Biochemical Mechanisms of Plant Adaptation under Radiation Impact

Radiation impact on plants Pentaphylloides fruticosa (L.) O. Schwarz has been studied. It has been established, that the radiation factor pressure initiates adaptation processes affecting the growth and development of plants, as well as physiological and biochemical reorganization of the metabolic processes determining population existence in a habitat. It is experimentally demonstrated that the biosynthesis of the total content of flavonoids in Pentaphylloides fruticosa leaves is intensified under radiation impact. It is revealed that the content of flavonols (both total and in groups) in P. fruticosa leaves demonstrates a 2.3-fold increase as compared to the reference, and at the same time the difference against the reference increases with the increase in the contamination level. Individual flavonoid components have been shown to form different types of response to radiation influence in an organism. The content of hyperosyde, quercitrin and kaempferol decreases with the increase in radiation contamination, the content of other flavonoid components, on the contrary, increases. The qualitative flavonoid content in leaves of both irradiated and reference plants remains constant. Phenomena of leaf surface reduction, a lengthwise decrease in the annual spear and leafstalk gain, an increase in the number of leaves on a spear. It has been found that with the increase in irradiation the differences against the reference increased according to the majority of criteria. Different organs of Pentaphylloides fruticosa exhibit different accumulative ability with respect to radionuclides: the content of Sr-90 in leaves is higher compared to that in stems irrespective of the level of contamination, whereas for Cs-137 such a correlation is not observed.