JASMONATE MODULATES DEVELOPMENT-REGULATED AND LIGHT-REGULATED ALKALOID BIOSYNTHESIS IN CATHARANTHUS-ROSEUS

Methyl jasmonate, a chemical inducer of secondary metabolism, has been shown to promote vindoline biosynthesis in developing seedlings, as a result of induction of tryptophan decarboxylase (TDC) and desacetylvi ndoline 4-hydroxylase (D4H). The present studies suggest that jasmonat e-based induction of TDC and D4H activities involves modulation of tra nscriptional, post-transcriptional and post-translational controls. Th e effects of jasmonate on both enzymes were transient with maximum TDC activity appearing 12h earlier than that of D4H. Jasmonate treatment of etiolated seedlings neither enhanced TDC activity nor could it repl ace the light requirement for D4H induction. Jasmonate, therefore, app ears to modulate events which are already triggered by developmental a nd environmental specific controls. Salicylic acid, another chemical i nducer of secondary metabolism, was ineffective in activating either T DC or D4H under the experimental conditions used. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.