ALLENE OXIDE SYNTHASE AND ALLENE OXIDE CYCLASE, ENZYMES OF THE JASMONIC ACID PATHWAY, LOCALIZED IN GLYCINE-MAX TISSUES

Because jasmonic acid regulates a number of processes, including the e xpression of vegetative storage proteins in soybean (Glycine max L.) l eaves, the relative activity of a specific portion of the jasmonic aci d biosynthetic pathway in soybean tissues was examined. Allene oxide s ynthase and allene oxide cyclase were examined because they constitute a branch point leading specifically from 13(S)-hydroperoxy-9(Z), 11(E ), 15(Z)-octadecatrienoic acid to 12-oxo-phytodienoic acid, the precur sor of jasmonic acid. From growing plants, seed coats (hila plus testa e) of green fruits (38 d postanthesis) were most active, eliciting abo ut 1.5 times greater activity on a per milligram of protein basis than the next most active tissue, which was the pericarp. Leaves from frui ting plants were only one-seventh as active as seed coats, and activit ies in both immature cotyledons and embryonic axes were very low. No a ctivity was detected in any part of stored, mature seeds. After 72 h o f germination of stored seeds, a small amount of activity, about 4% of that in immature seed coats, was found in the plumule-hypocotyl-root, and no activity was detected in the cotyledons. The high levels of ja smonic acid biosynthetic enzymes in soybean pericarp and seed coat sug gest a role for jasmonic acid in the transfer of assimilate to seeds.