Nitrate reductase in detached embryos may serve as a marker of the preharvest tolerance of wheat seeds
We have observed an easily determinable parameter indicative of genetic pre-harvest sprouting (PHS) tolerance – the presence of an endosperm factor, presumably ABA, capable of inhibiting nitrate reductase (NR) induction in the embryo in the presence of NO3. This finding has importance not only for the early rapid screening of PHS tolerant of cereal cultivars but may also be an important tool to determine the mechanism of NR inhibition either by genetic repression or by post-translational down regulation of NR activity. In this work we sought a simple
relationship between ABA content and NR activity level that we assumed to be closely related to PHS susceptibility. Studied the relationship between ABA content, dry weight and ability to germinate in seeds of examined wheat varieties resistant to preharvest sprouting Lutescens 70, and unstable – Novosibirskaya 67. The data obtained are shown that the level of ABA reaching its maximum to 40-45 days . The maximum content of ABA for both varieties accounted for 40 days after flowering, when the grains reach maximum wet weight in the future, as the ripening hormone levels quickly decreased with the decrease in fresh weight of grain . The level of ABA in embryos unstable to pre-harvest sprouting wheat Novosibirskaya 67 ranged from 20 to 40% below the level of the hormone in the grains resistant Lutescens 70
wheat. The results showed a significant increase in the ability to germinate, since it is a phase 40-45 DAP. Reduction of endogenous ABA content in grains at the final stage of maturation, with a relatively high percentage of germination, can be explained by the need and ensuring to the start of the germination process of the seed.
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