title: Glutathione and tryptophan metabolites are key players in Arabidopsis nonhost resistance against Colletotrichum gloeosporioides.
abstract: The nonhost resistance of Arabidopsis against hemibiotrophic fungi in the genus Colletotrichum consists of pre- and post-invasive immune responses. Previously, we reported EDR1 and PEN2 as important components of Arabidopsis pre-invasive resistance toward non-adapted Colletotrichum gloeosporioides (Cg). However, despite their defect in entry control pen2 and edr1 mutants terminated further growth of this pathogen by activating the post-invasive hypersensitive response (HR) accompanied by plant cell death. In the present study, we showed that γ-glutamylcysteine synthetase (GSH1), which is required for glutathione biosynthesis, and tryptophan (Trp) metabolism contribute to pre- and post-invasive non-host resistance against Cg. We found GSH1 to be involved in the PEN2-dependent entry control of Cg. Opposite to pen2 and edr1, gsh1 mutants failed to restrict the invasive growth of the pathogen, which demonstrated the requirement for GSH1 during post-invasive non-host resistance. Based on the infection and metabolic phenotypes of Arabidopsis mutants defective in Trp metabolism, we showed that the biosynthesis of Trp-derived phytochemicals is also essential for resistance to Cg during the post-invasive HR. By contrast, GSH1 and these metabolites are dispensable for the induction of HR cell death, which is triggered in the non-invaded mesophyll cells adjacent to the Cg-invaded epidermal cells.
authors.affiliation: Graduate School of Agriculture; Kyoto University; Kyoto, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Hiruma
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukunaga
authors.forename: Paweł
authors.initials: P
authors.lastname: Bednarek
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Takano
mesh_terms: D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D020231:Colletotrichum; D060467:Disease Resistance / Q000276:immunology*; D005978:Glutathione / Q000378:metabolism*; D008954:Models, Biological; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D014364:Tryptophan; D005978:Glutathione
keywords: CYP79B; Colletotrichum; GSH1; antifungal metabolites; cell death; hypersensitive response; nonhost resistance; postinvasive defense