Metabolic arms race between a plant and a fungal pathogen

Abstract

AbstractIn this work, we uncover a metabolite interaction between barley and the fungal pathogenBipolaris sorokiniana(Bs), involving hordedanes, a previously undescribed set of labdane-related diterpenoids with antimicrobial properties.Bsinfection of barley roots elicits hordedane synthesis from a 600-kb gene cluster. Heterologous reconstruction of the synthesis pathway in yeast produced several hordedanes, including one of the most advanced products 19-b-hydroxy-hordetrienoic acid (19-OH-HTA). Barley mutants in the diterpene synthase genes of the cluster are unable to produce hordedanes but, unexpectedly, show reducedBscolonization. Accordingly, 19-OH-HTA enhances both germination and growth ofBs, while it inhibits other fungi, andBschemically modifies 19-OH-HTA. Thus, plant and pathogen molecular interactions extend beyond protein-protein recognition and the simple detoxification of plant antimicrobial metabolites.One-Sentence SummaryA fungal pathogen uses barley diterpenoid phytoalexins to facilitate root colonization.