Effect of Abscisic Acid on Enzyme Induction in Lemna minor L.

Summary The activities of several photosynthetic enzymes (PEP-carboxylase, NAD-malate dehydrogenase, malic enzyme, ribulokinase, RuDP-carboxylase) were found to be higher in Lemna minor L. plants grown in the presence of ABA. This increase in the activity of the enzymes was not a function of the concentration of ABA, and the enhanced activities reached their peak within two days of growth in ABA, although significant effects could be observed even after a days incubation. The after-effects of ABA treatment on enzyme activities persisted for several days, and no appreciable fall in the activities could be recorded upto 5—10 days after the plants were transferred to a medium devoid of ABA. The ABA level in plants grown in 7.6 × 10 -6 M ABA was found to be about two times higher than in the control plants. The results with antimetabolites indicate that, in Lemna the effects of ABA are possibly mediated by its action at the translation level of enzyme synthesis.