Jasmonate-dependent induction of indole glucosinolates in Arabidopsis by culture filtrates of the nonspecific pathogen Erwinia carotovora

Elicitors from the plant pathogen Erwinia carotovora trigger coordinate ind uction of the tryptophan (Trp) biosynthesis pathway and Try oxidizing genes in Arabidopsis. To elucidate the biological role of such pathogen-induced activation we characterized the production of secondary defense metabolites such as camalexin and indole glucosinolates derived from precursors of thi s pathway. Elicitor induction was followed by a specific increase in 3-indo lylmethylglucosinolate (IGS) content, but only a barely detectable accumula tion of the indole-derived phytoalexin camalexin. The response is mediated by jasmonic acid as shown by lack of IGS induction in the jasmonate-insensi tive mutant coil-1. In accordance with this, methyl jasmonate was able to t rigger ICS accumulation in Arabidopsis. In contrast, ethylene and salicylic acid seem to play a minor role in the response. They did not trigger alter ations in IGS levels, and methyl jasmonate- or elicitor-induced IGS accumul ation in NnhC and ethylene-insensitive ein2-1 mutant plants was similar as in the wild type. The breakdown products of IGS and other glucosinolates we re able to inhibit growth of E. carotovora. The results suggest that IGS is of importance in the defense against bacterial pathogens.