title: Glycolate oxidase modulates reactive oxygen species-mediated signal transduction during nonhost resistance in Nicotiana benthamiana and Arabidopsis.
abstract: In contrast to gene-for-gene disease resistance, nonhost resistance governs defense responses to a broad range of potential pathogen species. To identify specific genes involved in the signal transduction cascade associated with nonhost disease resistance, we used a virus-induced gene-silencing screen in Nicotiana benthamiana, and identified the peroxisomal enzyme glycolate oxidase (GOX) as an essential component of nonhost resistance. GOX-silenced N. benthamiana and Arabidopsis thaliana GOX T-DNA insertion mutants are compromised for nonhost resistance. Moreover, Arabidopsis gox mutants have lower H(2)O(2) accumulation, reduced callose deposition, and reduced electrolyte leakage upon inoculation with hypersensitive response-causing nonhost pathogens. Arabidopsis gox mutants were not affected in NADPH oxidase activity, and silencing of a gene encoding NADPH oxidase (Respiratory burst oxidase homolog) in the gox mutants did not further increase susceptibility to nonhost pathogens, suggesting that GOX functions independently from NADPH oxidase. In the two gox mutants examined (haox2 and gox3), the expression of several defense-related genes upon nonhost pathogen inoculation was decreased compared with wild-type plants. Here we show that GOX is an alternative source for the production of H(2)O(2) during both gene-for-gene and nonhost resistance responses.
authors.affiliation: Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73402, USA.
authors.forename: Clemencia M
authors.initials: CM
authors.lastname: Rojas
authors.forename: Muthappa
authors.initials: M
authors.lastname: Senthil-Kumar
authors.forename: Keri
authors.initials: K
authors.lastname: Wang
authors.forename: Choong-Min
authors.initials: CM
authors.lastname: Ryu
authors.forename: Amita
authors.initials: A
authors.lastname: Kaundal
authors.forename: Kirankumar S
authors.initials: KS
authors.lastname: Mysore
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D044224:Pseudomonas syringae / Q000472:pathogenicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000382:microbiology
chemical_list: D017382:Reactive Oxygen Species; D000429:Alcohol Oxidoreductases; C020821:glycollate oxidase