DINOR-OXO-PHYTODIENOIC ACID - A NEW HEXADECANOID SIGNAL IN THE JASMONATE FAMILY

Jasmonic acid and its precursors are potent regulatory molecules in pl ants, We devised a method for the simultaneous extraction of these com pounds from plant leaves to quantitate changes in the levels of jasmon ate family members during health and on wounding, During our study, we identified a novel 16-carbon cyclopentenoic acid in leaf extracts fro m Arabidopsis and potato, The new compound, a member of the jasmonate family of signals, was named dinor-oxo-phytodienoic acid, Dinor-oxo-ph ytodienoic acid was not detected in the Arabidopsis mutant fad5, which is incapable of synthesizing 7Z,10Z,13Z-hexadecatrienoic acid (16:3), suggesting that the metabolite is derived directly from plastid 16:3 rather than by beta-oxidation of the 18-carbon 12-oxo-phytodienoic aci d, Simultaneous quantitation of jasmonate family members in healthy le aves of Arabidopsis and potato suggest that different plant species ha ve different relative levels of jasmonic acid, oxo-phytodienoic acid, and dinor-oxo-phytodienoic acid. We term these profiles ''oxylipin sig natures.'' Dinor-oxo-phytodienoic acid levels increased dramatically i n Arabidopsis and potato leaves on wounding, suggesting roles in wound signaling, Treatment of Arabidopsis with micromolar levels of dinor-o xo-phytodienoic acid increased the ability of leaf extracts to transfo rm linoleic acid into the alpha-ketol 13-hydroxy-12-oxo-9(Z) octadecen oic acid indicating that the compound can regulate part of its own bio synthetic pathway, Tightly regulated changes in the relative levels of biologically active jasmonates may permit sensitive control over meta bolic, developmental, and defensive processes in plants.