Tryptophan-derived secondary metabolites in Arabidopsis thaliana confer non-host resistance to necrotrophic Plectosphaerella cucumerina fungi

摘要: A defence pathway contributing to non-host resistance biotrophic fungi in Arabidopsis involves the synthesis and targeted delivery of tryptophan (trp)-derived metabolites indol glucosinolates (IGs) camalexin at pathogen contact sites. We have examined whether these are also rate-limiting for colonization by necrotrophic fungi. Inoculation with adapted or non-adapted isolates ascomycete Plectosphaerella cucumerina triggers accumulation trp-derived metabolites. found that their depletion cyp79B2 cyp79B3 mutants renders fully susceptible each three tested P. isolates, super-susceptible an isolate. This assigns a key role secondary limiting growth both However, 4-methoxy-indol-3-ylmethylglucosinolate, which is generated P450 monooxygenase CYP81F2, hydrolyzed PEN2 myrosinase, together antimicrobial play minor restricting necrotrophs. contrasts major two phytochemicals invasive powdery mildew fungi, thereby implying existence other unknown responses cucumerina. Impaired cucumerina, but not fungus Erysiphe pisi, on plants largely restored irx1 background, shows constitutive peptides. Our findings imply differential contributions antimicrobials pathogens.