Jasmonate modulates development- 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 desacetylvindoline 4-hydroxylase (D4H). The present studies suggest that jasmonate-based induction of TDC and D4H activities involves modulation of transcriptional, post-transcriptional and post-translational controls. The effects of jasmonate on both enzymes were transient with maximum TDC activity appearing 12 h earlier than that of D4H. Jasmonate treatment of etiolated seedlings neither enhanced TDC activity nor could it replace the light requirement for D4H induction. Jasmonate, therefore, appears to modulate events which are already triggered by developmental and environmental specific controls. Salicylic acid, another chemical inducer of secondary metabolism, was ineffective in activating either TDC or D4H under the experimental conditions used.