title: The glutathione peroxidase-mediated reactive oxygen species resistance, fungicide sensitivity and cell wall construction in the citrus fungal pathogen Alternaria alternata.
abstract: The ability to detoxify reactive oxygen species (ROS) is critical for pathogenicity in the necrotrophic fungus Alternaria alternata. We report a glutathione peroxidase 3 (AaGPx3) involved in the complex signalling network that is essential for the detoxification of cellular stresses induced by ROS and for A. alternata pathogenesis in citrus. AaGPx3 deletion mutants displayed increased sensitivity to H2 O2 and many ROS-generating compounds. AaGPx3 is required for correct fungal development as the AaGPx3 mutant strains showed a severe reduction in conidiation. AaGPx3 mutants accumulated higher chitin content than the wild-type and were less sensitive to the cell wall-targeting compounds calcofluor white and Congo red, as well as the fungicides fludioxonil and vinclozolin, suggesting a role of the glutathione systems in fungal cell wall construction. Virulence assays revealed that AaGPx3 is required for full virulence. The expression of AaGPx3 was downregulated in fungal strains carrying defective NADPH oxidase (Nox) or the oxidative stress responsive regulators YAP1 and HOG1, all implicated in ROS resistance. These results further support the important role of ROS detoxification during A. alternata pathogenesis in citrus. Overall, our study provides genetic evidence to define the central role of AaGPx3 in the biological and pathological functions of A. alternata.
authors.affiliation: Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, USA.
authors.forename: Siwy Ling
authors.initials: SL
authors.lastname: Yang
authors.affiliation: Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan.
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Yu
authors.affiliation: Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, USA.|Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan.
authors.forename: Kuang-Ren
authors.initials: KR
authors.lastname: Chung
mesh_terms: D000528:Alternaria / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D002473:Cell Wall / Q000378:metabolism*; D002686:Chitin / Q000378:metabolism; D002957:Citrus / Q000382:microbiology*; D004149:Dioxoles / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics; D005659:Fungicides, Industrial / Q000494:pharmacology*; D005979:Glutathione Peroxidase / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D019255:NADPH Oxidases / Q000235:genetics; D010080:Oxazoles / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011758:Pyrroles / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014774:Virulence / Q000187:drug effects
chemical_list: D004149:Dioxoles; D005656:Fungal Proteins; D005659:Fungicides, Industrial; D010080:Oxazoles; D011758:Pyrroles; D017382:Reactive Oxygen Species; D002686:Chitin; D005979:Glutathione Peroxidase; D019255:NADPH Oxidases; C108339:fludioxonil; C025643:vinclozolin