Dynamics of protection antioxidant system of representatives of Amelanchier Medik. genus during ontogenesis under Steppe Pridniprov’e conditions

Antioxidant reaction in leaves of the representatives of Amelanchier Medik. genus introduced in Steppe Pridniprov’e during vegetative period  is studied. Activity of bensidin-peroxidase (BPOD), guaiacol-peroxidase (GPOD) and catalase (CAT) in leaves of four kinds Amelanchier Medik is analysed. Specific features of dynamics of enzymes activity in leaves of representatives of Amelanchier Medik. genus are defined according to phases of seasonal development and in reply to action of hydrothermal stress. On the basis of the received results the wide range of interspecific variability of enzymes activity in leaves of Amelanchier kinds, introduced in new conditions of existance is shown. The studied kinds were characterised by high activity ВРОD in all vegetative season. The greatest activity in leaves of all kinds was shown in a phase of secondary growth, in the most adverse hydrothermal mode that testified to passage of adaptive processes in plants. It is established, that unlike A. ovalis in which leaves level of activity BPOD was equal enough, other kinds in process of ontogenesis have shown sharper differences in activity of enzyme. The difference was essential, especially at A. canadensis in which leaves in May and June sharp falling of activity in 4,0 and 2,9 times accordingly in comparison with April was noticed, and in July and August – sharp increase that testified to a stressful condition of plants. The opposite tendency is found out in dynamics of activity GPOD i CAT. In the beginning phases of active growth (April) at all kinds the highest activity of enzymes, but, since May and till the end of the supervision period was observed, activity sharply went down at all kinds Amelanchier. Essential activation GPOD in a phase of active growth can be connected with processes of lignification to an greater degree, rather than with protection against oxidative stress. Thus in leaves of A. ovalis and A. canadensis higher activity gvaiacol-peroxidase, than at A. spicata and A. florida was observed. Small increase of activity was observed in June and to an greater measure in three kinds: A. ovalis, A. florida і A. spicata. In leaves of A. canadensis activity increase was marked in August in comparison with the period from May till July. The analysis of dynamics of catalase activity in leaves of representatives Amelanchier Medik. has shown similitude as well as at gvaiacol-peroxidase: the highest level was observed in April, and further there was an essential recession of enzyme activity. Dynamics of catalase activity during vegetation has appeared the most similar at kinds of A. ovalis and A. canadensis. In leaves of A. florida unlike last kinds the small peak of activity in July was marked, and in August activity again went down on 21,8 % in comparison with July. A. spicata has shown essential increase of activity САТ in August in comparison with July in 6,4 times. Thus, found out different directions of activity changes of oxidoreductases specify in participation antioxidant systems in realisation of different ways of adaptation of kinds-introducents of Amelanchier Medik. genus in ontogenesis process in the conditions of Pridneprov’e Steppe. Variability of enzymes activity level in leaves of Amelanchier Medik. in the course of vegetation means the adaptation to conditions of environment and as a whole displays adaptive ability of the investigated kinds at the expense of high antioxidant potential to counteract development of oxidative stress at action adverse of abiotic factors.