colour under UV with fuming in NH3 vapour,
Joseph Onyilagha; Adil Bala; Rebecca Hallett; Margaret Gruber; Juliana Soroka; Neil Westcott
Selenium hyperaccumulation reduces plant arthropod loads in the field.
The elemental defense hypothesis proposes that some plants hyperaccumulate toxic elements as a defense mechanism. In this study the effectiveness of selenium (Se) as an arthropod deterrent was investigated under field conditions. Arthropod loads were measured over two growing seasons in Se hyperaccumulator habitats in Colorado, USA, comparing Se hyperaccumulator species (Astragalus bisulcatus and Stanleya pinnata) with nonhyperaccumulators (Camelina microcarpa, Astragalus americanus, Descurainia pinnata, Medicago sativa, and Helianthus pumilus). The Se hyperaccumulating plant species, which contained 1000-14 000 microg Se g(-1) DW, harbored significantly fewer arthropods (c. twofold) and fewer arthropod species (c. 1.5-fold) compared with nonhyperaccumulator species that contained < 30 microg Se g(-1) DW. Arthropods collected on Se-hyperaccumulating plants contained three- to 10-fold higher Se concentrations than those found on nonhyperaccumulating species, but > 10-fold lower Se concentrations than their hyperaccumulator hosts. Several arthropod species contained > 100 microg Se g(-1) DW, indicating Se tolerance and perhaps feeding specialization. These results support the elemental defense hypothesis and suggest that invertebrate herbivory may have contributed to the evolution of Se hyperaccumulation. PMID:18028291
Galeas, Miriam L; Klamper, Erin M; Bennett, Lindsay E; Freeman, John L; Kondratieff, Boris C; Quinn, Colin F; Pilon-Smits, Elizabeth A H
[Cu-hyperaccumulators in mining area].
Plant species distributing in three Cu-mining area were investigated, and Cu concentrations in soils and plants were analyzed. The results showed that Cu ore deposit mostly was distributed at the altitude of about 630 m. Elsholtzia splendens and Rumex acetosa were distributed only on the Cu ore deposit or the place with high Cu concentration, and the maximum Cu concentrations in these two plants were 1060 mg.kg-1 DW and 1006 mg.kg-1 DW, which reached the critical of hyperaccumulator. Cu accumulations in Elsholtzia splendens and Rumex acetosa were positively and closely correlated with Cu concentration in soil. PMID:12385229
Jiang, Liying; Shi, Weiyong; Yang, Xiaoe; Fu, Chengxin; Chen, Weiguang
REGULAR ARTICLE Enhanced decomposition of selenium hyperaccumulator litter
REGULAR ARTICLE Enhanced decomposition of selenium hyperaccumulator litter in a seleniferous-Smits Received: 2 April 2010 /Accepted: 19 May 2010 # Springer Science+Business Media B.V. 2010 Abstract Selenium
A pot culture experiment was used to determine the differences in uptake characteristics of a cadmium hyperaccumulator Solanum nigrum L. discovered in China, an ecotype from Melbourne, Australia and a non-hyperaccumulator Solanum melogena Australian ecotype was not significantly different to the China ecotype. In particular, Cd concentration in leaves and shoots of S. nigrum collected from Australia were 166.0 and 146.3 mg kg(-1) respectively when 20 mg kg(-1) Cd spiked, and were not significantly different to the ecotype imported from China which had 109.8 and 85.3 mg kg(-1) respectively, in the stems and leaves. In contrast, the tolerance of the eggplant to Cd was significantly less than the two S. nigrum ecotypes. Although some morphological properties of S. nigrum collected from Australia were different from that of the plants collected from China, Cd hyperaccumulator characteristics of two ecotypes were similar. The results suggested that the tolerance and uptake of Cd may be a constitutive trait of this species. PMID:23488006
Wei, Shuhe; Clark, Gary; Doronila, Augustine Ignatius; Jin, Jian; Monsant, Alison Carol
Arsenic species and leachability in the fronds of the hyperaccumulator Chinese brake (Pteris June 2002; accepted 9 December 2002 ``Capsule'': Arsenic was predominantly present as inorganic arsenite in the fronds of the hyperaccumulator Chinese brake. Abstract Arsenic speciation is important
Ma, Lena
Arsenic speciation, and arsenic and phosphate distribution in arsenic hyperaccumulator Pteris examined the roles of arsenic translocation and reduction, and P distribution in arsenic detoxification of Pteris vittata L. (Chinese Brake fern), an arsenic hyperaccumulator and Pteris ensiformis L. (Slender
Ma, Lena
A novel member of the WRKY gene family, designated TcWRKY53, was isolated from a cadmium (Cd)-treated Thlaspi caerulescens cDNA library by differential screening. WRKY proteins specifically bind to W-boxes, which are found in the promoters of many\\u000a genes involved in defense and response to environmental stress. TcWRKY53 contains a 975-bp open reading frame encoding a putative protein of 324 amino
Wei Wei; Yuxiu Zhang; Lu Han; Ziqiu Guan; Tuanyao Chai
Selenium Distribution and Speciation in the Hyperaccumulator Astragalus bisulcatus and Associated
Selenium Distribution and Speciation in the Hyperaccumulator Astragalus bisulcatus and Associated 82007 (A.L.W.) The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may influence species composition and Se cycling in seleniferous ecosystems. Selenium (Se) hyperaccumulation
Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes.
John L. Freeman; Li Hong Zhang; Matthew A. Marcus; Sirine Fakra; Steve P. McGrath
Ģ Few studies have investigated plant-plant interactions involving hyperaccumulator plants. Here, we investigated the effect of selenium (Se) hyperaccumulation on neighboring plants. Ģ Soil and litter Se concentrations were determined around the hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and around the nonhyperaccumulators Medicago sativa and Helianthus pumilus. We also compared surrounding vegetative cover, species composition and Se concentration in two plant species (Artemisia ludoviciana and Symphyotrichum ericoides) growing either close to or far from Se hyperaccumulators. Then, Arabidopsis thaliana germination and growth were compared on soils collected next to the hyperaccumulators and the nonhyperaccumulators. Ģ Soil collected around hyperaccumulators contained more Se (up to 266 mg Se kg(-1) ) than soil collected around nonhyperaccumulators. Vegetative ground cover was 10% lower around Se hyperaccumulators compared with nonhyperaccumulators. The Se concentration was higher in neighboring species A. ludoviciana and S. ericoides when growing close to, compared with far from, Se hyperaccumulators. A. thaliana showed reduced germination and growth, and higher Se accumulation, when grown on soil collected around Se hyperaccumulators compared with soil collected around nonaccumulators. Ģ In conclusion, Se hyperaccumulators may increase the surrounding soil Se concentration (phytoenrichment). The enhanced soil Se contents around hyperaccumulators can impair the growth of Se-sensitive plant species, pointing to a possible role of Se hyperaccumulation in elemental allelopathy. PMID:21371042
El Mehdawi, Ali F; Quinn, Colin F; Pilon-Smits, Elizabeth A H
The screening of hyperaccumulators is still very much needed for phytoremediation. With properties such as strong tolerance to adverse environment, fast growing and highly reproductive rate, weed species may be an ideal plant for phytoremediation. The objectives of this study were to examine the tolerance and hyperaccumulative characteristics of 24 species in 9 families to Cd, Pb, Cu and Zn by using the outdoor pot-culture experiment. In the screening experiment, only Conyza canadensis and Rorippa globosa displayed Cd-hyperaccumulative characteristics. In a further concentration gradient experiment, C. canadensis was affirmed that it is not a Cd hyperaccumulator. Only R. globosa, indicated all Cd hyperaccumulative characteristics, especially Cd concentration in its stems and leaves were higher than 100 mg/kg, the minimum Cd concentration what a Cd-hyperaccumulator should accumulate. Thus, R. globosa was further validated as a Cd-hyperaccumulator. PMID:18483772
Wei, Shuhe; Zhou, Qixing; Xiao, Hong; Yang, Chuanjie; Hu, Yahu; Ren, Liping
Identification of Endogenous Gibberellins in the Winter Annual Weed Thlaspi arvense L
Eleven endogenous gibberellins (GAs) were identified by combined gas chromatography-mass spectrometry in purified extracts from shoots of field pennycress (Thlaspi arvense L.): GA1,9,12,15,19,20,24,29,44,51,53. Traces of GA8 and GA25 were tentatively indicated by combined gas chromatography-mass spectrometry-selected ion monitoring. Comparison of the total ion current traces indicated that GA19 and GA44 were most abundant, while GA12,15,20,24,29,53 occurred in lesser amounts. Only small amounts of GA1,9,51 were present. The levels of GA8 and GA25 were barely detectable. Consideration of hydroxylation patterns of the ent-gibberellane ring structure indicates two families of GAs: one with a C-13 hydroxyl group (GA1,8,19,20,29,44,53) and another whose members are either nonhydroxylated (GA9,12,15,24,25) or lack a C-13 hydroxyl group (GA51). This suggests that in field pennycress there are two parallel pathways for GA metabolism with an early branch point from GA12: an early C-13 hydroxylation pathway, leading ultimately to GA1 and GA8 and a C-13 deoxy pathway culminating in the formation of GA9 and GA51. PMID:16664632
Metzger, James D.; Mardaus, Marcia C.
REGULAR ARTICLE Hyperaccumulation of nickel by Alyssum corsicum
and plant transpiration rate. The most soluble compounds had the highest Ni uptake, with the exception of Ni plant uptake and transpiration rate. In ser- pentine soils and insoluble NiO plant transpiration rate and the plant transpiration rate. Keywords Ni minerals . Alyssum . Hyperaccumulators . Ni solubility
Sparks, Donald L.
REVIEW ARTICLE Ecological aspects of plant selenium hyperaccumulation
REVIEW ARTICLE Ecological aspects of plant selenium hyperaccumulation A. F. El Mehdawi & E. A. H.1%), manganese (Mn, >1%), nickel (Ni, >0.1%), selenium (Se, >0.1%) and zinc (Zn, >1%). The element levels accumu system. Selenium naturally occurs as a trace element in most soils. Soil Se levels are typically below 1
Manganese tolerance and accumulation in six Mn hyperaccumulators or accumulators
This study used hydroponics cultivation to investigate the manganese (Mn) accumulation and tolerance abilities of six speciesŚPhytolacca americana L., Poa annua L., Comnyza canadensis L., Cynodon dactylon L., Polygonum hydropiper L., and Polygonum perfoliatum L. We found that P. perfoliatum, P. hydropiper, and P. americana were Mn-hyperaccumulators and that P. perforliatum have superior Mn accumulation and toleration abilities over the
Peng Liu; Xiumei Tang; Chunfeng Gong; GenDi Xu
RESEARCH ARTICLE Open Access Selenium hyperaccumulation offers protection
of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting (Tetranychus urticae). Results: Astragalus bisulcatus and S. pinnata with high Se concentrations (greater than. bisulcatus and S. pinnata plants rather than high-Se plants. Spider mite populations on A. bisulcatus
Selenium-Tolerant Diamondback Moth Disarms Hyperaccumulator Plant Defense
Summary Background: Some plants hyperaccumulate the toxic element selenium (Se) to extreme levels, up to 1% of dry weight. The function of this intriguing phenomenon is obscure. Results: Here, we show that the Se in the hyperaccumu- lator prince's plume (Stanleya pinnata) protects it from caterpillar herbivory because of deterrence and toxicity. In its natural habitat, however, a newly discovered
John L. Freeman; Colin F. Quinn; Matthew A. Marcus; Sirine Fakra; Elizabeth A. H. Pilon-Smits
Zinc Hyperaccumulation and Uptake by Potentilla Griffithii Hook
The ability of Potentilla griffithii Hook var. velutina Cardot to hypaeraccumulate zinc (Zn) was identified through field survey and hydroponic experiments. Our results showed that P. griffithii could be classified as a new Zn hyperaccumulator. Zn concentrations in the shoots of P. griffithii averaged 6250 mg kg (3870¢8530 mg kg) growing in Zn-rich soils. The highest Zn concentration was observed
Rongliang Qiu; Xiaohang Fang; Yetao Tang; Suojun Du; Xiaowen Zeng; Eric Brewer
Selenium hyperaccumulation offers protection from cell disruptor herbivores
Background Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se) hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf periphery, making them potentially more susceptible to some herbivore feeding modes than others. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting herbivores, the western flower thrips (Frankliniella occidentalis) and the two-spotted spider mite (Tetranychus urticae). Results Astragalus bisulcatus and S. pinnata with high Se concentrations (greater than 650 mg Se kg-1) were less subject to thrips herbivory than plants with low Se levels (less than 150 mg Se kg-1). Furthermore, in plants containing elevated Se levels, leaves with higher concentrations of Se suffered less herbivory than leaves with less Se. Spider mites also preferred to feed on low-Se A. bisulcatus and S. pinnata plants rather than high-Se plants. Spider mite populations on A. bisulcatus decreased after plants were given a higher concentration of Se. Interestingly, spider mites could colonize A. bisulcatus plants containing up to 200 mg Se kg-1 dry weight, concentrations which are toxic to many other herbivores. Selenium distribution and speciation studies using micro-focused X-ray fluorescence (?XRF) mapping and Se K-edge X-ray absorption spectroscopy revealed that the spider mites accumulated primarily methylselenocysteine, the relatively non-toxic form of Se that is also the predominant form of Se in hyperaccumulators. Conclusions This is the first reported study investigating the protective effect of hyperaccumulated Se against cell-disrupting herbivores. The finding that Se protected the two hyperaccumulator species from both cell disruptors lends further support to the elemental defense hypothesis and increases the number of herbivores and feeding modes against which Se has shown a protective effect. Because western flower thrips and two-spotted spider mites are widespread and economically important herbivores, the results from this study also have potential applications in agriculture or horticulture, and implications for the management of Se-rich crops. PMID:20799959
Role of Gibberellins in the Environmental Control of Stem Growth in Thlaspi arvense L
Field pennycress (Thlaspi arvense L.) is a winter annual that requires a cold treatment for the induction of stem elongation. An inbred line was selected in which no stem elongation was observed in plants grown for 6 months at 21░C regardless of the prevailing photoperiod. Increased exposure time of plants grown initially at 21░C to cold (2░C) induced a greater rate of stem elongation when the plants were returned to 21░C. Moreover, longer cold treatments resulted in a greater maximum stem height and reduced the lag period for the onset of measurable internode elongation. The optimal temperature range for thermoinduced stem growth was broad: rates of stem growth in plants maintained for 4 weeks at either 2░ or 10░C were virtually identical. However, a 4-week thermoinductive treatment at 15░C resulted in a greater lag period for the initiation of stem elongation and a decreased growth rate. The rate of cold-induced stem elongation was greater in plants subjected to long days than for plants subjected to short days following the cold treatment. Thus, photoperiod does not control the induction of stem elongation, but does regulate stem elongation in progress. Exogenous gibberellin A3 (GA3) was able to substitute for the cold requirement, but elicited a greater response in plants maintained under long days than short days. This indicates that photoperiod influences the plant's sensitivity to GAs. The GA biosynthesis inhibitor, 2-chloroethyltrimethyl ammonium chloride, inhibited low temperature-induced stem elongation, and this inhibition was completely reversed by exogenous GA3. These results suggest that cold-induced stem elongation in field pennycress is mediated by some change in the endogenous GA status. PMID:16664213
Metzger, James D.
Summary. Nickel hyperaccumulation, resulting in plant Ni contents of >1000 mg kgу dry mass, has been shown to defend plants against folivorous herbivores. We determined whether this elemental defence tactic protected hyperaccumulating plants from attack by a phloem-feeding herbivore. We used the pea aphid, Acyrthosiphon pisum, and the Ni-hyperaccumulating plant Streptanthus polygaloides. Aphids were allowed to colonize mixed arrays of
Robert S. Boyd; Scott N. Martens
Concentrations of metals including manganese, nickel, copper and zinc were measured in soil from a copper mine spoil heap in the Grand Canyon, Arizona, and in three plant species growing on the spoil. The soil had high concentrations of available copper and zinc, and the herbaceous perennial Thlaspi montanum var fendleri contained amounts of Ni, Cu and Zn in direct
R. J. Hobbs; B. Streit
bisulcatus, hyper- accumulation, plant┬Łplant interactions, selenium (Se), Stanleya pinnata. Summary ┬Ę Few concentrations were determined around the hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and around
Selenium-tolerant diamondback moth disarms hyperaccumulator plantdefense
Background Some plants hyperaccumulate the toxic element selenium (Se) to extreme levels, up to 1% of dry weight. The function of this intriguing phenomenon is obscure. Results Here, we show that the Se in the hyperaccumulator prince's plume (Stanleya pinnata) protects it from caterpillar herbivory because of deterrence and toxicity. In its natural habitat, however, a newly discovered variety of the invasive diamondback moth (Plutella xylostella) has disarmed this elemental defense. It thrives on plants containing highly toxic Se levels and shows no oviposition or feeding deterrence, in contrast to related varieties. Interestingly, a Se-tolerant wasp (Diadegma insulare) was found to parasitize the tolerant moth. The insect's Se tolerance mechanism was revealed by X-ray absorption spectroscopy and liquid chromatography--mass spectroscopy, which showed that the Se-tolerant moth and its parasite both accumulate methylselenocysteine, the same form found in the hyperaccumulator plant, whereas related sensitive moths accumulate selenocysteine. The latter is toxic because of its nonspecific incorporation into proteins. Indeed, the Se-tolerant diamondback moth incorporated less Se into protein. Additionally, the tolerant variety sequestered Se in distinct abdominal areas, potentially involved in detoxification and larval defense to predators. Conclusions Although Se hyperaccumulation protects plants from herbivory by some invertebrates, it can give rise to the evolution of unique Se-tolerant herbivores and thus provide a portal for Se into the local ecosystem. In a broader context, this study provides insight into the possible ecological implications of using Se-enriched crops as a source of anti-carcinogenic selenocompounds and for the remediation of Se-polluted environments.
Freeman, J.L.; Quinn, C.F.; Marcus, M.A.; Fakra, S.; Pilon-Smits,E.A.H.
Summary. The elevated Ni concentration of Ni hyper- accumulator plants has been proposed to be an effec- tive chemical defence against herbivores. To test this hypothesis, we fed leaves from hyperaccumulator and non-hyperaccumulator populations of South African Senecio coronatus to a generalist herbivore species, the brown garden snail (Helix aspersa). Snails fed hyperac- cumulator leaves experienced significantly greater mor- tality
Robert S. Boyd; Micheal A. Davis; Michael A. Wall; Kevin Balkwill
American Journal of Botany 89(6): 9981003. 2002. THE DEFENSIVE ROLE OF NI HYPERACCUMULATION BY
998 American Journal of Botany 89(6): 998┬Ł1003. 2002. THE DEFENSIVE ROLE OF NI HYPERACCUMULATION that such dietary dilution is one mechanism whereby some herbivores can circumvent elemental plant defenses. Key words: Brassicaceae; elemental defense; heavy metals; herbivory; Ni hyperaccumulation; plant defense
Boyd, Robert S.
Hyperaccumulators and Herbivores--A Bayesian Meta-Analysis of Feeding Choice Trials
hypothesis for the evolution of the metal hyperaccumulation trait in plants is as a defense against for the evolution of hyperaccumulator plants and concluded that the herbivory/pathogen-defense hypoth- esis herbivores. A central piece of evidence expected for this hypothesis is that plants benefit from herbivores
Vesk, Peter
Effects of selenium on arsenic uptake in arsenic hyperaccumulator Pteris vittata L. Mrittunjai: Hyperaccumulator Selenium Glutathione Non protein thiol TBARs a b s t r a c t Selenium (Se) is a non by Elsevier Ltd. 1. Introduction Selenium (Se) is an essential nutrient for humans and animals (Schwartz
Ma, Lena
An Arsenate-activated Glutaredoxin from the Arsenic Hyperaccumulator Fern Pteris vittata L To elucidate the mechanisms of arsenic resistance in the arsenic hyperaccumulator fern Pteris vittata L., a c) reported that Chinese brake fern Pteris vittata was resistant to arsenic and was capable
Ma, Lena
ARSENIC UPTAKE BY TWO HYPERACCUMULATOR FERNS FROM FOUR ARSENIC CONTAMINATED SOILS A. O. FAYIGA and compare arsenic accumulation from four arsenic contaminated soils by two arsenic hyperaccumulators, Pteris for the plants, and total As, Mehlich-3 P and As, exchangeable K and Ca, and arsenic fractionation were performed
Ma, Lena
. ┬Ę Hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and nonaccumulators Astragalus drummondii and Stanleya: Astragalus, hyperaccumulation, phytoenrichment, plant┬Łplant interactions, selenium, Stanleya. Summary accumulated relatively more C-Se-C and less selenate when growing adjacent to S. pinnata. Both
Uptake and Cellular Compartmentalization of Metals from the Rhizosphere by Hyperaccumulating Plants in hyperaccumulating plants. Previous attempts to establish the path of metal ingress into plant tissues have suffered-vivo response of plants to heavy metals in the rhizosphere. We first focused on characterizing the species
Sparks, Donald L.
Molecular mechanisms of selenium tolerance and hyperaccumulation in Stanleya pinnata.
The molecular mechanisms responsible for selenium (Se) tolerance and hyperaccumulation were studied in the Se hyperaccumulator Stanleya pinnata (Brassicaceae) by comparing it with the related secondary Se accumulator Stanleya albescens using a combination of physiological, structural, genomic, and biochemical approaches. S. pinnata accumulated 3.6-fold more Se and was tolerant to 20 microm selenate, while S. albescens suffered reduced growth, chlorosis and necrosis, impaired photosynthesis, and high levels of reactive oxygen species. Levels of ascorbic acid, glutathione, total sulfur, and nonprotein thiols were higher in S. pinnata, suggesting that Se tolerance may in part be due to increased antioxidants and up-regulated sulfur assimilation. S. pinnata had higher selenocysteine methyltransferase protein levels and, judged from liquid chromatography-mass spectrometry, mainly accumulated the free amino acid methylselenocysteine, while S. albescens accumulated mainly the free amino acid selenocystathionine. S. albescens leaf x-ray absorption near-edge structure scans mainly detected a carbon-Se-carbon compound (presumably selenocystathionine) in addition to some selenocysteine and selenate. Thus, S. albescens may accumulate more toxic forms of Se in its leaves than S. pinnata. The species also showed different leaf Se sequestration patterns: while S. albescens showed a diffuse pattern, S. pinnata sequestered Se in localized epidermal cell clusters along leaf margins and tips, concentrated inside of epidermal cells. Transcript analyses of S. pinnata showed a constitutively higher expression of genes involved in sulfur assimilation, antioxidant activities, defense, and response to (methyl)jasmonic acid, salicylic acid, or ethylene. The levels of some of these hormones were constitutively elevated in S. pinnata compared with S. albescens, and leaf Se accumulation was slightly enhanced in both species when these hormones were supplied. Thus, defense-related phytohormones may play an important signaling role in the Se hyperaccumulation of S. pinnata, perhaps by constitutively up-regulating sulfur/Se assimilation followed by methylation of selenocysteine and the targeted sequestration of methylselenocysteine. PMID:20498337
Freeman, John L; Tamaoki, Masanori; Stushnoff, Cecil; Quinn, Colin F; Cappa, Jennifer J; Devonshire, Jean; Fakra, Sirine C; Marcus, Matthew A; McGrath, Steve P; Van Hoewyk, Doug; Pilon-Smits, Elizabeth A H
NSF/EPA Team Up on Grants to Treat Pollution with Plants
... NSF's Integrative Plant Biology and Environmental Engineering/Environmental Technology Programs. EPA ... Basis for Heavy Metal Accumulation and Tolerance in the Hyperaccumulating Plant Species, Thlaspi ...
Genetic and Molecular Dissection of Arsenic Hyperaccumulation in the fern Pteris vittata.
Pteris vittata is a fern that is extraordinary in its ability to tolerate hyperaccumulate high levels of arsenic (As). The goals of the proposed research, to identify the genes that are necessary for As hyperaccumulation in P. vittata using molecular and genetic approaches and to understand the physiology of arsenic uptake and distribution in the living plant, were accomplished during the funding period. The genes that have been identified may ultimately enable the engineering or selection of other plants capable of As hyperaccumulation. This is important for the phytoremediation of arsenic-contaminated soils in areas where P. vittata cannot grow.
Jo Ann Banks; David Salt
Prosopis pubescens (screw bean mesquite) seedlings are hyperaccumulators of copper.
Due to health reasons, toxic metals must be removed from soils contaminated by mine tailings and smelter activities. The phytoremediation potential of Prosopis pubescens (screw bean mesquite) was examined by use of inductively-coupled plasma optical emission spectroscopy. Transmission electron microscopy was used to observe ultrastructural changes of parenchymal cells of leaves in the presence of copper. Elemental analysis was used to localize copper within leaves. A 600-ppm copper sulfate exposure to seedlings for 24 days resulted in 31,000 ppm copper in roots, 17,000 ppm in stems, 11,000 in cotyledons and 20 ppm in the true leaves. For a plant to be considered a hyperaccumulator, the plant must accumulate a leaf-to-root ratio <1. Screw bean mesquite exposed to copper had a leaf-to-root ratio of 0.355 when cotyledons were included. We showed that P. pubescens grown in soil is a hyperaccumulator of copper. We recommend that this plant should be field tested. PMID:23612918
Zappala, Marian N; Ellzey, Joanne T; Bader, Julia; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge
Tissue Fractions of Cadmium in Two Hyperaccumulating Jerusalem Artichoke Genotypes
In order to investigate the mechanisms in two Jerusalem artichoke (Helianthus tuberosus L.) genotypes that hyperaccumulate Cd, a sand-culture experiment was carried out to characterize fractionation of Cd in tissue of Cd-hyperaccumulating genotypes NY2 and NY5. The sequential extractants were: 80%?v/v ethanol (FE), deionized water (FW), 1?M NaCl (FNaCl), 2%?v/v acetic acid (FAcet), and 0.6?M HCl (FHCl). After 20 days of treatments, NY5 had greater plant biomass and greater Cd accumulation in tissues than NY2. In both genotypes the FNaCl fraction was the highest in roots and stems, whereas the FAcet and FHCl fractions were the highest in leaves. With an increase in Cd concentration in the culture solution, the content of every Cd fraction also increased. The FW and FNaCl ratios in roots were lower in NY5 than in NY2, while the amount of other Cd forms was higher. It implied that, in high accumulator, namely, NY5, the complex of insoluble phosphate tends to be shaped more easily which was much better for Cd accumulation. Besides, translocation from plasma to vacuole after combination with protein may be one of the main mechanisms in Cd-accumulator Jerusalem artichoke genotypes. PMID:24883399
Long, Xiaohua; Ni, Ni; Liu, Zhaopu; Rengel, Zed; Jiang, Xin; Shao, Hongbo
Molecular Dissection of The Cellular Mechanisms Involved In Nickel Hyperaccumulation in Plants
Hyperaccumulator plant species are able to accumulate between 1-5% of their biomass as metal. However, these plants are often small, slow growing, and do not produce a high biomass. Phytoextraction, a cost-effective, in situ, plant based approach to soil remediation takes advantage of the remarkable ability of hyperaccumulating plants to concentrate metals from the soil and accumulate them in their harvestable, above-ground tissues. However, to make use of the valuable genetic resources identified in metal hyperaccumulating species, it will be necessary to transfer this material to high biomass rapidly growing crop plants. These plants would then be ideally suited to the phytoremediation process, having the ability to produce large amount of metal-rich plant biomass for rapid harvest and soil cleanup. Although progress is being made in understanding the genetic basis of metal hyperaccumulation a more complete understanding will be necessary before we can take full advantage of the genetic potential of these plants.
David E. Salt
Selenium Hyperaccumulator Plants Stanleya pinnata and Astragalus bisulcatus Are Colonized by Se Astragalus bisulcatus and Stanleya pinnata. Selenium accumulation, localization and speciation were: Bruchidae) and seed chalcid larvae (Bruchophagus mexicanus, Hymenoptera: Eurytomidae). Stanleya pinnata
Long-term sulfate, selenate and molybdate accumulation and translocation were investigated in two ecotypes of Stanleya pinnata and non-hyperaccumulator Brassica juncea under different levels of applied sulfate and selenate. Morphological differences were observed between the ecotypes of S. pinnata, but few differences in selenium (Se) and sulfur (S) accumulation were measured. Se-to-S ratios were nearly identical between the ecotypes under all treatments. When compared with B. juncea, several unique trends were observed in the hyperaccumulators. While both S. pinnata ecotypes showed no significant effect on Se content of young leaves when the supplied sulfate in the growth medium was increased tenfold (from 0.5 to 5 mM), the Se levels in B. juncea decreased 4- to 12-fold with increased sulfate in the growth medium. Furthermore, S. pinnataÆs S levels decreased slightly with high levels of supplied Se, suggesting competitive inhibition of uptake, while B. juncea showed higher S levels with increasing Se, possibly due to up-regulation of sulfate transporters. Both ecotypes of S. pinnata showed much larger Se concentrations in young leaves, while B. juncea showed slightly higher levels of Se in older leaves relative to young. Molybdenum (Mo) levels significantly decreased in S. pinnata with increasing sulfate and selenate in the medium; B. juncea did not show the same trends. These findings support the hypothesis that S. pinnata contains a modified sulfate transporter with a higher specificity for selenate. PMID:24233101
Harris, Jonathan; Schneberg, Kathryn A; Pilon-Smits, Elizabeth A H
Using the gamma-glutamylcysteine synthetase inhibitor, L-buthionine-[S,R]-sulphoximine (BSO), the role for phytochelatins (PCs) was evaluated in Cu, Cd, Zn, As, Ni, and Co tolerance in non-metallicolous and metallicolous, hypertolerant populations of Silene vulgaris (Moench) Garcke, Thlaspi caerulescens J.&C. Presl., Holcus lanatus L., and Agrostis castellana Boiss. et Reuter. Based on plant-internal PC-thiol to metal molar ratios, the metals' tendency to induce PC accumulation decreased in the order As/Cd/Cu > Zn > Ni/Co, and was consistently higher in non-metallicolous plants than in hypertolerant ones, except for the case of As. The sensitivities to Cu, Zn, Ni, and Co were consistently unaffected by BSO treatment, both in non-metallicolous and hypertolerant plants, suggesting that PC-based sequestration is not essential for constitutive tolerance or hypertolerance to these metals. Cd sensitivity was considerably increased by BSO, though exclusively in plants lacking Cd hypertolerance, suggesting that adaptive cadmium hypertolerance is not dependent on PC-mediated sequestration. BSO dramatically increased As sensitivity, both in non-adapted and As-hypertolerant plants, showing that PC-based sequestration is essential for both normal constitutive tolerance and adaptive hypertolerance to this metalloid. The primary function of PC synthase in plants and algae remains elusive. PMID:12432030
Schat, Henk; Llugany, MercĶ; Vooijs, Riet; Hartley-Whitaker, Jeanette; Bleeker, Petra M
An experimental assessment of the defence hypothesis of nickel (Ni) hyperaccumulation in Alyssum was lacking. Also, to date no study had investigated the effects of hyperaccumulator litter on a detritivore species. We\\u000a performed several experiments with model arthropods representatives of two trophic levels: Tribolium castaneum (herbivore) and Porcellio dilatatus (detritivore). In no-choice trials using artificial food disks with different Ni
M. Teresa Gonńalves; Susana C. Gonńalves; Ant¾nio Portugal; Sandra Silva; Josķ Paulo Sousa; Helena Freitas
Background and Aims Nickel (Ni) hyperaccumulation is a rare form of physiological specialization shared by a small number of angiosperms growing on ultramafic soils. The evolutionary patterns of this feature among European members of tribe Alysseae (Brassicaceae) are investigated using a phylogenetic approach to assess relationships among Ni hyperaccumulators at the genus, species and below-species level. Methods Internal transcribed spacer (ITS) sequences were generated for multiple accessions of Alysseae. Phylogenetic trees were obtained for the genera of the tribe and Alyssum sect. Odontarrhena. All accessions and additional herbarium material were tested for Ni hyperaccumulation with the dimethylglyoxime colorimetric method. Key Results Molecular data strongly support the poorly known hyperaccumulator endemic Leptoplax (Peltaria) emarginata as sister to hyperaccumulator species of Bornmuellera within Alysseae. This is contrary to current assumptions of affinity between L. emarginata and the non-hyperaccumulator Peltaria in Thlaspideae. The lineage Bornmuellera¢Leptoplax is, in turn, sister to the two non-hyperaccumulator Mediterranean endemics Ptilotrichum rupestre and P. cyclocarpum. Low ITS sequence variation was found within the monophyletic Alyssum sect. Odontarrhena and especially in A. murale sensu lato. Nickel hyperaccumulation was not monophyletic in any of three main clades retrieved, each consisting of hyperaccumulators and non-hyperaccumulators of different geographical origin. Conclusions Nickel hyperaccumulation in Alysseae has a double origin, but it did not evolve in Thlaspideae. In Bornmuellera¢Leptoplax it represents an early synapomorphy inherited from an ancestor shared with the calcicolous, sister clade of Mediterranean Ptilotrichum. In Alyssum sect. Odontarrhena it has multiple origins even within the three European clades recognized. Lack of geographical cohesion suggests that accumulation ability has been lost or gained over the different serpentine areas of south Europe through independent events of microevolutionary adaptation and selection. Genetic continuity and strong phenotypic plasticity in the A. murale complex call for a reduction of the number of Ni hyperaccumulator taxa formally recognized. PMID:20724306
Cecchi, Lorenzo; Gabbrielli, Roberto; Arnetoli, Miluscia; Gonnelli, Cristina; Hasko, Agim; Selvi, Federico
Oilseed crops are sources of oils and seed meal having a multitude of uses. While the domestication of soybean and rapeseed took extended periods of time, new genome-based techniques have ushered in an era where crop domestication can occur rapidly. One attractive target for rapid domestication is the winter annual plant Field Pennycress (Thlaspi arvense L.; pennycress; Brassicaceae). Pennycress grows widespread throughout temperate regions of the world and could serve as a winter oilseed-producing cover crop. If grown throughout the USA Midwest Corn Belt, for example, pennycress could produce as much as 840L/ha oils and 1470kg/ha press-cake annually on 16 million hectares of farmland currently left fallow during the fall through spring months. However, wild pennycress strains have inconsistent germination and stand establishment, un-optimized maturity for a given growth zone, suboptimal oils and meal quality for biofuels and food production, and significant harvest loss due to pod shatter. In this review, we describe the virtues and current shortcomings of pennycress and discuss how knowledge from studying Arabidopsis thaliana and other Brassicas, in combination with the advent of affordable next generation sequencing, can bring about the rapid domestication and improvement of pennycress and other crops. PMID:25219314
Sedbrook, John C; Phippen, Winthrop B; Marks, M David
Elemental and metabolite profiling of nickel hyperaccumulators from New Caledonia.
Leaf material from nine Ni hyperaccumulating species was collected in New Caledonia: Homalium kanaliense (Vieill.) Briq., Casearia silvana Schltr, Geissois hirsuta Brongn. & Gris, Hybanthus austrocaledonicus Seem, Psychotria douarrei (G. Beauvis.) Dõniker, Pycnandra acuminata (Pierre ex Baill.) Swenson & Munzinger (syn Sebertia acuminata Pierre ex Baill.), Geissois pruinosa Brongn. & Gris, Homalium deplanchei (Viell) Warb. and Geissois bradfordii (H.C. Hopkins). The elemental concentration was determined by inductively-coupled plasma optical emission spectrometry (ICP-OES) and from these results it was found that the species contained Ni concentrations from to 250-28,000 mg/kg dry mass. Gas chromatography mass spectrometry (GC-MS)-based metabolite profiling was then used to analyse leaves of each species. The aim of this study was to target Ni-binding ligands through correlation analysis of the metabolite levels and leaf Ni concentration. Approximately 258 compounds were detected in each sample. As has been observed before, a correlation was found between the citric acid and Ni concentrations in the leaves for all species collected. However, the strongest Ni accumulator, P. douarrei, has been found to contain particularly high concentrations of malonic acid, suggesting an additional storage mechanism for Ni. A size exclusion chromatography separation protocol for the separation of Ni-complexes in P. acuminata sap was also applied to aqueous leaf extracts of each species. A number of metabolites were identified in complexes with Ni including Ni-malonate from P. douarrei. Furthermore, the levels for some metabolites were found to correlate with the leaf Ni concentration. These data show that Ni ions can be bound by a range of small molecules in Ni hyperaccumulation in plants. PMID:22795763
Callahan, Damien L; Roessner, Ute; Dumontet, Vincent; De Livera, Alysha M; Doronila, Augustine; Baker, Alan J M; Kolev, Spas D
Symphyotrichum ericoides was shown earlier to contain hyperaccumulator levels of selenium (Se) in the field (>1000 mg kg(-1) dry weight (DW)), but only when growing next to other Se hyperaccumulators. It was also twofold larger next to hyperaccumulators and suffered less herbivory. This raised two questions: whether S. ericoides is capable of hyperaccumulation without neighbor assistance, and whether its Se-derived benefit is merely ecological or also physiological. Here, in a comparative greenhouse study, Se accumulation and tolerance of S. ericoides were analyzed in parallel with hyperaccumulator Astragalus bisulcatus, Se accumulator Brassica juncea and related Asteraceae Machaeranthera tanacetifolia. Symphyotrichum ericoides and M. tanacetifolia accumulated Se up to 3000 and 1500 mg Se kg(-1) DW, respectively. They were completely tolerant to these Se levels and even grew 1.5- to 2.5-fold larger with Se. Symphyotrichum ericoides showed very high leaf Se/sulfur (S) and shoot/root Se concentration ratios, similar to A. bisulcatus and higher than M. tanacetifolia and B. juncea. Se X-ray absorption near-edge structure spectroscopy showed that S. ericoides accumulated Se predominantly (86%) as C-Se-C compounds indistinguishable from methyl-selenocysteine, which may explain its Se tolerance. Machaeranthera tanacetifolia accumulated 55% of its Se as C-Se-C compounds; the remainder was inorganic Se. Thus, in this greenhouse study S. ericoides displayed all of the characteristics of a hyperaccumulator. The larger size of S. ericoides when growing next to hyperaccumulators may be explained by a physiological benefit, in addition to the ecological benefit demonstrated earlier. PMID:24423113
El Mehdawi, Ali F; Reynolds, Ray Jason B; Prins, Christine N; Lindblom, Stormy D; Cappa, Jennifer J; Fakra, Sirine C; Pilon-Smits, Elizabeth A H
Changes in the activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and the contents of malondialdehyde (MDA), chlorophyll, free proline and phytochelatins (PCs) in Solanum nigrum, the newly discovered Cd-hyperaccumulator were examined and compared with a non-hyperaccumulator Solanum melongena. It was indicated that leaf SOD and POD activity of S. nigrum was significantly higher than that
Rui-Lian Sun; Qi-Xing Zhou; Fu-Hong Sun; Cai-Xia Jin
A novel technology to obtain highly efficient biosorbent from the endophytes of a hyperaccumulator is reported. This technology is more convenient than the traditional method of obtaining biosorbents by experimentally screening many types of biomass by trial and error. Using this technology, endophytic fungus (EF) LSE10 was isolated from the cadmium hyperaccumulator Solanum nigrum L. It was identified as Microsphaeropsis
Xiao Xiao; Shenglian Luo; Guangming Zeng; Wanzhi Wei; Yong Wan; Liang Chen; Hanjun Guo; Zhe Cao; Lixia Yang; Jueliang Chen; Qiang Xi
Hyperaccumulation by a Fern Plant Ma, L.Q., D. Sylvia, Y. Cai, K. Downum and J.-F. Gaillard 9/2001 to 8/2004 Arsenic discovered the only known arsenic hyperaccumulating plant, Brake fern, which accumulates >2% arsenic in its objective of this research is to understand and enhance arsenic uptake by Brake fern, with the ultimate goal
Ma, Lena
Low molecular weight thiols in arsenic hyperaccumulator Pteris vittata upon exposure to arsenic; accepted 25 September 2003 ``Capsule'': Arsenic induces synthesis of low molecular weight thiols in the arsenic hyperaccumulator Pteris vittata. Abstract Low molecular weight thiol-containing compounds have
Ma, Lena
Mitochondria are important targets of metal toxicity and are also vital for maintaining metal homeostasis. Here, we examined the potential role of mitochondria in homeostasis of nickel in the roots of nickel hyperaccumulator plant Alyssum murale. We evaluated the biochemical basis of nickel tolerance by comparing the role of mitochondria in closely related nickel hyperaccumulator A. murale and non-accumulator Alyssum montanum. Evidence is presented for the rapid and transient influx of nickel in root mitochondria of nickel hyperaccumulator A. murale. In an early response to nickel treatment, substantial nickel influx was observed in mitochondria prior to sequestration in vacuoles in the roots of hyperaccumulator A. murale compared with non-accumulator A. montanum. In addition, the mitochondrial Krebs cycle was modulated to increase synthesis of malic acid and citric acid involvement in nickel hyperaccumulation. Furthermore, malic acid, which is reported to form a complex with nickel in hyperaccumulators, was also found to reduce the reactive oxygen species generation induced by nickel. We propose that the interaction of nickel with mitochondria is imperative in the early steps of nickel uptake in nickel hyperaccumulator plants. Initial uptake of nickel in roots results in biochemical responses in the root mitochondria indicating its vital role in homeostasis of nickel ions in hyperaccumulation. PMID:23322782
Agrawal, Bhavana; Czymmek, Kirk J.; Sparks, Donald L.; Bais, Harsh P.
of selenium hyperaccumulator Stanleya pinnata and related non-accumulator Stanleya elata with hyperaccumulator) HA Stanleya pinnata, Alternaria seleniiphila (A1) and Aspergillus leporis (AS117), were used to inoculate S. pinnata and related non-HA Stanleya elata. Growth and Se and sulfur (S) accumulation were
To directly select submerged macrophytes with high accumulation capability from the field, 24 eutrophic lakes along the middle and lower reaches of the Yangtze River were investigated in the study. These eutrophic lakes have large amounts of heavy metals in both water and sediments because of human activities. The results showed that Najas marina is a hyperaccumulator of As and Cd, Ceratophyllum demersum is a hyperaccumulator of Co, Cr, and Fe, and Vallisneria natans is a hyperaccumulator of Pb. Strong positive correlations were found between concentrations of heavy metals in tissues of submerged macrophytes, probably because of coaccumulation of heavy metals. However, for most heavy metals, no significant correlations were found between submerged macrophytes and their surrounding environments. In conclusion, N. marina, C. demersum, and V. natans are good candidate species for removing heavy metals from eutrophic lakes. PMID:23582178
Xing, Wei; Wu, Haoping; Hao, Beibei; Huang, Wenmin; Liu, Guihua
Feasibility of using hyperaccumulating plants to bioremediate metal-contaminated soil
A feasibility study was carried out to determine whether selected plants were capable of hyperaccumulating anthropogenic sources of metals found in soils from three contaminated sites. A trial was conducted using the previously reported hyperaccumulators, Armeria maritima (thrift), Impatiens balsamina (balsam), Alyssum saxatile (gold dust), and the control species, Brassica oleracea (cabbage). Although none of these plants showed any substantial hyperaccumulation of Cu, Zn, Pb, and Cd, it was established that there is an optimum period in the life-cycle of these plants in which the metal concentration reaches a maximum. This period was dependent on the metal, soil, and plant type. The current paper describes the data obtained for Zn and Cu uptake by thrift.
Kelly, R.J. [Dames and Moore, Sydney, New South Wales (Australia); Guerin, T.F. [Minenco Bioremediation Services, Bundoora, Victoria (Australia)
Elemental hyperaccumulation in plants is hypothesized to represent a plant defense mechanism. The objective of this study was to determine whether selenium (Se) hyperaccumulation offers plants long-term protection from the black-tailed prairie dog (Cynomys ludovicianus). Prairie dogs are a keystone species. The hyperaccumulator Stanleya pinnata (prince's plume) co-occurs with prairie dogs in seleniferous areas in the western United States. Stanleya pinnata plants pretreated with high or low Se concentrations were planted on two prairie dog towns with different levels of herbivory pressure, and herbivory of these plants was monitored over 2 years. Throughout this study, plants with elevated Se levels suffered less herbivory and survived better than plants with low leaf Se concentrations. This study indicates that the Se in hyperaccumulator S. pinnata protects the plant in its natural habitat from herbivory by the black-tailed prairie dog. The results from this study support the hypothesis that herbivory by prairie dogs or similar small mammals has been a contributing selection pressure for the evolution of plant Se hyperaccumulation in North America. This study is the first to test the ecological significance of hyperaccumulation over a long period in a hyperaccumulator's natural habitat. PMID:21628258
Freeman, John L; Quinn, Colin F; Lindblom, Stormy Dawn; Klamper, Erin M; Pilon-Smits, Elizabeth A H
Some plants can hyperaccumulate the element selenium (Se) up to 10,000 mg Se kg(-1) dry weight. Hyperaccumulation has been hypothesized to defend against herbivory. In laboratory studies high Se levels protect plants from invertebrate herbivores and pathogens. However, field studies and mammalian herbivore studies that link Se accumulation to herbivory protection are lacking. In this study a combination of field surveys and manipulative field studies were carried out to determine whether plant Se accumulation in the field deters herbivory by black-tailed prairie dogs (Cynomys ludovicianus). The Se hyperaccumulator Astragalus bisulcatus (two-grooved milkvetch) occurs naturally on seleniferous soils in the Western USA, often on prairie dog colonies. Field surveys have shown that this Se hyperaccumulator is relatively abundant on some prairie dog colonies and suffers less herbivory than other forb species. This protection was likely owing to Se accumulation, as judged from subsequent manipulative field experiments. When given a choice between pairs of plants of the Se hyperaccumulator Stanleya pinnata (prince's plume) that were pretreated with or without Se, prairie dogs preferred to feed on the plants with low Se; the same results were obtained for the non-hyperaccumulator Brassica juncea (Indian mustard). Plants containing as little as 38 mg Se kg(-1) DW were protected from herbivory. Taken together these results shed light on the functional significance of Se hyperaccumulation and the possible selection pressures driving its evolution. They also have implications for the use of plants in Se phytoremediation, or as Se-fortified crops. PMID:18278517
Quinn, Colin F; Freeman, John L; Galeas, Miriam L; Klamper, Erin M; Pilon-Smits, Elizabeth A H
Antimony uptake, efflux and speciation in arsenic hyperaccumulator Pteris vittata.
