MODULATION OF THE ACTIVITY OF 2 HYDROXYCINNAMOYL TRANSFERASES IN WOUND-HEALING POTATO-TUBER DISCS IN RESPONSE TO PECTINASE OR ABSCISIC-ACID

The activity of two enzymes known to be involved in the biosynthesis o f cell-wall phenolics in wound-healing potato tuber tissues was monito red in tuber discs treated with abscisic acid (ABA), pectinase, arachi donic acid, or jasmonic acid. Tyramine hydroxycinnamoyl transferase (T HT) activity was strongly stimulated by pectinase and, to a lower exte nt, by ABA. By contrast, omega-hydroxypalmitic acid hydroxycinnamoyl t ransferase (HHT), which is a good marker of suberin biosynthesis, was induced by ABA, but not by pectinase treatments. Neither arachidonic a cid, a known elicitor of phytoalexin biosynthesis in potato tubers, no r jasmonic acid, a putative intermediate in the signal transduction to wounding, significantly modified the time course or the intensity of induction of THT or HHT activities.