Induction of Acquired Resistance in Rice to Rice Blast by Syringolin, an Elicitor from Pseudomonas Syringae Pv. Syringae

Abstract

Recognition by rice plants (Oryza sativa) of the non-host pathogen Pseudomonas syringae pv. syringae leads to local acquired resistance to the rice blast fungus Pyricularia oryzae accompanied by the accumulation of a set of transcripts. We have identified and isolated a compound secreted by the bacteria that, when applied to rice leaves, elicits accumulation of defense gene transcripts and increases resistance to P. oryzae, but is not toxic for the fungus. This compound, which we name syringolin, is a novel peptide in which the two non-proteinogenic amino acids 5-methyl-4-amino-2-hexenoic acid and 3,4-dehydrolysine form a 12-membered ring that is attached by peptide bond to a valine that in turn is linked to a second valine via a urea moiety. Thus, syringolin appears to be one of the determinants of the non-host pathogen P. syringae pv. syringae that can be perceived by rice plants.