METABOLISM OF ARACHIDONIC-ACID INVOLVED IN ITS ELICITING ACTIVITY IN POTATO-TUBER

A 5-lipoxygenase from potato converts arachidonic acid (AA) to the unstable and reactive intermediate 5-S-hydroperoxyeicosatetraenoic acid (5-S-HPETE) which, at a concentration of 1 μg per tuber slice, induces phytoalexin accumulation to higher levels than those induced by AA at 20 μg per slice. However the tissue browning elicited by the 5-S-HPETE was lower than that elicited by AA, indicating that 5-S-HPETE may account for phytoalexin induction but not for the whole browning process. GC-MS analyses of lipid extracts of potato tuber slices treated with 1-[14C]AA and other polyunsaturated fatty acids showed no incorporation of these acids into potato lipid fractions. © 1992.