INDUCTION OF 2 PRENYLTRANSFERASES FOR THE ACCUMULATION OF COUMARIN PHYTOALEXINS IN ELICITOR-TREATED AMMI-MAJUS CELL-SUSPENSION CULTURES

Two dimethylallyl diphosphate: umbelliferone dimethylallyltransferase (prenyltransferase) activities, catalysing the 6-prenylation and the 7-O-prenylation, respectively, of umbelliferone in the course of phytoalexin synthesis, increased in Ammi majus cell suspension cultures in response to elicitor treatment. Both enzyme activities were dependent on Mg2+ or Mn2+ with significant preference for Mg2+ in the 6-prenylation reaction. Whereas darkgrown cells did not contain these activities, both prenyltransferase activities were induced rapidly by the addition of elicitor reaching a first maximum after 10-14 hr and a second maximum beyond 30 hr. Other coumarin specific, elicitor-induced enzyme activities of A. majus cells, in contrast, showed only one maximum of activity within the 50 hr experimental period, while the pattern of induction of phenylalanine ammonia-lyase activity resembled that of the prenyltransferases with maxima at ca 8 hr and 20-30 hr. Preliminary data suggest that the apparent biphasic induction of these enzyme activities is due to post-translational enzyme modifications. © 1990.