formed between the fungus and host plant can be influenced by soil microorganisms present in the mycorrhizosphere. For example, soil bacteria from the genera Paenibacillus and Burkholderia alter the branching structure of the root, whereas Bacillus species increase root growth and mycorrhizal colonization. The fungus does not require a specific soil but seems to prefer acidic and nutrient-deficient soil. Suillus luteus produces hydroxamic acid-based siderophores, which are compounds that can chelate iron and extract it from the soil in nutrient-poor conditions. Ignacio Chapela and colleagues analysed the carbon uptake of S. luteus in Ecuador, concluding pine plantations accompanied by S. luteus deplete carbon stored in the soil and raising concerns that these might not be a remedy for rising carbon dioxide levels in the atmosphere. The fungus has been shown to provide a protective effect against heavy metal toxicity when associated with the host Pinus sylvestris, preventing copper accumulation in the needles, and protecting seedlings against cadmium toxicity. Owing to its frequent rate of sexual reproduction and the resulting extensive gene flow within populations, the fungus can rapidly evolve a trait to tolerate otherwise toxic levels of heavy metals in the environment. The genetic basis of this adaptation—intriguing to researchers investigating the bioremediation potential of metal-adapted plants and their fungal associates—are contained in the genome sequence of S. luteus, published in 2015. Suillus luteus fruit bodies are sometimes infested with larvae, though not nearly as often as S. granulatus or B. edulis. Damage from maggots is much more common in warmer months, and rare late in the season with cooler weather. In a Finnish study, researchers found that 70–95% of fruit bodies collected from typical forest habitats were infested with larvae; the most common species were the flies Mycetophila fungorum, Pegomya deprimata, and Pegohylemyia silvatica. In contrast, other studies have shown that fruit bodies collected from pine plantations are relatively free of larvae. The fungus produces microscopic crystals of oxalic acid at the surface of its hyphae, a feature that is thought to help deter grazing by the springtail species Folsomia candida. Edibility Suillus luteus is an edible mushroom, but the slime/pileipellis must be removed. Although some authors regard it as one of low quality, and generally inferior to co-occurring species such as Boletus pinophilus, the species is considered a delicacy in Slavic cultures (known as maslyata in Russian or maślaki in Polish, deriving from words meaning "buttery"). It was