[Regeneration mechanisms of ontogenetic radioadaptation in plants]

Experimental data were obtained that in pea seedlings modified by decapitation of main root had increased radioresistance (radioadaptation), fixed by various parameters of growth activity of lateral roots, and decreased ability to repair sublethal damages, detected by method of acute gamma-irradiation dose fractionation. These facts both with enlargement of dose dependence shoulder in lateral roots of decapitated seedlings led to conclusion that main role in such mechanism of radioadaptation effect of decapitation belongs to supercellular processes such as repopulation and regeneration. Conclusion was confirmed by the additional comparative investigations of cyto- and histological parameters of apical meristems of intact (control) and decapitated (experiment) lateral roots. It was shown, that the decapitated seedlings had increased mitotic activity of apical meristems of lateral roots and total volume of their meristematic zone. So at the moment of application of irradiation in the test-dose decapitated variant had significantly more meristematic cells of certain size that allowed biological object to form necessary (critical) amount of elements for valid or more complete postradiation recovery.