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SOME FEATURES OF EMBRYOLOGY OF Rosa spinosissima L., R. canina L. AND R. × damascena Mill. INTACT AND VIRUS-INFECTED PLANTS

Due to high decorative and economically valuable traits, roses have long been used in garden and park construction, and as medicinal and aromatic raw materials. Selection carried out with roses for many years, has resulted in more than 30 thousand cultivars. To create new forms and varieties, it is necessary to in-depth know species biology, including developments of generative elements. This paper shows the study of male and female generative structure formation in two wild species of Rosa genus, Rosa spinosissima L. and R. canina L., naturally grown on the north-eastern slope of Mount Chatyr-Dag, and in two R. 1⁄2 damascena Mill. cultivars, which may be involved in breeding as parental plants. As a result, we have determined the main embryological types of generative sphere formation in these species. It has been shown that the anthers are four-nested with two thecas, the wall of microsporangium is formed centripetal. A formed wall of microsporangium consists of epidermis, endothecium, 2-3 middle layers and tapetum, which is a derivative of a secondary parietal tissue. A tetrad of microspores is formed simultaneously. Differentiation mitosis in microspores leads to the formation of 2 celled pollen grains. Mature pollen grains are 2 celled with 3 pores. Microsporangium wall of the mature anther is represented by the epidermis covered with cuticle, fibrous endothecium and remnants of a middle layer. Morphogenicity and viability of mature pollen of these species and varieties have been established (abnormal pollen grains can be up to 30 %). Pollen sizes were measured. The diameter of pollen grains varies from 19 to 30 microns. The influence of viral infection on the formation of pollen grains has been shown, which causes an increase in the number of pollen abnormalities, changes the pollen grain size and ultimately leads to pollen grain degeneration. Defective pollen grains can be up to 50 %. Gynoecium of rose consists of many free carpels, each contains 1-2 ovules. Rosa ovule is anatropous, bitegmal, crassinucellate. Multicellular hypostase with thick-walled cells is formed in chalasa area. Micropyle is formed by an internal integument, which in its development is ahead of the outer one. Archesporium is polycelled and differentiated in the subepidermal layer of ovule. As a result of meiosis, linear tetrads of megaspores are mostly formed, of which chalasal or epichalasal megaspores were functionally active to derive embryo sacs of Polygonum-type. Mature embryo sacs are 8 nucleate and 7 celled. Egg apparatus consists of egg and 2 synergids, antipods are represented by three cells. Majority of embryo sacs gradually are obliterated, and only one of them matures. The studied species of genus Rosa are entomophilous plants pollinated by insects. It has been concluded that in selection, while choosing parental forms for hybridization, attention should be paid not only to the viability of their generative structures, but also to plant viral infection, since the presence of pathogens has led to a significant decrease in reproductive ability.