Even though antimony (Sb) and arsenic (As) are chemical analogs, differences exist on how they are taken up and translocated in plants. We investigated 1) Sb uptake, efflux and speciation in arsenic hyperaccumulator Pteris vittata after 1 d exposure to 1.6 or 8 mg/L antimonite (SbIII) or antimonate (SbV), 2) Sb uptake by PV accessions from Florida, China, and Brazil after 7 d exposure to 8 mg/L SbIII, and 3) Sb uptake and oxidation by excised PV fronds after 1 d exposure to 8 mg/L SbIII or SbV. After 1 d exposure, P. vittata took 23-32 times more SbIII than SbV, with all Sb being accumulated in the roots with the highest at 4,192 mg/kg. When exposed to 8 mg/L SbV, 98% of Sb existed as SbV in the roots. In comparison, when exposed to 8 mg/L SbIII, 81% of the total Sb remained as SbIII and 26% of the total Sb was effluxed out into the media. The three PV accessions had a similar ability to accumulate Sb at 12,000 mg/kg in the roots, with >99% of total Sb in the roots. Excised PV fronds translocated SbV more efficiently from the petioles to pinnae than SbIII and were unable to oxidize SbIII. Overall, P. vittata displayed efficient root uptake and efflux of SbIII with limited ability to translocate and transform in the roots. PMID:24370668
Tisarum, Rujira; Lessl, Jason T; Dong, Xiaoling; de Oliveira, Letuzia M; Rathinasabapathi, Bala; Ma, Lena Q
Forms of Zinc Accumulated in the Hyperaccumulator Arabidopsis halleri1
The chemical forms of zinc (Zn) in the Zn-tolerant and hyperaccumulator Arabidopsis halleri and in the non-tolerant and nonaccumulator Arabidopsis lyrata subsp. petraea were determined at the molecular level by combining chemical analyses, extended x-ray absorption spectroscopy (EXAFS), synchrotron-based x-ray microfluorescence, and ?EXAFS. Plants were grown in hydroponics with various Zn concentrations, and A. halleri specimens growing naturally in a contaminated site were also collected. Zn speciation in A. halleri was independent of the origin of the plants (contaminated or non-contaminated) and Zn exposure. In aerial parts, Zn was predominantly octahedrally coordinated and complexed to malate. A secondary organic species was identified in the bases of the trichomes, which contained elevated Zn concentrations, and in which Zn was tetrahedrally coordinated and complexed to carboxyl and/or hydroxyl functional groups. This species was detected thanks to the good resolution and sensitivity of synchrotron-based x-ray microfluorescence and ?EXAFS. In the roots of A. halleri grown in hydroponics, Zn phosphate was the only species detected, and is believed to result from chemical precipitation on the root surface. In the roots of A. halleri grown on the contaminated soil, Zn was distributed in Zn malate, Zn citrate, and Zn phosphate. Zn phosphate was present in both the roots and aerial part of A. lyrata subsp. petraea. This study illustrates the complementarity of bulk and spatially resolved techniques, allowing the identification of: (a) the predominant chemical forms of the metal, and (b) the minor forms present in particular cells, both types of information being essential for a better understanding of the bioaccumulation processes. PMID:12481065
Sarret, Geraldine; Saumitou-Laprade, Pierre; Bert, Valerie; Proux, Olivier; Hazemann, Jean-Louis; Traverse, Agnes; Marcus, Matthew A.; Manceau, Alain
-1 arsenic). Bulk and rhizosphere soil samples were analyzed for water-soluble As (WS-As) and P (WS-266, indicating that the rate of As-solubilization was more rapid than that of plant uptake to be used to clean up arsenic-contaminated soils. It uses plants that hyperaccumulate arsenic
Ma, Lena
metals. Published by Elsevier Ltd. Keywords: Phytoremediation; Heavy metals; Arsenic uptake; Speciation (EPA, 2001). Phytoremediation, the use of plants for environmental restoration, has been proposed of phytoremediation (Reeves and Baker, 2000). Hyperaccumulators are plants and/or genotypes that accumulate metals
Ma, Lena
Journal of Chromatography A, 1043 (2004) 249254 Arsenic complexes in the arsenic hyperaccumulator
Journal of Chromatography A, 1043 (2004) 249┬Ł254 Arsenic complexes in the arsenic hyperaccumulator-exchange chromatography┬Łhydride generation┬Łatomic fluorescence spectroscopy and size-exclusion chromatographyIII-tris-thiolate complexes through thiolate bonds by us- ing size-exclusion chromatography (SEC) or electrospray ionization
Ma, Lena
Thiol synthesis and arsenic hyperaccumulation in Pteris vittata (Chinese brake fern)
Thiol synthesis and arsenic hyperaccumulation in Pteris vittata (Chinese brake fern) Weihua Zhanga in arsenic detoxification. Abstract Pteris vittata (Chinese brake fern) has potential for phytoremediation to be a supplement. ├? 2004 Elsevier Ltd. All rights reserved. Keywords: Pteris vittata; Chinese brake fern; Thiols
Ma, Lena
Using phosphate rock to immobilize metals in soil and increase arsenic uptake by hyperaccumulator rate (Fayiga et al., 2004). Phosphate rock has been shown to immobilize metals in contaminated soils Pteris vittata Abioye O. Fayiga, Lena Q. Ma * Soil and Water Science Department, University of Florida
Ma, Lena
SHORT COMMUNICATION Successful Seed Germination of the Nickel Hyperaccumulator Stackhousia tryonii
? Background and Aims Stackhousia tryonii, a rare nickel hyperaccumulating herb, is endemic to ultramafic (serpentine) soils of central Queensland, Australia. The effects of eight dormancy-relieving treatments on germina- tion of stored seeds of Stackhousia tryonii were investigated under controlled light and temperature conditions. ? Methods The treatments were: untreated (control i), leached and dehydrated (primed control ii), treating with
Astragalus bisulcatus and Stanleya pinnata1 John L. Freeman, Li Hong Zhang, Matthew A. Marcus, Sirine Fakra, Rothamsted Research, Harpenden, Herts AL5 2JQ, United Kingdom (S.P.M.) Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present
Molecular Mechanisms of Selenium Tolerance and Hyperaccumulation in Stanleya pinnata1[W][OA
Molecular Mechanisms of Selenium Tolerance and Hyperaccumulation in Stanleya pinnata1[W][OA] John L- accumulator Stanleya pinnata (Brassicaceae) by comparing it with the related secondary Se accumulator Stanleya albescens using a combination of physiological, structural, genomic, and biochemical approaches. S. pinnata
Selenium hyperaccumulation offers protection from cell disruptor herbivores Colin F. Quinn1,#
. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata. pinnata with high Se concentrations (greater than 650 mg Se kg-1 ) were less subject to thrips herbivory. Spider mites also preferred to feed on low-Se A. bisulcatus and S. pinnata plants rather than high
bisulcatus and Stanleya pinnata and nonaccumulators Astragalus drummondii and Stanleya elata were, hyperaccumulation, phytoenrichment, plant┬Łplant interactions, selenium, Stanleya. Summary ┬Ę This study investigated accumulated relatively more C-Se-C and less selenate when growing adjacent to S. pinnata. Both
Zn deficiency is among the leading health risk factors in developing countries. Breeding of Zn-enriched crops is expected to be facilitated by molecular dissection of plant Zn hyperaccumulation (i.e., the ability of certain plants to accumulate Zn to levels >100-fold higher than normal plants). The model hyperaccumulators Arabidopsis halleri and Noccaea caerulescens share elevated nicotianamine synthase (NAS) expression relative to nonaccumulators among a core of alterations in metal homeostasis. Suppression of Ah-NAS2 by RNA interference (RNAi) resulted in strongly reduced root nicotianamine (NA) accumulation and a concomitant decrease in root-to-shoot translocation of Zn. Speciation analysis by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry showed that the dominating Zn ligands in roots were NA and thiols. In NAS2-RNAi plants, a marked increase in Zn-thiol species was observed. Wild-type A. halleri plants cultivated on their native soil showed elemental profiles very similar to those found in field samples. Leaf Zn concentrations in NAS2-RNAi lines, however, did not reach the Zn hyperaccumulation threshold. Leaf Cd accumulation was also significantly reduced. These results demonstrate a role for NAS2 in Zn hyperaccumulation also under near-natural conditions. We propose that NA forms complexes with Zn(II) in root cells and facilitates symplastic passage of Zn(II) toward the xylem. PMID:22374395
Deinlein, Ulrich; Weber, Michael; Schmidt, Holger; Rensch, Stefan; Trampczynska, Aleksandra; Hansen, Thomas H.; Husted, S?ren; Schjoerring, Jan K.; Talke, Ina N.; Kramer, Ute; Clemens, Stephan
The Sedum alfredii Hance hyperaccumulating ecotype (HE) has the ability to hyperaccumulate cadmium (Cd), as well as zinc (Zn) and lead (Pb) in above-ground tissues. Although many physiological studies have been conducted with these plants, the molecular mechanisms underlying their hyper-tolerance to heavy metals are largely unknown. Here we report on the generation of 9.4 gigabases of adaptor-trimmed raw sequences and the assembly of 57,162 transcript contigs in S. alfredii Hance (HE) shoots by the combination of Roche 454 and Illumina/Solexa deep sequencing technologies. We also have functionally annotated the transcriptome and analyzed the transcriptome changes upon Cd hyperaccumulation in S. alfredii Hance (HE) shoots. There are 110 contigs and 123 contigs that were up-regulated (Fold Change ?2.0) and down-regulated (Fold Change ?0.5) by chronic Cd treatment in S. alfredii Hance (HE) at q-value cutoff of 0.005, respectively. Quantitative RT-PCR was employed to compare gene expression patterns between S. alfredii Hance (HE) and non-hyperaccumulating ecotype (NHE). Our results demonstrated that several genes involved in cell wall modification, metal translocation and remobilization were more induced or constitutively expressed at higher levels in HE shoots than that in NHE shoots in response to Cd exposure. Together, our study provides large-scale expressed sequence information and genome-wide transcriptome profiling of Cd responses in S. alfredii Hance (HE) shoots. PMID:23755133
Yang, Xiaoe; Liu, Jian-Xiang
Flowering in the winter annual field pennycress (Thlaspi arvense L.) is induced by exposure to low temperature (4/sup 0/C). /sup 14/C GA/sub 12/ was applied externally to the apices of two thermoinduced and two control plants. After incubation for 2 days at 21/sup 0/C, the plants were harvested, and a 2-cm apical section and the remainder of each plant were analyzed separately for the presence of radiolabeled metabolites. More radioactivity was found in the acidic ethyl acetate fraction from an extract of the apices of induced plants than that of noninduced plants. Conversely, the fraction prepared from the rest of the induced plant tissue was less radioactive than the noninduced sample. Gradient-eluted reverse phase HPLC of the samples revealed labeled compounds that co-chromatographed with several endogenous gibberellins.
Hazebroek, J.; Metzger, J.
Concentrations of metals including manganese, nickel, copper and zinc were measured in soil from a copper mine spoil heap in the Grand Canyon, Arizona, and in three plant species growing on the spoil. The soil had high concentrations of available copper and zinc, and the herbaceous perennial Thlaspi montanum var fendleri contained amounts of Ni, Cu and Zn in direct proportion to the soil concentrations (EDTA extractable). Another herbaceous perennial, Phlox austromontana, and the woody perennial Juniperus osteosperma had considerably lower amounts of these elements. These findings are discussed in relation to other studies, and it is suggested that figures for metal accumulation by plants should always be related to plant-available soil concentrations.
Hobbs, R.J.; Streit, B.
Enhanced root-to-shoot translocation of cadmium in the hyperaccumulating ecotype of Sedum alfredii
Sedum alfredii (Crasulaceae) is the only known Cd-hyperaccumulating species that are not in the Brassica family; the mechanism of Cd hyperaccumulation in this plant is, however, little understood. Here, a combination of radioactive techniques, metabolic inhibitors, and fluorescence imaging was used to contrast Cd uptake and translocation between a hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of S. alfredii. The Km of 109Cd influx into roots was similar in both ecotypes, while the Vmax was 2-fold higher in the HE. Significant inhibition of Cd uptake by low temperature or metabolic inhibitors was observed in the HE, whereas the effect was less pronounced in the NHE. 109Cd influx into roots was also significantly decreased by high Ca in both ecotypes. The rate of root-to-shoot translocation of 109Cd in the HE was >10 times higher when compared with the NHE, and shoots of the HE accumulated dramatically higher 109Cd concentrations those of the NHE. The addition of the metabolic inhibitor carbonyl cyanide m-chlorophenylhydrazone (CCCP) resulted in a significant reduction in Cd contents in the shoots of the HE, and in the roots of the NHE. Cd was distributed preferentially to the root cylinder of the HE but not the NHE, and there was a 3¢5 times higher Cd concentration in xylem sap of the HE in contrast to the NHE. These results illustrate that a greatly enhanced rate of root-to-shoot translocation, possibly as a result of enhanced xylem loading, rather than differences in the rate of root uptake, was the pivotal process expressed in the Cd hyperaccumulator HE S. alfredii. PMID:18603654
Lu, Ling-li; Tian, Sheng-ke; Yang, Xiao-e; Wang, Xiao-chang; Brown, Patrick; Li, Ting-qiang; He, Zhen-li
Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and gamma-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in addition to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism. PMID:16920881
Freeman, John L; Zhang, Li Hong; Marcus, Matthew A; Fakra, Sirine; McGrath, Steve P; Pilon-Smits, Elizabeth A H
Remediation of heavy metal contaminated sites using hyperaccumulators presents a promising alternative to current environmental methodologies. In the pot-culture experiment, the effects of Cd, and Cd¢As on the growth and its accumulation in the Cd-hyperaccumulator (Solanum nigrum L.) were determined. No reduction in plant height and shoot dry biomass was noted when the plants were grown at Cd concentration of
Yuebing Sun; Qixing Zhou; Chunyan Diao
Some plants can hyperaccumulate the element selenium (Se) up to 10,000Āmg Se kg?1 dry weight. Hyperaccumulation has been hypothesized to defend against herbivory. In laboratory studies high Se levels protect\\u000a plants from invertebrate herbivores and pathogens. However, field studies and mammalian herbivore studies that link Se accumulation\\u000a to herbivory protection are lacking. In this study a combination of field surveys
Colin F. Quinn; John L. Freeman; Miriam L. Galeas; Erin M. Klamper; Elizabeth A. H. Pilon-Smits
NASA Astrophysics Data System (ADS)
A field survey was conducted to identify potential hyperaccumulators of Pb, Zn or Cd in the Beichang Pb/Zn mine outcrop in Yunnan Province, China. The average total concentrations of Pb, Zn, and Cd in the soils were up to 28,438, 5,109, and 52 mg kg-1, respectively. A total of 68 plant species belonging to 60 genera of 37 families naturally colonizing the outcrop were recorded. According to metal accumulation in the plants and translocation factor (TF), Silene viscidula was identified as potential hyperaccumulator of Pb, Zn, and Cd with mean shoot concentrations of 3,938 mg kg-1 of Pb (TF = 1.2), 11,155 mg kg-1 of Zn (TF = 1.8) and 236 mg kg-1 of Cd (TF = 1.1), respectively; S. gracilicanlis (Pb 3,617 mg kg-1, TF = 1.2) and Onosma paniculatum (Pb 1,837 mg kg-1, TF = 1.9) were potential Pb hyperaccumulators. Potentilla griffithii (Zn 8,748 mg kg-1, TF = 1.5) and Gentiana sp. (Zn 19,710 mg kg-1, TF = 2.7) were potential Zn hyperaccumulators. Lysimachia deltoides (Cd 212 mg kg-1, TF = 3.2) was a potential Cd hyperaccumulator. These new plant resources could be used to explore the mechanisms of Pb, Zn and/or Cd hyperaccumulation, and the findings could be applied for the phytoremediation of Pb, Zn and/or Cd-contaminated soils.
Wang, S. L.; Liao, W. B.; Yu, F. Q.; Liao, B.; Shu, W. S.
Ģ This study investigated how selenium (Se) affects relationships between Se hyperaccumulator and nonaccumulator species, particularly how plants influence their neighbors' Se accumulation and growth. Ģ Hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and nonaccumulators Astragalus?drummondii and Stanleya?elata were cocultivated on seleniferous or nonseleniferous soil, or on gravel supplied with different selenate concentrations. The plants were analyzed for growth, Se accumulation and Se speciation. Also, root exudates were analyzed for Se concentration. Ģ The hyperaccumulators showed 2.5-fold better growth on seleniferous than on nonseleniferous soil, and up to fourfold better growth with increasing Se supply; the nonaccumulators showed the opposite results. Both hyperaccumulators and nonaccumulators could affect growth (up to threefold) and Se accumulation (up to sixfold) of neighboring plants. Nonaccumulators S.Āelata and A.Ādrummondii accumulated predominantly (88-95%) organic C-Se-C; the remainder was selenate. S.Āelata accumulated relatively more C-Se-C and less selenate when growing adjacent to S.Āpinnata. Both hyperaccumulators released selenocompounds from their roots. A.Ābisulcatus exudate contained predominantly C-Se-C compounds; no speciation data could be obtained for S.Āpinnata. Ģ Thus, plants can affect Se accumulation in neighbors, and soil Se affects competition and facilitation between plants. This helps to explain why hyperaccumulators are found predominantly on seleniferous soils. PMID:22269105
Mehdawi, Ali F El; Cappa, Jennifer J; Fakra, Sirine C; Self, James; Pilon-Smits, Elizabeth A H
Hyperaccumulator is the main point of phytoremediating contaminated soils by heavy metals, and the identification of hyperaccumulator is still the difficult and key step of phytoremediation. The outdoor pot-culture experiment was used to study the hyperaccumulative characteristics of 7 widely distributing weed species in Northeast of China to heavy metals. The results in screening experiment showed that Taraxacum mongolicum and Bidens pilosa indicated strong tolerance to Cd single and Cd-Pb-Cu-Zn combined pollution, their Cd concentration in shoot were higher than that in roots, and the Cd enhancement factors (ratio of heavy metal concentration in shoot to that in soil) in shoots were greater than 1 too, which displayed that the two plants were with Cd hyperaccumulative characteristics. In concentration gradient experiment, Cd concentration in leaves of B. pilosa were all greater than 100 mg x kg(-1) the minimum of Cd-hyperaccumulator should have under the conditions of 25, 50, 100 mg x kg(-1) Cd added. Meanwhile, the shoot biomass of B. pilosa did not reduce significantly (p <0.05), Cd concentration in its shoots were higher than those in roots. But for T. mongolicum, Cd concentration in its shoots were not greater than 100 mg x kg(-1) in any treatment. Thus, only B. pilosa can be regarded as Cd-hyperaccumulator. PMID:19143394
Wei, Shu-He; Yang, Chuan-Jie; Zhou, Qi-Xing
A new, nickel-hyperaccumulating species of Rinorea (Violaceae), Rinorea niccolifera Fernando, from Luzon Island, Philippines, is described and illustrated. This species is most similar to the widespread Rinorea bengalensis by its fasciculate inflorescences and smooth subglobose fruits with 3 seeds, but it differs by its glabrous ovary with shorter style (5 mm long), the summit of the staminal tube sinuate to entire and the outer surface smooth, generally smaller leaves (3-8 cm long ū 2-3 cm wide), and smaller fruits (0.6-0.8 cm diameter). Rinorea niccolifera accumulates to >18,000 Ąg g(-1) of nickel in its leaf tissues and is thus regarded as a Ni hyperaccumulator. PMID:24843295
Fernando, Edwino S; Quimado, Marilyn O; Doronila, Augustine I
Abstract A new, nickel-hyperaccumulating species of Rinorea (Violaceae), Rinorea niccolifera Fernando, from Luzon Island, Philippines, is described and illustrated. This species is most similar to the widespread Rinorea bengalensis by its fasciculate inflorescences and smooth subglobose fruits with 3 seeds, but it differs by its glabrous ovary with shorter style (5 mm long), the summit of the staminal tube sinuate to entire and the outer surface smooth, generally smaller leaves (3¢8 cm long ū 2¢3 cm wide), and smaller fruits (0.6¢0.8 cm diameter). Rinorea niccolifera accumulates to >18,000 Ąg g-1 of nickel in its leaf tissues and is thus regarded as a Ni hyperaccumulator. PMID:24843295
Fernando, Edwino S.; Quimado, Marilyn O.; Doronila, Augustine I.
210023, China b Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA a r As accumulation by PV, with 17.5% more As in AsIII'┐Įsoil than AsV'┐Įsoil (36 vs. 31 mg plant'┐Į1 ). As concentration changes in As'┐Įhyperaccumulator Pteris vittata (PV). PV was grown for 60'┐Įd in a soil spiked with 200 mg kg
Ma, Lena
Solanum nigrum is a newly discovered Cd-hyperaccumulator. In the present study, the protective effects of proline against cadmium toxicity\\u000a of callus and regenerated shoots of S. nigrum are investigated based on a high frequency in vitro shoot regeneration system. Proline pretreatment reduces the reactive\\u000a oxygen species levels and protects the plasma membrane integrity of callus under cadmium stress, and therefore
Jin Xu; HengXia Yin; Xia Li
The Cd accumulation and biomass characteristics of a newly found Cd-hyperaccumulator Solanum nigrum L. were investigated at the flowering stage and the mature stage. The results showed that the concentration of Cd in the stems and leaves of S. nigrum harvested at the flowering stage was up to 83.1% and 85.5% of that at the mature stage, and the dry-weight
Shuhe Wei; Qixing Zhou; Pavel V. Koval
.ĀĀ The cellular compartmentation of elements was analysed in the Zn hyperaccumulator Arabidopsis halleri (L.) O'Kane & Al-Shehbaz (=Cardaminopsis halleri) using energy-dispersive X-ray microanalysis of frozen-hydrated tissues. Quantitative data were obtained using oxygen as\\u000a an internal standard in the analyses of vacuoles, whereas a peak\\/background ratio method was used for quantification of elements\\u000a in pollen and dehydrated trichomes. Arabidopsis halleri
Hendrik K³pper; Enzo Lombi; Fang-Jie Zhao; Steve P. McGrath
Agrobacterium\\u000a tumefaciens strain LBA4404 containing the plasmid pBI121, carrying the reporter gene uidA and the kanamycin resistance gene nptII, was used for gene transfer experiments in selenium (Se)-hyperaccumulator Astragalus racemosus. The effects of kanamycin on cell growth and division and acetosyringone on transformation efficiency were evaluated. The\\u000a optimal concentration of kanamycin that could effectively inhibit cell growth and division in
Diane E. Darlington; Chiu-Yueh Hung; Jiahua Xie
A Novel Arsenate Reductase from the Arsenic Hyperaccumulating Fern Pteris vittata1
Pteris vittata sporophytes hyperaccumulate arsenic to 1% to 2% of their dry weight. Like the sporophyte, the gametophyte was found to reduce arsenate [As(V)] to arsenite [As(III)] and store arsenic as free As(III). Here, we report the isolation of an arsenate reductase gene (PvACR2) from gametophytes that can suppress the arsenate sensitivity and arsenic hyperaccumulation phenotypes of yeast (Saccharomyces cerevisiae) lacking the arsenate reductase gene ScACR2. Recombinant PvACR2 protein has in vitro arsenate reductase activity similar to ScACR2. While PvACR2 and ScACR2 have sequence similarities to the CDC25 protein tyrosine phosphatases, they lack phosphatase activity. In contrast, Arath;CDC25, an Arabidopsis (Arabidopsis thaliana) homolog of PvACR2 was found to have both arsenate reductase and phosphatase activities. To our knowledge, PvACR2 is the first reported plant arsenate reductase that lacks phosphatase activity. CDC25 protein tyrosine phosphatases and arsenate reductases have a conserved HCX5R motif that defines the active site. PvACR2 is unique in that the arginine of this motif, previously shown to be essential for phosphatase and reductase activity, is replaced with a serine. Steady-state levels of PvACR2 expression in gametophytes were found to be similar in the absence and presence of arsenate, while total arsenate reductase activity in P. vittata gametophytes was found to be constitutive and unaffected by arsenate, consistent with other known metal hyperaccumulation mechanisms in plants. The unusual active site of PvACR2 and the arsenate reductase activities of cell-free extracts correlate with the ability of P. vittata to hyperaccumulate arsenite, suggesting that PvACR2 may play an important role in this process. PMID:16766666
Ellis, Danielle R.; Gumaelius, Luke; Indriolo, Emily; Pickering, Ingrid J.; Banks, Jo Ann; Salt, David E.
The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may affect ecological interactions and whether associated partners may affect Se hyperaccumulation. The Se hyperaccumulator Astragalus bisulcatus was collected in its natural seleniferous habitat, and x-ray fluorescence mapping and x-ray absorption near-edge structure spectroscopy were used to characterize Se distribution and speciation in all organs as well as in encountered microbial symbionts and herbivores. Se was present at high levels (704¢4,661 mg kg?1 dry weight) in all organs, mainly as organic C-Se-C compounds (i.e. Se bonded to two carbon atoms, e.g. methylselenocysteine). In nodule, root, and stem, up to 34% of Se was found as elemental Se, which was potentially due to microbial activity. In addition to a nitrogen-fixing symbiont, the plants harbored an endophytic fungus that produced elemental Se. Furthermore, two Se-resistant herbivorous moths were discovered on A. bisulcatus, one of which was parasitized by a wasp. Adult moths, larvae, and wasps all accumulated predominantly C-Se-C compounds. In conclusion, hyperaccumulators live in association with a variety of Se-resistant ecological partners. Among these partners, microbial endosymbionts may affect Se speciation in hyperaccumulators. Hyperaccumulators have been shown earlier to negatively affect Se-sensitive ecological partners while apparently offering a niche for Se-resistant partners. Through their positive and negative effects on different ecological partners, hyperaccumulators may influence species composition and Se cycling in seleniferous ecosystems. PMID:22645068
Valdez Barillas, Jose R.; Quinn, Colin F.; Freeman, John L.; Lindblom, Stormy D.; Fakra, Sirine C.; Marcus, Matthew A.; Gilligan, Todd M.; Alford, Elan R.; Wangeline, Ami L.; Pilon-Smits, Elizabeth A.H.
The nickel (Ni) hyperaccumulator Alyssum murale has been developed as a commercial crop for phytoremediation/phytomining Ni from metal-enriched soils. Here, metal co-tolerance, accumulation and localization were investigated for A. murale exposed to metal co-contaminants. A. murale was irrigated with Ni-enriched nutrient solutions containing basal or elevated concentrations of cobalt (Co) or zinc (Zn). Metal localization and elemental associations were investigated in situ with synchrotron X-ray microfluorescence (SXRF) and computed-microtomography (CMT). A. murale hyperaccumulated Ni and Co (> 1000 {micro}g g{sup -1} dry weight) from mixed-metal systems. Zinc was not hyperaccumulated. Elevated Co or Zn concentrations did not alter Ni accumulation or localization. SXRF images showed uniform Ni distribution in leaves and preferential localization of Co near leaf tips/margins. CMT images revealed that leaf epidermal tissue was enriched with Ni but devoid of Co, that Co was localized in the apoplasm of leaf ground tissue and that Co was sequestered on leaf surfaces near the tips/margins. Cobalt-rich mineral precipitate(s) form on leaves of Co-treated A. murale. Specialized biochemical processes linked with Ni (hyper)tolerance in A. murale do not confer (hyper)tolerance to Co. A. murale relies on a different metal storage mechanism for Co (exocellular sequestration) than for Ni (vacuolar sequestration).
Tappero, R.; Peltier, E; Grafe, M; Heidel, K; Ginder-Vogel, M; Livi, K; Rivers, M; Marcus, M; Chaney, R; Sparks, D
Zn isotope fractionation may provide new insights into Zn uptake, transport and storage mechanisms in plants. It was investigated here in the Zn hyperaccumulator Arabidopsis halleri and the nonaccumulator A. petraea. Plant growth on hydroponic solution allowed us to measure the isotope fractionation between source Zn (with Zn(2+) as dominant form), shoot and root. Zn isotope mass balance yields mean isotope fractionation between plant and source Zn ?(66)Zn(in-source) of -0.19 ▒ 0.20ē in the nonaccumulator and of -0.05 ▒ 0.12ē in the hyperaccumulator. The isotope fractionation between shoot Zn and bulk Zn incorporated (?(66)Zn(shoot-in)) differs between the nonaccumulator and the hyperaccumulator and is function of root-shoot translocation (as given by mass ratio between shoot Zn and bulk plant Zn). The large isotope fractionation associated with sequestration in the root (0.37ē) points to the binding of Zn(2+) with a high affinity ligand in the root cell. We conclude that Zn stable isotopes may help to estimate underground and aerial Zn storage in plants and be useful in studying extracellular and cellular mechanisms of sequestration in the root. PMID:21882835
Aucour, A M; Pichat, S; Macnair, M R; Oger, P
The defense hypothesis is commonly used to explain the adaptive role of metal hyperaccumulation. We tested this hypothesis using two Brassicaceae congeneric species: Alyssum pintodasilvae, a Ni hyperaccumulator, and the non-accumulator Alyssum simplex both growing on serpentine soils in Portugal. Artificial diet disks amended with powdered leaves from each plant species were used to compare the performance (mortality, biomass change) and feeding behavior of Tribolium castaneum in no-choice and choice tests. The performance of T. castaneum was not affected at several concentrations of A. pintodasilvae or A. simplex in no-choice tests. However, the consumption of plant-amended disks was significantly lower than that of control disks, irrespectively of the species fed. Accordingly, when insects were given an alternative food choice, disks of both plant species were significantly less consumed than control disks. Moreover, insects did not discriminate between disks in the combination "A. pintodasilvae+A. simplex". Contrary to our expectations, these results suggest that both plant species have equally effective defenses against herbivory. While Ni is believed to be part of the deterrence mechanism in the hyperaccumulator A. pintodasilvae, it seems likely that organic compounds, possibly glucosinolates, play an important role in the defense of A. simplex or in both species. PMID:23892018
Vilas Boas, Liliana; Gonńalves, Susana C; Portugal, Ant¾nio; Freitas, Helena; Gonńalves, M Teresa
Mn accumulation and tolerance in Celosia argentea Linn.: a new Mn-hyperaccumulating plant species.
Identifying a hyperaccumulator is an important groundwork for the phytoextraction of heavy metal-contaminated soil. Celosia argentea Linn., which grew on a Mn tailing wasteland, was found to hyperaccumulate Mn (14 362mgkg(-1) in leaf dry matter) in this study. To investigate Mn tolerance and accumulation in C. argentea, a hydroponic culture experiment was conducted in a greenhouse. Results showed that the biomass and the relative growth rate of C. argentea were insignificantly different (p>0.05) at the Mn supply level ranging from 2.5mgL(-1) (control) to 400mgL(-1). Manganese concentrations in leaves, stems, and roots reached maxima of 20228, 8872, and 2823mgkg(-1) at 600mgMnL(-1), respectively. The relative rate of Mn accumulation increased by 91.2% at 400mgMnL(-1). Over 95% of the total Mn taken up by C. argentea was translocated to shoots. Thus, C. argentea exhibits the basic characteristics of a Mn-hyperaccumulator. This species has great potential to remediate Mn-contaminated soil cheaply and can also aid the studies of Mn uptake, translocation, speciation, distribution and detoxification in plants. PMID:24444455
Liu, Jie; Shang, Weiwei; Zhang, Xuehong; Zhu, Yinian; Yu, Ke
in Hyperaccumulator Plants. Tuesday, November 3, 2009: 3:00 PM Convention Center, Room 334, Third Floor Matthew Siebecker1, Tiziana Centofanti2, Rufus Chaney2 and Donald Sparks1, (1)Plant and Soil Sciences, Univ. of Delaware, Newark, DE (2)USDA-ARS, Beltsville, MD Hyperaccumulating plants have an extraordinary ability
Sparks, Donald L.
Root cell walls accumulate metal cations both during acquisition from the environment and removal from the protoplast to avoid toxicity, but molecular forms of the metals under field conditions remain elusive. We have identified how copper is bound to cell walls of intact roots of native Thlaspi arvense by combining synchrotron X-ray fluorescence and absorption techniques (XANES and EXAFS) at the nano-, micro-, and bulk scales. The plants grew naturally in sediment in a stormwater runoff basin at copper concentrations typical of urban ecosystems. About 90% of acquired copper is bound in vivo to cell walls as a unique five-coordinate Cu(II)-bis(L-histidinato) complex with one L-histidine behaving as a tridentate ligand (histamine-like chelate) and the other as a bidentate ligand (glycine-like chelate). Tridentate binding of Cu(II) would provide thermodynamic stability to protect cells against copper toxicity, and bidentate binding may enable kinetic lability along the cell wall through protein-protein docking with the non-bonded imidazole group of histidine residues. EXAFS spectra are provided as ESI to facilitate further identification of Cu-histidine and distinction of Cu-N from Cu-O bonds in biomolecules. PMID:24185827
Manceau, Alain; Simionovici, Alexandre; Lanson, Martine; Perrin, Jonathan; Tucoulou, Rķmi; Bohic, Sylvain; Fakra, Sirine C; Marcus, Matthew A; Bedell, Jean-Philippe; Nagy, Kathryn L
Field pennycress (Thlaspi arvense L.) has potential as an oilseed crop that may be grown during fall (autumn) and winter months in the Midwestern United States and harvested in the early spring as a biodiesel feedstock. There has been little agronomic improvement in pennycress through traditional breeding. Recent advances in genomic technologies allow for the development of genomic tools to enable rapid improvements to be made through genomic assisted breeding. Here we report an annotated transcriptome assembly for pennycress. RNA was isolated from representative plant tissues, and 203 million unique Illumina RNA-seq reads were produced and used in the transcriptome assembly. The draft transcriptome assembly consists of 33 873 contigs with a mean length of 1242 bp. A global comparison of homology between the pennycress and Arabidopsis transcriptomes, along with four other Brassicaceae species, revealed a high level of global sequence conservation within the family. The final assembly was functionally annotated, allowing for the identification of putative genes controlling important agronomic traits such as flowering and glucosinolate metabolism. Identification of these genes leads to testable hypotheses concerning their conserved function and to rational strategies to improve agronomic properties in pennycress. Future work to characterize isoform variation between diverse pennycress lines and develop a draft genome sequence for pennycress will further direct trait improvement. PMID:23786378
Dorn, Kevin M; Fankhauser, Johnathon D; Wyse, Donald L; Marks, M David
Engineering copper hyperaccumulation in plants by expressing a prokaryotic copC gene.
In this work, engineering Cu-hyperaccumulation in plants was approached. First, the copC gene from Pseudomonas sp. Az13, encoding a periplasmic Cu-binding protein, was expressed in Arabidopsis thaliana driven by the CaMV35S promoter (transgenic lines 35S-copC). 35S-copC lines showed up to 5-fold increased Cu accumulation in roots (up to 2000 ?g Cu. g(-1)) and shoots (up to 400 ?g Cu. g(-1)), compared to untransformed plants, over the limits established for Cu-hyperaccumulators. 35S lines showed enhanced Cu sensitivity. Second, copC was engineered under the control of the cab1 (chlorophyll a/b binding protein 1) promoter, in order to drive copC expression to the shoots (transgenic lines cab1-copC). cab1-copC lines showed increased Cu translocation factors (twice that of wild-type plants) and also displayed enhanced Cu sensitivity. Finally, subcellular targeting the CopC protein to plant vacuoles was addressed by expressing a modified copC gene containing specific vacuole sorting determinants (transgenic lines 35S-copC-V). Unexpectedly, increased Cu-accumulation was not achieved-neither in roots nor in shoots-when compared to 35S-copC lines. Conversely, 35S-copC-V lines did display greatly enhanced Cu-hypersensitivity. Our results demonstrate the feasibility of obtaining Cu-hyperaccumulators by engineering a prokaryotic Cu-binding protein, but they highlight the difficulty of altering the exquisite Cu homeostasis in plants. PMID:23020547
RodrĒguez-Llorente, Ignacio D; Lafuente, Alejandro; Doukkali, Bouchra; Caviedes, Miguel A; Pajuelo, Eloisa
Interactions between endophytic bacterial communities and hyperaccumulators in heavy metal-polluted sites are not fully understood. In this study, the diversity of stem-associated endophytic bacterial communities of two hyperaccumulators (Solanum nigrum L. and Phytolacca acinosa Roxb.) growing in mine soils was investigated using molecular-based methods. The denaturing gradient gel electrophoresis (DGGE) analysis showed that the endophytic bacterial community structures were affected by both the level of heavy metal pollution and the plant species. Heavy metal in contaminated soil determined, to a large extent, the composition of the different endophytic bacterial communities in S. nigrum growing across soil series (five sampling spots, and the concentration of Cd is from 0.2 to 35.5 mg/kg). Detailed analysis of endophytic bacterial populations by cloning of 16S rRNA genes amplified from the stems of the two plants at the same site revealed a different composition. A total of 51 taxa at the genus level that included ?-, ?-, and ?-Proteobacteria (68.8% of the two libraries clones), Bacteroidetes (9.0% of the two libraries clones), Firmicutes (2.0% of the two libraries clones), Actinobacteria (16.4% of the two libraries clones), and unclassified bacteria (3.8% of the two libraries clones) were found in the two clone libraries. The most abundant genus in S. nigrum was Sphingomonas (23.35%), while Pseudomonas prevailed in P. acinosa (21.40%). These results suggest that both heavy metal pollution and plant species contribute to the shaping of the dynamic endophytic bacterial communities associated with stems of hyperaccumulators. PMID:24595752
Chen, Liang; Luo, Shenglian; Chen, Jueliang; Wan, Yong; Li, Xiaojie; Liu, Chengbin; Liu, Feng
Molecular Mechanisms of Selenium Tolerance and Hyperaccumulation in Stanleya pinnata1[W][OA
The molecular mechanisms responsible for selenium (Se) tolerance and hyperaccumulation were studied in the Se hyperaccumulator Stanleya pinnata (Brassicaceae) by comparing it with the related secondary Se accumulator Stanleya albescens using a combination of physiological, structural, genomic, and biochemical approaches. S. pinnata accumulated 3.6-fold more Se and was tolerant to 20 ?m selenate, while S. albescens suffered reduced growth, chlorosis and necrosis, impaired photosynthesis, and high levels of reactive oxygen species. Levels of ascorbic acid, glutathione, total sulfur, and nonprotein thiols were higher in S. pinnata, suggesting that Se tolerance may in part be due to increased antioxidants and up-regulated sulfur assimilation. S. pinnata had higher selenocysteine methyltransferase protein levels and, judged from liquid chromatography-mass spectrometry, mainly accumulated the free amino acid methylselenocysteine, while S. albescens accumulated mainly the free amino acid selenocystathionine. S. albescens leaf x-ray absorption near-edge structure scans mainly detected a carbon-Se-carbon compound (presumably selenocystathionine) in addition to some selenocysteine and selenate. Thus, S. albescens may accumulate more toxic forms of Se in its leaves than S. pinnata. The species also showed different leaf Se sequestration patterns: while S. albescens showed a diffuse pattern, S. pinnata sequestered Se in localized epidermal cell clusters along leaf margins and tips, concentrated inside of epidermal cells. Transcript analyses of S. pinnata showed a constitutively higher expression of genes involved in sulfur assimilation, antioxidant activities, defense, and response to (methyl)jasmonic acid, salicylic acid, or ethylene. The levels of some of these hormones were constitutively elevated in S. pinnata compared with S. albescens, and leaf Se accumulation was slightly enhanced in both species when these hormones were supplied. Thus, defense-related phytohormones may play an important signaling role in the Se hyperaccumulation of S. pinnata, perhaps by constitutively up-regulating sulfur/Se assimilation followed by methylation of selenocysteine and the targeted sequestration of methylselenocysteine. PMID:20498337
Freeman, John L.; Tamaoki, Masanori; Stushnoff, Cecil; Quinn, Colin F.; Cappa, Jennifer J.; Devonshire, Jean; Fakra, Sirine C.; Marcus, Matthew A.; McGrath, Steve P.; Van Hoewyk, Doug; Pilon-Smits, Elizabeth A.H.
Analyses were carried out to identify boron (B) hyperaccumulating plant species in an actively B- mined area of Kirka, Eskiflehir, Turkey. Only 4 plant species, Gypsophila sphaerocephala Fenzl ex Tchihat. var. sphaerocephala (Caryophyllaceae), Gypsophila perfoliata L. (Caryophyllaceae), Puccinellia distans (Jacq.) Parl. subsp. distans (Gramineae) and Elymus elongatus (Host) Runemark subsp. turcicus (McGuire) Melderis (Gramineae), were identified in the highest B-
Mehmet BABAO; Ali TOPAL; H³seyin DURAL
NASA Astrophysics Data System (ADS)
The absorption and accumulation of Pb, Zn, Cu and Cd in some endurant weed plant species that survived in an old smeltery in Liaoning, China, were systematically investigated. Potential hyperaccumulative characteristics of these species were also discussed. The results showed that metal accumulation in plants differed with species, tissues and metals. Endurant weed plants growing in this contaminated site exhibited high metal adaptability. Both the metal exclusion and detoxification tolerance strategies were involved in the species studied. Seven species for Pb and four species for Cd were satisfied for the concentration time level standard for hyperaccumulator. Considering translocation factor (TF) values, one species for Pb, seven species for Zn, two species for Cu and five species for Cd possessed the characteristic of hyperaccumulator. Particularly, Abutilon theophrasti Medic, exhibited strong accumulative ability to four heavy metals. Although enrichment coefficients of all samples were lesser than 1 and the absolute concentrations didnÆt reach the standard, species mentioned above were primarily believed to be potential hyperaccumulators.
Cui, Shuang; Zhou, Qixing; Chao, Lei
A new method, the artificially high soil cadmium (Cd) concentration method, was used to screen for Cd hyperaccumulators among winter farmland weeds. Galinsoga parviflora was the most promising remedial plant among 5 Cd accumulators or hyperaccumulators. In Cd concentration gradient experiments, as soil Cd concentration increased, root and shoot biomass decreased, and their Cd contents increased. In additional concentration gradient experiments, superoxide dismutase and peroxidase activities increased with soil Cd concentrations up to 75?mg?kg(-1) , while expression of their isoenzymes strengthened. Catalase (CAT) activity declined and CAT isoenzyme expression weakened at soil Cd concentrations less than 50?mg?kg(-1) . The maxima of Cd contents in shoots and roots were 137.63?mg?kg(-1) and 105.70?mg?kg(-1) , respectively, at 100?mg?kg(-1) Cd in soil. The root and shoot bioconcentration factors exceeded 1.0, as did the translocation factor. In a field experiment, total extraction of Cd by shoots was 1.35?mg?m(-2) to 1.43?mg?m(-2) at soil Cd levels of 2.04?mg?kg(-1) to 2.89?mg?kg(-1) . Therefore, the artificially high soil Cd concentration method was effective for screening Cd hyperaccumulators. Galinsoga parviflora is a Cd hyperaccumulator that could be used to efficiently remediate Cd-contaminated farmland soil. Environ Toxicol Chem 2014;33:2422-2428. ® 2014 SETAC. PMID:25053512
Lin, Lijin; Jin, Qian; Liu, Yingjie; Ning, Bo; Liao, Ming'an; Luo, Li
Little is known about how fungi affect plant selenium (Se) accumulation. Here we investigate the effects of two fungi on Se accumulation, translocation, and chemical speciation in the hyperaccumulator Astragalus racemosus and the non-accumulator Astragalus convallarius. The fungi, Alternaria astragali (A3) and Fusarium acuminatum (F30), were previously isolated from Astragalus hyperaccumulator rhizosphere. A3-inoculation enhanced growth of A. racemosus yet inhibited growth of A. convallarius. Selenium treatment negated these effects. F30 reduced shoot-to-root Se translocation in A. racemosus. X-ray microprobe analysis showed no differences in Se speciation between inoculation groups. The Astragalus species differed in Se localization and speciation. A. racemosus root-Se was distributed throughout the taproot and lateral root and was 90 % organic in the lateral root. The related element sulfur (S) was present as a mixture of organic and inorganic forms in the hyperaccumulator. Astragalus convallarius root-Se was concentrated in the extreme periphery of the taproot. In the lateral root, Se was exclusively in the vascular core and was only 49 % organic. These findings indicate differences in Se assimilation between the two species and differences between Se and S speciation in the hyperaccumulator. The finding that fungi can affect translocation may have applications in phytoremediation and biofortification. PMID:23117393
Lindblom, Stormy Dawn; Fakra, Sirine C; Landon, Jessica; Schulz, Paige; Tracy, Benjamin; Pilon-Smits, Elizabeth A H
The influence of various cadmium concentrations on organic acid levels in leaves of the Cd hyperaccumulator, Solanum nigrum L. and a closely related species, Solanum melongena L., were investigated. In particular, the relationship of organic acids with Cd accumulation in the two plants was investigated. The results showed that Cd accumulation in the shoots of S. nigrum was significantly higher
Rui-lian Sun; Qi-xing Zhou; Cai-xia Jin
Phytoremediation is a cost-effective, simple and sustainable beneficiary technique to purify the polluted environment. Solanum nigrum L., a newly found cadmium (Cd) hyperaccumulator, has shown the potential to remediate Cd-contaminated soils. Present study investigated the effects of fertilizer amendments on the Cd uptake by S. nigrum. Chicken manure and urea are usual agricultural fertilizers and more environmental friendly. The results
Shuhe Wei; Yunmeng Li; Qixing Zhou; Mrittunjai Srivastava; Siuwai Chiu; Jie Zhan; Zhijie Wu; Tieheng Sun
Extraordinarily high leaf metal concentrations in metal hyperaccumulator plants may serve as an elemental defence against herbivores. However, mixed results have been reported and studies using comparative approaches are missing. We investigated the deterrent and toxic potential of metals employing the hyperaccumulator Arabidopsis halleri. Effects of zinc (Zn) and cadmium (Cd) on the preferences of three Brassicaceae specialists were tested in paired-choice experiments using differently treated plant material, including transgenic plants. In performance tests, we determined the toxicity and joint effects of both metals incorporated in an artificial diet on the survival of a generalist. Feeding by all specialists was significantly reduced by metal concentrations from above 1000Ā?gĀZnĀg(-1) DW and 18Ā?gĀCdĀg(-1) DW. By contrast, metals did not affect oviposition. Generalist survival decreased with increasing concentrations of individual metals, whereby the combination of Zn and Cd had an additive toxic effect even at the lowest applied concentrations of 100Ā?gĀZnĀg(-1) and 2Ā?gĀCdĀg(-1) . Metal hyperaccumulation protects plants from herbivory resulting from deterrence and toxicity against a wide range of herbivores. The combination of metals exacerbates toxicity through joint effects and enhances elemental defence. Thus, metal hyperaccumulation is ecologically beneficial for plants. PMID:24383491
Kazemi-Dinan, Ardeshir; Thomaschky, Sina; Stein, Ricardo J; Krõmer, Ute; M³ller, Caroline
, and other elements, in an effort to ascertain the mechanism used by this plant to tolerate extremely highThe hyperaccumulator Alyssum murale uses complexation with nitrogen and oxygen donor ligands for Ni Laboratory, Department of Plant and Soil Sciences, University of Kentucky, N122S Agricultural Sciences North
Sparks, Donald L.
of hyperaccumulator plant species in useful phytoextraction technologies. Much research has focused on elements which and are cost prohibitive; and on plant species which offer no useful phytoextraction capability (e.g., Brassica of this review is phytoextraction, a developing technology that uses plants to accumulate elements from
Sparks, Donald L.
