A novel jasmonate- and elicitor-responsive element in the periwinkle secondary metabolite biosynthetic gene Str interacts with a jasmonate- and elicitor-inducible AP2-domain transcription factor, ORCA2

Jasmonate (JA) is an important plant stress hormone that induces various pl ant defense responses, including the biosynthesis of protective secondary m etabolites. The induction of the secondary metabolite biosynthetic gene Str ictosidine synthase (Str) in Catharanthus roseus (periwinkle) cells by elic itor requires JA as a second messenger. A 42 bp region in the Str promoter is both necessary and sufficient for JA- and elicitor-responsive expression . This region is unlike other previously identified JA-responsive regions, and contains a GCC-box-like element. Yeast one-hybrid screening identified cDNAs encoding two AP2-domain proteins. These octade-canoid-derivative resp onsive Catharanthus AP2-domain (ORCA) proteins bind in a sequence-specific manner the JA- and elicitor-responsive element. ORCA2 trans-activates the S tr promoter and its expression is rapidly inducible with JA and elicitor, w hereas Orca1 is expressed constitutively. The results indicate that a GCC-b ox-like element and ORCA2 play key roles in JA- and elicitor-responsive exp ression of the terpenoid indole alkaloid biosynthetic gene Str.