Formation of 4-hydroxy-2-alkenals in barley leaves

In barley leaves 13-lipoxygenases are induced by jasmonates. This leads to induction of lipid peroxidation. Here we show by in vitro studies that thes e processes may further lead to autoxidative formation of (2E)-4-hydroxy-2- hexenal from (3Z)-hexenal. In barley leaves 13-lipoxygenases (13-LOXs) are induced by salicylate and j asmonate. We showed by metabolic profiling that upon salicylate and in the case of salicylate treatment 13-LOX-derived products are formed, indicating lipid peroxidation, and are specifically directed into the reductase branc h of the LOX pathway leading mainly to the accumulation of (13S, 9Z, 11E,15 Z)-13-hydroxy-9,11,15-octadecatrienoic acid (13-HOT) [1]. Also jasmonate tr eatment mainly leads to lipid peroxidation, and the accumulated 13-LOX-deri ved product is (13S,9Z,11E,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic aci d (13-HPOT). 13-HPOT is directed into the reductase (sic).