SIMILARITIES OF THE BIOLOGICAL-ACTIVITIES OF CORONATINE AND CORONAFACIC ACID TO THOSE OF JASMONIC ACID

Coronatine, a phytotoxin produced by Pseudomonas syringae pv. atropurp urea and an amide of coronafacic acid and coronamic acid, is known to induce the expansion of cells in potato tubers just as jasmonic acid ( JA) does. Furthermore, the chemical structure of coronafacic acid rese mbles that of JA to some extent. These observations led us to postulat e that coronatine and related compounds might have biological activiti es similar to those of JA. We compared the biological activities of co ronatine and coronafacic acid to those of JA in four jasmonate-respons ive assay systems, namely, in assays for tuber-inducing activity (with single-node segments of potato stems), for cell expansion-inducing ac tivity (with cells of potato tubers), for cell division-inhibiting act ivity (with soybean callus) and for senescence-promoting activity (wit h oat leaves). Coronatine had a positive effect in all these assays an d its activity was 100 to 10 000 times higher than that of JA in terms of the threshold concentration for activity. Coronafacic acid also ga ve a positive result in all the assays, but its activity was slightly weaker than that of JA in two assay systems. These results suggest tha t the special configuration of side chains with respect to the plane o f the cyclopentanone ring, namely, the 1R, 2S configuration in JA and the 3aS, 7aR configuration in coronatine and coronafacic acid, is nece ssary for these various biological activities.