Radiotracer techniques were employed to characterize 65Zn adsorption and desorption in root-cell-wall of hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) species of Sedum alfredii Hance. The results indicated that at the end of a 30 min short time radioisotope loading period, comparable amounts of 65Zn were accumulated in the roots of the two ecotypes Sedum alfredii, whereas 2.1-fold more 65Zn remains in NHE root after 45-min desorption. At the end of 60 min uptake period, no difference of 65Zn accumulation was observed in undesorbed root-cell-wall of Sedum alfredii. However, 3.0-fold more 65Zn accumulated in desorbed root-cell-wall of NHE. Zn2+ binding in root-cell-wall preparations of NHE was greater than that in HE under high Zn2+ concentration. All these results suggested that root-cell-wall of the two ecotypes Sedum alfredii had the same ability to adsorb Zn2+, whereas the desorption characteristics were different, and with most of 65Zn binding on root of HE being available for loading into the xylem, as a result, more 65Zn was translocated to the shoot. PMID:17266186
Li, Ting-qiang; Yang, Xiao-e; Meng, Fan-hua; Lu, Ling-li
In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylolytics and cellulolytics) and bacterial resistance to Co, Cr, and Ni in bulk and rhizosphere soils of three populations of the Ni-hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum and the excluder Dactylis glomerata from ultramafic sites (two populations in Northeast (NE) Portugal (Samil (S), Morais (M)) and one population in Northwest (NW) Spain (Melide (L)). The relationship between bioavailable metal concentrations (H2O-soluble) and microbial densities were analysed. Significant differences in microbial densities and metal-resistance were observed between the two species and their three populations. The hyperaccumulator showed higher microbial densities (except cellulolytics) and a greater rhizosphere effect, but this was only observed in S and M populations. These populations of A. serpyllifolium also showed selective enrichment of Ni-tolerant bacteria at the rhizosphere where Ni solubility was enhanced (densities of Ni-resistant bacteria were positively correlated with H2O-soluble Ni). These rhizobacteria could solubilise Ni in the soil and potentially improve phytoextraction strategies. PMID:19810353
Becerra-Castro, C; Monterroso, C; GarcĒa-Lest¾n, M; Prieto-Fernßndez, A; Acea, M J; Kidd, P S
Cellular Sequestration of Cadmium in the Hyperaccumulator Plant Species Sedum alfredii1[C][W
Spatial imaging of cadmium (Cd) in the hyperaccumulator Sedum alfredii was investigated in vivo by laser ablation inductively coupled plasma mass spectrometry and x-ray microfluorescence imaging. Preferential Cd accumulation in the pith and cortex was observed in stems of the Cd hyperaccumulating ecotype (HE), whereas Cd was restricted to the vascular bundles in its contrasting nonhyperaccumulating ecotype. Cd concentrations of up to 15,000 ?g g?1 were measured in the pith cells, which was many fold higher than the concentrations in the stem epidermis and vascular bundles in the HE plants. In the leaves of the HE, Cd was mainly localized to the mesophyll and vascular cells rather than the epidermis. The distribution pattern of Cd in both stems and leaves of the HE was very similar to calcium but not zinc, irrespective of Cd exposure levels. Extended x-ray absorption fine structure spectroscopy analysis showed that Cd in the stems and leaves of the HE was mainly associated with oxygen ligands, and a larger proportion (about 70% in leaves and 47% in stems) of Cd was bound with malic acid, which was the major organic acid in the shoots of the plants. These results indicate that a majority of Cd in HE accumulates in the parenchyma cells, especially in stems, and is likely associated with calcium pathways and bound with organic acid (malate), which is indicative of a critical role of vacuolar sequestration of Cd in the HE S. alfredii. PMID:22025609
Tian, Shengke; Lu, Lingli; Labavitch, John; Yang, Xiaoe; He, Zhenli; Hu, Hening; Sarangi, Ritimukta; Newville, Matt; Commisso, Joel; Brown, Patrick
Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and {gamma}-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in addition to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism.
Freeman, J.L.; Zhang, L.H.; Marcus, M.A.; Fakra, S.; McGrath,S.P.; Pilon-Smits, E.A.H.
Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and ?-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in addition to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism. PMID:16920881
Freeman, John L.; Zhang, Li Hong; Marcus, Matthew A.; Fakra, Sirine; McGrath, Steve P.; Pilon-Smits, Elizabeth A.H.
Little is known about how fungi affect elemental accumulation in hyperaccumulators (HAs). Here, two rhizosphere fungi from selenium (Se) HA Stanleya pinnata, Alternaria seleniiphila (A1) and Aspergillus leporis (AS117), were used to inoculate S. pinnata and related non-HA Stanleya elata. Growth and Se and sulfur (S) accumulation were analyzed. Furthermore, X-ray microprobe analysis was used to investigate elemental distribution and speciation. Growth of S. pinnata was not affected by inoculation or by Se. Stanleya elata growth was negatively affected by AS117 and by Se, but combination of both did not reduce growth. Selenium translocation was reduced in inoculated S. pinnata, and inoculation reduced S translocation in both species. Root Se distribution and speciation were not affected by inoculation in either species; both species accumulated mainly (90%) organic Se. Sulfur, in contrast, was present equally in organic and inorganic forms in S. pinnata roots. Thus, these rhizosphere fungi can affect growth and Se and/or S accumulation, depending on host species. They generally enhanced root accumulation and reduced translocation. These effects cannot be attributed to altered plant Se speciation but may involve altered rhizosphere speciation, as these fungi are known to produce elemental Se. Reduced Se translocation may be useful in applications where toxicity to herbivores and movement of Se into the food chain is a concern. The finding that fungal inoculation can enhance root Se accumulation may be useful in Se biofortification or phytoremediation using root crop species. PMID:24032473
Lindblom, Stormy Dawn; Fakra, Sirine C; Landon, Jessica; Schulz, Paige; Tracy, Ben; Pilon-Smits, Elizabeth A H
Root responses to soil Ni heterogeneity in a hyperaccumulator and a non-accumulator species.
We compared root responses of the Ni-hyperaccumulator plant Berkheya coddii Rossler with the non-accumulator plant Cicer arietinum L. to Ni heterogeneity in soil. We grew plants in growth containers filled with control soil, homogeneously spiked, and heterogeneously spiked soil with Ni concentrations of 62 and 125 mg kg(-1). Neutron radiography (NR) was used to observe the root distribution and the obtained images were analysed to reveal the root volumes in the spiked and unspiked segments of the growth container. There was no significant difference in root distribution pattern of B. coddii among different concentrations of Ni. Unlike B. coddii, the roots of C. arietinum initially grew into the spiked segments. However, the later developing roots did not penetrate the spiked segment suggesting an avoidance strategy. Our results indicate that, B. coddii does not forage towards the Ni-rich patches, although presence of Ni in soil changes its root morphology. PMID:19427726
Moradi, Ahmad B; Conesa, Hķctor M; Robinson, Brett H; Lehmann, Eberhard; Kaestner, Anders; Schulin, Rainer
X-ray absorption spectroscopy at the Ni-K edge in Stackhousia tryonii Bailey hyperaccumulator
Young plants of Stackhousia tryonii Bailey were exposed to 34 mM Ni kg-1 in the form of NiSO4- 6H2O solution and grown under controlled glasshouse conditions for a period of 20 days. Fresh leaf, stem and root samples were analysed in vivo by micro x-ray absorption spectroscopy (XAS) at the Ni-K edge.Both x-ray absorption near edge structure and extended x-ray absorption fine structure spectra were analysed, and theresulting spectra were compared with spectra obtained from nine biologically important Ni-containing model compounds. The results revealed that themajority of leaf, stem and root Ni in the hyperaccumulator was chelated by citrate.Our results also suggest that in leavesNi is complexed by phosphate and histidine, and in stems and roots, phytate and histidine. The XAS results provide an important physiological insightinto transport, detoxification and storage of Ni in S. tryonii plants.
Ionescu, Mihail; Bhatia, Naveen P.; Cohen , David D.; Siegele, R.; Marcus, Matthew A.; Fakra, Sirine C.; Foran, G.; Kachenko, A.
A field study was conducted to evaluate the phytoremediation efficiency of cadmium (Cd) contaminated soil utilizing the Cd hyperaccumulator Beta vulgaris L. var. cicla during one growing season (about 2 months) on farmland in Zhangshi Irrigation Area, the representative wastewater irrigation area in China. Results showed that B. vulgaris L. var. cicla is a promising plant in the phytoremediation of Cd contaminated farmland soil. The maximum of Cd phytoremediation efficiency by B. vulgaris L. var. cicla reached 144.6 mg/ha during one growing season. Planting density had a significant effect on the plant biomass and the overall Cd phytoremediation efficiency (p < 0.05). The amendment of organic manure promoted the biomass increase of B. vulgaris L. var. cicla (p < 0.05) but inhibited the Cd phytoremediation efficiency. PMID:22286610
Song, Xueying; Hu, Xiaojun; Ji, Puhui; Li, Yushuang; Chi, Guangyu; Song, Yufang
Evaluation of hyperaccumulator plant species grown in metalliferous sites in Albania
NASA Astrophysics Data System (ADS)
Heavy metal contamination of soils causes serious problems to our society. A small number of interesting plant species have been identified that can grow in soils containing high levels of heavy metals, and can also accumulate these metals to high concentrations in the shoot. The heavy metal contents in root, shoot, leaves and flowers of spontaneous plants grown in metalliferous sites in Albania together with the elemental composition of the native soils were determined by X-ray fluorescence spectrometry. Efficiency of photosynthetic apparatus of analyzed ecotypes was evaluated via chlorophyll fluorescence imaging during induction kinetics. Response of plant root system to the presence of metals, the available pools of metals to plants, effect of plant biomass to phytoextraction, photosynthetic pigment metabolism and chlorophyll fluorescence signature of leaves allowed to characterize hyperaccumulator properties and to detect the variation between selected ecotypes to heavy metal accumulation.
Babani, F.; Civici, N.; Mullaj, A.; Kongjika, E.; Ylli, A.
Uranium phytoextraction, the use of plants to extract U from contaminated soils, is an emerging technology. The authors report on the development of this technology for the cleanup of U-contaminated soils. In this research, they investigated the effects of various soil amendments on U desorption from soil to soil solution, studied the physiological characteristics of U uptake and accumulation in plants, and developed techniques to trigger U hyperaccumulation in plants. A key to the success of U phytoextraction is to increase soil U availability to plants. The authors have found that some organic acids can be added to soils to increase U desorption from soil to soil solution and to trigger a rapid U accumulation in plants. Of the organic acids (acetic acid, citric acid, and malic acid) tested, citric acid was the most effective in enhancing U accumulation in plants. Shoot U concentrations of Brassica juncea and Brassica chinensis grown in a U-contaminated soil increased from less than 5 mg kg{sup {minus}1} to more than 5,000 mg kg{sup {minus}1} in citric acid-treated soils. To their knowledge, this is the highest shoot U concentration reported for plants grown on U-contaminated soils. Using this U hyperaccumulation technique, they are now able to increase U accumulation in shoots of selected plant species grown in two U-contaminated soils by more than 1,000-fold within a few days. The results suggest that U phytoextraction may provide an environmentally friendly alternative for the cleanup of U-contaminated soils.
Huang, J.W.; Blaylock, M.J.; Kapulnik, Y.; Ensley, B.D. [Phytotech Inc., Monmouth Junction, NJ (United States)] [Phytotech Inc., Monmouth Junction, NJ (United States)
Noccaea caerulescens is an extremophile plant species belonging to the Brassicaceae family. It has adapted to grow on soils containing high, normally toxic, concentrations of metals such as nickel, zinc, and cadmium. Next to being extremely tolerant to these metals, it is one of the few species known to hyperaccumulate these metals to extremely high concentrations in their aboveground biomass. In order to provide additional molecular resources for this model metal hyperaccumulator species to study and understand the mechanism of adaptation to heavy metal exposure, we aimed to provide a comprehensive database of transcript sequences for N. caerulescens. In this study, 23,830 transcript sequences (isotigs) with an average length of 1025 bp were determined for roots, shoots and inflorescences of N. caerulescens accession "Ganges" by Roche GS-FLEX 454 pyrosequencing. These isotigs were grouped into 20,378 isogroups, representing potential genes. This is a large expansion of the existing N. caerulescens transcriptome set consisting of 3705 unigenes. When translated and compared to a Brassicaceae proteome set, 22,232 (93.2%) of the N. caerulescens isotigs (corresponding to 19,191 isogroups) had a significant match and could be annotated accordingly. Of the remaining sequences, 98 isotigs resembled non-plant sequences and 1386 had no significant similarity to any sequence in the GenBank database. Among the annotated set there were many isotigs with similarity to metal homeostasis genes or genes for glucosinolate biosynthesis. Only for transcripts similar to Metallothionein3 (MT3), clear evidence for an additional copy was found. This comprehensive set of transcripts is expected to further contribute to the discovery of mechanisms used by N. caerulescens to adapt to heavy metal exposure. PMID:24999345
Lin, Ya-Fen; Severing, Edouard I; Te Lintel Hekkert, Bas; Schijlen, Elio; Aarts, Mark G M
The aim of this study was to isolate and characterize endophytic bacteria from roots, stems and leaves of Zn\\/Cd hyperaccumulator\\u000a Sedum alfredii. Endophytic bacteria were observed in roots, stems and leave of S. alfredii, with a significantly higher density in roots, followed by leave and stems. A total of fourteen bacterial endophytes were\\u000a isolated and are closely related phylogenetically to
Long Xinxian; Chen Xuemei; Chen Yagang; Wong Jonathan Woon-Chung; Wei Zebin; Wu Qitang
Investigations of soil-root interactions are hampered by the difficult experimental accessibility of the rhizosphere. Here\\u000a we show the potential of Magnetic Resonance Imaging (MRI) as a non-destructive measurement technique in combination with numerical\\u000a modelling to study the dynamics of the spatial distribution of dissolved nickel (Ni2+) around the roots of the nickel hyperaccumulator plant Berkheya coddii. Special rhizoboxes were used
A. B. Moradi; S. E. Oswald; J. A. Nordmeyer-Massner; K. P. Pruessmann; B. H. Robinson; R. Schulin
Valuable endophytic strains facilitating plants growth and detoxification of heavy metals are required because the application\\u000a of plant¢endophyte symbiotic system is a promising potential technique to improve efficiency of phytoremediation. In this\\u000a study, endophytic bacterium LRE07 was isolated from cadmium hyperaccumulator Solanum nigrum L. It was identified as Serratia sp. by 16S rRNA sequence analysis. The endophytic bacterium LRE07 was
Shenglian Luo; Yong Wan; Xiao Xiao; Hanjun Guo; Liang Chen; Qiang Xi; Guangming Zeng; Chengbin Liu; Jueliang Chen
The fern Pityrogramma calomelanos is a hyperaccumulator of arsenic that grows readily on arsenic-contaminated soils in the Ron Phibun district of southern Thailand. P. calomelanos accumulates arsenic mostly in the fronds (up to 8350 ?g As g?1 dry mass) while the rhizoids contain the lowest concentrations of arsenic (88¢310 ?g As g?1 dry mass). The arsenic species in aqueous extracts
Kevin Francesconi; Pornsawan Visoottiviseth; Weeraphan Sridokchan; Walter Goessler
Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined. The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 ?mol/L Zn2+ and/or 200 ?mol/L Cd2+ increased linearly within 15 d. Contents of total S, glutathione (GSH) and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd2+ treatment than under Zn2+ treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn2+-treated shoots than in Cd2+-treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2+-treated leaf than in the Cd2+-treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2+ and Cd2+ for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2. PMID:18357627
Chao, Yue-en; Zhang, Min; Tian, Sheng-ke; Lu, Ling-li; Yang, Xiao-e
Gulf annual ryegrass has been identified as potential Pi hyperaccumulator, however the molecular mechanism remains largely\\u000a unknown. A suppression subtractive hybridization (SSH) analysis was used to evaluate the phosphate (Pi) responsive genome\\u000a expression pattern changes in Gulf annual ryegrass (Lolium multiflorum L.). Differential screening identified 384 putative Pi-starvation induced cDNAs. Bioinformatic analysis revealed that 116\\u000a cDNAs are nonredundant unigenes of
Perumal Venkatachalam; Ajay Jain; Shivendra Sahi; Kashchandra Raghothama
Genetic variation in salt (Na(2)SO(4), NaCl) and boron (B) tolerance among four ecotypes of the selenium (Se) hyperaccumulator Stanleya pinnata (Pursh) Britton was utilized to select tolerant genotypes capable of phytoremediating Se from salt, B, and Se-laden agricultural drainage sediment. The few individual salt/B tolerant genotypes were successfully selected from among a large population of highly salt/B sensitive seedlings. The distribution, hyperaccumulation, and volatilization of Se were then examined in selected plants capable of tolerating the high salt/B laden drainage sediment. Salt/B tolerant genotypes from each of the four ecotypes had mean Se concentrations ranging from 2510 ▒ 410 to 1740 ▒ 620 in leaves and 3180 ▒ 460 to 2500 ▒ 1060 in seeds (?g Se g(-1) DW ▒ SD), while average daily Se volatilization rates ranged from 722 ▒ 375 to 1182 ▒ 575 (?g Se m(-2) d(-1) ▒ SD). After two growing seasons (?18 months), we estimated that hyperaccumulation and volatilization of Se by tolerant S. pinnata genotypes and their associated microbes can remove approximately 30% of the total soil Se in 0-30 cm sediment. The salt/B tolerant S. pinnata genotypes selected and characterized herein represent promising new tools for the successful phytoremediation of Se from salt/B and Se-laden agricultural drainage sediments. PMID:21988205
Freeman, John L; Ba±uelos, Gary S
We isolated and characterized As-resistant endophytic bacteria (AEB) from two arsenic hyperaccumulators. Their plant growth promoting traits and the relation between As tolerance and transformation were evaluated. A total of 41 and 33 AEB were isolated from Pteris vittata (PV) and Pteris multifida (PM) respectively. PV AEB represented 2genera while PM AEB comprised of 12 genera, with Bacillus sp. being the most dominant bacteria from both plants. All AEB had limited ability in solubilizing P and producing indole acetic acid (IAA) and siderophore. All isolates tolerated 10mM arsenate (As(V)), with PV isolates being more tolerant to As(V) and PM more tolerant to arsenite (As(III)). Bacterial arsenic tolerance was related to their ability in As(III) oxidation and As(V) reduction as well as their ability to retain As in the biomass to a varying extent. Though AEB showed limited plant growth promoting traits, they were important in arsenic tolerance and speciation in plants. PMID:25065783
Zhu, Ling-Jia; Guan, Dong-Xing; Luo, Jun; Rathinasabapathi, Bala; Ma, Lena Q
We investigated the effects of arsenic species on As accumulation, plant growth and rhizospheric changes in As-hyperaccumulator Pteris vittata (PV). PV was grown for 60-d in a soil spiked with 200ĀmgĀkg(-1) arsenate (AsV-soil) or arsenite (AsIII-soil). Diffusive gradients in thin-films technique (DGT) were used to monitor As uptake by PV. Interestingly AsIII-soil produced the highest PV biomass at 8.6ĀgĀplant(-1), 27% and 46% greater than AsV-soil and the control. Biomass increase was associated with As-induced P uptake by PV. Although AsIII was oxidized to AsV during the experiment, As species impacted As accumulation by PV, with 17.5% more As in AsIII-soil than AsV-soil (36 vs. 31ĀmgĀplant(-1)). As concentration in PV roots was 30% higher in AsV-soil whereas As concentration in PV fronds was 7.9% greater in AsIII-soil, suggesting more rapid translocation of AsIII than AsV. These findings were important to understand the mechanisms of As uptake, accumulation and translocation by PV. PMID:25103044
Xu, Jia Yi; Li, Hong Bo; Liang, Shuang; Luo, Jun; Ma, Lena Q
A rare earth element (REE) hyperaccumulator, Dicranopteris dichotoma, that accumulates more than 0.1% REEs dry leaf mass has been discovered in southern China. The different components of chloroplast were isolated and the concentration of REEs in each component was determined by ICP-MS. The experimental data indicated that about 8% of total leaf REEs was present in the chloroplast of Dicranopteris dichotoma. In order to thoroughly study the distribution of REEs among different components of chloroplast, the membrane of chloroplast, the intact thylakoid and the photosystem II (PS II system) of D. dichotoma were isolated from the chloroplast. It was found that half of total chloroplast REEs was stored at the membrane of the chloroplast and another half was in the thylakoid. And 25% of total chloroplast REEs was bound with PS II system of D.dichotoma. The concentration of REEs in chlorophyll a was only at the level of microg/g on the bases of chlorophylls. These data are useful for understanding of both the storage of REEs in chloroplast and the effect of REEs on the photosynthesis of plants. PMID:12827335
Wang, Xiao-Ping; Shan, Xiao-Quan; Zhang, Shu-Zhen; Wen, Bei
[Preliminary analysis of manganese uptake mechanism in the hyperaccumulator Phytolacca americana L].
Phytolacca americana L. (P. americana) is a manganese (Mn) hyperaccumulator plant discovered in southern China, and knowledge of Mn uptake characteristics and mechanisms on this plant may provide essential and critical information for phytoremediation. Synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) microprobe was empolyed in this study to explore the Mn distribution in the root cross-section of P. americana, and effects of metabolic inhibitors (DNP and Na3VO4) and Ca-channel inhibitor (LaCl3) on Mn uptake of P. americana was also investigated under laboratory conditions. Results showed that P. americana has strong abilities for absorpting and accumulating Mn, and the Mn concentration in root, stem, and leaf of P. americana may reach up to 402, 208, and 601 mg x kg(-1) DW, respectively, even only treated with 5 micromol x L(-1) Mn. The highest Mn content can be found in the vascular bundle of root, and then the epidermis, while the lowest Mn content can be observed in the cortex. The Mn content increased when shifted from cortex to vascular bundle, indicating that there was an active transportation in Mn absorption of P. americana root, and the inhibitory effect of DNP and Na3VO4 on Mn uptake further verified the possibilities of active absorption. The Mn uptake was inhibited by 30% with LaCl3, suggesting that Mn uptake in P. americana also closely related to the Ca-channel. PMID:24455960
Xu, Xiang-Hua; Li, Ren-Ying; Liu, Cui-Ying; Shi, Ji-Yan; Lin, Jia
Selenium (Se) hyperaccumulator plants can concentrate the toxic element Se up to 1% of shoot (DW) which is known to protect hyperaccumulator plants from generalist herbivores. There is evidence for Se-resistant insect herbivores capable of feeding upon hyperaccumulators. In this study, resistance to Se was investigated in seed chalcids and seed beetles found consuming seeds inside pods of Se-hyperaccumulator species Astragalus bisulcatus and Stanleya pinnata. Selenium accumulation, localization and speciation were determined in seeds collected from hyperaccumulators in a seleniferous habitat and in seed herbivores. Astragalus bisulcatus seeds were consumed by seed beetle larvae (Acanthoscelides fraterculus Horn, Coleoptera: Bruchidae) and seed chalcid larvae (Bruchophagus mexicanus, Hymenoptera: Eurytomidae). Stanleya pinnata seeds were consumed by an unidentified seed chalcid larva. Micro X-ray absorption near-edge structure (ĄXANES) and micro-X-Ray Fluorescence mapping (ĄXRF) demonstrated Se was mostly organic C-Se-C forms in seeds of both hyperaccumulators, and S. pinnata seeds contained ?24% elemental Se. Liquid chromatography-mass spectrometry of Se-compounds in S. pinnata seeds detected the C-Se-C compound seleno-cystathionine while previous studies of A. bisulcatus seeds detected the C-Se-C compounds methyl-selenocysteine and ?-glutamyl-methyl-selenocysteine. Micro-XRF and ĄXANES revealed Se ingested from hyperaccumulator seeds redistributed throughout seed herbivore tissues, and portions of seed C-Se-C were biotransformed into selenocysteine, selenocystine, selenodiglutathione, selenate and selenite. Astragalus bisulcatus seeds contained on average 5,750 Ąg Se g(-1), however adult beetles and adult chalcid wasps emerging from A. bisulcatus seed pods contained 4-6 Ąg Se g(-1). Stanleya pinnata seeds contained 1,329 Ąg Se g(-1) on average; however chalcid wasp larvae and adults emerging from S. pinnata seed pods contained 9 and 47 Ąg Se g(-1). The results suggest Se resistant seed herbivores exclude Se, greatly reducing tissue accumulation; this explains their ability to consume high-Se seeds without suffering toxicity, allowing them to occupy the unique niche offered by Se hyperaccumulator plants. PMID:23226523
Freeman, John L; Marcus, Matthew A; Fakra, Sirine C; Devonshire, Jean; McGrath, Steve P; Quinn, Colin F; Pilon-Smits, Elizabeth A H
Selenium (Se) hyperaccumulator plants can concentrate the toxic element Se up to 1% of shoot (DW) which is known to protect hyperaccumulator plants from generalist herbivores. There is evidence for Se-resistant insect herbivores capable of feeding upon hyperaccumulators. In this study, resistance to Se was investigated in seed chalcids and seed beetles found consuming seeds inside pods of Se-hyperaccumulator species Astragalus bisulcatus and Stanleya pinnata. Selenium accumulation, localization and speciation were determined in seeds collected from hyperaccumulators in a seleniferous habitat and in seed herbivores. Astragalus bisulcatus seeds were consumed by seed beetle larvae (Acanthoscelides fraterculus Horn, Coleoptera: Bruchidae) and seed chalcid larvae (Bruchophagus mexicanus, Hymenoptera: Eurytomidae). Stanleya pinnata seeds were consumed by an unidentified seed chalcid larva. Micro X-ray absorption near-edge structure (ĄXANES) and micro-X-Ray Fluorescence mapping (ĄXRF) demonstrated Se was mostly organic C-Se-C forms in seeds of both hyperaccumulators, and S. pinnata seeds contained ?24% elemental Se. Liquid chromatography¢mass spectrometry of Se-compounds in S. pinnata seeds detected the C-Se-C compound seleno-cystathionine while previous studies of A. bisulcatus seeds detected the C-Se-C compounds methyl-selenocysteine and ?-glutamyl-methyl-selenocysteine. Micro-XRF and ĄXANES revealed Se ingested from hyperaccumulator seeds redistributed throughout seed herbivore tissues, and portions of seed C-Se-C were biotransformed into selenocysteine, selenocystine, selenodiglutathione, selenate and selenite. Astragalus bisulcatus seeds contained on average 5,750 Ąg Se g?1, however adult beetles and adult chalcid wasps emerging from A. bisulcatus seed pods contained 4¢6 Ąg Se g?1. Stanleya pinnata seeds contained 1,329 Ąg Se g?1 on average; however chalcid wasp larvae and adults emerging from S. pinnata seed pods contained 9 and 47 Ąg Se g?1. The results suggest Se resistant seed herbivores exclude Se, greatly reducing tissue accumulation; this explains their ability to consume high-Se seeds without suffering toxicity, allowing them to occupy the unique niche offered by Se hyperaccumulator plants. PMID:23226523
Freeman, John L.; Marcus, Matthew A.; Fakra, Sirine C.; Devonshire, Jean; McGrath, Steve P.; Quinn, Colin F.; Pilon-Smits, Elizabeth A. H.
Some heavy metals (HM) are highly reactive and consequently can be toxic to living cells when present at high levels. Consequently, strategies for reducing HM toxicity in the environmental must be undertaken. This work focused on evaluating the Nickel (Ni) accumulation potential of the hyperaccumulator Solanum nigrum L., and the participation of metallothioneins (MT) in the plant Ni homeostasis. Metallothioneins (MT) are gene-encoded metal chelators that participate in the transport, sequestration and storage of metals. After different periods of exposure to different Ni concentrations, plant biometric and biochemical parameters were accessed to determine the effects caused by this pollutant. Semi-quantitative RT-PCR reactions were performed to investigate the specific accumulation of MT-related transcripts throughout the plant and in response to Ni exposure. The data obtained revealed that Ni induced toxicity symptoms and accumulated mostly in roots, where it caused membrane damage in the shock-treated plants, with a parallel increase of free proline content, suggesting that proline participates in protecting root cells from oxidative stress. The MT-specific mRNA accumulation analysis showed that MT2a- and MT2d-encoding genes are constitutively active, that Ni stimulated their transcript accumulation, and also that Ni induced the de novo accumulation of MT2c- and MT3-related transcripts in shoots, exerting no influence on MT1 mRNA accumulation. These results strongly suggest the involvement of MT2a, MT2c, MT2d and MT3 in S. nigrum Ni homeostasis and detoxification, this way contributing to the clarification of the roles the various types of MTs play in metal homeostasis and detoxification in plants. PMID:22763093
Ferraz, Pedro; Fidalgo, Fernanda; Almeida, Agostinho; Teixeira, Jorge
Cd-induced changes in leaf proteome of the hyperaccumulator plant Phytolacca americana.
Cadmium (Cd) is highly toxic to all organisms. Soil contamination by Cd has become an increasing problem worldwide due to the intensive use of Cd-containing phosphate fertilizers and industrial zinc mining. Phytolacca americana L. is a Cd hyperaccumulator plant that can grow in Cd-polluted areas. However, the molecular basis for its remarkable Cd resistance is not known. In this study, the effects of Cd exposure on protein expression patterns in P.americana was investigated by 2-dimensional gel electrophoresis (2-DE). 2-DE profiles of leaf proteins from both control and Cd-treated (400?M, 48h) seedlings were compared quantitatively using ImageMaster software. In total, 32 differentially expressed protein spots were identified using MALDI-TOF/TOF mass spectrometry coupled to protein database search, corresponding to 25 unique gene products. Of those 14 were enhanced/induced while 11 reduced under Cd treatment. The alteration pattern of protein expression was verified for several key proteins involved in distinct metabolic pathways by immuno-blot analysis. Major changes were found for the proteins involved in photosynthetic pathways as well as in the sulfur- and GSH-related metabolisms. One-third of the up-regulated proteins were attributed to transcription, translation and molecular chaperones including a protein belonging to the calreticulin family. Other proteins include antioxidative enzymes such as 2-cys-peroxidase and oxidoreductases. The results of this proteomic analysis provide the first and primary information regarding the molecular basis of Cd hypertolerance in P. americana. PMID:21723586
Zhao, Le; Sun, Yong-Le; Cui, Su-Xia; Chen, Mei; Yang, Hao-Meng; Liu, Hui-Min; Chai, Tuan-Yao; Huang, Fang
.1016/j.cub.2011.07.033 Article Selenium Hyperaccumulators Facilitate Selenium-Tolerant Neighbors via surrounding selenium (Se) hyperaccumula- tor plants was shown earlier to be enriched in Se, impairing selenium (Se) is a trace element for many animals as a component of selenoproteins, which are redox
Hydrangea (Hydrangea macrophylla) is tolerant of acidic soils in which toxicity generally arises from the presence of the soluble aluminum (Al) ion. When hydrangea is cultivated in acidic soil, its resulting blue sepal color is caused by the Al complex formation of anthocyanin. The concentration of vacuolar Al in blue sepal cells can reach levels in excess of approximately 15 mM, suggesting the existence of an Al-transport and/or storage system. However, until now, no Al transporter has been identified in Al hyperaccumulating plants, animals or microorganisms. To identify the transporter being responsible for Al hyperaccumulation, we prepared a cDNA library from blue sepals according to the sepal maturation stage, and then selected candidate genes using a microarray analysis and an in silico study. Here, we identified the vacuolar and plasma membrane-localized Al transporters genes vacuolar Al transporter (VALT) and plasma membrane Al transporter 1 (PALT1), respectively, which are both members of the aquaporin family. The localization of each protein was confirmed by the transient co-expression of the genes. Reverse transcription-PCR and immunoblotting results indicated that VALT and PALT1 are highly expressed in sepal tissue. The overexpression of VALT and PALT1 in Arabidopsis thaliana conferred Al-tolerance and Al-sensitivity, respectively. PMID:22952644
Negishi, Takashi; Oshima, Kenshiro; Hattori, Masahira; Kanai, Masatake; Mano, Shoji; Nishimura, Mikio; Yoshida, Kumi
Hydrangea (Hydrangea macrophylla) is tolerant of acidic soils in which toxicity generally arises from the presence of the soluble aluminum (Al) ion. When hydrangea is cultivated in acidic soil, its resulting blue sepal color is caused by the Al complex formation of anthocyanin. The concentration of vacuolar Al in blue sepal cells can reach levels in excess of approximately 15 mM, suggesting the existence of an Al-transport and/or storage system. However, until now, no Al transporter has been identified in Al hyperaccumulating plants, animals or microorganisms. To identify the transporter being responsible for Al hyperaccumulation, we prepared a cDNA library from blue sepals according to the sepal maturation stage, and then selected candidate genes using a microarray analysis and an in silico study. Here, we identified the vacuolar and plasma membrane-localized Al transporters genes vacuolar Al transporter (VALT) and plasma membrane Al transporter 1 (PALT1), respectively, which are both members of the aquaporin family. The localization of each protein was confirmed by the transient co-expression of the genes. Reverse transcription-PCR and immunoblotting results indicated that VALT and PALT1 are highly expressed in sepal tissue. The overexpression of VALT and PALT1 in Arabidopsis thaliana conferred Al-tolerance and Al-sensitivity, respectively. PMID:22952644
Negishi, Takashi; Oshima, Kenshiro; Hattori, Masahira; Kanai, Masatake; Mano, Shoji; Nishimura, Mikio; Yoshida, Kumi
NASA Astrophysics Data System (ADS)
Certain plants known as `metal hyperaccumulators' can accumulate exceptional concentrations of elements such as zinc, manganese, nickel, cobalt, copper, selenium, cadmium or arsenic in their above ground tissue. In members of the genus Alyssum, nickel concentrations can reach values as high as 3% of leaf dry biomass. These plants must possess very effective mechanisms for the transport, chelation and sequestration of such elements within their tissues to avoid the toxic effects of free metal ions. Evidence from a number of different techniques suggests that nickel is concentrated primarily in the outermost, epidermal tissue of leaves of Alyssum hyperaccumulators, but there is currently no consensus on the principal sites of nickel sequestration. In this study, high resolution secondary ion mass spectrometry (NanoSIMS) analysis has been performed on longitudinal sections of Alyssum lesbiacum leaves. Elemental maps were obtained which revealed the high concentrations of nickel in the peripheral regions of the large unicellular stellate leaf hairs (trichomes) and in the epidermal cell layer. Electron probe microanalysis (EPMA) was used to provide independent confirmation of elemental distribution in the specimens, but the superior spatial resolution and high chemical sensitivity of the NanoSIMS technique provided a more detailed image of elemental distribution in these biological specimens at the cellular level.
Smart, K. E.; Kilburn, M. R.; Salter, C. J.; Smith, J. A. C.; Grovenor, C. R. M.
NASA Astrophysics Data System (ADS)
Certain terrestrial plants are able to accumulate metals such as zinc, manganese, nickel, cobalt, or copper in their above-ground biomass. The largest group of these so-called "metal hyperaccumulators" is to be found among certain species in the family Brassicaceae endemic to ultramafic soils. For example, nickel concentrations in members of the genus Alyssum can reach 3% of the leaf dry biomass. However, nickel levels in the root tissue of these plants are low, suggesting that hyperaccumulation is associated with effective metal translocation from root to shoot and sequestration of the metal in non-toxic form within the leaves. To investigate the sites of nickel localization within A. lesbiacum, leaf cross-sections were examined by nuclear microscopy using PIXE and RBS on the Oxford Scanning Proton Microprobe (SPM) with a spatial resolution of 1 ?m. This paper describes the sample preparation and analysis methods and presents some preliminary results indicating that nickel is sequestered to a considerable degree within the epidermal trichomes on the leaf surface.
Krõmer, U.; Grime, G. W.; Smith, J. A. C.; Hawes, C. R.; Baker, A. J. M.
Amending soils with Se-hyperaccumulator plant derived sources of selenium (Se) may be useful for increasing the Se content in food crops in Se-deficient regions of the world. In this study we evaluated total Se and the different chemical species of Se in broccoli and carrots grown in soils amended with ground shoots of the Se-hyperaccumulator Stanleyapinnata. With increasing application rates of S. pinnata, total plant Se concentrations increased to nutritionally ideal levels inside edible parts. Selenium compounds in aqueous extracts were analyzed by SAX-HPLC-ICPMS and identified as a variety of mainly organic-Se forms. Together with bulk Se K-edge X-ray absorption near-edge structure (XANES) analysis performed on broccoli florets, carrot roots and shoots, dried ground S. pinnata, and the amended soil at post-plant, we demonstrate that Se-enriched S. pinnata is valuable as a soil amendment for enriching broccoli and carrots with healthful forms of organic-Se. PMID:25053099
Ba±uelos, Gary S; Arroyo, Irvin; Pickering, Ingrid J; Yang, Soo In; Freeman, John L
The Zn/Cd hyperaccumulator, Noccaea caerulescens, has been studied extensively for its ability to accumulate high levels of Zn and Cd in its leaves. Previous studies have indicated that the Zn and Cd hyperaccumulation trait exhibited by this species involves different transport and tolerance mechanisms. It has also been well documented that certain ecotypes of N.Ācaerulescens are much better Cd hyperaccumulators than others. However, there does not seem to be much ecotypic variation for Zn hyperaccumulation in N.Ācaerulescens. In this study we employed a comparative transcriptomics approach to look at root and shoot gene expression in Ganges and Prayon plants in response to Cd stress to identify transporter genes that were more highly expressed in either the roots or shoots of the superior Cd accumulator, Ganges. Comparison of the transcriptomes from the two ecotypes of Noccaea caerulescens identified a number of genes that encoded metal transporters that were more highly expressed in the Ganges ecotype in response to Cd stress. Characterization of one of these transporters, NcNramp1, showed that it is involved in the influx of Cd across the endodermal plasma membrane and thus may play a key role in Cd flux into the stele and root-to-shoot Cd transport. NcNramp1 may be one of the main transporters involved in Cd hyperaccumulation in N.Ācaerulescens and copy number variation appears to be the main reason for high NcNramp1 gene expression underlying the increased Cd accumulation in the Ganges ecotype. PMID:24547775
Milner, Matthew J; Mitani-Ueno, Namiki; Yamaji, Naoki; Yokosho, Kengo; Craft, Eric; Fei, Zhangjun; Ebbs, Stephen; Clemencia Zambrano, M; Ma, Jian Feng; Kochian, Leon V
Valuable endophytic strains facilitating plants growth and detoxification of heavy metals are required because the application of plant-endophyte symbiotic system is a promising potential technique to improve efficiency of phytoremediation. In this study, endophytic bacterium LRE07 was isolated from cadmium hyperaccumulator Solanum nigrum L. It was identified as Serratia sp. by 16S rRNA sequence analysis. The endophytic bacterium LRE07 was resistant to the toxic effects of heavy metals, solubilized mineral phosphate, and produced indoleacetic acid and siderophore. The heavy metal detoxification was studied in growing LRE07 cells. The strain bound over 65% of cadmium and 35% of zinc in its growing cells from single metal solutions 72 h after inoculation. Besides the high removal efficiencies in single-ion system, an analogous removal phenomenon was also observed in multi-ions system, indicating that the endophyte possesses specific and remarkable heavy metal remediation abilities. PMID:20953602
Luo, Shenglian; Wan, Yong; Xiao, Xiao; Guo, Hanjun; Chen, Liang; Xi, Qiang; Zeng, Guangming; Liu, Chengbin; Chen, Jueliang
Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was used to investigate the metabolism of selenium and arsenic after single and simultaneous supplementation. Size exclusion and ion-pairing reversed phase liquid chromatography were coupled to an inductively coupled plasma mass spectrometer to obtain putative metabolic information of the selenium and arsenic species in C. comosum after a mild aqueous extraction. The chromatographic results depict that selenium and arsenic species were sequestered in the roots and generally conserved upon translocation to the leaves. The data suggest that selenium was directly absorbed by C. comosum roots when supplemented with Se(VI), but a combination of passive and direct absorption occurred when supplemented with Se(IV) due to the partial oxidation of Se(IV) to Se(VI) in the rhizosphere. Higher molecular weight selenium species were more prevalent in the roots of plants supplemented with Se(IV), but in the leaves of plants supplemented with Se(VI) due to an increased translocation rate. When supplemented as As(III), arsenic is proposed to be passively absorbed as As(III) and partially oxidized to As(V) in the plant root. Although total elemental analysis demonstrates a selenium and arsenic antagonism, a compound containing selenium and arsenic was not present in the general aqueous extract of the plant. PMID:19273464
Afton, Scott E; Catron, Brittany; Caruso, Joseph A
Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was used to investigate the metabolism of selenium and arsenic after single and simultaneous supplementation. Size exclusion and ion-pairing reversed phase liquid chromatography were coupled to an inductively coupled plasma mass spectrometer to obtain putative metabolic information of the selenium and arsenic species in C. comosum after a mild aqueous extraction. The chromatographic results depict that selenium and arsenic species were sequestered in the roots and generally conserved upon translocation to the leaves. The data suggest that selenium was directly absorbed by C. comosum roots when supplemented with SeVI, but a combination of passive and direct absorption occurred when supplemented with SeIV due to the partial oxidation of SeIV to SeVI in the rhizosphere. Higher molecular weight selenium species were more prevalent in the roots of plants supplemented with SeIV, but in the leaves of plants supplemented with SeVI due to an increased translocation rate. When supplemented as AsIII, arsenic is proposed to be passively absorbed as AsIII and partially oxidized to AsV in the plant root. Although total elemental analysis demonstrates a selenium and arsenic antagonism, a compound containing selenium and arsenic was not present in the general aqueous extract of the plant. PMID:19273464
Afton, Scott E.; Catron, Brittany; Caruso, Joseph A.
