REGULATION OF 3-HYDROXY-3-METHYLGLUTARYL-COENZYME-A REDUCTASE BY WOUNDING AND METHYL JASMONATE - IMPLICATIONS FOR THE PRODUCTION OF ANTICANCER ALKALOIDS

HMGR (3-hydroxy-3-methylglutaryl-coenzyme A reductase; E.C.1.1.1.34) s upplies mevalonate for the synthesis of many plant primary and seconda ry metabolites, including the terpenoid component of indole alkaloids. Suspension cultures of Camptotheca acuminara and Catharanthus roseus, two species valued for their anticancer indole alkaloids, were treate d with the elicitation signal transducer methyl jasmonate (MeJA). RNA gel blot analysis from MeJA treated cultures showed a transient suppre ssion of HMGR mRNA, followed by an induction in HMGR message. Leaf dis ks from transgenic tobacco plants containing a chimeric hmg1::GUS cons truct were also treated with MeJA and showed a dose dependent suppress ion of wound-inducible GUS activity. The suppression of the wound resp onse by MeJA was limited to the first 4 h post-wounding, after which t ime MeJA application had no effect. The results are discussed in relat ion to the differential regulation of HMGR isogenes in higher plants.