Pattern of 32P incorporation in DNA and RNA by root forming hypocotyl cuttings of vigna

Both etiolated (OL+24D) and light grown (12L+12D) seedings of Vigna catjang Endl. exhibited five distinct anatomical stages (stage 1 to stage v) of equal durations at the base of their hypocotyl cuttings during adventitious root formation. The dimensions of rooting priomordia only varied in these two sets of experiments. Furthermore, the etiolated cuttings produced lesser amount of roots as compared to light grown cuttings. Modifications of rooting behaviour by promotive and inhibitive IAA and GA3 was more or less identical in both the sets of experiments. 32P in corporation studies revealed stage III (Just disorganisation stage) as the period of highest metabolic activity, the efficiency, however, depdnding on the age of the cuttings. Patterns of 32P incorporation by nucleic acids, indicated clearly that both DNA and RNA synthesis increased during adventitious root formation, the maximum intensity of synthetic events taking place during just disorganisation stage (i.e. stage III). By comparing the rates of synthesis of RNA and DNA, at hypocotyl bases, the former proved to be significantly higher as compared to DNA synthesis. (author)