Hyperaccumulator of Pb in native plants growing on Peruvian mine tailings
NASA Astrophysics Data System (ADS)
Tailings usually provide an unfavourable substrate for plant growth because of their extreme pH, low organic matter and nutrients, high concentrations of trace elements and physical disturbance, such as bad soil structure, and low water availability. Heavy metal contamination has also been one serious problem in the vicinity of mine sites due to the discharge and dispersion of mine-waste materials into the ecosystem. Moreover, Pb is considered a target metal when undertaking soil remediation, because it is usually quite immobile and not readily accumulated in upper plant parts. The presence of vegetation reduces water and wind erosion, which may decrease the downward migration of contaminants into the groundwater and improve aesthetical aspects. Plants growing on naturally metal-enriched soils are of particular interest in this perspective, since they are genetically tolerant to high metal concentrations, have an excellent adaptation to this multi-stress environment. Efficient phytoextraction requires plant species combining both high metal tolerance and elevated capacity for metal uptake and metal translocation to easily harvestable plant organs (e.g. shoots). Soil and plant samples were taken in Peru, at a polymetallic mine (mainly Ag, Pb and Cu) in Cajamarca Province, Hualgayoc district. Top soils (0-20 cm) were analysed for physical and chemical properties by standard methods. Total Pb concentrations in top soils were determined by ICP-OES. Pb content in plants were analysed separately (aerial and root system) by ICP-MS. Ti content was used as an indicator for contamination of plant samples with soil particles. Translocation Factor (TF) and Shoot Accumulation Factor (SAF) were determined to assess the tolerance strategies developed by these species and to evaluate their potential for phytoremediation purposes. The non-polluted soils had near neutral pH (6.8▒0.1), a great content of organic carbon (42 ▒ 4.0 gĢkg-1) and a silt loamy texture. Soil and plant samples were taken at four locations (CA1, CA2, CA3, CA4) with different levels of Pb. The Pb soil content (mean ▒ standard deviation) in mgĢkg-1 is as follows: CA1 3992 ▒ 301; CA2 10128 ▒ 2247, CA3 14197 ▒ 895, CA4 16060 ▒ 810. The non-polluted value around the mine was Pb 124 mgĢkg-1. Unusual elevated concentrations of Pb (over 1000 mg kg-1) and TF greater than one were detected in shoots of 6 different plants species (Ageratina sp., Achirodine alata, Cortaderia apalothica, Epilobium denticulatum, Taraxacum officinalis and Trifolium repens). The location CA4 has the maximum content of Pb in the shoots of Ageratina sp. (5045▒77 mgĢkg-1), C. apalothica (3367▒188 mgĢkg-1), E. denticulatum (13599▒848 mgĢkg-1), T. officinalis (2533▒47 mgĢkg-1) and T. repens (2839▒231 mgĢkg-1). However, the BF (Bioaccumulation Factor) was smaller than one. Despite the low BF index, the great TFs for Pb indicate that these plant species effectively translocate this metal (i.e., 2.4 for Ageratina sp., 2.3 for C. apalothica, 1.6 for T. repens, 1.5 for A. alata, 1.3 for T. officinalis and 1.2 for E. denticulatum). It seems that the BF is not a reliable index when the metal soil concentration is extremely large. Controlled-environment studies must be performed to definitively confirm the Pb hyperaccumulation character of cited plant species.
Bech, Jaume; Roca, Nuria; Boluda, Rafael; Tume, Pedro; Duran, Paola; Poma, Wilfredo; Sanchez, Isidoro
Sedum alfredii, a cadmium (Cd) and zinc (Zn) hyperaccumulator at a mine located in Qu Zhou City, Zhejiang Province, China, can accumulate\\u000a Cd and Zn exceeding 1,000 and 10,000Āmg kg?1, respectively in its shoot (dry weight) when growing under metal-contaminated habitats. Several strains of bacteria were\\u000a isolated from the rhizosphere of S. alfredii thriving in different Pb\\/Zn mines in Hunan
W. C. Li; Z. H. Ye; M. H. Wong
The phenomenon of metal hyperaccumulation by plants is often explained by a pathogen or herbivore defense hypothesis. However, some insects feeding on metal hyperaccumulating plants are adapted to the high level of metals in plant tissues. Former studies on species that feed on the leaves of Berkheya coddii Roessler 1958 (Asteraceae), a nickel-hyperaccumulating plant, demonstrated several protective mechanisms involved in internal distribution, immobilization, and elimination of Ni from the midgut and Malpighian tubules. These species are mainly coleopterans, including the lady beetle, Epilachna nylanderi (Mulsant 1850) (Coleoptera: Coccinellidae), collected from the ultramafic ecosystem near Barberton in South Africa. By performing particle-induced X-ray emission microanalysis elemental microanalysis (PIXE), this study examined whether Ni may be harmful to internal body systems that decide on insect reactivity (central nervous system [CNS]), their reproduction, and the relationships between Ni and other micronutrients. Data on elemental distribution of nine selected elements in target organs of E. nylanderi were compared with the existing data for other insect species adapted to the excess of metals. Micro-PIXE maps of seven regions of the CNS showed Ni mainly in the neural connectives, while cerebral ganglia were better protected. Concentrations of other bivalent metals were lower than those of Ni. Testis, compared with other reproductive organs, showed low amounts of Ni. Zn was effectively regulated at physiological dietary levels. In insects exposed to excess dietary Zn, it was also accumulated in the reproductive organs. Comparison of E. nylanderii with other insects that ingest hyperaccumulating plants, especially chrysomelid Chrysolina clathrata (Clark) (Coleoptera: Chrysomelidae), showed lower protection of the CNS and reproductive organs. PMID:25399425
Mesjasz-Przyby?owicz, Jolanta; Or?owska, El?bieta; Augustyniak, Maria; Nakonieczny, Miros?aw; Tarnawska, Monika; Przyby?owicz, Wojciech; Migula, Pawe?
We investigated effects of arsenate (AsV), chromate (CrVI) and sulfate on As and Cr uptake and translocation by arsenic hyperaccumulator Pteris vittata (PV), which was exposed to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25ĀmM for 2-wk in hydroponic system. PV was effective in accumulating large amounts of As (4598 and 1160Āmg/kg in the fronds and roots at 0.05ĀmM AsV) and Cr (234 and 12,630Āmg/kg in the fronds and roots at 0.05ĀmM CrVI). However, when co-present, AsV and CrVI acted as inhibitors, negatively impacting their accumulation in PV. Arsenic accumulation in the fronds was reduced by 92% and Cr by 26%, indicating reduced As and Cr translocation. However, addition of sulfate increased uptake and translocation of As by 26-28% and Cr by 1.63 fold. This experiment demonstrated that As and Cr inhibited each other in uptake and translocation by PV but sulfate enhanced As and Cr uptake and translocation by PV. PMID:24056188
de Oliveira, Let·zia Maria; Ma, Lena Q; Santos, Jorge A G; Guilherme, Luiz R G; Lessl, Jason T
Mechanisms of cadmium (Cd)-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata were investigated using photosynthesis limitation analysis. P.Ādivaricata seedlings were grown in nutrient solution containing 0, 5, 10, 25, 50, or 75Ā?M Cd for 2 weeks. Total limitations to photosynthesis (TL) increased from 0% at 5Ā?M Cd to 68.8% at 75Ā?M Cd. CO2 diffusional limitation (DL) made the largest contribution to TL, accounting for 93-98% of TL in the three highest Cd treatments, compared to just 2-7% of TL attributable to biochemical limitation (BL). Microscopic imaging revealed significantly decreased stomatal density and mesophyll thickness in the three highest Cd treatments. Chlorophyll fluorescence parameters related to photosynthetic biochemistry (Fv/Fm, NPQ, ?PSII, and qP) were not significantly decreased by increased Cd supply. Our results suggest that increased DL in leaves is the main cause of Cd-induced inhibition of photosynthesis in P.Ādivaricata, possibly due to suppressed function of mesophyll and stomata. Analysis of chlorophyll fluorescence showed that Cd supply had little effect on photochemistry parameters, suggesting that the PSII reaction centers are not a main target of Cd inhibition of photosynthesis in P.Ādivaricata. PMID:24077231
Tang, Lu; Ying, Rong-Rong; Jiang, Dan; Zeng, Xiao-Wen; Morel, Jean-Louis; Tang, Ye-Tao; Qiu, Rong-Liang
The Kotodesh genotype of the nickel (Ni) hyperaccumulator Alyssum murale was examined to determine the compartmentalization and internal speciation of Ni, and other elements, in an effort to ascertain the mechanism used by this plant to tolerate extremely high shoot (stem and leaf) Ni concentrations. Plants were grown either hydroponically or in Ni enriched soils from an area surrounding an historic Ni refinery in Port Colborne, Ontario, Canada. Electron probe micro-analysis (EPMA) and synchrotron based micro X-ray fluorescence ({mu}-SXRF) spectroscopy were used to determine the metal distribution and co-localization and synchrotron X-ray and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopies were used to determine the Ni speciation in plant parts and extracted sap. Nickel is concentrated in the dermal leaf and stem tissues of A. murale bound primarily to malate along with other low molecular weight organic ligands and possibly counter anions (e.g., sulfate). Ni is present in the plant sap and vasculature bound to histidine, malate and other low molecular weight compounds. The data presented herein supports a model in which Ni is transported from the roots to the shoots complexed with histidine and stored within the plant leaf dermal tissues complexed with malate, and other low molecular weight organic acids or counter-ions.
McNear, Jr., D.; Chanay, R; Sparks, D
Plants with capacity to accumulate high levels of selenium (Se) are desired for phytoremediation and biofortification. Plants of genus Astragalus accumulate and tolerate high levels of Se, but their slow growth, low biomass and non-edible properties limit their direct utilization. Genetic engineering may be an alternative way to produce edible or high biomass Se-accumulating plants. The first step towards this goal is to isolate genes that are responsible for Se accumulation and tolerance. Later, these genes can be introduced into other edible and high biomass plants. In the present study, we applied fluorescent differential display to analyze the transcript profile of Se-hyperaccumulator A. racemosus treated with 20 ?M selenate (K(2)SeO(4)) for 2 weeks. Among 125 identified Se-responsive candidate genes, the expression levels of nine were induced or suppressed more than twofold by selenate treatment in two independent experiments while 14 showed such changes when treated with selenite (K(2)SeO(3)). Six of them were found to respond to both selenate and selenite treatments. A novel gene CEJ367 was found to be highly induced by both selenate (1,920-fold) and selenite (579-fold). Root- or shoot-preferential expression of nine genes was further investigated. These identified genes may allow us to create Se-enriched transgenic plants. PMID:22362314
Hung, Chiu-Yueh; Holliday, Bronwyn M; Kaur, Harvinder; Yadav, Ruchi; Kittur, Farooqahmed S; Xie, Jiahua
Subcellular distribution of rare earth elements (REEs, including 14 lanthanides and yttrium) in a newly discovered REE hyperaccumulator, Pronephrium simplex (P. simplex), was determined by a chemical sequence extraction followed by ICP-MS analysis. Results showed that most REEs are associated with cell wall and proteins, and REEs concentration in the proteins, 2899.5mugg(-1), is much higher than those in the cell wall; in the chloroplast of P. simplex, REEs distribute almost equally in chloroplast membrane and thylakoid, while most REEs in the thylakoid are binding with photosystem II (PS II); a new REE-binding peptide in the lamina of P. simplex, which can accumulate REEs up to 3000mugg(-1) and has higher affinity with light REEs, was characterized, indicating that its molecular mass is 5073Da, and may have beta-sheet structure; isoelectrofocusing electrophoretic photograph indicated that it is acidic peptide with IP of 3.7. Such information should be useful for understanding of both the storage and physiological role of REEs in P. simplex and further studies on the phytoremediation of REEs contaminated environments. PMID:18970723
Lai, Ying; Wang, Qiuquan; Yang, Limin; Huang, Benli
In vivo speciation of zinc in Noccaea caerulescens in response to nitrogen form and zinc exposure
Nitrate has been shown to enhance Zn hyperaccumulation in the shoots of Noccaea caerulescens (formerly Thlaspi caerulescens) (Prayon); however, the mechanisms beyond the effect of nitrogen form are unknown. This study used synchrotron X-ray absorption\\u000a near-edge spectroscopy (XANES) on alive and intact plants at room temperature to examine whether enhanced Zn hyperaccumulation\\u000a in nitrate-fed plants was associated with differences in
Alison C. Monsant; Peter Kappen; Yaodong Wang; Paul J. Pigram; Alan J. M. Baker; Caixian Tang
A greenhouse pot experiment was conducted to study the effects of three types of single inoculum [indigenous mycorrhizas (IM) isolated from As mine, Glomus mosseae (GM) and Glomus intraradices (GI)] and two types of mixed inoculum (mixed with IM and either GM or GI) on the growth response of Pteris vittata (hyperaccumulator) and Cynodon dactylon (non-hyperaccumulator) at three levels of As concentrations (0, 100 and 200mgkg(-1)). Both mycorrhizal plants exhibited significantly higher biomass, and N and P accumulation in its tissue than the control. Among the mycorrhizal inoculum, the mixed inoculum IM/GM promoted substantially higher mycorrhizal colonization and arsenate reductase activity in P. vittata than C. dactylon, among all As levels. The portion of Paris arbuscular mycorrhizal structure (observed in colonized roots) together with the highest As translocation factor of 10.2 in P. vittata inoculated with IM/GM was also noted. It was deduced that IM/GM inoculum may be the best choice for field inoculation at any contaminated lands as the inoculum exhibited better adaptation to variable environmental conditions and hence benefited the host plants. PMID:23755987
Leung, H M; Leung, A O W; Ye, Z H; Cheung, K C; Yung, K K L
Although the period covered by this progress report began on December 20, 1994, which was the date that DOE approved the Interagency Agreement, the agreement was not approved by USDA until January 9, 1995 and the first scientists working on the project were not hired until February 1, 1995. The first goal of the research supported by the Interagency Agreement is to use hydroponic techniques to identify plant species and genotypes with potential for heavy metal hyperaccumulation for planting on a test site at Silverbow Creek and for radionuclide ({sup 90}Sr and {sup 137}Cs) accumulation on a test site at INEL, Idaho, later this year. The second goal of this research is to identify soil amendment procedures that will enhance the bioavailability of heavy metals and radionuclides in the soil without increasing the movement of the contaminants of concern (COC`s) into the groundwater. Our initial research covered in this report focuses on the first goal.
Kochian, L.; Brady, D.; Last, M.; Ebbs, S.
This laboratory has been involved in a collaborative project focusing on a range of issues related to the phytoremediation of heavy metal-and radionuclide- contaminated soils. While much of the research has been fundamental in nature, involving physiological and molecular characterizations of the mechanisms of hyperaccumulation in plants, the laboratory is also investigating more practical issues related to phytoremediation. A central issue in this latter research has been the identification of amendments capable of increasing the bioavailability and subsequent phytoextraction of radionuclides. The results described here detail these efforts for uranium and Cs-137. A study was also conducted on a Cs-137 contaminated site at Brookhaven National Laboratory (BNL), which allowed application of the laboratory and greenhouse results to a field setting.
Kochian, L.
Hyperaccumulation: A Phytoremedial Approach
\\u000a The prime requisite of agriculture is soil which serves as a reservoir of nutrients and water for the crops. Unfortunately,\\u000a all the soil available on this planet is not arable, fertile, and it remains agriculturally unproductive. Land is mainly contaminated\\u000a with heavy metals like Zn, Pb, Cr, Ni, and Cd. Metal-rich mine tailings, metal smelting, electroplating, gas exhausts, fuel\\u000a production,
Shalini Srivastava; Pritee Goyal
To identify potential regulators of photoassimilate partitioning, we screened for rice mutant plants that accumulate high levels of starch in the leaf blades, and a mutant line leaf starch excess 1 (LSE1) was obtained and characterized. The starch content in the leaf blades of LSE1 was more than 10-fold higher than that in wild-type plants throughout the day, while the sucrose content was unaffected. The gene responsible for the LSE1 phenotype was identified by gene mapping to be a gene encoding ?-glucan water dikinase, OsGWD1 (Os06g0498400), and a 3.4-kb deletion of the gene was found in the mutant plant. Despite the hyperaccumulation of starch in their leaf blades, LSE1 plants exhibited no significant change in vegetative growth, presenting a clear contrast to the reported mutants of Arabidopsis thaliana and Lotus japonicus in which disruption of the genes for ?-glucan water dikinase leads to marked inhibition of vegetative growth. In reproductive growth, however, LSE1 exhibited fewer panicles per plant, lower percentage of ripened grains and smaller grains; consequently, the grain yield was lower in LSE1 plants than in wild-type plants by 20~40%. Collectively, although ?-glucan water dikinase was suggested to have universal importance in leaf starch degradation in higher plants, the physiological priority of leaf starch in photoassimilate allocation may vary among plant species. PMID:23750161
Hirose, Tatsuro; Aoki, Naohiro; Harada, Yusuke; Okamura, Masaki; Hashida, Yoichi; Ohsugi, Ryu; Akio, Miyao; Hirochika, Hirohiko; Terao, Tomio
Nowadays, submersed aquatic macrophytes play a key role in stream ecology and they are often used as biomonitors of freshwater quality. So, these plants appear as natural candidates to stream rehabilitation experiments. Among them, the stream macrophyte Myriophyllum alterniflorum is used recently as biomonitor and is potentially useful for the restoration of heavy-metal contaminated localities. The best way to obtain a mass production of watermilfoil plants is micropropagation. We developed in vitro culture of M. alterniflorum and the effects of five media on the plant development were assessed. Five morphological and four physiological endpoints were examined leading to the recommendation of the Murashige and Skoog medium for ecotoxicological studies on chlorophyllous parts, and of the Gaudet medium for root cytotoxicity and phytoremediation studies. Micropropagated clones were acclimatized in a synthetic medium and in situ reintroduction was performed efficiently. This is the first report of micropropagated plants transplantation in streams. The successful establishment of watermilfoil beds even in polluted areas strongly suggested that ecological restoration using micropropagated watermilfoil is a promising biotechnology for phytoremediation and rehabilitation of degraded areas. Moreover, high bioconcentration factors evidenced that watermilfoil hyperaccumulates Cd and Cu, and could be potentially used in phytoremediation studies. PMID:23819265
Delmail, David; Labrousse, Pascal; Hourdin, Philippe; Larcher, Laure; Moesch, Christian; Botineau, Michel
In order to select appropriate amendments for cropping hyperaccumulator or normal plants on contaminated soils and establish the relationship between Cd sorption characteristics of soil amendments and their capacity to reduce Cd uptake by plants, batch sorption experiments with 11 different clay minerals and organic materials and a pot experiment with the same amendments were carried out. The pot experiment was conducted with Sedum alfredii and maize (Zea mays) in a co-cropping system. The results showed that the highest sorption amount was by montmorillonite at 40.82 mg/g, while mica was the lowest at only 1.83 mg/g. There was a significant negative correlation between the n value of Freundlich equation and Cd uptake by plants, and between the logarithm of the stability constant K of the Langmuir equation and plant uptake. Humic acids (HAs) and mushroom manure increased Cd uptake by S. alfredii, but not maize, thus they are suitable as soil amendments for the co-cropping S. alfredii and maize. The stability constant K in these cases was 0.14¢0.16 L/mg and n values were 1.51¢2.19. The alkaline zeolite and mica had the best fixation abilities and significantly decreased Cd uptake by the both plants, with K ? 1.49 L/mg and n ? 3.59. PMID:24912231
Sun, Yan; Wu, Qi-Tang; Lee, Charles C.C.; Li, Baoqin; Long, Xinxian
To understand how microbial communities and functional genes respond to arsenic contamination in the rhizosphere of Pteris vittata, five soil samples with different arsenic contamination levels were collected from the rhizosphere of P. vittata and nonrhizosphere areas and investigated by Biolog, geochemical, and functional gene microarray (GeoChip 3.0) analyses. Biolog analysis revealed that the uncontaminated soil harbored the greatest diversity of sole-carbon utilization abilities and that arsenic contamination decreased the metabolic diversity, while rhizosphere soils had higher metabolic diversities than did the nonrhizosphere soils. GeoChip 3.0 analysis showed low proportions of overlapping genes across the five soil samples (16.52% to 45.75%). The uncontaminated soil had a higher heterogeneity and more unique genes (48.09%) than did the arsenic-contaminated soils. Arsenic resistance, sulfur reduction, phosphorus utilization, and denitrification genes were remarkably distinct between P. vittata rhizosphere and nonrhizosphere soils, which provides evidence for a strong linkage among the level of arsenic contamination, the rhizosphere, and the functional gene distribution. Canonical correspondence analysis (CCA) revealed that arsenic is the main driver in reducing the soil functional gene diversity; however, organic matter and phosphorus also have significant effects on the soil microbial community structure. The results implied that rhizobacteria play an important role during soil arsenic uptake and hyperaccumulation processes of P. vittata. PMID:20833780
Xiong, Jinbo; Wu, Liyou; Tu, Shuxin; Van Nostrand, Joy D.; He, Zhili; Zhou, Jizhong; Wang, Gejiao
This study investigates the heavy metal-resistant bacterial endophytes of Cd-hyperaccumulator Solanum nigrum L. grown on a mine tailing by using cultivation-dependent technique. Thirty Cd-tolerant bacterial endophytes were isolated from roots, stems, and leaves of S. nigrum L. and classified by amplified ribosomal DNA-restriction analysis into 18 different types. Phylogenetic analysis based on 16S rDNA sequences showed that these isolates belonged to four groups: Actinobacteria (43%), Proteobacteria (23%), Bacteroidetes (27%) and Firmicutes (7%). All the isolates were then characterized for their plant growth promoting traits as well as their resistances to different heavy metals; and the actual plant growth promotion and colonization ability were also assessed. Four isolates were re-introduced into S. nigrum L. under Cd stress and resulted in Cd phytotoxicity decrease, as dry weights of roots increased from 55% to 143% and dry weights of above-ground from 64% to 100% compared to the uninoculated ones. The total Cd accumulation of inoculated plants increased from 66% to 135% (roots) and from 22% to 64% (above-ground) compared to the uninoculated ones. Our research suggests that bacterial endophytes are a most promising resource and may be the excellent candidates of bio-inoculants for enhancing the phytoremediation efficiency. PMID:21868057
Luo, Sheng-lian; Chen, Liang; Chen, Jue-liang; Xiao, Xiao; Xu, Tao-ying; Wan, Yong; Rao, Chan; Liu, Cheng-bin; Liu, Yu-tang; Lai, Cui; Zeng, Guang-ming
We investigated lichen species in the habitats of the copper (Cu)-hyperaccumulating moss Scopelophila cataractae and found that the cup lichens Cladonia subconistea and C. humilis grow on this moss. We performed X-ray fluorescence and inductively coupled plasma mass (ICP-MS) analysis of lichen samples and measured the visible absorption spectra of the pigments extracted from the samples to assess the effect of Cu stress on the cup lichens. The chlorophyll a/b ratio and degradation of chlorophyll a to pheophytin a were calculated from the spectral data. X-ray fluorescence analysis indicated that Cu concentrations in cup lichens growing on S. cataractae were much higher than those in control samples growing on non-polluted soil. Moreover, Cu microanalysis showed that Cu concentrations in parts of podetia of C. subconistea growing on S. cataractae increased as the substrate (S. cataractae) was approached, whereas those of C. humilis growing on S. cataractae decreased as the substrate was approached. This reflects the difference in the route of Cu ions from the source to the podetia. Furthermore, ICP-MS analysis confirmed that C. subconistea growing on S. cataractae was heavily contaminated with Cu, indicating that this lichen is Cu tolerant. We found a significant difference between the visible absorption spectra of pigments extracted from the Cu-contaminated and control samples. Hence, the spectra could be used to determine whether a cup lichen is contaminated with Cu. Chlorophyll analysis showed that cup lichens growing on S. cataractae were affected by Cu stress. However, it also suggested that the areas of dead moss under cup lichens were a suitable substrate for the growth of the lichen. Moreover, it suggested that cup lichens had allolepathic effects on S. cataractae; it is likely that secondary metabolites produced by cup lichens inhibited moss growth. PMID:22906716
Nakajima, Hiromitsu; Fujimoto, Kenjiro; Yoshitani, Azusa; Yamamoto, Yoshikazu; Sakurai, Haruka; Itoh, Kiminori
Stable Zn isotope signatures offer a potential tool for tracing Zn uptake and transfer mechanisms within plant-soil systems. Zinc isotopic compositions were determined in the Zn hyperaccumulator Noccaea caerulescens collected at a Zn-contaminated site (Viviez), a serpentine site (Vosges), and a noncontaminated site (Sainte Eulalie) in France. Meanwhile, a Zn-tolerant plant ( Silene vulgaris ) was also collected at Viviez for comparison. While ?(66)Zn was substantially differentiated among N. caerulescens from the three localities, they all exhibited an enrichment in heavy Zn isotopes of 0.40-0.72ē from soil to root, followed by a depletion in heavy Zn from root to shoot (-0.10 to -0.50ē). The enrichment of heavy Zn in roots is ascribed to the transport systems responsible for Zn absorption into root symplast and root-to-shoot translocation, while the depletion in heavy Zn in shoots is likely to be mediated by a diffusive process and an efficient translocation driven by energy-required transporters (e.g., NcHMA4). The mass balance yielded a bulk Zn isotopic composition between plant and soil (?(66)Zn(plant-soil)) of -0.01ē to 0.63ē in N. caerulescens , indicative of high- and/or low-affinity transport systems operating in the three ecotypes. In S. vulgaris , however, there was no significant isotope fractionation between whole plant and rhizosphere soil and between root and shoot, suggesting that this species appears to have a particular Zn homeostasis. We confirm that quantifying stable Zn isotopes is useful for understanding Zn accumulation mechanisms in plants. PMID:22891730
Tang, Ye-Tao; Cloquet, Christophe; Sterckeman, Thibault; Echevarria, Guillaume; Carignan, Jean; Qiu, Rong-Liang; Morel, Jean-Louis
This study is to investigate the possibility of zinc (Zn) biofortification in the grains of rice (Oryza sativa L.) by inoculation of endophytic strains isolated from a Zn hyperaccumulator, Sedum alfredii Hance. Five endophytic strains, Burkholderia sp. SaZR4, Burkholderia sp. SaMR10, Sphingomonas sp. SaMR12, Variovorax sp. SaNR1, and Enterobacter sp. SaCS20, isolated from S. alfredii, were inoculated in the roots of Japonica rice Nipponbare under hydroponic condition. Fluorescence images showed that endophytic strains successfully colonized rice roots after 72 h. Improved root morphology and plant growth of rice was observed after inoculation with endophytic strains especially SaMR12 and SaCS20. Under hydroponic conditions, endophytic inoculation with SaMR12 and SaCS20 increased Zn concentration by 44.4% and 51.1% in shoots, and by 73.6% and 83.4% in roots, respectively. Under soil conditions, endophytic inoculation with SaMR12 and SaCS20 resulted in an increase of grain yields and elevated Zn concentrations by 20.3% and 21.9% in brown rice and by 13.7% and 11.2% in polished rice, respectively. After inoculation of SaMR12 and SaCS20, rhizosphere soils of rice plants contained higher concentration of DTPA-Zn by 10.4% and 20.6%, respectively. In situ micro-X-ray fluorescence mapping of Zn confirmed the elevated Zn content in the rhizosphere zone of rice treated with SaMR12 as compared with the control. The above results suggested that endophytic microbes isolated from S. alfredii could successfully colonize rice roots, resulting in improved root morphology and plant growth, increased Zn bioavailability in rhizosphere soils, and elevated grain yields and Zn densities in grains. PMID:24447030
Wang, Yuyan; Yang, Xiaoe; Zhang, Xincheng; Dong, Lanxue; Zhang, Jie; Wei, Yanyan; Feng, Ying; Lu, Lingli
The effects of heavy metals and phytoextraction practices on a soil microbial community were studied during 12 months using a hyperaccumulating plant (Thlaspi caerulescens) grown in an artificially contaminated soil. The 16S ribosomal RNA genes of the Bacteria and the ?-Proteobacteria and the amoA gene (encoding the ?-subunit of ammonia monooxygenase) were PCR-amplified and analysed by denaturing gradient gel electrophoresis
Fabienne Gremion; Antonis Chatzinotas; Karin Kaufmann; William Von Sigler; Hauke Harms
Joint effects of arsenic (As) and cadmium (Cd) on the growth of Bidens pilosa L. and its uptake and accumulation of As and Cd were investigated using the field pot-culture experiment. The results showed that single Cd (
Sun, Yue-bing; Zhou, Qi-xing; Liu, Wei-tao; An, Jing; Xu, Zhi-qiang; Wang, Lin
The focus of this article was to explore the translocation of (109)Cd, (57)Co, (65)Zn, (63)Ni, and (134)Cs via xylem and phloem in the newly found hyperaccumulator Solanum nigrum L. Two experiments with the uptake via the roots and transport of (109)Cd, (57)Co, and (65)Zn labeled by roots, and the redistribution of (109)Cd, (65)Zn, (57)Co, (63)Ni, and (134)Cs using flap label in S. nigrum in a hydroponic culture with a standard nutrient solution were conducted. The results showed that (109)Cd added for 24Āh to the nutrient medium of young plants was rapidly taken up, transferred to the shoot, and accumulated in the cotyledons and the oldest leaves but was not efficiently redistributed within the shoot afterward leading to a rather low content in the fruits. In contrast, (57)Co was more slowly taken up and released to the shoot, but afterward, this element was redistributed from older leaves to younger leaves and maturing fruits. (65)Zn was rapidly taken up and transferred to the shoot (mainly to the youngest leaves and not to the cotyledons). Afterward, this radionuclide was redistributed within the shoot to the youngest organs and finally accumulated in the maturing fruits. After flap labeling, all five heavy metals tested ((109)Cd, (57)Co, (65)Zn, (63)Ni, (134)Cs) were exported from the labeled leaf and redistributed within the plant. The accumulation in the fruits was most pronounced for (63)Ni and (65)Zn, while a relatively high percentage of (57)Co was finally found in the roots. (134)Cs was roughly in the middle of them. The transport of (109)Cd differed from that previously reported for wheat or lupin and might be important for the potential of S. nigrum to hyperaccumulate cadmium. PMID:24604268
Wei, Shuhe; Anders, Iwona; Feller, Urs
Phytoremediation refers to the use of plants for extraction and detoxification of pollutants, providing a new and powerful weapon against a polluted environment. In some plants, such as Thlaspi spp, heavy metal ATPases are involved in overall metal ion homeostasis and hyperaccumulation. P1B-ATPases pump a wide range of cations, especially heavy metals, across membranes against their electrochemical gradients. Determination of the protein characteristics of P1B-ATPases in hyperaccumulator plants provides a new opportuntity for engineering of phytoremediating plants. In this study, using diverse weighting and modeling approaches, 2644 protein characteristics of primary, secondary, and tertiary structures of P1B-ATPases in hyperaccumulator and nonhyperaccumulator plants were extracted and compared to identify differences between proteins in hyperaccumulator and nonhyperaccumulator pumps. Although the protein characteristics were variable in their weighting, tree and rule induction models; glycine count, frequency of glutamine-valine, and valine-phenylalanine count were the most important attributes highlighted by 10, five, and four models, respectively. In addition, a precise model was built to discriminate P1B-ATPases in different organisms based on their structural protein features. Moreover, reliable models for prediction of the hyperaccumulating activity of unknown P1B-ATPase pumps were developed. Uncovering important structural features of hyperaccumulator pumps in this study has provided the knowledge required for future modification and engineering of these pumps by techniques such as site-directed mutagenesis. PMID:21573033
Ashrafi, E.; Alemzadeh, A.; Ebrahimi, M.; Ebrahimie, E.; Dadkhodaei, N.; Ebrahimi, M.
This quarterly report describes experiments on uptake of a variety of heavy metals by plants. Titles of report sections are (1) Alleviation of heavy-metal induced micronutrient deficiency through foliar fertilization, (2) Second screen for Zn, Cu, and Cd accumulation, (3) Characterization of the root Zn hyperaccumulation by Thlaspi caerulescens, (4) Comparison of commercial Brassica accessions obtained from the Iowa seed bank, (5) Second screening experiment for the accumulation of Cs and Sr by plants, (6) Effect of Ca on Cs and Sr accumulation by selected dicot species, and (7) Preliminary investigations into the forms of uranium taken up by plants.
Kochian, L.
Phytoremediation of heavy metal polluted soils and water: progresses and perspectives.
Environmental pollution affects the quality of pedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources. PMID:18357623
Lone, Mohammad Iqbal; He, Zhen-li; Stoffella, Peter J; Yang, Xiao-e
Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives*
Environmental pollution affects the quality of pedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources. PMID:18357623
Lone, Mohammad Iqbal; He, Zhen-li; Stoffella, Peter J.; Yang, Xiao-e
Accumulation and hyperaccumulation of copper in plants
NASA Astrophysics Data System (ADS)
Copper is natural component of our environment. Flow of copper(II) ions in the environment depends on solubility of compounds containing this metal. Mobile ion coming from soil and rocks due to volcanic activity, rains and others are then distributed to water. Bio-availability of copper is substantially lower than its concentration in the aquatic environment. Copper present in the water reacts with other compounds and creates a complex, not available for organisms. The availability of copper varies depending on the environment, but moving around within the range from 5 to 25 % of total copper. Thus copper is stored in the sediments and the rest is transported to the seas and oceans. It is common knowledge that copper is essential element for most living organisms. For this reason this element is actively accumulated in the tissues. The total quantity of copper in soil ranges from 2 to 250 mg / kg, the average concentration is 30 mg / kg. Certain activities related to agriculture (the use of fungicides), possibly with the metallurgical industry and mining, tend to increase the total quantity of copper in the soil. This amount of copper in the soil is a problem particularly for agricultural production of food. The lack of copper causes a decrease in revenue and reduction in quality of production. In Europe, shows the low level of copper in total 18 million hectares of farmland. To remedy this adverse situation is the increasing use of copper fertilizers in agricultural soils. It is known that copper compounds are used in plant protection against various illnesses and pests. Mining of minerals is for the development of human society a key economic activity. An important site where the copper is mined in the Slovakia is nearby SmolnĒka. Due to long time mining in his area (more than 700 years) there are places with extremely high concentrations of various metals including copper. Besides copper, there are also detected iron, zinc and arsenic. Various plant species have adapted on such stress. The aim of this study is to investigate the behaviour of copper in plants and to assess its potential effect on the surrounding environment. To detect copper in biological samples electrochemical methods were employed particularly differential pulse voltammetry (DPV). Copper gave signals at 0.02 V measured by DPV. The obtained calibration dependence was linear (R2 = 0.995). Further, this method was utilized for determination of copper in real soil samples obtained from previously mentioned heavy-metal-polluted mining area. The content varied within range from tens to hundreds of mg of copper per kg of the soil. Moreover, we focused on investigation of copper influence on seedlings of Norway spruce. The seedlings were treated with copper (0, 0.1, 10 and 100 mM) for four weeks. We observed anatomical-morphological changes and other biochemical parameters in plants. We determined that seedlings synthesized more than 48 % protective thiols (glutathione and phytochelatins) compared to control ones. We investigated copper distribution in plant tissues by diphenylcarbazide staining. We found out that copper is highly accumulated in parenchymal stalk cells. In needles, change in auto-fluorescence of parenchymal cells of mesoderm similarly to endodermis cells. Besides, we analyzed samples of plants from the polluted area (spruce, pin, birch). The data obtained well correlated with previously mentioned. Acknowledgement The work on this experiment was supported by grant: INCHEMBIOL MSM0021622412.
Adam, V.; Trnkova, L.; Huska, D.; Babula, P.; Kizek, R.
Rhizosphere Characteristics of the Arsenic Hyperaccumulator Pteris
- contaminated sites have been reported for Australia (3). Concentrations of As in freshwater and (fodder) crops produce secondary waste (9). Phytoextraction, the use of green plants to clean up contaminated soil, has
Ma, Lena
/lis, and Thlaspi montanum; (c) Erysimum asperum, which is unconditionally rejected by both adults and larvae spectabilis ~ + + + Thlaspi rnontanum ~ + + + ErysJmum asperum Chonspora tenel/a n + + _ Thlaspi arvense n
Chew, Frances Sze-Ling
Interactions between plant and rhizosphere microbial communities in a metalliferous soil.
In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems. PMID:20036453
Epelde, Lur; Becerril, Josķ M; Barrutia, Oihana; Gonzßlez-Oreja, Josķ A; Garbisu, Carlos
RESEARCH PAPER Antioxidant responses of hyper-accumulator and
concentration in the growth medium, the most being found in P. vittata fronds showing no toxicity symptoms three fern species. Thiobarbituric acid- reacting substances, indicators of stress in plants, were found words: Antioxidant responses, arsenic, hyper-accumula- tion, Nephrolepis exaltata, Pteris ensiformis
Ma, Lena
REGULAR ARTICLE Hyperaccumulation of nickel by Alyssum corsicum
that Ni uptake is related to Ni solubility and plant transpiration rate. The most soluble compounds had a low solubility but a rela- tively high plant uptake and transpiration rate. In ser- pentine soils and insoluble NiO plant transpiration rate was high but uptake was very low and statistically comparable
Sparks, Donald L.
Antimony uptake, efflux and speciation in arsenic hyperaccumulator Pteris vittata
of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210046, China c of Sb has drastically increased due to its use in car brake linings and fire retardants (Maher, 2009
Ma, Lena
There is huge variability among populations of the hyperaccumulator Noccaea caerulescens (formerly Thlaspi caerulescens) in their capacity to tolerate and accumulate cadmium. To gain new insights into the mechanisms underlying this variability, we estimated cadmium fluxes and further characterized the N. caerulescens heavy metal ATPase 4 (NcHMA4) gene in three populations (two calamine, Saint-Fķlix-de-PalliĶres, France and Prayon, Belgium; one serpentine, Puente Basadre, Spain) presenting contrasting levels of tolerance and accumulation. Cadmium uptake and translocation varied among populations in the same way as accumulation; the population with the highest cadmium concentration in shoots (Saint Fķlix-de-PalliĶres) presented the highest capacity for uptake and translocation. We demonstrated that the four NcHMA4 copies identified in a previous study are not fixed at the species level, and that the copy truncated in the C-terminal part encodes a functional protein. NcHMA4 expression and gene copy number was lower in the serpentine population, which was the least efficient in cadmium translocation compared to the calamine populations. NcHMA4 expression was associated with the vascular tissue in all organs, with a maximum at the crown. Overall, our results indicate that differences in cadmium translocation ability of the studied populations appear to be controlled, at least partially, by NcHMA4, while the overexpression of NcHMA4 in the two calamine populations may result from convergent evolution. PMID:22581842
Craciun, Adrian R; Meyer, Claire-Lise; Chen, Jiugeng; Roosens, Nancy; De Groodt, Ruth; Hilson, Pierre; Verbruggen, Nathalie
Matricaria chamomilla is not a hyperaccumulator, but tolerant to cadmium stress
The influence of low (3ĀĄM) and high (60 and 120ĀĄM) cadmium (Cd) concentrations were studied on selected aspects of metabolism in 4-week-old chamomile (Matricaria chamomilla L.) plants. After 10ĀdaysÆ exposure, dry mass accumulation and nitrogen content were not significantly altered under any of the levels of Cd. However, there was a significant decline in chlorophyll and water content in the
Jozef Kovß?ik; Jaroslav Tomko; Martin Ba?kor; Miroslav Rep?ßk
An unusual dark blue-green lichen, Lecanora sierrae, was discovered over 30 years ago by Czehura near copper mines in the Lights Creek District, Plumas County, Northern California. Using atomic absorption spectroscopy, Czehura found that dark green lichen samples from Warren Canyon contained 4% Cu in ash and suggested that its colour was due to copper accumulation in the cortex. The present study addressed the hypothesis that the green colour in similar material we sampled from Warren Canyon in 2008, is caused by copper localization in the thallus. Optical microscopy and electron microprobe analysis of specimens of L. sierrae confirmed that copper localization took place in the cortex. Elemental analyses of L. sierrae and three other species from the same localities showed high enrichments of copper and selenium, suggesting that copper selenates or selenites might occur in these lichens and be responsible for the unusual colour. Copyright ?? 2011 British Lichen Society.
Purvis, O.W.; Bennett, J.P.; Spratt, J.
An unusual dark blue-green lichen, Lecanora sierrae, was discovered over 30 years ago by Czehura near copper mines in the Lights Creek District, Plumas County, Northern California. Using atomic absorption spectroscopy, Czehura found that dark green lichen samples from Warren Canyon contained 4% Cu in ash and suggested that its colour was due to copper accumulation in the cortex. The present study addressed the hypothesis that the green colour in similar material we sampled from Warren Canyon in 2008, is caused by copper localization in the thallus. Optical microscopy and electron microprobe analysis of specimens of L. sierrae confirmed that copper localization took place in the cortex. Elemental analyses of L. sierrae and three other species from the same localities showed high enrichments of copper and selenium, suggesting that copper selenates or selenites might occur in these lichens and be responsible for the unusual colour.
Purvis, O. W.; Bennett, J. P.; Spratt, J.
The extraction of nickel (Ni) from ultramafic soils by phytomining can be achieved using Alyssum murale cultures. This study presents a new process for the valorization of Ni accumulated by this plant through the production of a Ni ammonium disulfate salt (Ni(NH(4))(2)(SO(4))(2).6H(2)O). The process comprises an initial leaching of the ashes of A. murale with a sulphuric acid solution (1.9 M H(2)SO(4), T=95 ░C, t=240 min, TS=150 g ash L(-1)), producing a leachate rich in Ni (10.2 g Ni L(-1); 96% Ni solubilisation), Mg, P, K, Fe, Ca and Al. The pH of the acid leachate is increased to 5.0 with NaOH (5M), followed by an evaporation step which produced a purified solution rich in Ni (21.3 g NiL(-1)) and an iron hydroxide precipitate. The cold crystallization (T=2 ░C, t=6h) of this solution by the stoichiometric addition (ū 1.2) of ammonium sulfate generates a Ni ammonium disulfate salt, containing 13.2% Ni, that is potentially valuable to industry. PMID:22405560
Barbaroux, R; Plasari, E; Mercier, G; Simonnot, M O; Morel, J L; Blais, J F
Hyper-accumulation capability of Silene vulgaris in relation to its phylogeny
NSDL National Science Digital Library
The purpose of this work consisted in reviewing current literature to learn the absorption modality of these ions by the plant under study, identify the genes involved in the process and locate the evolution of this trait in the phylogenetic tree of the species.
Chi-Cheng Lin (Winowna State University;); Bruno Borsari (Winowna State University;)
and Its Utilization Potential for Phytoremediation Cong Tu, Lena Q. Ma,* and Bhaskar Bondada ABSTRACT in the phytoremediation of arsenic-contaminated soils. The the past few decades, much effort has been devoted (0.030┬Ł0.200) lettuce (0.020┬Ł0.250) mossesmated that the phytoremediation market in the United
Ma, Lena
\\u000a Arsenic is a toxic metalloid that is widespread in the environment due to both man-made and natural causes. Soils, food, and\\u000a ground water contaminated with arsenic pose serious health risks to millions of people in different parts of the World. While\\u000a engineering methods to remediate arsenic-contaminated environments are available, they are often prohibitively expensive and\\u000a cumbersome. It was discovered about
Bala Rathinasabapathi
CHARACTERIZATION OF ARSENIC RESISTANT BACTERIAL COMMUNITIES IN THE RHIZOSPHERE OF AN ARSENIC..................................................................................................................11 1.1 Environmental Sources of Arsenic..................................................................................11 1.1.1 Arsenic in the Environment
Ma, Lena
halleri's phytoextraction is the inoculation of plant roots by plant growth promoting bacteria (PGPB halleri roots. Bacteria effects on plant biomass and/or accumulating yield will be presented. Introduction production and/or plant Zn and Cd accumulation. The effect on selected PGPB bacteria on the A. halleri
Paris-Sud XI, Universit├® de
In its natural habitat, Astragalus bisulcatus can accumulate up to 0.65% (w/w) selenium (Se) in its shoot dry weight. X-ray absorption spectroscopy has been used to examine the selenium biochemistry of A. bisulcatus. High concentrations of the nonprotein amino acid Se-methylseleno-cysteine (Cys) are present in young leaves of A. bisulcatus, but in more mature leaves, the Se-methylseleno-Cys concentration is lower, and selenate predominates. Seleno-Cys methyltransferase is the enzyme responsible for the biosynthesis of Se-methylseleno-Cys from seleno-Cys and S-methyl-methionine. Seleno-Cys methyltransferase is found to be expressed in A. bisulcatus leaves of all ages, and thus the biosynthesis of Se-methylseleno-Cys in older leaves is limited earlier in the metabolic pathway, probably by an inability to chemically reduce selenate. A comparative study of sulfur (S) and Se in A. bisulcatus using x-ray absorption spectroscopy indicates similar trends for oxidized and reduced Se and S species, but also indicates that the proportions of these differ significantly. These results also indicate that sulfate and selenate reduction are developmentally correlated, and they suggest important differences between S and Se biochemistries. PMID:12644695
Pickering, Ingrid J.; Wright, Carrie; Bubner, Ben; Ellis, Danielle; Persans, Michael W.; Yu, Eileen Y.; George, Graham N.; Prince, Roger C.; Salt, David E.
Uranium phytoextraction, the use of plants to extract U from contaminated soils, is an emerging technology. The authors report on the development of this technology for the cleanup of U-contaminated soils. In this research, they investigated the effects of various soil amendments on U desorption from soil to soil solution, studied the physiological characteristics of U uptake and accumulation in
Jianwei W. Huang; Michael J. Blaylock; Yoram Kapulnik; Burt D. Ensley
been a serious problem worldwide. Anthropogenic sources including arsenical pesticides, food additives, it causes pollution in food chain, presenting a serious threat to http://dx.doi.org/10.1016/j health (Kaur et al., 2011). Arsenic is one of the most dan- gerous carcinogens and it is toxic to plants
Ma, Lena
Arsenic hyperaccumulation by aquatic macrophytes in the Taupo Volcanic Zone, New Zealand
Geothermal activity in the Taupo Volcanic Zone (TVZ), New Zealand, has resulted in elevated (0.01¢0.1mgL?1) levels of arsenic (As) in many of the region's soils, lakes and rivers. Some aquatic plants in the TVZ are known to accumulate inordinate amounts of As. We sampled 28 species of aquatic macrophytes and 11 terrestrial species from the TVZ along with ambient waters,
Brett Robinson; Nick Kim; Monica Marchetti; Christophe Moni; Lina Schroeter; Carlo van den Dijssel; Georgie Milne; Brent Clothier
Absorption of foliar-applied arsenic by the arsenic hyperaccumulating fern (Pteris vittata L.)
predominantly from anthropogenic activities. Because arsenic is a potent toxin and highly carcinogenic domains of the plant system through foliar pathways spurred us to explore if the fronds of the Chinese, 200, and 400 ppm) were applied to young and fertile fronds. A positive linear relationship existed
Ma, Lena
Effects of Plant Age on Arsenic Hyperaccumulation by Pteris vittata L.
