Structure-activity relationships of synthetic analogs of jasmonic acid andcoronatine on induction of benzo[c]phenanthridine alkaloid accumulation inEschscholzia californica cell cultures

A facile test system based on the accumulation of benzo[c]phenanthridine al kaloids in Eschscholzia californica cell suspension culture (an indicator o f defense gene activation) has been used to analyze a series of synthetic c ompounds for elicitor-like activity. Of the 200 jasmonic acid and coronatin e analogs tested with this system, representative results obtained with 49 of them are presented here. The following can be summarized concerning stru cture-actvity relationships: there is a large degree of plasticity allowed at the C-3 of jasmonic acid in the activation of defense genes. The carbony l moiety is not strictly required, but exocyclic double bond character appe ars necessary. The pentenyl side chain at C-2 cannot tolerate bulky groups at the terminal carbon and still be biologically active. Substitutions to t he C-1' position are tolerated if they can potentially undergo beta-oxidati on. Either an alkanoic acid or methyl ester is required at c-l, or a side c hain that can be shortened by beta-oxidation or by peptidase hydrolysis. Co ronatine and various derivatives thereof are not as effective as jasmonic a cid, and derivatives in inducing benzo[c]phenanthridine alkaloid accumulati on. Jasmonic acid rather than the octadecanoic precursors is therefore cons idered to be a likely signal transducer of defense gene activation in plant a.