EFFECT OF GIBBERELLIC ACID ON THE ACTIVITY OF RIBONUCLEASE FROM BLACK LOCUST SEEDLINGS

There was about two-fold stimulation of RNase activity by the application of GA3 at 20ppm to Black Locust seedlings for 48 hours. Stimulative effect of GA3 on RNase activity to the cotyledons, young stems and young roots of seedlings was basically the same. The increase in activity was inhibited by the administration of 5-fluorouracil,cycloheximide and puromycin but stimulated by the administration of actinomycin D. It seems likely that actinomycin D treatments resulted in maintenance of high levels of enzyme activity by inhibiting the production of substances associated with enzyme decay. Purification of labelled RNase revealed that GA3 enhanced the RNase activity mainly by its fresh synthesis.