September 2007 # Springer Science + Business Media B.V. 2007 Abstract Plant age affects its elemental uptake and iron accumulation in the roots of older plants may have affected the plant's efficiency-world, occurring from Europe Water Air Soil Pollut (2007) 186:289┬Ł295 DOI 10.1007/s11270-007-9485-y M. I. S
Ma, Lena
Hyperaccumulation of astaxanthin in a green alga Haematococcus pluvialis at elevated temperatures
Summary When a green algaHaematococcus pluvialis was cultivated at 30░C, astaxanthin production was 3-fold more increased than at 20░C. With acetate supplementation to 30░C culture, the alga synthesized over 2-fold more carotenoid than without addition. Tiron, a radical scavenger, however, severely blocked the stimulated carotenogenesis, suggesting that endogenously generated active oxygen was responsible for the highly stimulated carotenogenesis. From these
Agus Eko Tjahjono; Yachiyo Hayama; Toshihide Kakizono; Yoshio Terada; Naomichi Nishio; Shiro Nagai
Elsevier Ltd. All rights reserved. Keywords: Continuous phytoextraction; Plant arsenic uptake; Arsenic and animal health. It results from the exten- sive use of arsenic compounds such as pesticides, insecticides: email@example.com (L.Q. Ma). 0269-7491/$ - see front matter ├? 2007 Elsevier Ltd. All rights reserved
Ma, Lena
(superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase) in Chinese brake followed the same induces free radicals that may damage plant major cell macromolecules (proteins, lipids and DNA) (Fu
Ma, Lena
Identifying root exudates in field contaminated soil systems
NASA Astrophysics Data System (ADS)
Carbon (C) compounds exuded from plant roots comprise a significant and reactive fraction of belowground C pools. These exudates substantially alter the soil directly surrounding plant roots and play a vital role in the global C cycle, soil ecology, and ecosystem mobility of both nutrients and contaminants. In soils, the solubility and bioavailability of metals such as iron, zinc, and cadmium are intricately linked to the quantity and chemical characteristics of the C compounds allocated to the soil by plants. Cadmium (Cd), a toxic heavy metal, forms stronger bonds with reduced S- and N-containing compounds than with carboxylic acids, which may influence exudate composition in hyperaccumulator and tolerant plants grown in Cd contaminated soils. We hypothesize that hyperaccumulator plants will exude a larger quantity of aromatic N and chelating di- and tri-carboxylic acid molecules, while plants that exclude heavy metals from uptake will exude a larger proportion of reduced S containing molecules. This study examines how a variety of techniques can measure the low concentrations of complex organic mixtures exuded by hyperaccumulator and non-hyperaccumulator plants grown in Cd-contaminated soils. Two congeneric plants, Thlaspi caerulescens (Ganges ecotype), and T. caerulescens (Prayon ecotype) were grown in 0.5 kg pots filled with Cd-contaminated field soils from Chicago, IL. Field soils were contaminated as a result of the application of contaminated biosolids in the 1960's and 1970's. Pots were fitted for rhizon soil moisture samplers, micro-lysimeters developed for in situ collection of small volumes in unsaturated soils, prior to planting. Plants were grown for 8 weeks before exudate collection. After the 8 weeks of growth, a pulse-chase isotope tracer method using the C stable isotope, 13C, was employed to differentiate plant-derived compounds from background soil and microbial-derived compounds. Plants were placed in a CO2 impermeable chamber, and the soil surface was covered by CO2 impermeable sheets to ensure that all 13C in the soil results from photoassimilated C released by roots and not soil-atmosphere gas exchange. Ambient CO2 was drawn down in the system until the CO2 concentration within the tent was less than 50 ppm, after which the labeled 13CO2 was introduced, returning the CO2 concentration to the ambient level (~375 ppm). The CO2 pulse lasted for 60 minutes to allow enough time for 13C assimilation within the plants. In order to determine the ideal sampling time, soil pore water samples were extracted every 1-2 hours following the 13C pulse application, over the course of 24 hours. Samples were analyzed for delta 13C as well as %C, and results indicate that the greatest plant-derived dissolved organic C is present at about 6 hours following the 13C pulse. A second experiment will also be conducted using a combination of NMR and mass spectrometry methods to obtain detailed information regarding chemical structures within exudate samples.
Rosenfeld, C.; Martinez, C. E.
Chelant-assisted phytoextraction and accumulation of Zn by Zea mays.
Zea mays plants were exposed to soils with concentrations of Zn ranging from 64 to 1800ĀmgĀkg(-1) dw, and the efficiency of three selected chelating agents (trisodium citrate (CI), disodium oxalate (OX) and disodium dihydrogen ethylene-diamine-tetraacetate (EDTA)) in enhancing metal phytoextraction was compared. Zn concentration in plant tissues increased in conjunction with the metal concentration of the soil. EDTA was found to be the most efficient chelating amendment, increasing concentrations of Zn in shoots from 88ĀmgĀkg(-1) dw, at 64ĀmgĀkg(-1) dw soil, to 8026ĀmgĀkg(-1) dw at 1800ĀmgĀkg(-1) dw soil. The overall orders of BCFs and TFs which resulted from this study are: EDTAĀ>ĀH2OĀ>ĀOXĀ>ĀCI, and EDTANa2Ā>ĀOXĀ>ĀCIĀ>ĀH2O, respectively. The more effective uptake of Zn by plants for the control treatment (distilled water only) than for CI and OX was attributed to the neutral or slightly alkaline pH of the two chelant irrigation solutions. Instead, EDTA had a favorable effect on Zn uptake from soil due to its additive chelating and acidifying properties. Among the three chelants, only EDTA significantly increased the Zn phytoextraction potential of Z.Āmays, while CI and OX induced a low metal uptake from soil by plants. Although Z.Āmays has a lower Zn accumulation capacity than the hyperaccumulator Thlaspi caerulescens, it could be considered as a potential phytoremediator of soils with elevated Zn concentrations, especially when metal pollution extends to depths greater than 20Ācm. PMID:23845956
Gheju, M; Stelescu, I
Abnormal accumulation of trace metals by plants
The article describes the hyperaccumulation of metals by plants. Ranges for low, normal, high, and hyperaccumulating uptake are established. A partial list of hyperaccumulator species and their localities is included. Studies are reviewed and summarized for zinc, cadmium and lead, nickel, cobalt and copper, selenium, and cadmium and manganese hyperaccumulation.
Reeves, R.D.; Brooks, R.R. [Massey Univ., Palmerston North (New Zealand); Baker, A.J.M. [Univ. of Sheffield (United Kingdom)
The effects on the growth, physiological indexes and the cadmium (Cd) accumulation in Chlorophytum comosum under Cd stress were examined by pot-planting. The results showed that the tolerance index (TI) of C. comosum were all above 100 in soil Cd concentration of 100 mg kg(-1). The O(2?)? production rate and electrical conductivity of C. comosum were significantly positively correlated to Cd adding-concentration while the MDA content increased and had significant differences with the control. The activities of SOD, CAT, and POD all rose significantly in lower Cd concentration and the Cd threshold of them were around 10, 50 and 20 mg kg(-1), respectively. The Cd in C. comosum root and aboveground part reached 1,522 and 865Ę5 mg kg(-1), respectively, in Cd concentration of soil up to 200 mg kg(-1). For the advantages of high tolerance, high accumulation, and high ornamental value, C. comosum may have tremendous application value in the treatment of Cd-contaminated soils. PMID:21625926
Wang, Youbao; Yan, Aolei; Dai, Jie; Wang, NanNan; Wu, Dan
with frond As concentrations increasing up to 265% relative to the control. After 12 weeks, plants grown from the CCA soil, but had decreased leaching with ferns when compared to the control. For the ASC soil in protecting wood from bacterial, fungal, and insect attacks (Hing- ston et al., 2001). However, broad use
Ma, Lena
concentrations; these are termed non-accumulators (White et al., 2004). I of reactive oxygen species. Levels of ascorbic acid, glutathione, total sulfur and non-protein thiols were of Se has not yet been discovered (Zhang and Gladyshev, 2009). Most plant species accumulate less than
in a Zn- and Cd-contaminated dredged s├®diment sub- jected to a phytoremediation treatment with th├® of th├® phytoremediation treatment. months in order to reduce its water content. Thereafter, th├® s├®diment in th├® Nord-Pas de Calais r├®gion). Phytoremediation could be a way to treat th├©se polluted s├®di- ments
Boyer, Edmond
at the highest As application rate. Fur- fungi (unpublished data). In the low fertility soils wherethermore on soils in the southern United States. exploration of smaller pore spaces, greater carbon As amendment, but their pres- cate that Chinese brake fern is well colonized by AMence increased frond dry mass
Ma, Lena
The aim of this work was to evaluate effects of endophytic bacterium inoculation on plant growth and assess the possible mechanism of endophyte in heavy metal phytoremediation. Seeds of Solanum nigrum L. were inoculated with endophyte Serratia nematodiphila LRE07 and were subjected to Cd in the growing medium. Cd produced a significant inhibition on plant growth and a reduction in the content of photosynthetic pigments. The inoculation of endophytic bacterium alleviated the Cd-induced changes, resulting in more biomass production and higher photosynthetic pigments content of leaves compared with non-symbiotic ones. The beneficial effect was more obvious at relatively low Cd concentration (10 ?M). Based on the alteration of nutrient uptake and activated oxygen metabolism in infected plants, the possible mechanisms of endophytic bacterium in Cd phytotoxicity reduction can be concluded as uptake enhancement of essential mineral nutrition and improvement in the antioxidative enzymes activities in infected plant. PMID:22858258
Wan, Yong; Luo, Shenglian; Chen, Jueliang; Xiao, Xiao; Chen, Liang; Zeng, Guangming; Liu, Chengbin; He, Yejuan
Search for plant species - prodigious in P use - is important for both P-sufficient and -deficient conditions. Gulf and Marshall ryegrass (Lolium multiflorum), grown in sterile media containing different organic P substrates (AMP, ATP, GMP, and IHP), exhibited high rates of growth and shoot P concentrations. Growth increase in Gulf was significantly greater on IHP relative to other sources of organic P substrates. Growth was also dependent on an increasing concentration of IHP (0-20 mM) in this cultivar. P accumulations in Gulf exceeded 1% shoot dry weight from IHP, AMP, and ATP-equivalent to the P accrual from equimolar Pi source. Plants supplied with IHP had phytase activity in root extracts comparable to that in Pi-fed plants or control (no P). The extracellular phytase, however, increased by about 100% relative to that observed in root extracts- for both ryegrass cultivars, but there were no significant differences (P < 0.05) between plant groups grown on different substrates (IHP, Pi or control). No significant differences in phosphomonoesterase activities were evident between plant groups supplied with organic P (IHP, G1P) and inorganic source or control. This study establishes the high P-use efficiency in ryegrass, irrespective of P source. PMID:22035414
Sharma, Nilesh C; Sahi, Shivendra V
The distribution of rare earth elements (REEs) in the fern Dicranopteris dichotoma Bernh plants from a light rare earth elements mine (LRM) and a non-mining (NM) area in Longnan county of Jiangxi province,\\u000a China were investigated by means of inductively coupled plasma-mass spectrometry, transmission electron microscopy, and energy-dispersive\\u000a X-ray microanalysis. The photosynthetic characteristics of D. dichotoma were studied by chlorophyll
L. F. Wang; H. B. Ji; K. Z. Bai; L. B. Li; T. Y. Kuang
Nineteen native fern species collected from an area in Thailand with high arsenic concentration in soil and in ground water as a result of tin mining was screened for elevated arsenic concentration in fronds. Two species of fern were found to contain elevated arsenic in their fronds in nature: Pityrogrammacalomelanos (108¢1156ĀĄgĀg dried weight) and Pterisvittata (79ĀĄgĀg dried weight). Under hydroponic
Jirarut Wongkongkatep; Kensuke Fukushi; Preeda Parkpian; Ronald D. DeLaune; Aroon Jugsujinda
Brown adipose tissue (BAT) generates heat during adaptive thermogenesis through a combination of oxidative metabolism and uncoupling protein 1-mediated electron transport chain uncoupling, using both free-fatty acids and glucose as substrate. Previous rat-based work in 1942 showed that prolonged partial fasting followed by refeeding led to a dramatic, transient increase in glycogen stores in multiple fat depots. In the present study, the protocol was replicated in male CD1 mice, resulting in a 2000-fold increase in interscapular BAT (IBAT) glycogen levels within 4-12 hours (hr) of refeeding, with IBAT glycogen stores reaching levels comparable to fed liver glycogen. Lesser effects occurred in white adipose tissues (WAT). Over the next 36 hr, glycogen levels dissipated and histological analysis revealed an over-accumulation of lipid droplets, suggesting a potential metabolic connection between glycogenolysis and lipid synthesis. 24 hr of total starvation followed by refeeding induced a robust and consistent glycogen over-accumulation similar in magnitude and time course to the prolonged partial fast. Experimentation demonstrated that hyperglycemia was not sufficient to drive glycogen accumulation in IBAT, but that elevated circulating insulin was sufficient. Additionally, pharmacological inhibition of catecholamine production reduced refeeding-induced IBAT glycogen storage, providing evidence of a contribution from the central nervous system. These findings highlight IBAT as a tissue that integrates both canonically-anabolic and catabolic stimulation for the promotion of glycogen storage during recovery from caloric deficit. The preservation of this robust response through many generations of animals not subjected to food deprivation suggests that the over-accumulation phenomenon plays a critical role in IBAT physiology. PMID:23861810
Carmean, Christopher M; Bobe, Alexandria M; Yu, Justin C; Volden, Paul A; Brady, Matthew J
in turn regulate the activity of SNF1-related protein kinases 2 (SnRK2) family proteins (Fujii et al., 2009; Vlad et al., 2009). 8 Transcription activation of ABA-responsive genes is mediated by bZIP type transcription factors ABFs, such as ABI5... in turn regulate the activity of SNF1-related protein kinases 2 (SnRK2) family proteins (Fujii et al., 2009; Vlad et al., 2009). 8 Transcription activation of ABA-responsive genes is mediated by bZIP type transcription factors ABFs, such as ABI5...
Feng, Yue
Brown adipose tissue (BAT) generates heat during adaptive thermogenesis through a combination of oxidative metabolism and uncoupling protein 1-mediated electron transport chain uncoupling, using both free-fatty acids and glucose as substrate. Previous rat-based work in 1942 showed that prolonged partial fasting followed by refeeding led to a dramatic, transient increase in glycogen stores in multiple fat depots. In the present study, the protocol was replicated in male CD1 mice, resulting in a 2000-fold increase in interscapular BAT (IBAT) glycogen levels within 4¢12 hours (hr) of refeeding, with IBAT glycogen stores reaching levels comparable to fed liver glycogen. Lesser effects occurred in white adipose tissues (WAT). Over the next 36 hr, glycogen levels dissipated and histological analysis revealed an over-accumulation of lipid droplets, suggesting a potential metabolic connection between glycogenolysis and lipid synthesis. 24 hr of total starvation followed by refeeding induced a robust and consistent glycogen over-accumulation similar in magnitude and time course to the prolonged partial fast. Experimentation demonstrated that hyperglycemia was not sufficient to drive glycogen accumulation in IBAT, but that elevated circulating insulin was sufficient. Additionally, pharmacological inhibition of catecholamine production reduced refeeding-induced IBAT glycogen storage, providing evidence of a contribution from the central nervous system. These findings highlight IBAT as a tissue that integrates both canonically-anabolic and catabolic stimulation for the promotion of glycogen storage during recovery from caloric deficit. The preservation of this robust response through many generations of animals not subjected to food deprivation suggests that the over-accumulation phenomenon plays a critical role in IBAT physiology. PMID:23861810
Carmean, Christopher M.; Bobe, Alexandria M.; Yu, Justin C.; Volden, Paul A.; Brady, Matthew J.
37200-000, Brazil a r t i c l e i n f o Article history: Received 30 April 2013 Received in revised form to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25 mM for 2-wk in hydroponic system. PV was effective
Ma, Lena
l e i n f o Article history: Received 26 February 2009 Received in revised form 23 September 2009 shoot (stem and leaf) Ni concentrations. Plants were grown either hydroponically or in Ni enriched soils
New Phytologist (2004) 162: 655662 www.newphytologist.org 655 Blackwell Science, Ltd
plants from phloem-feeding herbivores. ┬Ę Indian mustard (Brassica juncea) grown with or without Se hyperaccumulation. Key words: selenium (Se), hyperaccumulation, herbivory, Brassica juncea, Myzus persicae. ┬® New
www.newphytologist.org 1 Blackwell Publishing Ltd
(Camelina microcarpa, Astragalus americanus, Descurainia pinnata, Medicago sativa, and Helianthus pumilus Se hyperaccumulator species (Astragalus bisulca- tus and Stanleya pinnata) with nonhyperaccumulators to the evolution of Se hyperaccumulation. Key words: Astragalus bisulcatus, Astragalus americana, Camelina
- extraction practices with three plant species (Silene vulgaris, Thlaspi caerulescens, and Zea mays in the rhizosphere of mycorrhizal maize was significantly higher than in rhizospheres of nonmycorrhizal S. vulgaris
Pawlowska, Teresa
An off-line normal-phase liquid chromatography-ICP-MS method has been used for separation and determination of the rare earth elements (REE) associated with chloroplast pigments of Dicranopteris dichotoma. The stability of REE-bound pigments was tested, and almost no destruction of REE-bound pigments occurred during the so-called normal-phase liquid chromatography. The accumulated free REE ions on the microcrystalline cellulose column were cleaned by elution with 5 mmol L(-1) 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507), to avoid exchange of these free ions with metals from the pigments. When these precautions were taken, the method was applied to the study of REE-bound pigments in D. dichotoma. ICP-MS results showed REE were present in chlorophylls and lutein, although REE concentrations in carotene and pheophytin were both below procedural blank levels. By careful analysis of the eluate fractions containing chlorophyll a it was found that REE-bound chlorophyll a in D. dichotoma was slightly enriched in the fractions with relatively short retention time. Results indicated that the retention time of REE-bound chlorophyll a might be slightly less than that of magnesium chlorophyll a, and REE-bound chlorophylls might be of relatively low polarity in comparison with magnesium bound chlorophylls. This phenomenon could be explained by the special double-decker sandwich-structure of REE-bound chlorophylls, as was reported by us and other authors. On the basis of these results we preferred to consider that REE can replace magnesium in chlorophyll a of D. dichotoma, and that the role of REE-bound chlorophylls in photosynthesis cannot be neglected. These data might be useful for understanding of both the properties of REE-bound pigments and the effect of REE on plant photosynthesis. PMID:15372132
Wei, Z G; Hong, F S; Yin, M; Li, H X; Hu, F; Zhao, G W; Wong, J W C
The current status of the elemental defense hypothesis in relation to pathogens
Metal hyperaccumulating plants are able to accumulate exceptionally high concentrations of metals, such as zinc, nickel, or cadmium, in their aerial tissues. These metals reach concentrations that would be toxic to most other plant species. This trait has evolved multiple times independently in the plant kingdom. Recent studies have provided new insight into the ecological and evolutionary significance of this trait, by showing that some metal hyperaccumulating plants can use high concentrations of accumulated metals to defend themselves against attack by pathogenic microorganisms and herbivores. Here, we review the evidence that metal hyperaccumulation acts as a defensive trait in plants, with particular emphasis on plant¢pathogen interactions. We discuss the mechanisms by which defense against pathogens might have driven the evolution of metal hyperaccumulation, including the interaction of this trait with other forms of defense. In particular, we consider how physiological adaptations and fitness costs associated with metal hyperaccumulation could have resulted in trade-offs between metal hyperaccumulation and other defenses. Drawing on current understanding of the population ecology of metal hyperaccumulator plants, we consider the conditions that might have been necessary for metal hyperaccumulation to be selected as a defensive trait, and discuss the likelihood that these were fulfilled. Based on these conditions, we propose a possible scenario for the evolution of metal hyperaccumulation, in which selective pressure for resistance to pathogens or herbivores, combined with gene flow from non-metallicolous populations, increases the likelihood that the metal hyperaccumulating trait becomes established in plant populations. PMID:24137169
Horger, Anja C.; Fones, Helen N.; Preston, Gail M.
Selenium Accumulation in Brassicaceae Plant Species and its Biotransfer to Insect Pollinators
plants employ innate defenses such as secondary compounds to guard against herbivoreplant species known as hyperaccumulators that have evolved to use certain elements as a defense against herbivores (
Hladun, Kristen
REGULAR ARTICLE Interaction of nickel and manganese in accumulation
REGULAR ARTICLE Interaction of nickel and manganese in accumulation and localization in leaves . Hyperaccumulator. Manganese localization . Nickel localization . Phytoremediation . trichomes Introduction More
Sparks, Donald L.
J. PHYS. IV FRANCE 7 (1997) Colloque C2, Supplement au Journal de Physique 111d'avril 1997
resolved concentrations can be measured. The aquaticplants Salvinia rotundiflora.Wolflabrasiliensis,Lemna minor (duckweed),and Azolla caroliniana (water fern) have been demonstrated to be hyperaccumulators
Paris-Sud XI, Universit├® de
Assessing the Bioavailability of Ni in Smelter Contaminated Soils. (S11-everhart242852-oral)
. Avena sativa, a nonhyperaccumulator, and Alyssum murale, a hyperaccumulator plant species, were grown when bioavailability decreased which was not the case for Avena sativa. The Ni bacterial biosensor
Sparks, Donald L.
-contami- concentrations (50 to 1000 mg kg 1 ) or forms (organic vs. inorganic nated soils include soil removal and washing, physical and arsenite vs. arsenate) applied to soils on growth and arsenic stabilization, and/or the use-enrichment and water stress. Crop Sci. 20: synthesis of soybean. (In Chinese, with English abstract.) Chinese
Ma, Lena
Batch experiments were designed to characterize a multiple metal resistant bacterium Burkholderia sp. D54 isolated from metal contaminated soils in the Dabaoshan Mine in South China, and a follow-up experiment was conducted\\u000a to investigate the effects of inoculating the isolate on plant growth and metal uptake by Sedum alfredii Hance grown on soils collected from a heavily contaminated paddy field
Junkang Guo; Shirong Tang; Xuehai Ju; Yongzhen Ding; Shangqiang Liao; Ningning Song
Environmental and Experimental Botany 74 (2011) 9097 Contents lists available at ScienceDirect
form 19 April 2011 Accepted 3 May 2011 Keywords: Brassica juncea Floral traits Hyperaccumulator conditions. Se accumulator (Brassica juncea) and Se hyperaccumulator (Stanleya pinnata) plants were irrigated not as high in B. juncea. Floral display width, petal area and seed pod length were significantly reduced
Trumble, John T.
-culture experiment showed that Cd concentrations in the stems and leaves of Solanum nigrum L. growing in a soil. Keywords: hyperaccumulator, cadmium, Solanum nigrum L., reme- diation of contaminated soils. DOI: 10. 50 No. 1 33 38 A newly-discovered Cd-hyperaccumulator So- lanum nigrum L. WEI Shuhe, ZHOU Qixing
Ma, Lena
-9317 Analysis of selenium accumulation, speciation and tolerance of potential selenium hyperaccumulator earlier to contain hyperaccumulator levels of selenium (Se) in the field (>1000 mg kg-1 dry weight (DW by a physiological benefit, in addition to the ecological benefit demonstrated earlier. Introduction Selenium
Additional information is presented on the distribution of various exotic species of Brassicaceae, introduced recently to central Mexico. Three populations of Thlaspi arvense L. and Sinapis alba L. are reported. The species Diplotaxis muralis (L.) DC., Hirschfeldia incana (L.) LagrĶze-Fossat and Brassica tournefortii Gouan, known previously from northern Mexico, are now naturalized at various localities in the central part of
Phytoextraction involves use of plants to remove toxic metals from soil. We examined the effects of phyto- extraction practices with three plant species (Silene vulgaris, Thlaspi caerulescens, and Zea mays) and a factorial variation of soil amendments (either an ammonium or nitrate source of nitrogen and the presence or absence of an elemental sulfur supplement) on arbuscular mycorrhizal (AM) fungi
1930 American Journal of Botany 99(12): 1930┬Ł1941, 2012; http://www.amjbot.org/ ┬® 2012 Botanical Society of America American Journal of Botany 99(12): 1930┬Ł1941. 2012. Several hyperaccumulator taxa
830 American Journal of Botany 101(5): 830┬Ł839, 2014; http://www.amjbot.org/ ┬® 2014 Botanical Society of America American Journal of Botany 101(5): 830┬Ł839. 2014. Hyperaccumulation is the intriguing
REVIEW ARTICLE Metallophytes--a view from the rhizosphere
tolerance, act as plant growth promoting microorganisms, alter elemental solubility, and have significant for root uptake, while root growth and morphology influence plant access to trace elements . Hyperaccumulation . Trace elements . Rhizosphere bacteria . Arbuscular mycorrhiza . Root structure Plant Soil (2010
(Stanleya pinnata) protects it from caterpillar herbivory because of deterrence and toxicity. In its natural on the same site [1]. Selenium (Se)-hyperaccumulating plants such as Stanleya pinnata (Brassicaceae
Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals
In general, hyperaccumulators are low biomass, slow-growing plants. High biomass non-hyperaccumulator plants by themselves are not a valid alternative for phytoextraction as they also have many limitations, such as small root uptake and little root-to-shoot translocation. In this context, chemically-induced phytoextraction (based on the fact that the application of certain chemicals, mostly chelating agents, to the soil significantly enhances metal
I. Alkorta; J. Hernßndez-Allica; J. M. Becerril; I. Amezaga; I. Albizu; M. Onaindia; C. Garbisu
Arsenic (As) accumulation and photosynthesis occur simultaneously in plants under As exposure. We investigated the effects of As and induced-phytoextraction methods on photosynthesis in two As hyperaccumulators (Pteris vittata and Pteris cretica var. nervosa) and two non-hyperaccumulators (Pteris semipinnata and Pteris ensiformis) under soil culture conditions. Chlorophyll fluorescence parameters (the maximum [Fv\\/Fm] and actual quantum efficiency [FPSII]) and the activities
Hong-Bin Wang; Fei Xie; Yan-Zhuo Yao; Bin Zhao; Qing-Qing Xiao; Yi-Hong Pan; Hai-Juan Wang
MetallophytesŚa view from the rhizosphere
Some plants hyperaccumulate metals or metalloids to levels several orders of magnitude higher than other species. This intriguing\\u000a phenomenon has received considerable attention in the past decade. While research has mostly focused on the above-ground organs,\\u000a roots are the sole access point to below-ground trace elements and as such they play a vital role in hyperaccumulation. Here\\u000a we highlight the
╔lan R. Alford; Elizabeth A. H. Pilon-Smits; Mark W. Paschke
Segetal vegetation of Central Yakutia
Seven associations of segetal vegetation are distinguished for the vast arable lands of Central Yakutia. Low species richness\\u000a and the prevalence of annual weeds are the main features of these communities. Only two dominant speciesSphallerocarpus gracilis andSaussurea amara represent Asian types of areals. Other dominantsFallopia convolvulus, Elytrigia repens, Chenopodium album, Brassica campestris, Lappula squarrosa, Scutellaria galericulata,\\u000a Thlaspi arvense, Avena fatua
B. M. Mirkin; N. P. Slepcova; K. E. Kononov
80523, USA b Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA c if they are promiscuous and affect Se tolerance in crop species. ┬® 2011 Elsevier B.V. All rights reserved. 1. firstname.lastname@example.com (E.A.H. Pilon-Smits). 1 Biology Department, Texas A&M University ┬Ł San Antonio, San Antonio, TX 78224
Classification and identification of metal-accumulating plant species by cluster analysis.
Identification and classification of metal-accumulating plant species is essential for phytoextraction. Cluster analysis is used for classifying individuals based on measured characteristics. In this study, classification of plant species for metal accumulation was conducted using cluster analysis based on a practical survey. Forty plant samples belonging to 21 species were collected from an ancient silver-mining site. Five groups such as hyperaccumulator, potential hyperaccumulator, accumulator, potential accumulator, and normal accumulating plant were graded. For Cd accumulation, the ancient silver-mining ecotype of Sedum alfredii was treated as a Cd hyperaccumulator, and the others were normal Cd-accumulating plants. For Zn accumulation, S. alfredii was considered as a potential Zn hyperaccumulator, Conyza canadensis and Artemisia lavandulaefolia were Zn accumulators, and the others were normal Zn-accumulating plants. For Pb accumulation, S. alfredii and Elatostema lineolatum were potential Pb hyperaccumulators, Rubus hunanensis, Ajuga decumbens, and Erigeron annuus were Pb accumulators, C. canadensis and A. lavandulaefolia were potential Pb accumulators, and the others were normal Pb-accumulating plants. Plant species with the potential for phytoextraction were identified such as S. alfredii for Cd and Zn, C. canadensis and A. lavandulaefolia for Zn and Pb, and E. lineolatum, R. hunanensis, A. decumbens, and E. annuus for Pb. Cluster analysis is effective in the classification of plant species for metal accumulation and identification of potential species for phytoextraction. PMID:24888623
Yang, Wenhao; Li, He; Zhang, Taoxiang; Sen, Lin; Ni, Wuzhong
The potential for heavy metal decontamination
Preliminary trials to assess the ability of plant species to extract metals are presented. A range of zinc and nickel hyperaccumulator plants from the Brassicaceae family, collected from diverse populations in Europe, were grown on plots along with nonaccumulating crop plants from the same family. Extraction efficiencies and the number of croppings required to reduce the total zinc in the soil to a concentration of 300 mg/kg are tabulated. Zinc accumulation remained high over a wide range of soil metal concentration. However, the concentration of nickel in the hyperaccumulators increased in accordance with increasing total nickel concentrations in the soil. Calculations suggest that there is an excellent potential for using hyperaccumulator species to remove metals from the rhizosphere where remediation can be considered over a period of years and multiple cropping is a viable option.
Baker, A.J.M. [Univ. of Sheffield (United Kingdom); McGrath, S.P.; Sidoli, C.M.D. [AFRC Institute of Arable Crops Research, Harpenden (United Kingdom); Reeves, R.D. [Massey Univ., Palmerston North (New Zealand)
Genetically transformed hairy root cultures were established for a range of plant species and applied in studies of growth and accumulation of heavy metals. Experiments were conducted using liquid nutrient medium containing elevated concentrations of Ni, Cd or Cu. Hairy roots of three hyperaccumulator species were tested for Ni uptake, of these, Alyssum bertolonii accumulated the highest Ni contents in
T. V. Nedelkoska; P. M. Doran
Chemoecology 15:179185 (2005) 09377409/05/0301797
00049-005-0310-z CHEMOECOLOGY A test of elemental defence against slugs by Ni in hyperaccumulator . Plants of all species grown on low-Ni soils had Slugs (Limax maximus) were fed plant material in no-choice tests over a 50-day period and survival and mass changes were recorded. All slugs fed
Boyd, Robert S.
New Phytologist (2003) 159: 461469 www.newphytologist.com 461 Blackwell Publishing Ltd.
. Selenium accumulation protects Brassica juncea from invertebrate herbivory and fungal infection Brady infection. ┬Ę Indian mustard (Brassica juncea) plants grown with or without Se were subjected to herbivory by caterpillars, but not by snails. Key words: Selenium, hyperaccumulation, herbivory, Brassica juncea, Pieris
Selenium accumulation in flowers and its effects on pollination
, an Se hyperaccumulator, and Brassica juncea, a comparable nonhyperaccumulator. Pollen germination methyl- selenocysteine (MeSeCys). Brassica juncea had higher Se concentrations in leaves than flowers June 2011 New Phytologist (2011) 192: 727┬Ł737 doi: 10.1111/j.1469-8137.2011.03832.x Key words: Brassica
Robert S. Boyd William J. Moar The defensive function of Ni in plants
. polygaloides, 40 and 9 mg kgA1 for S. breweri, and 93 and 0.5 mg kgA1 for S. tortuosus. Neonate or secondA1 for Zn or Mn. Nickel is the metal most frequently hyperaccumulated: 145 (66%) of the 220 metal
Boyd, Robert S.
Molecular approach for phytoremediation of metal-contaminated sites
Phytoremediation is the process which utilizes plants to extract, sequester, or detoxify pollutants in soils and surface waters. There are examples of many plants which can hyperaccumulate metals in their shoots. For example, Alyssum lesbiacum can be grown in Ni (II)-rich soil; nickel is rapidly transported into the plant and accumulates to 3% of the dry weight of above-ground tissues.
Shilpa Goel; Jahid A. Malik; Harsh Nayyar
Identification of a Cd accumulator Conyza canadensis.
One of key steps of phytoremediating heavy metal contaminated soils is still the identification of hyperaccumulator and accumulator. In a former published article, Conyza canadensis L. Cronq. expressed some basic properties of Cd-hyperaccumulators. In this study, concentration gradient experiment and two sample-analyzing experiments were used to identify whether this plant is a Cd-hyperaccumulator. When grown on soil spiked with Cd at the rate of 10 and 25 mg kg(-1) in concentration gradient experiment, C. canadensis had both Cd enrichment factor (EF) and Cd translocation factor (TF) greater than 1, while the shoot biomass did not differ significantly as compared to the control. On the other hand, with Cd-spiking rates of 10 and 25 mg kg(-1), the Cd concentration in the shoot did not exceed 100 mg kg(-1), which is considered as the minimum shoot Cd concentration to qualify as a hyperaccumulator. In the sample-analysis experiments from a Pb-Zn mine area and wastewater irrigation region, C. canadensis also showed Cd-accumulator characteristics. Based on the results accomplished, we propose C. canadensis as a Cd-accumulator. PMID:18653276
Wei, Shuhe; Zhou, Qixing; Saha, Uttam Kumar; Xiao, Hong; Hu, Yahu; Ren, Liping; Ping, Gu
Plant and Soil 258: 919, 2004. 2004 Kluwer Academic Publishers. Printed in the Netherlands.
-hyperaccumulating Nephrolepis exaltata Shuxin Tu1, Lena Ma1 & Thomas Luongo Soil and Water Science Department, University carbon; HMW ┬Ł high molecular weight; LMW ┬Ł low molecular weight; TF ┬Ł translocation factor Introduction, high molecular weight (HMW) and low molecular weight (LMW) ma- terials. The first includes mucilage
Ma, Lena
ORIGINAL ARTICLE Inoculation of Astragalus racemosus and Astragalus convallarius
ORIGINAL ARTICLE Inoculation of Astragalus racemosus and Astragalus convallarius with selenium Astragalus rac- emosus and the non-accumulator Astragalus convallarius. The fungi, Alternaria astragali (A3 as a mixture of organic and inorganic forms in the hyperaccumulator. Astragalus convallarius root
ORIGINAL ARTICLE Inoculation of Astragalus racemosus and Astragalus convallarius
ORIGINAL ARTICLE Inoculation of Astragalus racemosus and Astragalus convallarius with selenium-accumulator Astragalus convallarius. The fungi, Alternaria astragali (A3) and Fusarium acu- minatum (F30), were in the hyperaccumulator. Astragalus convallarius root-Se was concentrated in the extreme periphery of the taproot
Chemoecology 9:17 (1999) 09377409/99/01000107 $1.50+0.20
& Boyd 1994). No plant defensive tactic is completely effective against all plant enemies (Grubb 1992 (Brassicaceae) Robert S. Boyd1 and Scott N. Martens2 1 Department of Botany and Microbiology and Alabama Research papers Summary. Nickel hyperaccumulation, resulting in plant Ni contents of \\1000 mg kg-1 dry mass
Boyd, Robert S.
Plant Science 195 (2012) 8895 Contents lists available at SciVerse ScienceDirect
journal homepage: www.elsevier.com/locate/plantsci Review Plant defense using toxic inorganic ions 2012 Available online 4 July 2012 Keywords: Chemical ecology Herbivore defense Metal hyperaccumulation Plant┬Łinsect interactions Synergy a b s t r a c t The concept of plant defense using toxic mineral
Boyd, Robert S.
Gonzaga et al.90 Sci. Agric. (Piracicaba, Braz.), v.63, n.1, p.90-101, Jan./Feb. 2006
to workers. Phytoextraction, a strategy of phytoremediation, uses plants to clean up contaminated soils of molecular biology seems to hold the key for the future of the phytoremediation. Key words: environmental contamination, hyperaccumulator plants, phytoremediation FITOEXTRA├?├?O E HIPERACUMULA├?├?O DE ARS├?NIO POR ESP├?CIES
Ma, Lena
a great promise to phytoremediation, a plant- driven environmentallybenign clean up process wherein qualifies as an arsenic hyperaccumulator and thus has potential application in phytoremediation of arsenic contaminated sites. In order to model a successful phytoremediation strategy fqr arsenic contaminated sites
Ma, Lena
This presentation provides a broad overview of metal hyperaccumulator plants and biological accumulation technology. Plants that have been identified as having the greatest potentials for development as phytoremediator crops for metal-contaminated soils are very briefly discussed. Phytoextraction, rhizofiltration, and phytostabilization are briefly defined. Issues pertinent to large scale phytoremediation of soils are discussed, including biological and technological constraints.
Baker, A.J.M. [Univ. of Sheffield (United Kingdom); Reeves, R.D. [Massey Univ., Palmerston North (New Zealand)
Assessing Plants for Phytoremediation of Arsenic-Contaminated Soils
24 Assessing Plants for Phytoremediation of Arsenic-Contaminated Soils Nandita Singh and Lena Q. Ma. Phytoremediation is potentially a cost-effective and environmentally benign method of extracting pollutants from soils. Key Words: Arsenic (As); hyperaccumulation; phytoremediation; Pteris vittata. 1. Introduction
Ma, Lena
sources for drinking water. Phytoremediation, an emerging, plant-based technology for the removal of toxic open a door for phytoremediation of arsenic-contaminated soils. Speciation and distribution of arsenic B.V. All rights reserved. Keywords: Arsenic; Phytoremediation; Pteris vittata; Hyperaccumulator
Ma, Lena
Short communication A preliminary study of the role of nickel in enhancing flowering of the
ecology Hyperaccumulator Metallophyte Serpentine soil Reproductive fitness Ultramafic ecology Alyssum of Ni to reproduction in the species is unknown. We investigated if reproductive fitness is enhanced documented survival, as well as the proportion of individuals that flowered. We also quantified flower
Rajakaruna, Nishanta
Phytoaccumulation of Lead by Selected Wetland Plant Species
Several anthropogenic activities lead to the production of substantial amounts of aqueous effluents that contain various toxic trace and heavy metals and which pose potential threats to the wild habitat of wetlands. As a part of the remediation of heavy metals, it is necessary to identify some aquatic hyperaccumulator plants. To this end, a greenhouse study was conducted to investigate
Tapan Adhikari; Ajay Kumar; M. V. Singh; A. Subba Rao
International Journal of Phytoremediation, 11:313328, 2009 Copyright C Taylor & Francis Group, LLC
AND PHOSPHORUS LEVELS, AND FROND-HARVESTING ON ABSORPTION, TRANSLOCATION AND ACCUMULATION OF ARSENIC BY CHINESE 1 University of Florida, Institute of Food and Agricultural Science (IFAS), Mid-Florida Research of arsenic (As)- hyperaccumulator Chinese brake fern (Pteris vittata L.) to remove As from contaminated
Ma, Lena
Hyperaccumulators tolerate and accumulate extraordinarily high concentrations of heavy metals. Content of the metal chelator nicotianamine (NA) in the root of zinc hyperaccumulator Arabidopsis halleri is elevated compared with nonhyperaccumulators, a trait that is considered to be one of the markers of a hyperaccumulator. Using metabolite-profiling analysis of root secretions, we found that excess zinc treatment induced secretion of NA in A. halleri roots compared with the nonhyperaccumulator Arabidopsis thaliana. Metal speciation analysis further revealed that the secreted NA forms a stable complex with Zn(II). Supplying NA to a nonhyperaccumulator species markedly increased plant zinc tolerance by decreasing zinc uptake. Therefore, NA secretion from A. halleri roots facilitates zinc hypertolerance through forming a Zn(II)-NA complex outside the roots to achieve a coordinated zinc uptake rate into roots. Secretion of NA was also found to be responsible for the maintenance of iron homeostasis under excess zinc. Together our results reveal root-secretion mechanisms associated with hypertolerance and hyperaccumulation. PMID:25118254
Tsednee, Munkhtsetseg; Yang, Shun-Chung; Lee, Der-Chuen; Yeh, Kuo-Chen
1 Running head: Selenium and ecological partnerships in Astragalus1 2 Author for correspondence:10.1104/pp.112.199307 Copyright 2012 by the American Society of Plant Biologists #12;2 Selenium The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may affect38 ecological
Interest is increasing in using wetland plants in constructed wetlands to remove toxic elements from polluted wastewater. To identify those wetland plants that hyperaccumulate trace elements, 12 plant species were tested for their efficiency to bioconcentrate 10 potentially toxic trace elements including As, b, Cd, Cr, Cu, Pb, Mn, Hg, Ni, and Se. Individual plants were grown under carefully controlled
Jin-Hong Qian; Adel Zayed; Yong-Liang Zhu; Mei Yu; Norman Terry
Author's personal copy Sulfate and glutathione enhanced arsenic accumulation by arsenic
Author's personal copy Sulfate and glutathione enhanced arsenic accumulation by arsenic, Gainesville, FL 32611-0690, USA Sulfate and glutathione increased arsenic uptake and translocation in Pteris December 2009 Accepted 12 December 2009 Keywords: Sulfur Arsenic Hyperaccumulator GSH a b s t r a c
Ma, Lena
Characteristics of arsenic accumulation by Pteris and non-Pteris ferns T. Luongo & L.Q. Ma1
Characteristics of arsenic accumulation by Pteris and non-Pteris ferns T. Luongo & L.Q. Ma1 Soil author* Received 8 March 2005. Accepted in revised form 24 April 2005 Key words: arsenic, detoxification the mechanisms of arsenic hyperaccumulation in Pteris vittata by comparing the characteristics of arsenic
Ma, Lena
Zinc distribution and speciation in roots of various genotypes of tobacco exposed to Zn
Cell walls of roots have a great reactivity towards metals, and may act as a barrier limiting the entry of metals, especially in non-hyperaccumulating species. The aim of this study was to determine the localization and speciation of Zn in roots of tobacco (Nicotiana tabacum) grown in Zn-contaminated substrates. Chemical extractions and EXAFS spectroscopy were applied on whole roots and
Anne Straczek; G ┤ eraldine Sarret; Alain Manceau; Philippe Hinsinger; Nicolas Geoffroy; BenoŅt Jaillard
Sulfate and selenate uptake were investigated in both selenium (Se) hyperaccumulators (Astragalus racemosus and Astragalus bisulcatus) and closely related nonaccumulator species (Astragalus glycyphyllos and Astragalus drummondii). Sulfur (S) starvation increased Se accumulation, whereas increased selenate supply increased sulfate accumulation in both root and shoot tissues. cDNAs for homologs of groups 1 to 4 sulfate transporters were cloned from these Astragalus species to investigate patterns of expression and interactions with sulfate and selenate uptake. In contrast to all other previously analyzed plant species, abundant gene expression of putative sulfate transporters was observed for both Se-hyperaccumulating and nonaccumulating Astragalus, regardless of S and Se status. Furthermore, quantitative analysis of expression indicated a transcript level in Se-hyperaccumulating Astragalus comparable with other plant species under S deprivation. The high expression of sulfate transporters in certain Astragalus species may lead to enhanced Se uptake and translocation ability and therefore may contribute to the Se hyperaccumulation trait; however, it is not sufficient to explain S/Se discriminatory mechanisms. PMID:21972267
Cabannes, Emmanuelle; Buchner, Peter; Broadley, Martin R; Hawkesford, Malcolm J
Populations of Noccaea caerulescens show tremendous differences in their capacity to hyperaccumulate and hypertolerate metals. To explore the differences that could contribute to these traits, we undertook SOLiD high-throughput sequencing of the root transcriptomes of three phenotypically well-characterized N. caerulescens accessions, i.e., Ganges, La Calamine, and Monte Prinzera. Genes with possible contribution to zinc, cadmium, and nickel hyperaccumulation and hypertolerance were predicted. The most significant differences between the accessions were related to metal ion (di-, trivalent inorganic cation) transmembrane transporter activity, iron and calcium ion binding, (inorganic) anion transmembrane transporter activity, and antioxidant activity. Analysis of correlation between the expression profile of each gene and the metal-related characteristics of the accessions disclosed both previously characterized (HMA4, HMA3) and new candidate genes (e.g., for nickel IRT1, ZIP10, and PDF2.3) as possible contributors to the hyperaccumulation/tolerance phenotype. A number of unknown Noccaea-specific transcripts also showed correlation with Zn(2+), Cd(2+), or Ni(2+) hyperaccumulation/tolerance. This study shows that N. caerulescens populations have evolved great diversity in the expression of metal-related genes, facilitating adaptation to various metalliferous soils. The information will be helpful in the development of improved plants for metal phytoremediation. PMID:24559272
Halimaa, Pauliina; Lin, Ya-Fen; Ahonen, Viivi H; Blande, Daniel; Clemens, Stephan; Gyenesei, Attila; Hõiki÷, Elina; Kõrenlampi, Sirpa O; Laiho, Asta; Aarts, Mark G M; Pursiheimo, Juha-Pekka; Schat, Henk; Schmidt, Holger; Tuomainen, Marjo H; Tervahauta, Arja I
Aquatic arsenic: Phytoremediation using floating macrophytes
Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground\\/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively.
M. Azizur Rahman; H. Hasegawa
The possibility to clean heavy metal contaminated soils with hyperaccumulator plants has shown great potential. One of the most recently studied species used in phytoremediation applications are sunflowers. In this study, two cultivars of Helianthus annuus were used in conjunction with ethylene diamine tetracetic acid (EDTA) and citric acid (CA) as chelators. Two different concentrations of the chelators were studied
Cafer Turgut; M. Katie Pepe; Teresa J. Cutright
Thallium (TI) is an extremely toxic metal which, due to its similarities to K, is readily taken up by plants. Thallium is efficiently hyperaccumulated in Iberis intermedia as TI(I). Distribution and compartmentalization of TI in I. intermedia is highes...
