| Summary: | The work present quantitative changes and synthesis od: RNA fractions in wheat grain and endosperm during development and ripening. It was found that share of rRNA in total RNA decreases during development both, in the endosperm and in grain. Rapid drop of rRNA content in total RNA takes place in the endosperm since 31st day after blooming, and in grain - since 45th day after blooming. Absolute amount of rRNA, as calculated per 100 grains or endosperms, increases in the first half of grain formation period, and then decreases till the end of development. As a result of degradation of ribosomal RNA in endosperm, low-molecule fraction – 4 S, significantly increased at final stage of development. Decrease of rRNA fraction at final stage of development is not accompanied by an increase of absolute amount of 4 S RNA fraction. Incorporation of 3H-,uriidine into grain and endosperm RNA is highest at the begining of development. Further on it gradually decreases till the end of development. Synthesis of RNA in grain takes place throughout the whole development. Contrary to this, no incorporation of precursor into rRNA was noted during waxy and full ripeness of wheat grain.
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