Abstract
In compatible and incompatible interactions between oilseed rape Brassica napus and the downy mildew pathogen Peronospora parasitica,
three oxylipins were detected. Two of these compounds were trihydroxy oxylipins (9,12,13-trihydroxy-10(E)-octadecenoic acid [TriHOE1] and
9,12,13-trihydroxy-10(E),15(Z)-octadecenoic acid [TriHOE2]) derived from the 9-lipoxygenase (LOX) pathway, while the other was
(13S,9Z,11E,15Z)-13-hydroxy-9,11,15-octadecatrienoic acid [13-HOT], derived from the 13-LOX pathway. In incompatible interactions, the
three oxylipins appeared 12 h after inoculation, with concentrations of 13-HOT, for example, of 59 nmol gK1 FW. Concentrations of the three
oxylipins fell to considerably lower levels 96 h after inoculation in incompatible interactions. In contrast, the oxylipins did not appear in
compatible interactions until at least 48 h after inoculation and concentrations were much lower than those obtained in the incompatible
interactions. The possibility that these oxylipins might be involved in signalling and/or as antimicrobial compounds in oilseed rape resisting
infection by P. parasitica is discussed.