Metabolism of Jasmonic Acid

Abstract

(—)-Jasmonic acid [(—)-JA (Ia)] and its methyl ester (Ib) were found to be widespread in plants [15] and are considered to represent a new type of native PGRs with hormone-like properties [22, 23]. Further members of the group are (H-)-7-iso-JA (II), known as the major product of JA biosynthesis in fruits of Vicia faba [16] and in the fungus Botryodiplodia theobromae [17], as well as cucurbic acid (IV) [6,7] and a number of structurally related cyclopentanoidal C₁₂-acids isolated more recently [18, 19]. Some studies dealing with the biosynthesis of JA in plants clearly demonstrate a route starting from linolenic acid [25]. However, knowledge of the JA metabolism in plants is very limited [9, 10, 21]. Reports on the physiological activity of 9, 10-dihydrojasmonic acid (DJA, III) and recent results demonstrating its natural occurrence in broad bean fruits [19] prompted us to start tracer studies on the metabolism of radiolabeled rac-III, which then were followed by experiments using [2–¹⁴C]-(±)-JA (rac-Ia) confirming the pattern of major metabolites. The significance of metabolic routes of exogenously applied DJA and JA, respectively, will be discussed by comparing the known spectrum of naturally occurring JA analogues and derivatives including glucosyl and amino acid conjugates.