Accumulation of heavy metals in plants grown on mineralised soils of the Austrian Alps
A field survey of higher terrestrial plants growing on 18 metalliferous sites of the Austrian Alps was conducted to identify species accumulating exceptional large concentrations of Cd, Cu, Ni, Pb and Zn in shoots. Minuartia verna (Caryophyllaceae) was confirmed and Biscutella laevigata (Brassicaceae) newly identified as hyperaccumulators of Pb (>1000 mg kg?1 Pb in shoots). Metal concentrations in shoots exceeded
W. W Wenzel; F Jockwer
The Engineered Phytoremediation of Ionic and Methylmercury Pollution
Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and above ground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in above ground tissues for later harvest.
Richard Meagher; Sarah Marshburn; Andrew Heaton; Anne Marie Zimer; Raoufa Rahman
DOI 10.1007/s00442-007-0907-8 PLANT-ANIMAL INTERACTIONS -ORIGINAL PAPER
of the Se hyperaccumulator Stanleya pinnata (prince's plume) that were pretreated with or without Se phytoremediation, or as Se-forti- Wed crops. Keywords Astragalus bisulcatus ┬Ę Black-tailed prairie dog ┬Ę Stanleya pinnata Introduction While many plant species growing on soils with high con- centrations of metals
Selenium accumulation protects plants from herbivory by Orthoptera via toxicity and deterrence.
To investigate whether selenium (Se) accumulation in plants provides a chemical defense against generalist insect herbivores, the feeding preference and performance of a mix of orthopteran species were investigated. The selenium hyperaccumulator Stanleya pinnata and accumulator Brassica juncea were used in herbivory studies in the laboratory, and S. pinnata was also used in a manipulative field experiment. In laboratory studies, both crickets and grasshoppers avoided plants pretreated with selenate, while those given no choice died after eating leaves with elevated Se (447 +/- 68 and 230 +/- 68 microg Se g(-1) DW, respectively). B. juncea has previously been shown to accumulate selenate, while S. pinnata hyperaccumulates methyl-selenocysteine. Thus, these findings demonstrate that both inorganic and organic forms of selenium protect plants from herbivory. Grasshoppers fed S. pinnata contained methylselenocysteine in their midgut and absorbed this form into surrounding tissues. In a manipulative field experiment, methylselenocysteine protected S. pinnata from invertebrate herbivory and increased its long-term survival rate over an entire growth season. * In native habitats of selenium hyperaccumulators, orthopterans represent a major group of insect herbivores. Protection offered by organic selenium accumulation against these herbivores may have promoted the evolution of selenium hyperaccumulation in plants. PMID:17635224
Freeman, John L; Lindblom, Stormy Dawn; Quinn, Colin F; Fakra, Sirine; Marcus, Matthew A; Pilon-Smits, Elizabeth A H
Sulfate and selenate uptake were investigated in both selenium (Se) hyperaccumulators (Astragalus racemosus and Astragalus bisulcatus) and closely related nonaccumulator species (Astragalus glycyphyllos and Astragalus drummondii). Sulfur (S) starvation increased Se accumulation, whereas increased selenate supply increased sulfate accumulation in both root and shoot tissues. cDNAs for homologs of groups 1 to 4 sulfate transporters were cloned from these Astragalus species to investigate patterns of expression and interactions with sulfate and selenate uptake. In contrast to all other previously analyzed plant species, abundant gene expression of putative sulfate transporters was observed for both Se-hyperaccumulating and nonaccumulating Astragalus, regardless of S and Se status. Furthermore, quantitative analysis of expression indicated a transcript level in Se-hyperaccumulating Astragalus comparable with other plant species under S deprivation. The high expression of sulfate transporters in certain Astragalus species may lead to enhanced Se uptake and translocation ability and therefore may contribute to the Se hyperaccumulation trait; however, it is not sufficient to explain S/Se discriminatory mechanisms. PMID:21972267
Cabannes, Emmanuelle; Buchner, Peter; Broadley, Martin R.; Hawkesford, Malcolm J.
hyperaccumulators to remove arsenic from contaminated sites. It is considered as a cost-effective and environmental to adverse soil characteristics make it a good candi- date for phytoextraction. P. vittata exhibits.1016/j.envpol.2007.10.012 Available online at www.sciencedirect.com Environmental Pollution 154 (2008
Ma, Lena
Large spoils of metal-rich filtercake from the Port Kembla BHP steelworks were characterised by certain physical, chemical and biological parameters. The vegetation was assessed for potential metal hyperaccumulators and the presence of arbuscular mycorrhizae in the rhizospheres. Fresh filtercake (4 yr). Among the naturally colonising plants, Ricinus communis and Sonchus oleraceus are regarded the most suitable options for zinc and
A. G. Khan; T. M. Chaudhry; W. J. Hayes; C. S. Khoo; L. Hill; R. Fernandez; P. Gallardo
Mechanisms of cadmium detoxification in cattail ( Typha angustifolia L.)
Cadmium (Cd) is a widespread heavy metal pollutant and environmental and human health hazard, which may be partially resolved using green and cost-effective phytoremediation techniques. However, the efficiency of phytoremediation is often limited by the small biomass of Cd-hyperaccumulator plants. Although cattail (Typha angustifolia L.) is tolerant of heavy metals and has a high biomass, there is little information available
Weifeng Xu; Weiming Shi; Feng Yan; Biao Zhang; Jiansheng Liang
The mined ecotype of Sedum alfredii Hance has been identified to be a zinc (Zn) hyperaccumulator native to China. In the present article, the characteristics of cadmium (Cd) uptake and accumulation were compared with hydroponic experiments between the mined and the nonmined ecotypes of Sedum alfredii Hance. The results indicate that the plants of the mined ecotype (ME) have higher
Y. H. Xiong; X. E. Yang; Z. Q. Ye; Z. L. He
Arabidopsis halleri , a close wild relative of A. thaliana , is a clonal, insect-pollinated herb tolerant to heavy metals (Zn, Pd, Cd) and a hyperaccumulator of Zn and Cd. It is of partic- ular interest in the study of evolutionary processes and phytoremediation. However, little is known about its population gene flow patterns and the structure of its genetic
Harvesting a crop of gold in plants
The possibility of turning base metals into gold has intrigued many scientists since the early alchemists, and the discovery of significant gold uptake by plants has long been a `philosopher's stone'. But background levels of gold in plants are usually very low, rarely exceeding 10 ng per g dry tissue (10 p.p.b.). Hyperaccumulator plants, however, have 100 times the elemental
Christopher W. N. Anderson; Robert R. Brooks; Robert B. Stewart; Robyn Simcock
Mechanism of four methods for removing hazardous heavy metal are detailed and compared-chemical/physical remediation, animal remediation, phytoremediation and microremediation with emphasis on bio-removal aspects. The latter two, namely the use of plants and microbes, are preferred because of their cost-effectiveness, environmental friendliness and fewer side effects. Also the obvious disadvantages of other alternatives are listed. In the future the application of genetic engineering or cell engineering to create an expected and ideal species would become popular and necessary. However, a concomitant and latent danger of genetic pollution is realized by a few persons. To cope with this potential harm, several suggestions are put forward including choosing self-pollinated plants, creating infertile polyploid species and carefully selecting easy-controlled microbe species. Bravely, the authors point out that current investigation of noncrop hyperaccumulators is of little significance in application. Pragmatic development in the future should be crop hyperaccumulators (newly termed as "cropaccumulators") by transgenic or symbiotic approach. Considering no effective plan has been put forward by others about concrete steps of applying a hyperaccumulator to practice, the authors bring forward a set of universal procedures, which is novel, tentative and adaptive to evaluate hyperaccumulators' feasibility before large-scale commercialization. PMID:19864055
Wu, Gang; Kang, Hubiao; Zhang, Xiaoyang; Shao, Hongbo; Chu, Liye; Ruan, Chengjiang
Roles of organic acids and nitrate in the long-distance transport of cobalt (Co) in xylem saps of hyperaccumulator Alyssum murale and non-hyperaccumulator Trifolium subterraneum were studied under hydroponic conditions. Organic acids (oxalic, malic, malonic, citric, and fumaric) and nitrate in xylem sap samples were separated and determined simultaneously by reversed-phase high performance liquid chromatography after solid-phase extraction with nanosized hydroxyapatite. Results indicated that Co treatment significantly increased the concentrations of xylem oxalic and malic acids for the hyperaccumulator A. murale compared to the control but significantly decreased the concentrations of xylem nitrate and malonic acid; concentrations of citric acid in xylem sap samples did not show significant difference between the control and Co treatments. By analyzing the relationship between the concentrations of organic acids, nitrate, and concentrations of Co in xylem saps, it could be concluded that oxalic and malic acids in xylem saps seemed to participate in the long-distance Co translocation process, and citric acid did not relate to the xylem Co transport of A. murale and T. subterraneum. Our work might be very useful for understanding the mechanism of long-distance transport of heavy metals in hyperaccumulator. PMID:19300916
Wei, Wei; Wang, Yu; Wei, Zheng-Gui; Zhao, Hai-Yan; Li, Hui-Xin; Hu, Feng
Although phosphorus is an essential factor for proper plant growth in natural environments, an excess of phosphate in water sources causes serious pollution. In this paper we describe transgenic plants which hyperaccumulate inorganic phosphate (Pi) and which may be used to reduce environmental water pollution by phytoremediation. AtPHR1, a transcription factor for a key regulator of the Pi starvation response in Arabidopsis thaliana, was overexpressed in the ornamental garden plants Torenia, Petunia, and Verbena. The transgenic plants showed hyperaccumulation of Pi in leaves and accelerated Pi absorption rates from hydroponic solutions. Large-scale hydroponic experiments indicated that the enhanced ability to absorb Pi in transgenic torenia (AtPHR1) was comparable to water hyacinth a plant that though is used for phytoremediation causes overgrowth problems. PMID:23984322
Togami, Junichi; Mason, John G.; Chandler, Stephen F.; Tanaka, Yoshikazu
Phytoremediation of ionic and methylmercury pollution
Our long-term goal is to enable highly productive plant species to extract, resist, detoxify, and sequester the toxic elemental pollutants, like the heavy metal mercury. Our current working hypothesis is that transgenic plants controlling the transport, chemical speciation, electrochemical state. volatilization, and aboveground binding of mercury will: a) tolerate mercury and grow rapidly in mercury contaminated environments; b) prevent methylmercury from entering the food chain; c) remove mercury from polluted soil and . water; and d) hyperaccumulate mercury in aboveground tissues for later harvest. Progress toward these specific aims is reported: to increase the transport of mercury into roots and to aboveground vegetative organs; to increase biochemical sinks and storage for mercury in leaves; to increase leaf cell vacuolar storage of mercury; and to demonstrate that several stacked transgenes, when functioning in concert, enhance mercury resistance and hyperaccumulation to high levels.
Meagher, Richard B
Evaluation of three ornamental plants for phytoremediation of Pb-contamined soil.
Characteristics of accumulation and tolerance of lead (Pb) in Quamolit pennata, Antirrhinum majus L. and Celosia cristata pyramidalis were investigated to identify Pb-accumulating plants. In this study, pot culture experiment was conducted to assess whether these plants are Pb-hyperaccumulators or accumulators. The results indicated that the Pb enrichment factor (concentration in plant/soil) and Pb translocation factor (concentration in shoot/root) of these plants were principally <1 in pot culture and concentration gradient experiments. However, the Pb concentration in Celosia cristata pyramidalis shoots was higher than 1000 mg kg(-1), the threshold concentration for a Pb-hyperaccumulator. Shoot biomass of Celosia cristata pyramidalis had no significantly (p < 0.05) variation compared to the control. Based on these results, only Celosia cristata pyramidalis could be identified as a Pb-accumulator. PMID:23487996
Cui, Shuang; Zhang, Tingan; Zhao, Shanlin; Li, Ping; Zhou, Qixing; Zhang, Qianru; Han, Qing
Cloning and expression of Brassica napus beta-carbonic anhydrase cDNA.
A new full-length beta-carbonic anhydrase cDNA was obtained from Brassica napus by homologous cloning. The cDNA has an open-reading frame of 996 nucleotides, encoding 331 amino acids with a calculated molecular weight of 35,692 Da and an estimated pI value of 5.459. The deduced amino acid sequence of beta-carbonic anhydrase from Brassica napus shared significant identity with beta-carbonic anhydrases from Brassica carinata, Arabidopsis thaliana, and Thlaspi caerulescens (97.9%, 94%, and 93.5% identity, respectively). This cDNA was expressed in Escherichia coli BL21 (DE3) using the expression vector pET-32a(+). The expression band corresponded to the calculated mass plus the N-terminal fusion protein derived from the vector. PMID:20158161
Deng, Qiu-Hong; Li, Mao-Teng; Yu, Long-Jiang
In the yeast Saccharomyces cerevisiae inactivation of trehalose-6-phosphate (Tre6P) synthase (Tps1) encoded by the TPS1 gene causes a specific growth defect in the presence of glucose in the medium. The growth inhibition is associated with deregulation of the initial part of glycolysis. Sugar phosphates, especially fructose-1,6-bisphosphate (Fru1,6bisP), hyperaccumulate while the levels of ATP, Pi and downstream metabolites are rapidly depleted.
Beatriz M. Bonini; Patrick Van Dijck; Johan M. Thevelein
The term phytoremediation is used to describe the clean-up of heavy metals from contaminated soils by plants. In this study, we examined cadmium (Cd) accumulation by Brassica napus in comparison with the known Cd-hyperaccumulator Brassica juncea, in a hydroponic medium. Cd treatment was applied as a concentration series between 0 and 50?M for 15 days. Most of the Cd taken
Issam Nouairi; Wided Ben Ammar; Nabil Ben Youssef; Douja Ben Miled Daoud; Mohamed Habib Ghorbal; Mokhtar Zarrouk
Tolerance and metal uptake are two essential characteristics required for phytoextraction of metals from contaminated soils. We compared tolerance and Cu uptake of Elsholtzia splendens (reported previously to be a Cu hyperaccumulator) with Silene vulgaris (the Imsbach population, a well-known Cu-tolerant excluder species), using 30 soils varying widely in total Cu concentration (19¢8645 mg kg?1). We further investigated the effectiveness
Jing Song; Fang-Jie Zhao; Yong-Ming Luo; Steve P. McGrath; Hao Zhang
Author's personal copy Environmental and Experimental Botany 68 (2010) 222229
vittata Silicic acid Boric acid Mercury a b s t r a c t To better understand arsenite (AsIII) uptake via aquaporin channels by arsenic hyperaccumulator Pteris vittata, the effects of silicic and boric acid (As with or without 0.5 mM silicic acid (Si experiment) or 0.3 mM boric acid (B experiment), or (2) 15 M AsIII for 2 d
Ma, Lena
Thallium is an extremely toxic metal which, due to its similarities to K, is readily taken up by plants grown in Tl-contaminated\\u000a soils. Thallium is also a precious metal nearly as economically valuable as gold. Thallium is efficiently hyperaccumulated\\u000a in IberisĀintermedia as aqueous Tl(I) with highest concentrations within the vascular network of leaves. In this study we examine the utility
Kirk G. Scheckel; Rebecca Hamon; Laurence Jassogne; Mark Rivers; Enzo Lombi
BjDHNs Confer Heavy-metal Tolerance in Plants
Dehydrin gene transcript could be induced by heavy metals, and some dehydrins possess the ability to bind metals. However,\\u000a the correlation between dehydrins and heavy-metal stress is unknown. In order to elucidate the contribution of dehydrins to\\u000a heavy-metal stress tolerance in plants, we cloned two SK2-type dehydrin genes from heavy-metal hyperaccumulator Brassica juncea, and investigated their Cd\\/Zn tolerance in transgenic
Jin Xu; Yu Xiu Zhang; Wei Wei; Lu Han; Zi Qiu Guan; Zi Wang; Tuan Yao Chai
Plants with inordinately high concentrations of heavy metals (æhyperaccumulatorsÆ) can be used for phytoremediation (removal of contaminants from soils) or phytomining (growing a crop of plants to harvest the metals). Pot trials were used to investigate the effects of MgCO3, CaCO3, sulphur, chelating agents (NTA, DTPA, EDTA) and acid mine tailings on nickel and cobalt uptake by the South African
Eleven common vegetables (green bean, beetroot, green cabbage, lettuce, onion, pea, radish, spinach, tomato, turnip, and watercress) as well as the thallium hyperaccumulator Iberis intermedia, were grown in pot trials containing 0.7 and 3.7 mg\\/kg thallium added to a silt loam soil. The aims of the experiments were threefold: to estimate risks to human health of vegetables grown in thallium-rich
Cher LaCoste; Brett Robinson; Robert Brooks
Selenium phytoremediation potential of Stanleya pinnata
Disposal of saline irrigation wastewater in hydrologically closed sinks in the semi-arid western U.S. has concentrated selenium-rich salts to hazardous levels and phytoextraction, along with plant-enhanced volatilization of methyl-selenides, is an active area of research. Here, we provide an overview of our ongoing studies of Stanleya pinnata (Brassicaceae), a previously unstudied candidate that is a primary accumulator (hyperaccumulator) of Se
David R. Parker; Laura J. Feist; Tracey W. Varvel; David N. Thomason; Yiqiang Zhang
It is unclear whether certain plant species and plant diversity could reduce the impacts of multiple heavy metal pollution\\u000a on soil microbial structure and soil enzyme activities. Random amplified polymorphic DNA (RAPD) was used to analyze the genetic\\u000a diversity and microbial similarity in planted and unplanted soil under combined cadmium (Cd) and lead (Pb) pollution. A metal\\u000a hyperaccumulator, Brassica juncea,
Yang Gao; Chiyuan Miao; Jun Xia; Liang Mao; Yafeng Wang; Pei Zhou
Land application of biosolids to improve agricultural productivity is a cost-effective approach for resource recovery. Unfortunately, municipal biosolids often contain high concentrations of heavy metals, including zinc and copper. In this study, a co-cropping technique was investigated using a known zinc hyperaccumulator, Sedum alfredii, with a grain crop, Zea mays. After a 3-mo growth trial, the results indicate that when
Liu Xiaomei; Wu Qitang; M. Katherine Banks
Exploring lower limits of plant elemental defense by cobalt, copper, nickel, and zinc.
Elemental defense is a relatively newly recognized phenomenon in which plants use elements present in their tissue to reduce damage by herbivores or pathogens. In the present study, neonates of the generalist herbivore, Spodoptera exigua (H³bner) (Lepidoptera: Noctuidae), were fed artificial diets amended with varying concentrations of Co, Cu, Ni, and Zn that are hyperaccumulated by plants to determine minimum lethal concentrations (MLC) and minimum sublethal concentrations (MSC) for each metal. MLC values (dry mass) for Co (45Ā?g/g), Ni (230Ā?g/g), and Zn (280Ā?g/g) were below published minimum hyperaccumulator levels. MSC levels (dry mass) for Co (15Ā?g/g), Ni (140Ā?g/g), and Zn (200Ā?g/g) were at concentrations lower than published minimum accumulator levels. Furthermore, both MLC and MSC values for Zn were within normal tissue concentrations. These results indicate that elemental defense for Co, Ni, and Zn may be effective at concentrations lower than hyperaccumulator levels and so may be more widespread than previously believed. PMID:23584612
Cheruiyot, Dorothy J; Boyd, Robert S; Moar, William J
Analysis of arsenic in soil and vegetation of a contaminated area in Zarshuran, Iran.
To assess the potential for arsenic (As) hyperaccumulation of native plant species, plant and soil samples were collected from the Zarshuran area (north-western Iran), which has a history of As pollution from mining. Total and water-soluble As in the soil ranged from 11.2 to 6525 and from 0.004 to 13.08 mg kg(-1), respectively. Among 89 plant species, the highest foliar As concentrations were found in Isatis capadocica (up to 3000 mg kg(-1)) and Hesperis persica (up to 1500 mg kg(-1)). Over a broad range of soil As concentrations, these species maintained more than 10-fold increased foliar As concentrations and soil to leaf As transfer coefficients in comparison with all the other species sampled at the same sites. Based on these characteristics, in combination with their ability to accumulate As to concentrations exceeding 1000 mg kg(-1) on a dry weight basis in their foliage, both species should be classified as As hyperaccumulators. I. capadocica and H. persica, both Brassicacaeae, are the first terrestrial angiosperms shown to possess the As hyperaccumulation trait. Both species are fairly robust with relatively high biomass productivity and, therefore, potentially useful in on site phytoremediation, particularly I. capadocica, because of its higher robustness and As accumulation capacity. PMID:20734613
Karimi, Naser; Ghaderian, S Majid; Maroofi, Hosein; Schat, Henk
Screen of Chinese weed species for cadmium tolerance and accumulation characteristics.
The cadmium (Cd) tolerance and metal-accumulation characteristics of 29 species (18 families) of weed were studied by using outdoor pot-culture experiments. The results of this screening showed that Bidens pilosa and Kalimeris integrifolia (both Asteraceae) expressed some properties that are characteristic of Cd hyperaccumulators. In 10 mg/kg Cd-spiked soil, they accumulated a good deal of Cd in shoots (28 and 25 mg/kg DW, respectively) with high Cd enrichment factors (EFs; concentration in plant/soil). Cd accumulations in shoots were greater than those in roots (translocation factor (TF) >1, concentration in shoot/root) and the shoot biomasses did not decreased significantly compared to the unspiked control. The other weed species showed little accumulation of Cd, Pb, Cu, or Zn. In a concentration-gradient experiment, the Cd accumulation potentials of B. pilosa and K. integrifolia were examined further. Cd concentrations in leaves of B. pilosa growing in soils spiked with 25, 50, and 100 mg/kg Cd were up to 145, 160, and 192 mg/kg, respectively, and the Cd content in stems in the 100 mg/kg Cd-spiked soil was 115 mg/kg, all greater than the 100 mg/kg notional criterion for Cd hyperaccumulation. The Cd EFs and TFs were all greater than 1. The shoot biomasses did not decrease significantly compared to the controls. B. pilosa was thus shown to have some characteristics of a true Cd hyperaccumulator plant. PMID:19260234
Wei, Shuhe; Zhou, Qixing
Nickel accumulation by Streptanthus polygaloides (Brassicaceae) reduces floral visitation rate.
Hyperaccumulation is the phenomenon whereby plants take up and sequester in high concentrations elements that generally are excluded from above-ground tissues. It largely is unknown whether the metals taken up by these plants are transferred to floral rewards (i.e., nectar and pollen) and, if so, whether floral visitation is affected. We grew Streptanthus polygaloides, a nickel (Ni) hyperaccumulator, in short-term Ni supplemented soils and control soils to determine whether Ni is accumulated in floral rewards and whether floral visitation is affected by growth in Ni-rich soils. We found that while supplementation of soils with Ni did not alter floral morphology or reward quantity (i.e., anther size or nectar volume), Ni did accumulate in the nectar and pollen-filled anthers-providing the first demonstration that Ni is accumulated in pollinator rewards. Further, S. polygaloides grown in Ni-supplemented soils received fewer visits per flower per hour from both bees and flies (both na've to Ni-rich floral resources in the study area) relative to plants grown in control soils, although the probability a plant was visited initially was unaffected by Ni treatment. Our findings show that while Ni-rich floral rewards decrease floral visitation, floral visitors are not completely deterred, so some floral visitors may collect and ingest potentially toxic resources from metal-hyperaccumulating plants. In addition to broadening our understanding of the effects of metal accumulation on ecological interactions in natural populations, these results have implications for the use of insect-pollinated plants in phytoremediation. PMID:24477333
Meindl, George A; Ashman, Tia-Lynn
Biotechnological applications of serpentine soil bacteria for phytoremediation of trace metals.
Serpentine or ultramafic soils are produced by weathering and pedogenesis of ultramafic rocks that are characterized by high levels of Ni, Cr, and sometimes Co, but contain low levels of essential nutrients such as N, P, K, and Ca. A number of plant species endemic to serpentine soils are capable of accumulating exceptionally high concentrations of Ni, Zn, and Co. These plants are known as metal "hyperaccumulators." The function of hyperaccumulation depends not only on the plant, but also on the interaction of the plant roots with rhizosphere microbes and the concentrations of bioavailable metals in the soil. The rhizosphere provides a complex and dynamic microenvironment where microorganisms, in association with roots, form unique communities that have considerable potential for the detoxification of hazardous materials. The rhizosphere bacteria play a significant role on plant growth in serpentine soils by various mechanisms, namely, fixation of atmospheric nitrogen, utilization of 1-aminocyclopropane-1-carboxylic acid (ACC) as the sole N source, production of siderophores, or production of plant growth regulators (hormones). Further, many microorganisms in serpentine soil are able to solubilize "unavailable" forms of heavy metal-bearing minerals by excreting organic acids. In addition, the metal-resistant serpentine isolates increase the efficiency of phytoextraction directly by enhancing the metal accumulation in plant tissues and indirectly by promoting the shoot and root biomass of hyperaccumulators. Hence, isolation of the indigenous and stress-adapted beneficial bacteria serve as a potential biotechnological tool for inoculation of plants for the successful restoration of metal-contaminated ecosystems. In this study, we highlight the diversity and beneficial features of serpentine bacteria and discuss their potential in phytoremediation of serpentine and anthropogenically metal-contaminated soils. PMID:19514893
Rajkumar, Mani; Vara Prasad, Majeti Narasimha; Freitas, Helena; Ae, Noriharu
The concentrations of uranium, thorium, barium, nickel, strontium and lead in the samples of the tailings and plant species collected from a uranium mill tailings repository in South China were analyzed. Then, the removal capability of a plant for a target element was assessed. It was found that Phragmites australis had the greatest removal capabilities for uranium (820 ?g), thorium (103 ?g) and lead (1,870 ?g). Miscanthus floridulus had the greatest removal capabilities for barium (3,730 ?g) and nickel (667 ?g), and Parthenocissus quinquefolia had the greatest removal capability for strontium (3,920 ?g). In this study, a novel coefficient, termed as phytoremediation factor (PF), was proposed, for the first time, to assess the potential of a plant to be used in phytoremediation of a target element contaminated soil. Phragmites australis has the highest PFs for uranium (16.6), thorium (8.68), barium (10.0) and lead (10.5). Miscanthus floridulus has the highest PF for Ni (25.0). Broussonetia papyrifera and Parthenocissus quinquefolia have the relatively high PFs for strontium (28.1 and 25.4, respectively). On the basis of the definition for a hyperaccumulator, only Cyperus iria and Parthenocissus quinquefolia satisfied the criteria for hyperaccumulator of uranium (36.4 ?g/g) and strontium (190 ?g/g), and could be the candidates for phytoremediation of uranium and strontium contaminated soils. The results show that the PF has advantage over the hyperaccumulator in reflecting the removal capabilities of a plant for a target element, and is more adequate for assessing the potential of a plant to be used in phytoremediation than conventional method. PMID:21523506
Li, Guang-yue; Hu, Nan; Ding, De-xin; Zheng, Ji-fang; Liu, Yu-long; Wang, Yong-dong; Nie, Xiao-qin
The green clean: The emerging field of phytoremediation takes root
A few plants can biologically accumulate toxic metals from surrounding soils, a situation that could revolutionize environmental cleanup. By breeding a planting metal-munchers like alpine pennycress, scientist plan to clease waste zones of toxic levels of zinc, nickel and lead. From soil loaded with metal to radionuclide-laden water, researcher hope phytoremediation will provide a cheap way to clean man-made messes at mining, nuclear, and industrial sites. This article describes developments in the area of phytoremediation, including sections on plants called hyperaccumulators, how phytoremediators function, problems transferring phytoremediators from hydroculture to soils and problems which might prevent use of phytoremediators.
Brown, K.S.
The mechanisms by which Pteris vittata (L.) hyperaccumulates arsenic (As) have not been fully elucidated. To investigate how P. vittata tolerates high concentrations of arsenite, we compared the toxicities of various As compounds to P. vittata and Arabidopsis thaliana (L.). The phytotoxicities of As species were found to be in the order of arseniteĀ>ĀarsenateĀ>Ādimethylarsinic acid (DMAA) in A. thaliana, and in the order of DMAAĀ>ĀarsenateĀ>Āarsenite in P. vittata. P. vittata calli displayed a weaker ability to absorb arsenite than arsenate. These results demonstrate that P. vittata possesses mechanisms of As accumulation and detoxification. PMID:24084979
Dai, Wentao; Yang, Xuexi; Chen, Hui; Xu, Wenzhong; He, Zhenyan; Ma, Mi
Phytoremediation potential of Solanum nigrum L. under different cultivation protocols.
In this study, Solanum nigrum L. was used as a hyperaccumulator for remediation of cadmium contaminated soil, and 3 different cultivation protocols were investigated. The results showed that a double cropping treatment enhanced the phytoremediation efficiency significantly, since it increased the amount of Cd extracted in one growing season by a factor of 1.62 compared to single cropping. However, the labor cost for double cropping was twice that of single cropping. If the time consumed is considered as a cost of phytoremediation, the double cropping treatment might be considered as an effective and economic cultivation protocol by reducing the overall time required to reach the targeted soil quality. PMID:23778778
Qu, Guangzhou; Tong, Yan'an; Gao, Pengcheng; Zhao, Zuoping; Song, Xueying; Ji, Puhui
Arsenic in the rhizosphere soil solution of ferns.
The aim of this study was to explore the evidence of arsenic hyperaccumulation in plant rhizosphere solutions. Six common fern plants were selected and grown in three types of substrate: arsenic (As) -tailings, As-spiked soil, and soil-As-tailing composites. A rhizobox was designed with an in-situ collection of soil solutions to analyze changes in the As concentration and valence as well as the pH, dissolved organic carbon (DOC) and total nitrogen (TN). Arsenite composed less than 20% of the total As, and As depletion was consistent with N depletion in the rhizosphere solutions of the various treatments. The As concentrations in the rhizosphere and non-rhizosphere solutions in the presence of plants were lower than in the respective controls without plants, except for in the As-spiked soils. The DOC concentrations were invariably higher in the rhizosphere versus non-rhizosphere solutions from the various plants; however, no significant increase in the DOC content was observed in Pteris vittata, in which only a slight decrease in pH appeared in the rhizosphere compared to non-rhizosphere solutions. The results showed that As reduction by plant roots was limited, acidification-induced solubilization was not the mechanism for As hyperaccumulation. PMID:22908657
Wei, Chaoyang; Zheng, Huan; Yu, Jiangping
Arsenic alters uptake and distribution of sulphur in Pteris vittata.
Low-molecular-weight thiol (LMWT) synthesis has been reported to be directly induced by arsenic (As) in Pteris vittata, an As hyperaccumulator. Sulphur (S) is a critical component of LMWTs. Here, the effect of As treatment on the uptake and distribution of S in P. vittata was investigated. In P. vittata grown under low S conditions, the presence of As in the growth medium enhanced the uptake of SO4(2-), which was used for LMWT synthesis in fronds. In contrast, As application did not affect SO4(2-) uptake in Nephrolepis exaltata, an As non-hyperaccumulator. Moreover, the isotope microscope system revealed that S absorbed with As accumulated locally in a vacuole-like organelle in epidermal cells, whereas S absorbed alone was distributed uniformly. These results suggest that S is involved in As transport and/or accumulation in P. vittata. X-ray absorption near-edge structure analysis revealed that the major As species in the fronds and roots of P. vittata were inorganic As(III) and As(V), respectively, and that As-LMWT complexes occurred as a minor species. Consequently, in case of As accumulation in P. vittata, S possibly acts as a temporary ligand for As in the form of LMWTs in intercellular and/or intracellular transport (e.g. vacuolar sequestration). PMID:23611758
Watanabe, Toshihiro; Kouho, Ran; Katayose, Tomo; Kitajima, Nobuyuki; Sakamoto, Naoya; Yamaguchi, Noriko; Shinano, Takuro; Yurimoto, Hisayoshi; Osaki, Mitsuru
The application of vegetation cover for the phytomanagement of heavy metal-polluted soils needs prior investigation on the suitability of plant species. In this study, behaviors of Arrhenatherum elatius and Sonchus transcaspicus, two native perennial grasses that currently grow in a mine tailing, were investigated through plant metal concentration, phytotoxicity and their detoxification responses. Both of the species accumulated Ni, Cu, Cd, Co, Mn, Pb, Cr, and Zn in shoots far below criterion concentration as a hyperaccumulators; thus, neither of them were found to be hyperaccumulators. A. elatius accumulated metals in roots and then in shoots, on the contrary, in S. transcaspicus metals were preferentially accumulated in shoots. Plants exposure to such metals resulted in oxidative stress in the considered organs as indicated by the changes in chlorophyll fluorescence, chlorophyll contents, malondialdehyde (MDA) levels and antioxidative enzyme activities. A. elatius seemed to be more affected by metal-induced oxidative stress than S. transcaspicus. Correspondingly, S. transcaspicus showed a greater capacity to adapt to metal-induced oxidative stress, depending on more effective antioxidative defense mechanisms to protect itself from oxidative damage. These findings allowed us to conclude that both of these plant species could be suitable for the phytostabilization of metal-polluted soils. PMID:23819286
Lu, Yan; Li, Xinrong; He, Mingzhu; Zeng, Fanjiang
Uptake of metals and metalloids by plants growing in a lead-zinc mine area, Northern Vietnam.
This study was conducted to evaluate the phytoremediation and phytomining potential of 10 plant species growing naturally at one of the largest lead-zinc mines in Northern Vietnam. Total concentrations of heavy metals and arsenic were determined in the plant and in associated soil and water in and outside of the mine area. The results indicate that hyperaccumulation levels (mg kg(-1) dry weight) were obtained in Houttuynia cordata Thunb. (1140) and Pteris vittata L. (3750) for arsenic, and in Ageratum houstonianum Mill. (1130), Potamogeton oxyphyllus Miq. (4210), and P. vittata (1020) for lead. To the best of our knowledge, the present paper is the first report on metal accumulation and hyperaccumulation by H. cordata, A. houstonianum, and P. oxyphyllus. Based on the obtained concentrations of metals, bioconcentration and translocation factors, as well as the biomass of these plants, the two latter species and P. vittata are good candidates for phytoremediation of sites contaminated with arsenic and multi-metals. None of the collected plants was suitable for phytomining, given their low concentrations of useful metals (e.g., silver, gallium, and indium). PMID:21227580
Nguyen, Thi Hoang Ha; Sakakibara, Masayuki; Sano, Sakae; Mai, Trong Nhuan
Molecular Genetics of Metal Detoxification: Prospects for Phytoremediation
Unlike compounds that can be broken down, the remediation of most heavy metals and radionuclides requires physical extraction from contaminated sources. Plants can extract inorganics, but effective phytoextraction requires plants that produce high biomass, grow rapidly and possess high capacity-uptake for the inorganic substance. Either hyperaccumulator plants must be bred for increased growth and biomass or hyperaccumulation traits must be engineered into fast growing, high biomass plants. This latter approach requires fundamental knowledge of the molecular mechanisms in the uptake and storage of inorganics. Much has been learned in recent years on how plants and certain fungi chelate and transport selected heavy metals. This progress has been facilitated by the use of Schizosaccharomyces pombe as a model system. The use of a model organism for study permits rapid characterization of the molecular process. As target genes are identified in a model organism, their sequences can be modified for expression in a heterologous host or aid in the search of homologous genes in more complex organisms. Moreover, as plant nutrient uptake is intrinsically linked to the association with rhizospheric fungi, elucidating metal sequestration in this fungus permits additional opportunities for engineering rhizospheric microbes to assist in phytoextraction.
Ow, David W. firstname.lastname@example.com
The effects of plant¢microbe interactions between the hyperaccumulator Arabidopsis halleri and eight bacterial strains, isolated from the rhizosphere of A. halleri plants grown in a cadmium- and zinc-contaminated site, were analysed for shoot metal accumulation, shoot proteome, and the transcription of genes involved in plant metal homeostasis and hyperaccumulation. Cadmium and zinc concentrations were lower in the shoots of plants cultivated in the presence of these metals plus the selected bacterial strains compared with plants grown solely with these metals or, as previously reported, with plants grown with these metals plus the autochthonous rhizosphere-derived microorganisms. The shoot proteome of plants cultivated in the presence of these selected bacterial strains plus metals, showed an increased abundance of photosynthesis- and abiotic stress-related proteins (e.g. subunits of the photosynthetic complexes, Rubisco, superoxide dismutase, and malate dehydrogenase) counteracted by a decreased amount of plant defence-related proteins (e.g. endochitinases, vegetative storage proteins, and ?-glucosidase). The transcription of several homeostasis genes was modulated by the microbial communities and by Cd and Zn content in the shoot. Altogether these results highlight the importance of plant-microbe interactions in plant protein expression and metal accumulation and emphasize the possibility of exploiting microbial consortia for increasing or decreasing shoot metal content. PMID:21357773
Panigati, Monica; Furini, Antonella
Maize SUT1 functions in phloem loading
The functions of dicot sucrose transporters (SUTs) in apoplastic phloem loading of sucrose are well established; however, whether SUTs similarly function in monocots was unresolved. To address this question, we recently provided genetic evidence that ZmSUT1 from maize (Zea mays) is required for efficient phloem loading. sut1-m1 mutant plants hyperaccumulate carbohydrates in leaves, are defective in loading sucrose into the phloem, and have altered biomass partitioning. Presumably due to the hyperaccumulation of soluble sugars in leaves, mutations in ZmSUT1 lead to downregulation of chlorophyll accumulation, photosynthesis and stomatal conductance. However, because we had identified only a single mutant allele, we were not able to exclude the possibility that the mutant phenotypes were instead caused by a closely linked mutation. Based on a novel aspect of the sut1 mutant phenotype, secretion of a concentrated sugar solution from leaf hydathodes, we identified an additional mutant allele, sut1-m4. This confirms that the mutation of SUT1 is responsible for the impairment in phloem loading. In addition, the sut1-m4 mutant does not accumulate transcripts, supporting the findings reported previously that the original mutant allele is also a null mutation. Collectively, these data demonstrate that ZmSUT1 functions to phloem load sucrose in maize leaves. PMID:20404497
Slewinski, Thomas L; Garg, Anshu; Johal, Gurmukh S
The phenylpropanoid pathway is responsible for the biosynthesis of diverse and important secondary metabolites including lignin and flavonoids. The reduced epidermal fluorescence8 (ref8) mutant of Arabidopsis (Arabidopsis thaliana), which is defective in a lignin biosynthetic enzyme p-coumaroyl shikimate 3?-hydroxylase (C3?H), exhibits severe dwarfism and sterility. To better understand the impact of perturbation of phenylpropanoid metabolism on plant growth, we generated a chemically inducible C3?H expression construct and transformed it into the ref8 mutant. Application of dexamethasone to these plants greatly alleviates the dwarfism and sterility and substantially reverses the biochemical phenotypes of ref8 plants, including the reduction of lignin content and hyperaccumulation of flavonoids and p-coumarate esters. Induction of C3?H expression at different developmental stages has distinct impacts on plant growth. Although early induction effectively restored the elongation of primary inflorescence stem, application to 7-week-old plants enabled them to produce new rosette inflorescence stems. Examination of hypocotyls of these plants revealed normal vasculature in the newly formed secondary xylem, presumably restoring water transport in the mutant. The ref8 mutant accumulates higher levels of salicylic acid than the wild type, but depletion of this compound in ref8 did not relieve the mutantÆs growth defects, suggesting that the hyperaccumulation of salicylic acid is unlikely to be responsible for dwarfism in this mutant. PMID:24381065
Kim, Jeong Im; Ciesielski, Peter N.; Donohoe, Bryon S.; Chapple, Clint; Li, Xu
The soils developed under High Altitude Rocky Complexes in Brazil are generally of very low chemical fertility, with low base saturation and high exchangeable aluminium concentration. This stressful condition imposes evolutionary pressures that lead to ecological success of plant species that are able to tolerate or accumulate high amounts of aluminium. Several analytical methods are currently available for elemental mapping of biological structures, such as micro-X-ray fluorescence (?-EDX) and histochemical tests. The aim of this study was to combine ?-EDX analysis and histochemical tests to quantify aluminium in plants from High Altitude Rocky Complexes, identifying the main sites for Al-accumulation. Among the studied species, five showed total Al concentration higher than 1000 mg kg-1. The main Al-hyperaccumulator plants, Lavoisiera pectinata, Lycopodium clavatum and Trembleya parviflora presented positive reactions in the histochemical tests using Chrome Azurol and Aluminon. Strong positive correlations were observed between the total Al concentrations and data obtained by ?-EDX analysis. The ?-EDX analysis is a potential tool to map and quantify Al in hyperaccumulator species, and a valuable technique due to its non-destructive capacity. Histochemical tests can be helpful to indicate the accumulation pattern of samples before they are submitted for further ?-EDX scrutiny. PMID:24676168
Campos, Naiara V; Pereira, Tiago A R; Machado, Mariana F; Guerra, Marcelo B B; Tolentino, Glßucia S; Ara·jo, Josiane S; Rezende, MaĒra Q; Silva, Maria Carolina N A da; Schaefer, Carlos E G R
Phenotypic and molecular consequences of overexpression of metal-homeostasis genes.
Metal hyperaccumulating plants are able to store very large amounts of metals in their shoots. There are a number of reasons why it is important to be able to introduce metal hyperaccumulation traits into non-accumulating species (e.g., phytoremediation or biofortification in minerals) and to engineer a desired level of accumulation and distribution of metals. Metal homeostasis genes have therefore been used for these purposes. Engineered accumulation levels, however, have often been far from expected, and transgenic plants frequently display phenotypic features not related to the physiological function of the introduced gene. In this review, we focus on an aspect often neglected in research on plants expressing metal homeostasis genes: the specific regulation of endogenous metal homeostasis genes of the host plant in response to the transgene-induced imbalance of the metal status. These modifications constitute one of the major mechanisms involved in the generation of the plant's phenotype, including unexpected characteristics. Interestingly, activation of so-called "metal cross-homeostasis" has emerged as a factor of primary importance. PMID:24639682
Antosiewicz, Danuta M; Barabasz, Anna; Siemianowski, Oskar
Effects of selenium accumulation on reproductive functions in Brassica juncea and Stanleya pinnata.
Selenium (Se) is an essential micronutrient for many organisms, but is also a toxin and environmental pollutant at elevated levels. Due to its chemical similarity to sulphur, most plants readily take up and assimilate Se. Se accumulators such as Brassica juncea can accumulate Se between 0.01% and 0.1% of dry weight (DW), and Se hyperaccumulators such as Stanleya pinnata (Brassicaeae) contain between 0.1% and 1.5% DW of Se. While Se accumulation offers the plant a variety of ecological benefits, particularly protection from herbivory, its potential costs are still unexplored. This study examines the effects of plant Se levels on reproductive functions. In B. juncea, Se concentrations >0.05-0.1% caused decreases in biomass, pollen germination, individual seed and total seed weight, number of seeds produced, and seed germination. In S. pinnata there was no negative effect of increased Se concentration on pollen germination. In cross-pollination of B. juncea plants with different Se levels, both the maternal and paternal Se level affected reproduction, but the maternal Se concentration had the most pronounced effect. Interestingly, high-Se maternal plants were most efficiently pollinated by Se-treated paternal plants. These data provide novel insights into the potential reproductive costs of Se accumulation, interactive effects of Se in pollen grains and in the pistil, and the apparent evolution of physiological tolerance mechanisms in hyperaccumulators to avoid reproductive repercussions. PMID:21841173
Prins, Christine N; Hantzis, Laura J; Quinn, Colin F; Pilon-Smits, Elizabeth A H
Selenium accumulation in flowers and its effects on pollination.
