257:	Metabolic profiling of salicylate-induced oxylipins in barley leaves.

Authors:	Weichert, Heiko(A)Hause, Bettina(A)Wasternack, Claus(A)Feussner, Ivo, 19640.(A)
Affiliations:	(A): Institute of Plant Biochemistry, D-06120 Halle/Saale, Germany
Presenter:	Feussner, Ivo 19640., ifeussne@ipb.uni-halle.de

Adaptations of higher plants to abiotic or biotic stress are often accompanied with the occurrence of lipid peroxidation and metabolites derived therefrom. Lipid peroxidation may be the result of a controlled action of enzymes or the result of uncontrolled autoxidation. Oxylipins are formed and plant cells may adapt to changes in environmental conditions by the action of enzymes, whereas toxic compounds and cell damage appear upon autoxidation. During the development of salicylic acid (SA) mediated systemic activated resistance (SAR), lipid peroxidation has been observed as well. In barley leaves, SA treatment is accompanied with the induction of a specific set of lipoxygenase isoforms (LOXs). One of them is specifically induced by further chemicals known to form induced resistance. In addition, we recorded the metabolic profiles given by the LOX pathway reactions to elucidate putative physiological functions of these LOXs in SA-treated barley leaves. Within the leaves a massive accumulation of free linolenic acid is followed by the formation of (13S)-hydroperoxy linolenic acid. Moreover, different branches of the LOX pathway were found to be active, indicated by the endogenous accumulation of representative metabolites. The metabolic status and the degree of cell damage of the tissue under investigation will be discussed in qualitative and quantitative terms of the oxylipin profile leading to discussion on signaling and defense properties of these metabolites.