Ģ Selenium (Se) hyperaccumulation has a profound effect on plant-arthropod interactions. Here, we investigated floral Se distribution and speciation in flowers and the effects of floral Se on pollen quality and plant-pollinator interactions. Ģ Floral Se distribution and speciation were compared in Stanleya pinnata, an Se hyperaccumulator, and Brassica juncea, a comparable nonhyperaccumulator. Pollen germination was measured from plants grown with varying concentrations of Se and floral visitation was compared between plants with high and low Se. Ģ Stanleya pinnata preferentially allocated Se to flowers, as nontoxic methyl-selenocysteine (MeSeCys). Brassica juncea had higher Se concentrations in leaves than flowers, and a lower fraction of MeSeCys. For B. juncea, high floral Se concentration impaired pollen germination; in S. pinnata Se had no effect on pollen germination. Floral visitors collected from Se-rich S. pinnata contained up to 270 ?g g(-1), concentrations toxic to many herbivores. Indeed, floral visitors showed no visitation preference between high- and low-Se plants. Honey from seleniferous areas contained 0.4-1 ?g Se g(-1), concentrations that could provide human health benefits. Ģ This study is the first to shed light on the possible evolutionary cost, through decreased pollen germination in B. juncea, of Se accumulation and has implications for the management of seleniferous areas. PMID:21793829
Quinn, Colin F; Prins, Christine N; Freeman, John L; Gross, Amanda M; Hantzis, Laura J; Reynolds, Ray J B; Yang, Soo in; Covey, Paul A; Ba±uelos, Gary S; Pickering, Ingrid J; Fakra, Sirine C; Marcus, Matthew A; Arathi, H S; Pilon-Smits, Elizabeth A H
Optimal defense theory predicts that induction of defensive secondary metabolites in plants will be inversely correlated with constitutive expression of those compounds. Here, we asked whether camalexin, an important defense against fungal and bacterial pathogens, support this prediction in structured natural populations of Arabidopsis thaliana from the Iberian Peninsula. In common garden experiments, we found that genotypes from the VIE population constitutively hyper-accumulated camalexin. Camalexin concentrations were not induced significantly when plants were exposed to a temperature of 10░C for 48h. However, they were induced when plants were exposed to 48h of infection by the virulent bacterial pathogen, Pseudomonas syringae pv. tomato DC3000. Genotypes from the VIE population with the hyper-accumulation of camalexin were significantly more resistant to bacterial growth. Induction of camalexin was negatively correlated with constitutive camalexin concentrations following log transformation and two different corrections for autocorrelation, thus supporting the tradeoff predicted by optimal defense theory. Constitutive overexpression of camalexin was not explained by the only known natural genetic polymorphism at the Accelerated Cell Death 6, ACD6, locus. Collectively, the results support an important role of camalexin in defense against P. syringae as well as significant structured variation in defense levels within wild populations. PMID:25017162
Zhang, Nana; Lariviere, Andy; Tonsor, Stephen J; Traw, M Brian
Effects of selenium accumulation on reproductive functions in Brassica juncea and Stanleya pinnata
Selenium (Se) is an essential micronutrient for many organisms, but is also a toxin and environmental pollutant at elevated levels. Due to its chemical similarity to sulphur, most plants readily take up and assimilate Se. Se accumulators such as Brassica juncea can accumulate Se between 0.01% and 0.1% of dry weight (DW), and Se hyperaccumulators such as Stanleya pinnata (Brassicaeae) contain between 0.1% and 1.5% DW of Se. While Se accumulation offers the plant a variety of ecological benefits, particularly protection from herbivory, its potential costs are still unexplored. This study examines the effects of plant Se levels on reproductive functions. In B. juncea, Se concentrations >0.05¢0.1% caused decreases in biomass, pollen germination, individual seed and total seed weight, number of seeds produced, and seed germination. In S. pinnata there was no negative effect of increased Se concentration on pollen germination. In cross-pollination of B. juncea plants with different Se levels, both the maternal and paternal Se level affected reproduction, but the maternal Se concentration had the most pronounced effect. Interestingly, high-Se maternal plants were most efficiently pollinated by Se-treated paternal plants. These data provide novel insights into the potential reproductive costs of Se accumulation, interactive effects of Se in pollen grains and in the pistil, and the apparent evolution of physiological tolerance mechanisms in hyperaccumulators to avoid reproductive repercussions. PMID:21841173
Prins, Christine N.; Hantzis, Laura J.; Quinn, Colin F.; Pilon-Smits, Elizabeth A. H.
Effect of salinity on zinc uptake by Brassica juncea.
Salinity is a major worldwide problem that affects agricultural soils and limits the reclamation of contaminated sites. Despite the large number of research papers published about salt tolerance in Brassica juncea L., there are very few accounts concerning the influence of salinity on the uptake of trace metals. In this study, B. juncea plants divided through soil sets comprising 0, 900 and 1800 mg Zn kg(-1), were treated with solutions containing 0, 60 and 120 mmol L(-1) of NaCl, with the purpose of observing the effect of salt on Zn uptake, and some physiological responses throughout the 90 days experiment. Increasing concentrations of NaCl and Zn produced a decline in the ecophysiological and biochemical properties of the plants, with observable synergistic effects on parameters like shoot dry weight, leaf area, or photochemical efficiency. Nevertheless, plants treated with 60 mmol L(-1) of NaCl accumulated striking harvestable amounts of Zn per plant that largely exceed those reported for Thlaspi caerulescens. It was concluded that salinity could play an important role on the uptake of Zn by B. juncea. The potential mechanisms behind these results are discussed, as well as the implications for phytoremediation of Zn on saline and non-saline soils. PMID:24933880
Novo, LuĒs A B; Covelo, Emma F; Gonzßlez, LuĒs
Albugo candida is a destructive fungus infecting brassicaceous hosts. The genetic diversity within the A. candida complex from various host plants was investigated by sequence analysis of the internal transcribed spacer (ITS) region of rDNA and the cytochrome c oxidase subunit II (COX2) region of mtDNA. The aligned nucleotide sequences of A. candida shared significantly high distances, up to 20.4 and 8.9%, in two genes. The phylogenetic trees, obtained using the Bayesian method and maximum parsimony analysis, showed two separate groups that corresponded to the host genera. Group I included A. candida isolates infecting Arabis, Autrieta, Berteroa, Biscutella, Brassica, Cardaminopsis, Diplotaxis, Eruca, Erysimum, Heliophila, Iberis, Lunaria, Raphanus, Sinapis, Sisymbrium, and Thlaspi. Group II contained all isolates from Capsella, Descurainia, Diptychocarpus, Draba, and Lepidium. The genetic similarities between the two genes among isolates within Group I were 99.0-100% and 99.6-100%, while those within Group II were 90.4-100% and 91.1-100%, respectively, showing considerably lower values than for Group I. The A. candida isolates from Capsella bursa-pastoris in Korea are clearly separated by sequence analysis for the two genes compared to those from Wales, England, and the USA. Based on the molecular data from the two genes, we suggest the high degree of genetic diversity exhibited within A. candida complexes warrants their division into several distinct species. PMID:16644244
Choi, Young-Joon; Hong, Seung-Beom; Shin, Hyeon-Dong
A comparative study of salt tolerance parameters in 11 wild relatives of Arabidopsis thaliana
Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic Arabidopsis-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed Arabidopsis model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of Arabidopsis thaliana were compared: Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea (previously T. halophila), and Thlaspi arvense. Among these species, highly salt-tolerant (L. densiflorum and L. virginicum) and moderately salt-tolerant (M. triloba and H. incana) species were identified. Only T. parvula revealed a true halophytic habitus, comparable to the better studied Thellungiella salsuginea. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research. PMID:20595237
Orsini, Francesco; D'Urzo, Matilde Paino; Inan, Gunsu; Serra, Sara; Oh, Dong-Ha; Mickelbart, Michael V.; Consiglio, Federica; Jeong, Jae Cheol; Yun, Dae-Jin; Bohnert, Hans J.; Bressan, Ray A.; Maggio, Albino
A comparative study of salt tolerance parameters in 11 wild relatives of Arabidopsis thaliana.
Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic Arabidopsis-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed Arabidopsis model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of Arabidopsis thaliana were compared: Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea (previously T. halophila), and Thlaspi arvense. Among these species, highly salt-tolerant (L. densiflorum and L. virginicum) and moderately salt-tolerant (M. triloba and H. incana) species were identified. Only T. parvula revealed a true halophytic habitus, comparable to the better studied Thellungiella salsuginea. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research. PMID:20595237
Orsini, Francesco; D'Urzo, Matilde Paino; Inan, Gunsu; Serra, Sara; Oh, Dong-Ha; Mickelbart, Michael V; Consiglio, Federica; Li, Xia; Jeong, Jae Cheol; Yun, Dae-Jin; Bohnert, Hans J; Bressan, Ray A; Maggio, Albino
[Antioxidative response of Phytolacca americana and Nicotiana tabacum to manganese stresses].
Plant species capable of accumulating heavy metals are of considerable interest for phytoremediation and phytomining. The mechanism of Mn tolerance/hyperaccumulate in Phytolacca americana L. is less known. To elucidate the role of antioxidative enzyme in response to Mn, the 6-week-old seedling of Mn hyperaccumulator P. americana and non-accumulator-tobacco (Nicotiana tabacum) were exposed to half strength Hoagland solution with 1 mmol x L(-1) or 3 mmol x L(-1) MnCl2 for 4 days. The photosynthetic rate in P. americana decreased more slowly than that in tobacco, while the MDA content and electrolyte leakage in tobacco increased more rapidly than that in P. americana. For example, after exposure to 1 mmol x L(-1) Mn for 4 days, the photosynthetic rates of P. americana and tobacco in comparison to the control reduced by 13.3% and 75.5%, respectively. The MDA content and electrolyte leakage in tobacco increased by 347.3% and 120.1%, respectively, whereas Mn had no marked effect on both of it in P. americana, indicated that the oxidative damage in tobacco was more serious than that in P. americana. The activities of SOD and POD of both species increased rapidly with elevated Mn concentration and exposure time in both species, the increase of SOD activity in P. americana was higher than that in tobacco. CAT activity in tobacco declined rapidly, while the activity of CAT in P. americana was increased. The activities of SOD, POD and CAT in P. americana upon 1 mmol x L(-1) Mn exposure increased by 161.1%, 111.3% and 17.5%, respectively. The activities of SOD and POD in tobacco increased by 55.5% and 206.0%, respectively, while CAT activity decreased by 15.6%, indicating that the antioxidative enzymes in P. americana, particularly in CAT,could fully scavenge the reactive oxygen species generated by Mn toxicity. These results collectively indicate that the enzymatic antioxidation capacity is one of the important mechanisms responsible for Mn tolerance in hyperaccumulator plant species. PMID:20187406
Zhang, Yu-xiu; Huang, Zhi-bo; Zhang, Hong-mei; Li, Lin-feng; Chai, Tuan-yao
Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases. PMID:24736897
Cavaiuolo, Marina; Ferrante, Antonio
Phytoremediation potential of Eichornia crassipes in metal-contaminated coastal water.
The potential of Eichornia crassipes to serve as a phytoremediation plant in the cleaning up of metals from contaminated coastal areas was evaluated in this study. Ten metals, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn were assessed in water and the plant roots and shoots from the coastal area of Ondo State, Nigeria and the values were used to evaluate the enrichment factor (EF) and translocation factor (TF) in the plant. The critical concentrations of the metals were lower than those specified for hyperaccumulators thus classifying the plant as an accumulator but the EF and TF revealed that the plant accumulated toxic metals such as Cr, Cd, Pb and As both at the root and at the shoot in high degree, which indicates that the plant that forms a large biomass on the water surface and is not fed upon by animals can serve as a plant for both phytoextraction and rhizofiltration in phytoremediation technology. PMID:19414252
Agunbiade, Foluso O; Olu-Owolabi, Bamidele I; Adebowale, Kayode O
Untreated abandoned mines may result in hazards to ecosystems due to dispersion of various toxic elements such as arsenic (As) and lead (Pb). Phytoremediation is an alternative of remediation for large scale mine dumps. Plant species were sampled from two abandoned gold (Au) mines in South Korea. Plant samples were digested following the guidelines of US EPA Method 3050 (US-EPA, 1996) and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Concentrations and bioaccumulation factors of plants are reported and out-performing species are summarized. Poplar trees (Populus davidiana) growing on the Myoungbong tailings were suggested to be a potential species for revegetation of large scale Au mine tailings. Arsenic accumulations of bracken ferns (Pteridium aquilinum) sampled from the Duckum tailings were far lower than those of the reported hyperaccumulators, but the possible chronic adverse effects on residents through daily diet are of concern. PMID:16003579
Chang, Peichun; Kim, Ju-Yong; Kim, Kyoung-Woong
The engineered phytoremediation of ionic and methylmercury pollution 70054yr.2000.doc
Our long-term objective is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic heavy metal pollutants (Meagher, 2000). We have focused our research on the phytoremediation of soil and water-borne ionic and organic mercury (Meagher and Rugh, 1996; Meagher et al., 2000). Mercury pollution is a serious world-wide problem affecting the health of human and wild-life populations. The Department of Energy's Oak Ridge National Laboratory and Brookhaven National Laboratory have sites with significant levels of mercury contamination that could be cleaned by applying the scientific discoveries and new phytoremediation technologies described in this proposal. In the near future, the experience gained through engineering plants that hyperaccumulate mercury, can be applied to extraction or accumulation of various toxic heavy metal and radionuclide contaminates at dozens of DOE sites.
Meagher, Richard B.
The engineered phytoremediation of ionic and methylmercury pollution 70054yr.2001.doc
Our long-term objective is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic organic and heavy metal pollutants (Meagher, 2000) applying scientific strategies and technologies from a rapidly developing field called phytoremediation. The phytoremediation of toxic elemental and organic pollutants requires the use relatively different approaches (Meagher, 2000). Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and aboveground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in aboveground tissues for later harvest. Various parts of this strategy are being critically tested by examining different genes in model plants and field species and comparing the results to control plants as recently reviewed (Meagher et al., 2000; Rugh et al., 2000).
Meagher, Richard B.
A critical review of the arsenic uptake mechanisms and phytoremediation potential of Pteris vittata.
The discovery of the arsenic hyperaccumulator, Pteris vittata (Chinese brake fern), has contributed to the promotion of its application as a means of phytoremediation for arsenic removal from contaminated soils and water. Understanding the mechanisms involved in arsenic tolerance and accumulation of this plant provides valuable tools to improve the phytoremediation efficiency. In this review, the current knowledge about the physiological and molecular mechanisms of arsenic tolerance and accumulation in P. vittata is summarized, and an attempt has been made to clarify some of the unresolved questions related to these mechanisms. In addition, the capacity of P. vittata for remediation of arsenic-contaminated soils is evaluated under field conditions for the first time, and possible solutions to improve the remediation capacity of Pteris vittata are also discussed. PMID:24912227
Danh, Luu Thai; Truong, Paul; Mammucari, Raffaella; Foster, Neil
Selenometabolomics explored by speciation.
Selenium (Se) belongs to the same group as sulfur in the periodic table but possesses certain chemical properties characteristic of a metal. It is an essential element in animals but becomes severely toxic when the amount ingested exceeds the required level. On the other hand, Se is not essential in plants although some plants are Se hyperaccumulators. Se changes into several chemical forms when metabolized. Thus, the identification of selenometabolites would enable us to formulate a metabolic chart of Se. Recently, speciation analysis by hyphenated techniques has contributed immensely to the study of selenometabolomes, i.e., the entirety of selenometabolites. Indeed, speciation has unveiled some unique selenometabolites in biological samples. The aim of this review is to present newly identified selenometabolites in animals and plants by speciation using hyphenated techniques and to delineate the perspectives of Se biology and toxicology from the viewpoint of speciation. PMID:23123457
Ogra, Yasumitsu; Anan, Yasumi
NASA Astrophysics Data System (ADS)
In soils and plants of the southern shrub tundra, 15 polycyclic aromatic hydrocarbons (PAHs) have been detected by high-performance liquid chromatography. Polyarenes in emissions, soil organic horizons, and plants mainly include low-molecular-weight PAHs: naphthalene, fluorine, and pyrene. The contents of the total PAHs in soils and plants exceed the background levels by 3-5 times. The distribution of polyarenes among the organs of the studied plants is nonuniform and depends on the plant species and technogenic load on the area. The studied plants include both hyperaccumulators of polyarenes ( Pleurozium schreberi) and indicators of PAHs in the soil ( Polytrichum commune). Pleurozium schreberi is the most abundant species in the areas under study, and it accumulates the largest mass fraction of PAHs. The differences in the accumulation of PAHs by the plants of the tundra and taiga zones have been revealed.
Yakovleva, E. V.; Gabov, D. N.; Beznosikov, V. A.; Kondratenok, B. M.
Field trials contribute practical information towards the development of phytoremediation strategies that cannot be provided by laboratory tests. We conducted field experiments utilizing the Cd hyperaccumulator plant Solanum nigrum L., on farmland contaminated with 1.91 mg kg(-1) Cd in the soil. Our study showed that S. nigrum has a relatively high biomass. Planting density had a significant effect on the plant biomass and thus on overall Cd accumulation. For double harvesting, an optimal cutting position influenced the amount of Cd extracted from soils. Double cropping was found to significantly increase the amount of Cd extracted by S. nigrum. Fertilizing had no significant effect on plant biomass or on the Cd remediation of the soil over the short-term period. Our study indicates that S. nigrum can accumulate Cd from soils where the concentrations are relatively low, and thus has application for use in decontamination of slightly to moderately Cd-contaminated soil. PMID:21185631
Ji, Puhui; Sun, Tieheng; Song, Yufang; Ackland, M Leigh; Liu, Yang
Arsenic uptake by Lemna minor in hydroponic system.
Arsenic is hazardous and causes several ill effects on human beings. Phytoremediation is the use of aquatic plants for the removal of toxic pollutants from external media. In the present research work, the removal efficiency as well as the arsenic uptake capacity of duckweed Lemna minor has been studied. Arsenic concentration in water samples and plant biomass were determined by AAS. The relative growth factor of Lemna minor was determined. The duckweed had potential to remove as well as uptake arsenic from the aqueous medium. Maximum removal of more than 70% arsenic was achieved atinitial concentration of 0.5 mg/1 arsenic on 15th day of experimental period of 22 days. Removal percentage was found to decrease with the increase in initial concentration. From BCF value, Lemna minor was found to be a hyperaccumulator of arsenic at initial concentration of 0.5 mg/L, such that accumulation decreased with increase in initial arsenic concentration. PMID:24933913
Goswami, Chandrima; Majumder, Arunabha; Misra, Amal Kanti; Bandyopadhyay, Kaushik
Phytoremediation potential of aquatic macrophyte, Azolla.
Aquatic macrophytes play an important role in the structural and functional aspects of aquatic ecosystems by altering water movement regimes, providing shelter to fish and aquatic invertebrates, serving as a food source, and altering water quality by regulating oxygen balance, nutrient cycles, and accumulating heavy metals. The ability to hyperaccumulate heavy metals makes them interesting research candidates, especially for the treatment of industrial effluents and sewage waste water. The use of aquatic macrophytes, such as Azolla with hyper accumulating ability is known to be an environmentally friendly option to restore polluted aquatic resources. The present review highlights the phytoaccumulation potential of macrophytes with emphasis on utilization of Azolla as a promising candidate for phytoremediation. The impact of uptake of heavy metals on morphology and metabolic processes of Azolla has also been discussed for a better understanding and utilization of this symbiotic association in the field of phytoremediation. PMID:22396093
Sood, Anjuli; Uniyal, Perm L; Prasanna, Radha; Ahluwalia, Amrik S
Research on cadmium-zinc exchange in proteins is important for understanding one of the main sources of Cd's biological toxicity. Because of the similar properties of these two elements, most living organisms must prevent Cd from replacing Zn in Zn-requiring proteins in order for those proteins to function normally. Recent structural studies of a variety of proteins associated with the versatile physiological functions of Zn have revealed widespread instances of Cd-Zn exchange in proteins of a large number of living organisms. Ongoing work is focused on discovering the structural mechanisms of Cd-Zn exchange and the potentially diverse roles of Cd at Zn functional sites in proteins. This research is a prerequisite to understanding the evolution of Cd-tolerant species (e.g., Cd hyperaccumulating plants) and to the engineering of optimal strategies for protecting the public heath against Cd pollution. PMID:24806548
Tang, Lu; Qiu, Rongliang; Tang, Yetao; Wang, Shizhong
Cotton cytochrome P450 CYP82D regulates systemic cell death by modulating the octadecanoid pathway.
Plant oxylipins are derived from unsaturated fatty acids and play roles in plant growth and development as well as defence. Although recent studies have revealed that fatty acid metabolism is involved in systemic acquired resistance, the precise function of oxylipins in plant defence remains unknown. Here we report a cotton P450 gene SILENCE-INDUCED STEM NECROSIS (SSN), RNAi suppression of which causes a lesion mimic phenotype. SSN is also involved in jasmonate metabolism and the response to wounding. Fatty acid and oxylipin metabolite analysis showed that SSN overexpression causes hyperaccumulation of hydroxide and ketodiene fatty acids and reduced levels of 18:2 fatty acids, whereas silencing causes an imbalance in LOX (lipoxygenase) expression and excessive hydroperoxide fatty acid accumulation. We also show that an unknown oxylipin-derived factor is a putative mobile signal required for systemic cell death and hypothesize that SSN acts as a valve to regulate HR on pathogen infection. PMID:25371113
Sun, Longqing; Zhu, Longfu; Xu, Li; Yuan, Daojun; Min, Ling; Zhang, Xianlong
We studied the effects of sewage sludge compost on white wall rocket (Diplotaxis erucoides L.) compared with mineral fertilization and control (without any fertilizer) in a greenhouse experiment. The plants grown on the compost-amended soil showed a different growth dynamic: a significant delay in flowering and a bigger root system. Both the compost and the fertilization treatments increased biomass and seed yield. Heavy metal (Cu, Cd, Zn, Ni) distribution within the plant was in the following order: roots > leaves > stems, except for zinc which was homogeneously distributed. The balance of mineral nutrition was not affected by treatments. Zinc was the trace element which was most taken up. Unlike many species of Brassicaceae, white wall rocket is not a hyperaccumulator. Although sewage sludge compost improved plant growth, delay in flowering shows that it is necessary to take precautions when spreading sewage sludge in natural areas. PMID:11916052
Korboulewsky, Nathalie; Bonin, Gilles; Massiani, Catherine
Nitrates and Glucosinolates as Strong Determinants of the Nutritional Quality in Rocket Leafy Salads
Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases. PMID:24736897
Cavaiuolo, Marina; Ferrante, Antonio
Phytoremediation of Ionic and Methyl Mercury Pollution
Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to control the chemical speciation, electrochemical state, transport, and aboveground binding of mercury in order to manage this toxicant. To advance this mercury phytoremediation strategy, our planned research focuses on the following Specific Aims: (1) to increase the transport of mercury to aboveground tissue; (2) to identify small mercury binding peptides that enhance hyperaccumulation aboveground; (3) to test the ability of multiple genes acting together to enhance resistance and hyperaccumulation; (4) to construct a simple molecular system for creating male/female sterility, allowing engineered grass, shrub, and tree species to be released indefinitely at contaminated sites; (5) to test the ability of transgenic cottonwood and rice plants to detoxify ionic mercury and prevent methylmercury release from contaminated sediment; and (6) to initiate field testing with transgenic cottonwood and rice for the remediation of methylmercury and ionic mercury. The results of these experiments will enable the phytoremediation of methyl- and ionic mercury by a wide spectrum of deep-rooted, fast-growing plants adapted to diverse environments. We have made significant progress on all six of these specific aims as summarized below.
Meagher, Richard B.
Lead (Pb) is one of the most widespread heavy metal contaminant in soils. It is highly toxic to living organisms. Pb has no biological function but can cause morphological, physiological, and biochemical dysfunctions in plants. Plants have developed a wide range of tolerance mechanisms that are activated in response to Pb exposure. Pb affects plants primarily through their root systems. Plant roots rapidly respond either (i) by the synthesis and deposition of callose, creating a barrier that stops Pb entering (ii) through the uptake of large amounts of Pb and its sequestration in the vacuole accompanied by changes in root growth and branching pattern or (iii) by its translocation to the aboveground parts of plant in the case of hyperaccumulators plants. Here we review the interactions of roots with the presence of Pb in the rhizosphere and the effect of Pb on the physiological and biochemical mechanisms of root development. PMID:23750165
Fahr, Mouna; Laplaze, Laurent; Bendaou, Najib; Hocher, Valerie; Mzibri, Mohamed El; Bogusz, Didier; Smouni, Abdelaziz
Selenium hyperaccumulator Stanleya pinnata, Colorado ecotype, was supplied with water-soluble and biologically available selenate or selenite. Selenium distribution and tissue speciation were established using X-ray microscopy (micro-X-ray fluorescence and transmission X-ray microscopy) in two dimensions and three dimensions. The results indicate that S. pinnata tolerates, accumulates, and volatilizes significant concentrations of selenium when the inorganic form supplied is selenite and may possess novel metabolic capacity to differentiate, metabolize, and detoxify selenite concentrations surpassing field concentrations. The results also indicate that S. pinnata is a feasible candidate to detoxify selenium-polluted soil sites, especially locations with topsoil polluted with soluble and biologically available selenite. PMID:22392379
Amos, Wren; Webb, Samuel; Liu, Yijin; Andrews, Joy C; LeDuc, Danika L
The tie-dyed pathway promotes symplastic trafficking in the phloem.
The tie-dyed1 (tdy1) and tdy2 mutants of maize exhibit leaf regions with starch hyperaccumulation and display unusual genetic interactions, suggesting they function in the same physiological process. Tdy2 encodes a putative callose synthase and is expressed in developing vascular tissues of immature leaves. Radiolabelling experiments and transmission electron microscopy (TEM) revealed symplastic trafficking within the phloem was perturbed at the companion cell/sieve element interface. Here, we show that as reported for tdy2 mutants, tdy1 yellow leaf regions display an excessive oil-droplet phenotype in the companion cells. Based on the proposed function of Tdy2 as a callose synthase, our previous work characterizing Tdy1 as a novel, transmembrane-localized protein, and the present findings, we speculate how TDY1 and TDY2 might interact to promote symplastic transport of both solutes and developmentally instructive macromolecules during vascular development at the companion cell/sieve element interface. PMID:23603956
Baker, R Frank; Slewinski, Thomas L; Braun, David M
The Tie-dyed pathway promotes symplastic trafficking in the phloem
The tie-dyed1 (tdy1) and tdy2 mutants of maize exhibit leaf regions with starch hyperaccumulation and display unusual genetic interactions, suggesting they function in the same physiological process. Tdy2 encodes a putative callose synthase and is expressed in developing vascular tissues of immature leaves. Radiolabelling experiments and transmission electron microscopy (TEM) revealed symplastic trafficking within the phloem was perturbed at the companion cell/sieve element interface. Here, we show that as reported for tdy2 mutants, tdy1 yellow leaf regions display an excessive oil-droplet phenotype in the companion cells. Based on the proposed function of Tdy2 as a callose synthase, our previous work characterizing Tdy1 as a novel, transmembrane-localized protein, and the present findings, we speculate how TDY1 and TDY2 might interact to promote symplastic transport of both solutes and developmentally instructive macromolecules during vascular development at the companion cell/sieve element interface. PMID:23603956
Baker, R. Frank; Slewinski, Thomas L.; Braun, David M.
Leaves arise from the flank of the shoot apical meristem and are asymmetrical along the adaxial/abaxial plane from inception. Mutations perturbing dorsiventral cell fate acquisition in a variety of species can result in unifacial (radially symmetrical) leaves lacking adaxial/abaxial polarity. However, mutations in maize (Zea mays) ragged seedling2 (rgd2) condition cylindrical leaves that maintain dorsiventral polarity. Positional cloning reveals that rgd2 encodes an ARGONAUTE7 (AGO7)-like protein required to produce ta-siARF, a trans-acting small interfering RNA that targets abaxially located auxin response factor3a (arf3a) transcripts for degradation. Previous studies implicated ta-siARF in dorsiventral patterning of monocot leaves. Here, we show that arf3a transcripts hyperaccumulate but remain abaxialized in rgd2 mutant apices, revealing that ta-siARF function is not required for arf3a polarization. RGD2 also regulates miR390 accumulation and localization in maize shoot apices. Similar to the abaxialized maize mutant leafbladeless1 (lbl1), rgd2 mutants exhibit ectopic accumulation of the abaxial identity factor miR166 in adaxial domains. Thus, hyperaccumulation of arf3a and ectopic accumulation of miR166 are insufficient to condition abaxialized leaf phenotypes in maize. Finally, transcripts of a maize ago1 paralog overaccumulate in lbl1 but not in rgd2 mutants, suggesting that upregulation of ago1 combined with ectopic accumulation of miR166 contribute to abaxialized leaf formation in lbl1. We present a revised model for the role of small RNAs in dorsiventral patterning of maize leaves. PMID:20453116
Douglas, Ryan N; Wiley, Dan; Sarkar, Ananda; Springer, Nathan; Timmermans, Marja C P; Scanlon, Michael J
Tolerance and metal uptake are two essential characteristics required for phytoextraction of metals from contaminated soils. We compared tolerance and Cu uptake of Elsholtzia splendens (reported previously to be a Cu hyperaccumulator) with Silene vulgaris (the Imsbach population, a well-known Cu-tolerant excluder species), using 30 soils varying widely in total Cu concentration (19-8645 mg kg(-1)). We further investigated the effectiveness of different soil testing methods for predicting plant metal uptake. The results showed that both Elsholtzia splendens and Silene vulgaris were tolerant to Cu, especially Silene vulgaris. However, Elsholtzia splendens did not hyperaccumulate Cu, but behaved as a typical Cu excluder like Silene vulgaris. The concentrations of Cu in both plants correlated more closely with 1 M NH4NO3 extractable Cu, soil solution Cu, or effective Cu concentration determined using DGT, than with soil total Cu, EDTA extractable Cu or free Cu2+ activity. The relationships between soil solution properties and root Cu concentrations were further investigated using multiple regression. The results showed that increasing soil solution pH increased root Cu concentration when free Cu2+ activity was held constant, suggesting a higher phytoavailability of free Cu2+ at a higher pH. Soil solution DOC appeared to play two contrasting roles on the phytoavailability of Cu: (1) reducing Cu availability by complexing Cu; and (2) increasing Cu availability at the same level of free Cu2+ activity by providing a strong buffer for free Cu2+. The results are consistent with the intensity/capacity concept for phytoavailability of metals in soils. PMID:14720473
Song, Jing; Zhao, Fang-Jie; Luo, Yong-Ming; McGrath, Steve P; Zhang, Hao
Arabidopsis thaliana RPM1 encodes an intracellular immune sensor that conditions disease resistance to Pseudomonas syringae expressing the type III effector protein AvrRpm1. Conditional expression of this type III effector in a transgenic line carrying avrRpm1 under the control of a steroid-inducible promoter results in RPM1-dependent cell death that resembles the cell death response of the incompatible RPM1-avrRpm1 plant-bacterium interaction. This line was previously used in a genetic screen, which revealed two genes that likely function in the folding of pre-activation RPM1. We established a chemical screen for small molecules that suppress steroid-inducible and RPM1-avrRpm1-dependent cell death in Arabidopsis seedlings. Screening of a library comprising 6,800 compounds of natural origin identified two trichothecene-type mycotoxins, 4,15-diacetoxyscirpenol (DAS) and neosolaniol (NEO), which are synthesized by Fusarium and other fungal species. However, protein blot analysis revealed that DAS and NEO inhibit AvrRpm1 synthesis rather than suppress RPM1-mediated responses. This inhibition of translational activity likely explains the survival of the seedlings under screening conditions. Likewise, flg22-induced defense responses are also impaired at the translational, but not the transcriptional, level by DAS or NEO. Unexpectedly, both compounds not only prevented AvrRpm1 synthesis, but rather caused an apparent hyper-accumulation of RPM1 and HSP70. The hyper-accumulation phenotype is likely unrelated to the ribotoxic function of DAS and NEO and could be due to an inhibitory activity on the proteolytic machinery of Arabidopsis or elicitor-like activities of type A trichothecenes. PMID:20140739
Serrano, Mario; Hubert, David A; Dangl, Jeffery L; Schulze-Lefert, Paul; Kombrink, Erich
The extent of arsenic (As) and metal accumulation in fronds of the As hyperaccumulator Pteris vittata (Chinese brake fern) and in leaves of Cyperus involucratus, which grow on the surface of an old flotation tailings pond in the Zambian Copperbelt province, was studied. The tailings consist of two types of material with distinct chemical composition: (1) reddish-brown tailings rich in As, iron (Fe), and other metals, and (2) grey-green tailings with a lower content of As, Fe, and other metals, apart from manganese (Mn). P. vittata accumulates from 2350 to 5018Ā?gĀg(-1) As (total dry weight [dw]) in its fronds regardless of different total and plant-available As concentrations in both types of tailings. Concentrations of As in C. involucratus leaves are much lower (0.24-30.3Ā?gĀg(-1) dw). Contents of copper (Cu) and cobalt (Co) in fronds of P. vittata (151-237 and 18-38Ā?gĀg(-1) dw, respectively) and in leaves of C. involucratus (96-151 and 9-14Ā?gĀg(-1) dw, respectively) are high, whereas concentrations of other metals (Fe, Mn, and zinc [Zn]) are low and comparable with contents of the given metals in common plants. Despite great differences in metal concentrations in the two types of deposited materials, concentrations of most metals in plant tissues are very similar. This indicates an exclusion or avoidance mechanism operating when concentrations of the metals in substrate are particularly high. The results of the investigation show that Chinese brake fern is not only a hyperaccumulator of As but has adapted itself to high concentrations of Cu and Co in flotation tailings of the Zambian Copperbelt. PMID:20949352
K?Ēbek, Bohdan; Mihaljevi?, Martin; Sracek, Ondra; Knķsl, Ilja; Ettler, Vojt?ch; Nyambe, Imasiku
Lead (Pb) has become one of the most abundant heavy metal pollutants of the environment. With its large biomass, maize could be an important object for studying the phytoremediation of Pb-contaminated soil. In our previous research, we screened 19 inbred lines of maize for Pb concentration, and line 178 was identified to be a hyperaccumulator for Pb in both the roots and aboveground parts. To identify important genes and metabolic pathways related to Pb accumulation and tolerance, line 178 was underwent genome expression profile under Pb stress and a control (CK). A total of approximately 11 million cDNA tags were sequenced and 4 665 539 and 4 936 038 clean tags were obtained from the libraries of the test and CK, respectively. In comparison to CK, 2379 and 1832 genes were identified up- or downregulated, respectively, more than fivefolds under Pb stress. Interestingly, all the genes were related to cellular processes and signaling, information storage and processing or metabolism functions. Particularly, the genes involved in posttranslational modification, protein turnover and chaperones; signal transduction, carbohydrate transport and metabolism; and lipid transport and metabolism significantly changed under the treatment. In addition, seven pathways including ribosome, photosynthesis, and carbon fixation were affected significantly, with 118, 12, 34, 21, 18, 72 and 43 differentially expressed genes involved. The significant upregulation of the ribosome pathway may reveal an important secret for Pb tolerance of line 178. And the sharp increase of laccase transcripts and metal ion transporters were suggested to account in part for Pb hyperaccumulation in the line. PMID:22747913
Shen, Yaou; Zhang, Yongzhong; Chen, Jie; Lin, Haijian; Zhao, Maojun; Peng, Huanwei; Liu, Li; Yuan, Guangsheng; Zhang, Suzhi; Zhang, Zhiming; Pan, Guangtang
The fate and chemical speciation of arsenic (As) uptake, translocation and storage by the As hyperaccumulating fern Pityogramma calomelanos var. austroamericana (Pteridaceae) were examined using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and synchrotron-based {mu}-X-ray absorption near edge structure ({mu}-XANES) and {mu}-X-ray fluorescence ({mu}-XRF) spectroscopies. Chemical analysis revealed total As concentration was ca. 6.5 times greater in young fronds (5845 mg kg {sup -1} dry weight) than in old frons (903 mg kg {sup -1} DW) pinnae, As concentration decreased from the base (6822 mg kg {sup -1} DW) to the apex (4301 mg kg {sup -1}DW) of the fronds. The results from {mu}-XANES and {mu}-XRF of living tissues suggested that more than 60% of arsenate (As{sup v}) absorbed was reduced to arsenite (As{sup III}) in roots, prior to transport through vascular tissues as As{sup v} and As{sup III}. In pinnules, As{sup III} was the predominate redox species (72-90%), presumably as solvated, oxygen coordinated compounds. The presence of putative As{sup III}-sulphide (S{sup -2}) coordinationthroughout the fern tissues (4-25%) suggests that S{sup 2-} functional groups may contribute in the biochemical reduction of As{sup v} to As{sup III} during uptake and transport at a whole plant level. Organic arsenicals and thiol-rich compounds were not detected in the species and are unlikely to play a role in As hyperaccumulation in this fern. The study provides important insights into homeostatic regulation of As following As uptake in P. calomelanos var. austroamericana.
Heald, S. M.; Kachenko, A.; Graefe, M.; Singh, B.; X-Ray Science Division; Univ. of Sydney
[Promotion effects of microorganisms on phytoremediation of heavy metals-contaminated soil].
Taking Brassica juncea as a hyperaccumulator, a pot experiment was conducted to study the effects of Bacillusme gaterium - Bacillus mucilaginosus mixed agent and Aspergillus niger 30177 fermentation liquor on the phytoremediation of Cd, Pb, and Zn-contaminated soil. The B. gaterium - B. mucilaginosus mixed agent not only promoted the growth of B. juncea, but also increased the soil Cd, Pb, and Zn uptake by the hyperaccumulator, with the phytoremediation efficiency enhanced greatly. The enrichment amount of Cd, Pb and Zn in B. juncea on the soil added with soluble Cd, Pb and Zn increased by 1.18, 1.54 and 0.85 folds, while that on the soil added with Cd, Pb and Zn-contaminated sediment increased by 4.00, 0. 64 and 0. 65 folds, respectively, compared with the control. A. niger 30177 fermentation liquor increased the soil Cd, Pb, and Zn uptake by B. juncea. Comparing with the control, the enrichment amount of Cd, Pb and Zn in aboveground part of B. juncea on the soil added with soluble Cd, Pb and Zn increased by 88.82%, 129.04% and 16.80%, while that on the soil added with Cd, Pb and Zn-contaminated sediment increased by 78.95%, 113.63% and 33.85%, respectively. However, A. niger 30177 fermentation liquor decreased the B. juncea biomass greatly, having less effect in the enhancement of phytoremediation efficiency. The analysis of reversed-phase high performance liquid chromatography showed that the fermentation liquor of B. gaterium and B. mucilaginosus contained some organic acids such as oxalic acid and citric acid. These acids could dissolve the heavy metals to some degree, and accordingly, enhance the bioavailability of the metals. PMID:19947228
Yang, Zhuo; Wang, Zhan-Li; Li, Bo-Wen; Zhang, Rui-Fang
Foliar nutrient imbalances, including the hyperaccumulation of manganese (Mn), are correlated with symptoms of declining health in sensitive tree species growing on acidic forest soils. The objectives of this study were to: (1) compare foliar nutrient accumulation patterns of six deciduous (sugar maple (Acer saccharum Marsh.), red maple (Acer rubrum L.), red oak (Quercus rubra L.), white oak (Quercus alba L.), black cherry (Prunus serotina Ehrh.) and white ash (Fraxinus americana L.)) and three evergreen (eastern hemlock (Tsuga canadensis L.), white pine (Pinus strobus L.) and white spruce (Picea glauca (Moench) Voss.)) tree species growing on acidic forest soils; and (2) examine how leaf phenology and other traits that distinguish evergreen and deciduous tree species influence foliar Mn accumulation rates and sensitivity to excess Mn. For the first objective, leaf samples of seedlings from five acidic, non-glaciated field sites on Pennsylvania's Allegheny Plateau were collected and analyzed for leaf element concentrations. In a second study, we examined growth and photosynthetic responses of seedlings exposed to excess Mn in sand culture. In field samples, Mn in deciduous foliage hyperaccumulated to concentrations more than twice as high as those found in evergreen needles. Among species, sugar maple was the most sensitive to excess Mn based on growth and photosynthetic measurements. Photosynthesis in red maple and red oak was also sensitive to excess Mn, whereas white oak, black cherry, white ash and the three evergreen species were tolerant of excess Mn. Among the nine species, relative rates of photosynthesis were negatively correlated with foliar Mn concentrations, suggesting that photosynthetic sensitivity to Mn is a function of its rate of accumulation in seedling foliage. PMID:15519989
St Clair, Samuel B; Lynch, Jonathan P
Phytoremediation of Ionic and Methyl Mercury Pollution
Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.
Meagher, Richard B.
[Characteristics of cadmium tolerance and bioaccumulation of Bidens pilosa L. seedlings].
Bidens pilosa L. has been identified as a newly found Cd-hyperaccumulator. In the present study, the characteristics of its Cd tolerance (growth response and physiological and biochemical characteristics) and accumulation were examined. The results showed that low Cd treatments (< or =32 mg/kg) could enhance plant growth, the dry biomass of shoot and root increased by 32.4%-44.7% and 29.1%-57.6%, respectively, at Cd concentrations 8-32 mg/kg when compared with the control. The shoot dry biomass reached a maximum of 0.22 g/pot at a concentration 8 mg/kg of Cd. Meanwhile, under different Cd treatments, chlorophyll (Chl) and soluble protein contents in leaves slightly decreased, resulting in 23.3% and 41.5% reduction, respectively, compared with the control. The activities of superoxide dismutase (SOD) firstly decreased and then increased with increasing Cd concentration. Peroxidase (POD) activities and malondialdehyde (MDA) contents increased with increasing Cd concentration, with 1.2-6.6 and 1.1-1.5 times increase, respectively, relative to the control. However, the definite negative effects on the plant growth and characteristics of physiology and biochemistry were observed at higher Cd concentrations (50-100 mg/kg). In gradual experiments, the values of bioaccumulation and translocation were more than 1.0, furthermore, the concentration of Cd in shoots reached 119.1 mg/kg at the soil Cd level of 100 mg/kg, showing B. pilosa has the basic characteristics of a Cd-hyperaccumulator. The results above indicated that B. pilosa has strong capacity of Cd tolerance and accumulation, so it has potential and valuable application to phytoremediation of contaminated soils by Cd. PMID:19968126
Sun, Yue-bing; Zhou, Qi-xing; Wang, Lin; Liu, Wei-tao; Liu, Rui
Literature review: Phytoaccumulation of chromium, uranium, and plutonium in plant systems
Phytoremediation is an integrated multidisciplinary approach to the cleanup of contaminated soils, which combines the disciplines of plant physiology, soil chemistry, and soil microbiology. Metal hyperaccumulator plants are attracting increasing attention because of their potential application in decontamination of metal-polluted soils. Traditional engineering technologies may be too expensive for the remediation of most sites. Removal of metals from these soils using accumulator plants is the goal of phytoremediation. The emphasis of this review has been placed on chromium (Cr), plutonium (Pu), and uranium (U). With the exception of Cr, these metals and their decay products exhibit two problems, specifically, radiation dose hazards and their chemical toxicity. The radiation hazard introduces the need for special precautions in reclamation beyond that associated with non-radioactive metals. The uptake of beneficial metals by plants occurs predominantly by way of channels, pores, and transporters in the root plasma membrane. Plants characteristically exhibit a remarkable capacity to absorb what they need and exclude what they don`t need. But most vascular plants absorb toxic and heavy metals through their roots to some extent, though to varying degrees, from negligible to substantial. Sometimes absorption occurs because of the chemical similarity between beneficial and toxic metals. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metal from root to shoot. At the other extreme, hyperaccumulator plants absorb and concentrate metals in both roots and shoots. Some plant species endemic to metalliferous soils accumulate metals in percent concentrations in the leaf dry matter.
Hossner, L.R.; Loeppert, R.H.; Newton, R.J. [Texas A& M Univ., College Station, TX (United States); Szaniszlo, P.J. [Univ. of Texas, Austin, TX (United States)
Hyperaccumulators contain tubular cellulose and heavy metals, which can be used as the sources of carbon and metals to synthesize nanomaterials. In this paper, carbon nanotubes (CNTs), Cu(0.05)Zn(0.95)O nanoparticles, and CNTs/Cu(0.05)Zn(0.95)O nanocomposites were synthesized using Brassica juncea L. plants, and the ultraviolet (UV)-light-driven photocatalytic degradations of bisphenol A (BPA) using them as photocatalysts were studied. It was found that the outer diameter of CNTs was around 50 nm and there were a few defects in the crystal lattice. The synthesized Cu(0.05)Zn(0.95)O nanocomposites had a diameter of around 40 nm. Cu(0.05)Zn(0.95)O nanocomposites have grown on the surface of the CNTs and the outer diameter of them was around 100 nm. The synthesized hybrid carbon nanotubes using B. juncea could enhance the efficiency of photocatalytic degradation on BPA. The complete equilibration time of adsorption/desorption of BPA onto the surface of CNTs, Cu(0.05)Zn(0.95)O nanoparticles, and CNTs/Cu(0.05)Zn(0.95)O nanocomposites was within 30, 20, and 30 min, and approximately 14.9, 8.7, and 17.4 % BPA was adsorbed by them, respectively. The combination of UV light irradiation (90 min) with CNTs, Cu(0.05)Zn(0.95)O nanoparticles, and CNTs/Cu(0.05)Zn(0.95)O nanocomposites could lead to 48.3, 75.7, and 92.6 % decomposition yields of BPA, respectively. These findings constitute a new insight for synthesizing nanocatalyst by reusing hyperaccumulators. PMID:23135755
Qu, Jiao; Luo, Chunqiu; Yuan, Xing
Phytoextraction involves use of plants to remove toxic metals from soil. We examined the effects of phytoextraction practices with three plant species (Silene vulgaris, Thlaspi caerulescens, and Zea mays) and a factorial variation of soil amendments (either an ammonium or nitrate source of nitrogen and the presence or absence of an elemental sulfur supplement) on arbuscular mycorrhizal (AM) fungi (Glomales, Zygomycetes) at a moderately metal-contaminated landfill located in St. Paul, Minn. Specifically, we tested whether the applied treatments affected the density of glomalean spores and AM root colonization in maize. Glomalean fungi from the landfill were grouped into two morphotypes characterized by either light-colored spores (LCS) or dark-colored spores (DCS). Dominant species of the LCS morphotype were Glomus mosseae and an unidentified Glomus sp., whereas the DCS morphotype was dominated by Glomus constrictum. The density of spores of the LCS morphotype from the phytoremediated area was lower than the density of these spores in the untreated landfill soil. Within the experimental area, spore density of the LCS morphotype in the rhizosphere of mycorrhizal maize was significantly higher than in rhizospheres of nonmycorrhizal S. vulgaris or T. caerulescens. Sulfur supplement increased vesicular root colonization in maize and exerted a negative effect on spore density in maize rhizosphere. We conclude that phytoextraction practices, e.g., the choice of plant species and soil amendments, may have a great impact on the quantity and species composition of glomalean propagules as well as on mycorrhiza functioning during long-term metal-remediation treatments. PMID:10831433
Pawlowska, T E; Chaney, R L; Chin, M; Charvat, I
Evolution of Genome Size in Brassicaceae
Background and Aims Brassicaceae, with nearly 340 genera and more than 3350 species, anchors the low range of angiosperm genome sizes. The relatively narrow range of DNA content (0Ę16 pg < 1C < 1Ę95 pg) was maintained in spite of extensive chromosomal change. The aim of this study was to erect a cytological and molecular phylogenetic framework for a selected subset of the Brassicacae, and use this as a template to examine genome size evolution in Brassicaceae. Methods DNA contents were determined by flow cytometry and chromosomes were counted for 34 species of the family Brassicaceae and for ten Arabidopsis thaliana ecotypes. The amplified and sequenced ITS region for 23 taxa (plus six other taxa with known ITS sequences) were aligned and used to infer evolutionary relationship by parsimony analysis. Key Results DNA content in the species studied ranged over 8-fold (1C = 0Ę16¢1Ę31 pg), and 4Ę4-fold (1C = 0Ę16¢0Ę71 pg) excluding allotetraploid Brassica species. The 1C DNA contents of ten Arabidopsis thaliana ecotypes showed little variation, ranging from 0Ę16 pg to 0Ę17 pg. Conclusions The tree roots at an ancestral genome size of approximately 1x = 0Ę2 pg. Arabidopsis thaliana (1C = 0Ę16 pg; ~157 Mbp) has the smallest genome size in Brassicaceae studied here and apparently represents an evolutionary decrease in genome size. Two other branches that represent probable evolutionary decreases in genome size terminate in Lepidium virginicum and Brassica rapa. Branches in the phylogenetic tree that represent probable evolutionary increases in genome size terminate in Arabidopsis halleri, A. lyrata, Arabis hirsuta, Capsella rubella, Caulanthus heterophyllus, Crucihimalaya, Lepidium sativum, Sisymbrium and Thlaspi arvense. Branches within one clade containing Brassica were identified that represent two ancient ploidy events (2x to 4x and 4x to 6x) that were predicted from published comparative mapping studies. PMID:15596470
Host Suitability of 32 Common Weeds to Meloidogyne hapla in Organic Soils of Southwestern Quebec
Thirty-two weeds commonly found in the organic soils of southwestern Quebec were evaluated for host suitability to a local isolate of the northern root-knot nematode Meloidogyne hapla under greenhouse conditions. Galls were observed on the roots of 21 species. Sixteen of the 21 had a reproduction factor (Pf/Pi = final number of M. hapla eggs and juveniles per initial number of M. hapla juveniles per pot) higher than carrot (Pf/Pi = 0.37), the major host crop in this agricultural area. Tomato cv. Rutgers was also included as a susceptible host and had the highest Pf/Pi value of 13.7. Bidens cernua, B. frondosa, B. vulgata, Erysimum cheiranthoides, Eupatorium maculatum, Matricaria matricarioides, Polygonum scabrum, Thalictrum pubescens, Veronica agrestis, and Sium suave are new host records for M. hapla. Bidens cernua, B. frondosa, B. wulgata, D. carota, M. matricarioides, Pasticana sativa, P. scabrum, S. suave, and Thlaspi arvense sustained moderate to high galling by M. hapla and supported high M. hapla production (12.4 ? Pf/Pi ? 2.9). Capsella bursa-pastoris, Chrysanthemum leucanthemum, Gnaphalium uliginosum, Stellaria media, and Veronica agrestis sustained moderate galling and supported moderate M. hapla reproduction (2.8 ? Pf/Pi ? 0.5). Chenopodium album, C. glaucum, E. cheiranthoides, P. convolvulus, Portulaca oleracea, and Rorippa islandica supported low reproduction (0.25 ? Pf/Pi ? 0.02) and sustained low galling. Galling was observed on Senecio vulgaris but no eggs or juveniles; thus, S. vulgaris may be useful as a trap plant. Eupatorium maculatum, and T. pubescens harbored no distinct galling but supported low to moderate M. hapla reproduction, respectively. Amaranthus retroflexus, Ambrosia artemisiifolia, Echinochloa crusgalli, Erigeron canadensis, Oenothera parviflora, Panicum capillare, Setaria glauca, S. viridis, and Solidago canadensis were nonhosts. Our results demonstrate the importance of adequate weed control in an integrated program for the management of M. hapla in organic soil. PMID:19277189
Belair, G.; Benoit, D. L.
Host Suitability of 32 Common Weeds to Meloidogyne hapla in Organic Soils of Southwestern Quebec.
Thirty-two weeds commonly found in the organic soils of southwestern Quebec were evaluated for host suitability to a local isolate of the northern root-knot nematode Meloidogyne hapla under greenhouse conditions. Galls were observed on the roots of 21 species. Sixteen of the 21 had a reproduction factor (Pf/Pi = final number of M. hapla eggs and juveniles per initial number of M. hapla juveniles per pot) higher than carrot (Pf/Pi = 0.37), the major host crop in this agricultural area. Tomato cv. Rutgers was also included as a susceptible host and had the highest Pf/Pi value of 13.7. Bidens cernua, B. frondosa, B. vulgata, Erysimum cheiranthoides, Eupatorium maculatum, Matricaria matricarioides, Polygonum scabrum, Thalictrum pubescens, Veronica agrestis, and Sium suave are new host records for M. hapla. Bidens cernua, B. frondosa, B. wulgata, D. carota, M. matricarioides, Pasticana sativa, P. scabrum, S. suave, and Thlaspi arvense sustained moderate to high galling by M. hapla and supported high M. hapla production (12.4 = Pf/Pi >/= 2.9). Capsella bursa-pastoris, Chrysanthemum leucanthemum, Gnaphalium uliginosum, Stellaria media, and Veronica agrestis sustained moderate galling and supported moderate M. hapla reproduction (2.8 = Pf/Pi >/= 0.5). Chenopodium album, C. glaucum, E. cheiranthoides, P. convolvulus, Portulaca oleracea, and Rorippa islandica supported low reproduction (0.25 = Pf/Pi >/= 0.02) and sustained low galling. Galling was observed on Senecio vulgaris but no eggs or juveniles; thus, S. vulgaris may be useful as a trap plant. Eupatorium maculatum, and T. pubescens harbored no distinct galling but supported low to moderate M. hapla reproduction, respectively. Amaranthus retroflexus, Ambrosia artemisiifolia, Echinochloa crusgalli, Erigeron canadensis, Oenothera parviflora, Panicum capillare, Setaria glauca, S. viridis, and Solidago canadensis were nonhosts. Our results demonstrate the importance of adequate weed control in an integrated program for the management of M. hapla in organic soil. PMID:19277189
Bķlair, G; Benoit, D L
Phytoextraction involves use of plants to remove toxic metals from soil. We examined the effects of phytoextraction practices with three plant species (Silene vulgaris, Thlaspi caerulescens, and Zea mays) and a factorial variation of soil amendments (either an ammonium or nitrate source of nitrogen and the presence or absence of an elemental sulfur supplement) on arbuscular mycorrhizal (AM) fungi (Glomales, Zygomycetes) at a moderately metal-contaminated landfill located in St. Paul, Minn. Specifically, we tested whether the applied treatments affected the density of glomalean spores and AM root colonization in maize. Glomalean fungi from the landfill were grouped into two morphotypes characterized by either light-colored spores (LCS) or dark-colored spores (DCS). Dominant species of the LCS morphotype were Glomus mosseae and an unidentified Glomus sp., whereas the DCS morphotype was dominated by Glomus constrictum. The density of spores of the LCS morphotype from the phytoremediated area was lower than the density of these spores in the untreated landfill soil. Within the experimental area, spore density of the LCS morphotype in the rhizosphere of mycorrhizal maize was significantly higher than in rhizospheres of nonmycorrhizal S. vulgaris or T. caerulescens. Sulfur supplement increased vesicular root colonization in maize and exerted a negative effect on spore density in maize rhizosphere. We conclude that phytoextraction practices, e.g., the choice of plant species and soil amendments, may have a great impact on the quantity and species composition of glomalean propagules as well as on mycorrhiza functioning during long-term metal-remediation treatments. PMID:10831433
Pawlowska, Teresa E.; Chaney, Rufus L.; Chin, Mel; Charvat, Iris
Background Microalgae can accumulate considerable amounts of lipids under different nutrient-deficient conditions, making them as one of the most promising sustainable sources for biofuel production. These inducible processes provide a powerful experimental basis for fully understanding the mechanisms of physiological acclimation, lipid hyperaccumulation and gene expression in algae. In this study, three nutrient-deficiency strategies, viz nitrogen-, phosphorus- and iron-deficiency were applied to trigger the lipid hyperaccumulation in an oleaginous Chlorella pyrenoidosa. Regular patterns of growth characteristics, lipid accumulation, physiological parameters, as well as the expression patterns of lipid biosynthesis-related genes were fully analyzed and compared. Results Our results showed that all the nutrient stress conditions could enhance the lipid content considerably compared with the control. The total lipid and neutral lipid contents exhibit the most marked increment under nitrogen deficiency, achieving 50.32% and 34.29% of dry cell weight at the end of cultivation, respectively. Both photosynthesis indicators and reactive oxygen species parameters reveal that physiological stress turned up when exposed to nutrient depletions. Time-course transcript patterns of lipid biosynthesis-related genes showed that diverse expression dynamics probably contributes to the different lipidic phenotypes under stress conditions. By analyzing the correlation between lipid content and gene expression level, we pinpoint several genes viz. rbsL, me g6562, accA, accD, dgat g2354, dgat g3280 and dgat g7063, which encode corresponding enzymes or subunits of malic enzyme, ACCase and diacylglycerol acyltransferase in the de novo TAG biosynthesis pathway, are highly related to lipid accumulation and might be exploited as target genes for genetic modification. Conclusion This study provided us not only a comprehensive picture of adaptive mechanisms from physiological perspective, but also a number of targeted genes that can be used for a systematic metabolic engineering. Besides, our results also represented the feasibility of lipid production through trophic transition cultivation modes, throwing light on a two-stage microalgal lipid production strategy with which heterotrophy stage provides sufficient robust seed and nitrogen-starvation photoautotrophy stage enhances the overall lipid productivity. PMID:24479413
A Phytoremediation Strategy for Arsenic
A Phytoremediation Strategy for Arsenic Progress Report May, 2005 Richard B. Meagher Principal Investigator Arsenic pollution affects the health of several hundred millions of people world wide, and an estimated 10 million Americans have unsafe levels of arsenic in their drinking water. However, few environmentally sound remedies for cleaning up arsenic contaminated soil and water have been proposed. Phytoremediation, the use of plants to extract and sequester environmental pollutants, is one new technology that offers an ecologically sound solution to a devastating problem. We propose that it is less disruptive to the environment to harvest and dispose of several thousand pounds per acre of contaminated aboveground plant material, than to excavate and dispose of 1 to 5 million pounds of contaminated soil per acre (assumes contamination runs 3 ft deep). Our objective is to develop a genetics-based phytoremediation strategy for arsenic removal that can be used in any plant species. This strategy requires the enhanced expression of several transgenes from diverse sources. Our working hypothesis is that organ-specific expression of several genes controlling the transport, electrochemical state, and binding of arsenic will result in the efficient extraction and hyperaccumulation of arsenic into aboveground plant tissues. This hypothesis is supported by theoretical arguments and strong preliminary data. We proposed six Specific Aims focused on testing and developing this arsenic phytoremediation strategy. During the first 18 months of the grant we made significant progress on five Specific Aims and began work on the sixth as summarized below. Specific Aim 1: Enhance plant arsenic resistance and greatly expand sinks for arsenite by expressing elevated levels of thiol-rich, arsenic-binding peptides. Hyperaccumulation of arsenic depends upon making plants that are both highly tolerant to arsenic and that have the capacity to store large amounts of arsenic aboveground. Phytochelatins bind diverse thiol-reactive elements like As(III) and are synthesized from amino acids in a three-step enzymatic pathway utilizing three enzymes: ECS = gamma-glutamylcysteine synthetase; GS = GSH synthetase; and PS = phytochelatin synthase. We cloned each of the genes that encode these enzymes and used at least two different plant promoters to express them in transgenic Arabidopsis. We have shown that all three confer significant resistance to arsenic and allow rapid growth on a concentration of arsenic (300 micromolar) that kills wild-type seeds and plants.
Meagher, Richard B.
NASA Astrophysics Data System (ADS)
Current engineering-based technologies used to clean up soils are very costly and need lots of work. Phytoremediation is the use of plants to remove pollutants (i.e. heavy metals) from the environment or render them harmless. In the phytoremediation process several plant species can be used to reduce the concentrations of heavy metals in contaminated soils to environmentally acceptable levels. The idea of using rare plants which hyperaccumulate metals to selectively remove and recycle excessive soil metals has increasingly been examined as a potential practical and more cost effective technology than soil replacement, solidification, or washing strategies presently used. However, most hyperaccumulator species are not suitable for phytoremediation application in the field due to their small biomass and slow growth. Cultivation of woody plants in contaminated soils has showed potential for use in phytoremediation but also it provides aesthetic improvement in the field. In this study we studied the possibility of using the approach of phytoremediation of lead by Eucalyptus globulus in a lead-contaminated soil from an abandoned mine. Although Eucalytpus globulus prefer good ecological conditions in humid temperate climates, there are few studies that have showed their great potential in contaminated areas and important biomonitors of environmental quality. A test field was set up in an abandoned mine site (Alagoa, Portugal) in order to investigate the feasibility of phytoremediation of lead by Eucalyptus globulus. The field soil was characterized as follows: humus - 2.56-7.08%, pH in the soil water - 4.50-5.10, silte - 18-15% and total Pb - 67-239 mg/kg. The soils in some areas exceed the critical value (150 mg/kg) according with Portuguese law. Eucalytus globulus growing on the abandoned mine, contaminated with lead was studied. The results of shoots sample analysis (n = 15) show the total Pb levels of 0.170-0.093 mg/kg in the stem and 2.94-5.14 mg/kg in the leaves. The results obtain from this work suggest potential indicators for use of Eucalytus globulus in mining areas. Also the presence in the field of several generations of Eucalytus globulus and the existence of young plants near the main gallery suggest good adaptation in lead-contaminated soil.
Gerardo, R.; Kikuchi, R.
The diamondback moth, Plutella xylostella (L.), is an oligophagous insect that primarily feeds on members of the family Cruciferae. The development, survival, and reproductive potential of P. xylostella were studied on eight wild cruciferous species: Rorippa indica (L.) Hiern, Cardamine hirsuta L., Descurainia sophia (L.) Webb ex Prantl, Capsella bursa-pastoris (L.) Medic, Cardamine leucantha (Tausch) O. E. Schulz, Orychophragmus violaceus (L.) O. E. Schulz, Thlaspi arvense L., and Cardamine macrophylla Willd. Developmental durations of immatures from egg to adult emergence differed significantly among the plant species, with the longest period recorded on C. macrophylla (20.8 d) and the shortest on R. indica (15.8 d). The female pupae of P. xylostella reared on C. leucantha and T. arvense were lighter (4.2 and 4.3 mg/pupa) than those reared on other hosts (5.2-6.5 mg/pupa), and the male pupae from T. arvense were the lightest (3.1 mg/pupa) among all colonies. Survival from egg to adult emergence ranged from 95.7% on R. indica to 48.8% on T. arvense. The longevity (10.1 d) of P. xylostella female and the oviposition period (7.7 d) were the longest when larvae fed R. indica than those that fed on other wild hosts. Female adults of P. xylostella from O. violaceus, C. macrophylla, and Ca. bursa-pastoris had higher fecundity (305-351 eggs/female) than from other wild host plants, whereas that from R. indica had the lowest fecundity (134 eggs/female). C. hirsuta was the best wild host plant for P. xylostella because of the highest intrinsic rates of increase (rm = 0.2402), whereas T. arvense was the least favorable hosts with the lowest intrinsic rates of increase (rm = 0.1577). The results from this study will be useful for interpretation of the performance and population dynamics of P. xylostella on wild hosts and cultivated cruciferous vegetables. PMID:24367918
Niu, Yan-Qin; Sun, Yuan-Xing; Liu, Tong-Xian
Wild food plants used by the Tibetans of Gongba Valley (Zhouqu county, Gansu, China)
Background The ethnobotany of Tibetans is a seriously under-studied topic. The aim of the study was to investigate knowledge and use of wild food plants in a valley inhabited by Tibetans in the Gannan Tibetan Autonomous Region. Methods The field research was carried out in a wooded mountain valley in 9 neighbouring villages the Zhouqu (Brugchu) county, and comprised 17 interviews with single informants and 14 group interviews, involving 122 people altogether. Results We recorded the use of 81 species of vascular plants from 41 families. Fruits formed the largest category, with 42 species, larger than the wild greens category, with 36 species. We also recorded the culinary use of 5 species of edible flowers, 7 species with underground edible organs and 5 taxa of fungi. On average, 16.2 edible taxa were listed per interview (median ¢ 16). Green vegetables formed the largest category of wild foods (mean ¢ 8.7 species, median ¢ 9 species), but fruits were listed nearly as frequently (mean ¢ 6.9, median ¢ 6). Other categories were rarely mentioned: flowers (mean ¢ 0.2, median ¢ 0), underground edible parts (mean ¢ 0.3, median ¢ 0) and mushrooms (mean ¢ 1.5, ¢ median 1). Wild vegetables are usually boiled and/or fried and served as side-dishes (cai). They are often lacto-fermented. Wild fruits are mainly collected by children and eaten raw, they are not stored for further use. The most widely used wild vegetables are: Eleuterococcus spp., Pteridium aquilinum, Helwingia japonica, Aralia chinensis, Allium victorialis, Pteridium aquilinum, Ixeris chinensis, Thlaspi arvense and Chenopodium album. The culinary use of Caltha palustris as a green vegetable is very interesting. In its raw state, marsh marigold is a toxic plant, due to the presence of protoanemonin. In this area it is dried or lactofermented before use. The most commonly eaten fruits are: Pyrus xerophila, Prunus salicina, Berchemia sinica, Rubus spp. and Eleagnus umbellata. Conclusions The number of wild taxa eaten in the studied valley is relatively large compared to most studies from around the world. However, compared to the northern slope of the Qinling, in Shaanxi, the list is considerably shorter, in spite of the similar methodology applied and similar research effort involved. PMID:24502461
A study on cadmium phytoremediation potential of water lettuce, Pistia stratiotes L.
Aquatic macrophytes have tremendous potential for remediation of the heavy metal cadmium. The objective of this study was to investigate Cd phytoremediation ability of water lettuce, Pistia stratiotes L. The study was conducted with 5, 10, 15 and 20 mg L(-1) CdCl2 in hydroponic system for 21 days and the Cd concentrations in the root and shoot tissues were estimated by atomic absorption spectroscopy. The values obtained were used to evaluate the bioconcentration factor (BCF), translocation factor (TF) and translocation efficiency of this plant. The plant showed high Cd tolerance of up to 20 mg L(-1) but there was a general trend of decline in the root and shoot biomass. The maximum BCF values for root and shoot tissues were 2,294 and 870 respectively, obtained for 5 mg L(-1) Cd, which indicated that the plant was a Cd hyperaccumulator. The TF maxima was found to be 0.6 and as much as 60 % root to shoot translocation efficiency was observed for 15 mg L(-1) Cd which points towards the suitability of water lettuce for removing Cd from surface waters. PMID:24220931
Das, Suchismita; Goswami, Sunayana; Talukdar, Anupam Das
An experiment was designed to assess the capacity of Salvinia minima Baker to uptake and accumulate nickel in its tissues and to evaluate whether or not this uptake can affect its physiology. Our results suggest that S. minima plants are able to take up high amounts of nickel in its tissues, particularly in roots. In fact, our results support the idea that S. minima might be considered a hyper-accumulator of nickel, as it is able to accumulate 16.3 mg g(-1) (whole plant DW basis). Our results also showed a two-steps uptake pattern of nickel, with a fast uptake of nickel at the first 6 to 12h of being expose to the metal, followed by a slow take up phase until the end of the experiment at 144 h. S. minima thus, may be considered as a fern useful in the phytoremediation of residual water bodies contaminated with this metal. Also from our results, S. minima can tolerate fair concentrations of the metal; however, at concentrations higher than 80 ?M Ni (1.5 mg g(-1) internal nickel concentration), its physiological performance can be affected. For instance, the integrity of cell membranes was affected as the metal concentration and exposure time increased. The accumulation of high concentrations of internal nickel did also affect photosynthesis, the efficiency of PSII, and the concentration of photosynthetic pigments, although at a lower extent. PMID:25019564
Fuentes, Ignacio I; Espadas-Gil, Francisco; Talavera-May, Carlos; Fuentes, Gabriela; SantamarĒa, Jorge M
Polymetallic hyperaccumulating plants growing on wastes from former mining activity were used as the starting material in the preparation of novel plant-based Lewis acid catalysts. The preparation of biosourced Lewis acid catalysts is a new way to make use of mining wastes. These catalysts were characterized by X-ray fluorescence, X-ray diffraction, inductively coupled plasma mass spectrometry, and direct infusion electrospray ionization mass spectrometry. These analyses revealed a complex composition of metal species, present mainly as polymetallic chlorides. The catalysts proved to be efficient and recyclable in a solid-state version of the Garcia Gonzalez reaction, which has been underexploited until now in efforts to use carbohydrates from biomass. This methodology was extended to various carbohydrates to obtain the corresponding polyhydroxyalkyl furans in 38-98% yield. These plant-based catalysts may be a better alternative to classical Lewis acid catalysts that were previously used for the Garcia Gonzalez reaction, such as ZnCl2 , FeCl3 , and CeCl3 , which are often unrecyclable, require aqueous treatments, or rely on metals, the current known reserves of which will be consumed in the coming decades. Moreover, the plant-based catalysts allowed novel control of the Garcia Gonzalez reaction, as two different products were obtained depending on the reaction conditions. PMID:25044809
Escande, Vincent; Olszewski, Tomasz K; Petit, Eddy; Grison, Claude
Isolation and N-terminal sequencing of a novel cadmium-binding protein from Boletus edulis
NASA Astrophysics Data System (ADS)
A Cd-binding protein was isolated from the popular edible mushroom Boletus edulis, which is a hyperaccumulator of both Cd and Hg. Wild-growing samples of B. edulis were collected from soils rich in Cd. Cd radiotracer was added to the crude protein preparation obtained from ethanol precipitation of heat-treated cytosol. Proteins were then further separated in two consecutive steps; gel filtration and anion exchange chromatography. In both steps the Cd radiotracer profile showed only one distinct peak, which corresponded well with the profiles of endogenous Cd obtained by atomic absorption spectrophotometry (AAS). Concentrations of the essential elements Cu and Zn were low in the protein fractions high in Cd. N-terminal sequencing performed on the Cd-binding protein fractions revealed a protein with a novel amino acid sequence, which contained aromatic amino acids as well as proline. Both the N-terminal sequencing and spectrofluorimetric analysis with EDTA and ABD-F (4-aminosulfonyl-7-fluoro-2, 1, 3-benzoxadiazole) failed to detect cysteine in the Cd-binding fractions. These findings conclude that the novel protein does not belong to the metallothionein family. The results suggest a role for the protein in Cd transport and storage, and they are of importance in view of toxicology and food chemistry, but also for environmental protection.
Collin-Hansen, C.; Andersen, R. A.; Steinnes, E.
Lipid body accumulation alters calcium signaling dynamics in immune cells.
There is well-established variability in the numbers of lipid bodies (LB) in macrophages, eosinophils, and neutrophils. Similarly to the steatosis observed in adipocytes and hepatocytes during hyperinsulinemia and nutrient overload, immune cell LB hyper-accumulate in response to bacterial and parasitic infection and inflammatory presentations. Recently we described that hyperinsulinemia, both in vitro and in vivo, drives steatosis and phenotypic changes in primary and transformed mast cells and basophils. LB reach high numbers in these steatotic cytosols, and here we propose that they could dramatically impact the transcytoplasmic signaling pathways. We compared calcium release and influx responses at the population and single cell level in normal and steatotic model mast cells. At the population level, all aspects of Fc?RI-dependent calcium mobilization, as well as activation of calcium-dependent downstream signaling targets such as NFATC1 phosphorylation are suppressed. At the single cell level, we demonstrate that LB are both sources and sinks of calcium following Fc?RI cross-linking. Unbiased analysis of the impact of the presence of LB on the rate of trans-cytoplasmic calcium signals suggest that LB enrichment accelerates calcium propagation, which may reflect a Bernoulli effect. LB abundance thus impacts this fundamental signaling pathway and its downstream targets. PMID:25016314
Greineisen, William E; Speck, Mark; Shimoda, Lori M N; Sung, Carl; Phan, Nolwenn; Maaetoft-Udsen, Kristina; Stokes, Alexander J; Turner, Helen
Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula ū alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained. PMID:23903318
Xue, Liang-Jiao; Guo, Wenbing; Yuan, Yinan; Anino, Edward O.; Nyamdari, Batbayar; Wilson, Mark C.; Frost, Christopher J.; Chen, Han-Yi; Babst, Benjamin A.; Harding, Scott A.; Tsai, Chung-Jui
Ferns (Pteridophyta) are very important members of the plant kingdom that lag behind other taxa with regards to our understanding of their genetics, genomics, and molecular biology. We report here, to our knowledge, the first instance of stable transformation of fern with recovery of transgenic sporophytes. Spores of the arsenic hyperaccumulating fern Pteris vittata and tetraploid 'C-fern Express' (Ceratopteris thalictroides) were stably transformed by Agrobacterium tumefaciens with constructs containing the P. vittata actin promoter driving a GUSPlus reporter gene. Reporter gene expression assays were performed on multiple tissues and growth stages of gametophytes and sporophytes. Southern-blot analysis confirmed stable transgene integration in recovered sporophytes and also confirmed that no plasmid from A. tumefaciens was present in the sporophyte tissues. We recovered seven independent transformants of P. vittata and four independent C. thalictroides transgenics. Inheritance analyses using ?-glucuronidase (GUS) histochemical staining revealed that the GUS transgene was stably expressed in second generation C. thalictroides sporophytic tissues. In an independent experiment, the gusA gene that was driven by the 2ū Cauliflower mosaic virus 35S promoter was bombarded into P. vittata spores using biolistics, in which putatively stable transgenic gametophytes were recovered. Transformation procedures required no tissue culture or selectable marker genes. However, we did attempt to use hygromycin selection, which was ineffective for recovering transgenic ferns. This simple stable transformation method should help facilitate functional genomics studies in ferns. PMID:23933990
Muthukumar, Balasubramaniam; Joyce, Blake L; Elless, Mark P; Stewart, C Neal
Lead tolerance and accumulation in the gametophytes of the fern Athyrium yokoscense.
The fern Athyrium yokoscense is known to be highly tolerant to lead toxicity, and is a lead hyperaccumulator that can accumulate over 1,000 microg g(-1) of lead in its dry matter. In this work, we examined whether the gametophytic generation of A. yokoscense also resists lead toxicity like the sporophytic generation. Spore germination in A. yokoscense was more tolerant to Pb2+, compared to that in other fern species, such as Pteridium aquilinum, Lygodium japonicum and Pteris vittata. In addition, the early gametophyte development of A. yokoscense was not much affected by 10 microM Pb2+, as evaluated from the prothallial growth and rhizoid development. We also showed that Athyrium gametophytes could accumulate more than 10,000 microg g(-1) of lead, and that the lead was localized in the cytosol and vacuole of rhizoidal cells, as determined by a transmission electron micrograph. These results indicate that Athyrium gametophytes have the ability to accumulate lead in the rhizoids. Furthermore, the gametophytes were found to include a large amount of proanthocyanidins (condensed tannins). Because proanthocyanidins have a latent ability to complex with lead ions, the possible roles of proanthocyanidins in the lead tolerance and accumulation of Athyrium gametophytes are discussed. PMID:15843865
Kamachi, Hiroyuki; Komori, Ippei; Tamura, Hideo; Sawa, Yoshimi; Karahara, Ichirou; Honma, Yoshihiro; Wada, Naoya; Kawabata, Tokimasa; Matsuda, Kenji; Ikeno, Susumu; Noguchi, Munenori; Inoue, Hiroshi
Contamination of soils with copper (Cu) has become a serious problem in the environment. Phytoremediation is an emerging green technology that uses green plants to remediate heavy metal contaminated areas. This study was conducted to evaluate the potential of Jatropha curcasfor remediation of soils contaminated with Cu. Seedlings were planted in soils spiked with Cu in amount of 0, 50, 100, 200, 300, and 400 mg kg(-1) (Cu0, Cu50, Cu100, Cu200, Cu300, and Cu400) for a period of five months. The maximum height and number of leaves were recorded in control (Cu0) whereas the highest basal stem diameter was found in seedlings exposed to Cu50. Copper concentrations among plant parts were in the following trend: roots > stems > leaves. The highest total Cu concentration (665 +/- 1 mg kg(-1)) and total Cu removal (1.2 +/- 0.2%) based on total plant dry biomass were found in Cu400 and Cu50 treatments, respectively. J. curcas exhibited high root concentration factor (RCF > 1) and low translocation factor (TF < 1). Although Cu accumulation by the plant didn't reach the criteria of Cu hyperaccumulators, this species showed a potential to be used in phytostabilization of mildly Cu contaminated areas. However, the plant cannot be used for phytoextraction of Cu-contaminated soils. PMID:24912228
Ahmadpour, Parisa; Soleimani, Mohsen; Ahmadpour, Fatemeh; Abdu, Arifin
Leaves and flowers begin life as outgrowths from the edges of shoot apical meristems. Stem cell divisions in the meristem center replenish cells that are incorporated into organ primordia at the meristem periphery and leave the meristem. Organ boundaries, regions of limited growth that separate forming organs from the meristem, serve to isolate these two domains and are critical for coordination of organogenesis and meristem maintenance. Boundary formation and maintenance are poorly understood processes, despite the identification of a number of boundary-specific transcription factors. Here we provide genetic and biochemical evidence that the Arabidopsis thaliana transcription factor LATERAL ORGAN BOUNDARIES (LOB) negatively regulates accumulation of the plant steroid hormone brassinosteroid (BR) in organ boundaries. We found that ectopic expression of LOB results in reduced BR responses. We identified BAS1, which encodes a BR-inactivating enzyme, as a direct target of LOB transcriptional activation. Loss-of-function lob mutants exhibit organ fusions, and this phenotype is suppressed by expression of BAS1 under the LOB promoter, indicating that BR hyperaccumulation contributes to the lob mutant phenotype. In addition, LOB expression is BR regulated; therefore, LOB and BR form a feedback loop to modulate local BR accumulation in organ boundaries to limit growth in the boundary domain. PMID:23213252
Bell, Elizabeth M.; Lin, Wan-ching; Husbands, Aman Y.; Yu, Lifeng; Jaganatha, Venkateswari; Jablonska, Barbara; Mangeon, Amanda; Neff, Michael M.; Girke, Thomas; Springer, Patricia S.
Bioimaging using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers the capability to quantify trace elements and isotopes within tissue sections with a spatial resolution ranging about 10-100 ?m. Distribution analysis adds to clarifying basic questions of biomedical research and enables bioaccumulation and bioavailability studies for ecological and toxicological risk assessment in humans, animals and plants. Major application fields of mass spectrometry imaging (MSI) and metallomics have been in brain and cancer research, animal model validation, drug development and plant science. Here we give an overview of latest achievements in methods and applications. Recent improvements in ablation systems, operation and cell design enabled progressively better spatial resolutions down to 1 ?m. Meanwhile, a body of research has accumulated covering basic principles of the element architecture in animals and plants that could consistently be reproduced by several laboratories such as the distribution of Fe, Cu, Zn in rodent brain. Several studies investigated the distribution and delivery of metallo-drugs in animals. Hyper-accumulating plants and pollution indicator organisms have been the key topics in environmental science. Increasingly, larger series of samples are analyzed, may it be in the frame of comparisons between intervention and control groups, of time kinetics or of three-dimensional atlas approaches. PMID:24952624
Becker, J Sabine; Matusch, Andreas; Wu, Bei
Phytoremediation of heavy metals--concepts and applications.
The mobilization of heavy metals by man through extraction from ores and processing for different applications has led to the release of these elements into the environment. Since heavy metals are nonbiodegradable, they accumulate in the environment and subsequently contaminate the food chain. This contamination poses a risk to environmental and human health. Some heavy metals are carcinogenic, mutagenic, teratogenic and endocrine disruptors while others cause neurological and behavioral changes especially in children. Thus remediation of heavy metal pollution deserves due attention. Different physical and chemical methods used for this purpose suffer from serious limitations like high cost, intensive labor, alteration of soil properties and disturbance of soil native microflora. In contrast, phytoremediation is a better solution to the problem. Phytoremediation is the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments. It is a relatively recent technology and is perceived as cost-effective, efficient, novel, eco-friendly, and solar-driven technology with good public acceptance. Phytoremediation is an area of active current research. New efficient metal hyperaccumulators are being explored for applications in phytoremediation and phytomining. Molecular tools are being used to better understand the mechanisms of metal uptake, translocation, sequestration and tolerance in plants. This review article comprehensively discusses the background, concepts and future trends in phytoremediation of heavy metals. PMID:23466085
Ali, Hazrat; Khan, Ezzat; Sajad, Muhammad Anwar
Potential of weed species applied to remediation of soils contaminated with heavy metals.
To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially. PMID:15559831
Wei, Shu-He; Zhou, Qi-Xing; Wang, Xin; Cao, Wei; Ren, Li-Ping; Song, Yu-Fang
In hydrangea sepals, an aluminum complex of delphinidin-3-O-glucoside is responsible for the development of the blue color, and co-existing copigments mediate the solubilization and stabilization of the blue Al-anthocyanin complex which is localized in the sepal vacuole. In addition, hydrangeas are Al-hyperaccumulators and exhibit tolerance to acidic soils, in which the toxicity is due to soluble Al ion. Therefore, an Al-absorbing transport and storage system must exist in hydrangea. Recently, we cloned vacuolar and plasma membrane-localized Al-transporters, HmVALT, and HmPALT1, which are both members of the aquaporin family. However, HmPALT1 was only expressed in the sepals, indicating that a different Al-transporter should exist for absorption and long-distance transportation in the hydrangea plant. Using genetic information and microarray analysis, we identified an additional aluminum transporter gene, HmPALT2, which belongs to a member of the anion permease. The transcript was expressed in all tissues of hydrangea plants, and a transient expression study indicated that the gene product is localized to the plasma membrane. The results of an aluminum tolerance assay using yeast cells showed that the HmPALT2 is also involved in the transport of other metal(loid)s. The over-expression of HmPALT2 in Arabidopsis resulted in aluminum-hypersensitivity, suggesting that HmPALT2 should work as an aluminum transporter into cells in planta. PMID:23433438
Negishi, Takashi; Oshima, Kenshiro; Hattori, Masahira; Yoshida, Kumi
Many weakly basic amine-containing drugs are known to be extensively sequestered in acidic lysosomes by an ion trapping-type mechanism. The entrapment of drugs in lysosomes has been shown to influence drug activity, cancer cell selectivity, and pharmacokinetics and can cause the hyperaccumulation of various lipids associated with lysosomes. In this work, we have investigated the prolonged time-dependent effects of drugs on lysosomal properties. We have evaluated two amine-containing drugs with intermediate (propranolol) and high (halofantrine) relative degrees of lipophilicity. Interestingly, the cellular accumulation kinetics of these drugs exhibited a biphasic characteristic at therapeutically relevant exposure levels with an initial apparent steady-state occurring at 2 days followed by a second stage of enhanced accumulation. We provide evidence that this secondary drug accumulation coincides with the nuclear localization of transcription factor EB, a master regulator of lysosome biogenesis, and the appearance of an increased number of smaller and lipid-laden lysosomes. Collectively, these results show that hydrophobic lysosomotropic drugs can induce their own cellular accumulation in a time-dependent fashion and that this is associated with an expanded lysosomal volume. These results have important therapeutic implications and may help to explain sources of variability in drug pharmacokinetic distribution and elimination properties observed in vivo. ® 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3287-3296, 2014. PMID:25042198
Logan, Randall; Kong, Alex C; Krise, Jeffrey P
Phytoremediation of ionic and methylmercury pollution
Our long-term objective is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic organic and heavy metal pollutants (Meagher, 2000) applying scientific strategies and technologies from a rapidly developing field called phytoremediation. The phytoremediation of toxic elemental and organic pollutants requires the use relatively different approaches (Meagher, 2000). Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and aboveground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in aboveground tissues for later harvest. Various parts of this strategy are being critically tested by examining different genes in model plants and field species and comparing the results to control plants as we recently reviewed (Meagher et al., 2000; Rugh et al., 2000). A positive spin-off from this work on mercury has been a strategy for the phytoremediation of arsenic (Dhankher et al., 2002) and cadmium.
Meagher, Richard B.
Phytoremediation of soils contaminated with toxic elements and radionuclides
At many US Department of Energy (US DOE) facilities and other sites, surface soils over relatively large areas are contaminated with heavy metals, radionuclides, and other toxic elements, often at only a relatively small factor above regulatory action levels. Cleanup of such sites presents major challenges, because currently available soil remediation technologies can be very expensive. In response, the US DOE`s Office of Technology Development, through the Western Environmental Technology Office, is sponsoring research in the area of phytoremediation. Phytoremediation is an emerging technology that uses higher plants to transfer toxic elements and radionuclides from surface soils into aboveground biomass. Some plants, termed hyperaccumulators, take up toxic elements in substantial amounts, resulting in concentrations in aboveground biomass over 100 times those observed with conventional plants. After growth, the plant biomass is harvested, and the toxic elements are concentrated and reclaimed or disposed of. As growing, harvesting, and processing plant biomass is relatively inexpensive, phytoremediation can be a low-cost technology for remediation of extensive areas having lightly to moderately contaminated soils. This paper reviews the potential of hyper- and moderate accumulator plants in soil remediation, provides some comparative cost estimates, and outlines ongoing work initiated by the US DOE.
Cornish, J.E.; Goldberg, W.C. [MSE, Inc., Butte, MT (United States); Levine, R.S. [Dept. of Energy, Germantown, MD (United States). Office of Technology Development; Benemann, J.R.
Phytoremediation of Ionic and Methyl Mercury Pollution
Our long-term objective is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic organic and heavy metal pollutants by applying scientific strategies and technologies from a rapidly developing field called phytoremediation. The phytoremediation of toxic elemental and organic pollutants employs a variety of different approaches (Meagher, 2000). Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, transport, and aboveground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in aboveground tissues for later harvest and waste disposal. Various parts of this strategy are being critically tested by examining different genes in model plants and field species and comparing the results to control plants, as we reviewed previously (Meagher et al., 2000; Rugh et al., 2000). A positive spin-off from this work on mercury has been a strategy for the phytoremediation of arsenic (Dhankher et al., 2002) and cadmium (Dhankher et al., 2003).
Meagher, Richard B.
Phytoremediation of ionic and methylmercury pollution
Our long-term objective is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic organic and heavy metal pollutants (Meagher, 2000) applying scientific strategies and technologies from a rapidly developing field called phytoremediation. The phytoremediation of toxic elemental and organic pollutants requires the use relatively different approaches (Meagher, 2000). Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and aboveground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in aboveground tissues for later harvest. Various parts of this strategy are being critically tested by examining different genes in model plants and field species and comparing the results to control plants as we recently reviewed (Meagher et al., 2000; Rugh et al., 2000). A positive spin-off from this work on mercury has been a strategy for the phytoremediation of arsenic (Dhankher et al., 2002) and cadmium.
Meagher, Richard B.
Siderophores, produced by Pseudomonas aeruginosa, released slightly more Fe (53.6?mol) than that chelated by ethylenediaminetetraacetic acid (EDTA; i.e. 43.7?mol) in batch experiment using As-adsorbed ferrihydrite. More importantly, about 1.79?mol of As was found to be associated with siderophores in the aqueous phase due to siderophore-As complex formation when siderophores were used to release As from ferrihydrite. In contrast, As was not detected in the aqueous phase when EDTA was used, probably due to the readsorption of released As to ferrihydrite. A series of pot experiment was conducted to investigate the effect of siderophores as a microbial iron-chelator on As uptake by Cretan brake fern (Pteris cretica L.) during phtoextraction. Results revealed that P. cretica, a known As hyperaccumulator, grown in the siderophore-amended soil showed about 3.7 times higher As uptake (5.62mg-Asg(-1)-plant) than the plant grown in the EDTA-treated soil (1.51mg-Asg(-1)-plant). In addition, As taken up by roots of P. cretica in the presence of siderophores seemed to be favorably translocated to shoots (i.e. stems and leaves). About 79% of the accumulated As was detected in the shoots in the presence of siderophores after ten weeks. Fluorescence microscopic analysis confirmed that As in the roots was delivered to the leaves of P. cretica as a siderophore-As complex. PMID:25215655
Jeong, Seulki; Moon, Hee Sun; Nam, Kyoungphile
We evaluated the effectiveness of arsenic (As) hyperaccumulator Pteris vittata to continuously remove As from three contaminated-soils containing 26-126mgkg(-1) As over 7 harvests in 3.5 years. Changes in As speciation in soils, amended with P fertilizer (P-soil) or insoluble phosphate rock (PR-soil), were assessed via sequential fractionation. Arsenic in available (soluble+exchangeable), non-labile (bound to amorphous+crystalline Fe/Al oxides), and residual fractions constituted ?12%, ?80%, and ?8% of soil As. Soluble As declined while exchangeable As was unchanged, likely due to replenishment from non-labile As, which accounted for ?87% of decline in total soil As. Although plant-available As is important, the non-labile As better predicted the frond As concentration in P. vittata, with the correlation being r=0.90 and 0.64 for PR-soils and P-soils. P. vittata removed 44% of soil As from PR-soils compared to 33% from P-soils, suggesting the low-soluble P from PR was more effective than P fertilizer in enhancing As uptake by P. vittata. To facilitate acquisition of P from PR, P. vittata produced larger root biomass to solubilize non-labile As, allowing for more efficient phytoextraction. PMID:25108101
Lessl, Jason T; Luo, Jun; Ma, Lena Q
On March 11, 2011, one of the negative effects of the tsunami phenomenon that devastated the Pacific coast of the Tohoku district in Japan was the deposition of a wide range of arsenic (As) contamination to the soil. To remediate such a huge area of contamination, phytoremediation by Pteris vittata, an As-hyperaccumulator, was considered. To evaluate the efficacy of applying P. vittata to the area, the salt tolerance of P. vittata and the phytoextraction of As from soil samples were investigated. For the salt tolerance test, spore germination was considerably decreased at an NaCl level of more than 100ĀmM. At 200ĀmM, the gametophytes exhibited a morphological defect. Furthermore, the growth inhibition of P. vittata was observed with a salinity that corresponded to 66.2 mS/m of electric conductivity (EC) in the soil. A laboratory phytoremediation experiment was conducted using As-contaminated soils for 166Ādays. P. vittata grew and accumulated As at 264Āmg/kg-DW into the shoots. Consequently, the soluble As in the soil was evidently decreased. These results showed that P. vittata was applicable to the phytoremediation of As-contaminated soil with low salinity as with the contamination caused by the 2011 tsunami. PMID:25320850
Sugawara, Kazuki; Kobayashi, Akihiro; Endo, Ginro; Hatayama, Masayoshi; Inoue, Chihiro
Arsenic uptake and translocation by plants in pot and field experiments.
A work undertaken by pot and field experiments to assess the suitability of poplars and ferns for the in-situ, phytoextraction, of a dumping site with residues from the roasting process of arseno-pyrite is reported. The main characteristic of this site is the high content of both the As metalloid and heavy metals (e.g., Al, Fe, Cu, Co, Cr, Pb). Two poplar clones (Populus deltoides 'Dvina' and Populus x canadensis 'Orion') and Pteris vittata (Chinese brake fern) were planted in the contaminated soil both ex situ in pots and in situ. Plant survival, As accumulation in plant tissues, leaf content of pigments, soluble proteins, activity of catalase and SH-groups in both roots and leaves were evaluated during a 24-month study period. Both poplar and fern plants exhibited an increase in the activity of catalase and SH group contents when grown in the presence of pyrite ashes. The results showed that the co-planting system (arsenic-hyperaccumulator fern Pteris vittata and Populus clones) was suitable for phytoextraction of multi-contaminated dumping sites. Agronomic measures such as irrigation, soil tillage and amendments also seem to be necessary for the successful establishment of poplar trees and ferns in contaminated soils in order to enhance plant growth through the improvement of soil conditions. PMID:24933886
Ciurli, A; Lenzi, L; Alpi, A; Pardossi, A
Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P.Āvittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P.Āvittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. PMID:21840633
Ye, Wen-Ling; Khan, M Asaduzzaman; McGrath, Steve P; Zhao, Fang-Jie
The metal concentrations in a copper mine tailings and Desert broom (Baccharis sarothroides Gray) plants were investigated. The metal concentrations in plants, soil cover, and tailings were determined using ICP-OES. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in tailings was 526.4, 207.4, 89.1, 84.5, 51.7, 49.6, 39.7, and 35.6 mg kg?1, respectively. The concentration of all elements in soil cover was 10~15% higher than that of the tailings, except for molybdenum. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in roots was 818.3, 151.9, 73.9, 57.1, 40.1, 44.6, 96.8, and 26.7 mg kg?1 and 1214.1, 107.3, 105.8, 105.5, 55.2, 36.9, 30.9, and 10.9 mg kg?1 for shoots, respectively. Considering the translocation factor, enrichment coefficient, and the accumulation factor, desert broom could be a potential hyperaccumulator of Cu, Pb, Cr, Zn, As, and Ni. PMID:17964035
Haque, Nazmul; Peralta-Videa, Jose R.; Jones, Gary L.; Gill, Thomas E.; Gardea-Torresdey, Jorge L.
Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 ?g g DW(-1)). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves >1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow. PMID:23649544
Machado-Estrada, Blenda; Calder¾n, Jaqueline; Moreno-Sßnchez, Rafael; RodrĒguez-Zavala, Josķ S