title: Dual roles of reactive oxygen species and NADPH oxidase RBOHD in an Arabidopsis-Alternaria pathosystem.
abstract: Arabidopsis (Arabidopsis thaliana) NADPH oxidases have been reported to suppress the spread of pathogen- and salicylic acid-induced cell death. Here, we present dual roles of RBOHD (for respiratory burst oxidase homolog D) in an Arabidopsis-Alternaria pathosystem, suggesting either initiation or prevention of cell death dependent on the distance from pathogen attack. Our data demonstrate that a rbohD knockout mutant exhibits increased spread of cell death at the macroscopic level upon inoculation with the fungus Alternaria brassicicola. However, the cellular patterns of reactive oxygen species accumulation and cell death are fundamentally different in the AtrbohD mutant compared with the wild type. Functional RBOHD causes marked extracellular hydrogen peroxide accumulation as well as cell death in distinct, single cells of A. brassicicola-infected wild-type plants. This single cell response is missing in the AtrbohD mutant, where infection triggers spreading-type necrosis preceded by less distinct chloroplastic hydrogen peroxide accumulation in large clusters of cells. While the salicylic acid analog benzothiadiazole induces the action of RBOHD and the development of cell death in infected tissues, the ethylene inhibitor aminoethoxyvinylglycine inhibits cell death, indicating that both salicylic acid and ethylene positively regulate RBOHD and cell death. Moreover, A. brassicicola-infected AtrbohD plants hyperaccumulate ethylene and free salicylic acid compared with the wild type, suggesting negative feedback regulation of salicylic acid and ethylene by RBOHD. We propose that functional RBOHD triggers death in cells that are damaged by fungal infection but simultaneously inhibits death in neighboring cells through the suppression of free salicylic acid and ethylene levels.
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Munich/Neuherberg, Germany.
authors.forename: Miklós
authors.initials: M
authors.lastname: Pogány
authors.forename: Uta
authors.initials: U
authors.lastname: von Rad
authors.forename: Sebastian
authors.initials: S
authors.lastname: Grün
authors.forename: Anita
authors.initials: A
authors.lastname: Dongó
authors.forename: Alexandra
authors.initials: A
authors.lastname: Pintye
authors.forename: Philippe
authors.initials: P
authors.lastname: Simoneau
authors.forename: Günther
authors.initials: G
authors.lastname: Bahnweg
authors.forename: Levente
authors.initials: L
authors.lastname: Kiss
authors.forename: Balázs
authors.initials: B
authors.lastname: Barna
authors.forename: Jörg
authors.initials: J
authors.lastname: Durner
mesh_terms: D000528:Alternaria / Q000502:physiology*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D004269:DNA, Bacterial / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010935:Plant Diseases / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013830:Thiadiazoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D005030:Ethylenes; D018749:RNA, Plant; D017382:Reactive Oxygen Species; C036483:T-DNA; D013830:Thiadiazoles; C015700:benzo-1,2,3-thiadiazole; C036216:ethylene; D019255:NADPH Oxidases; C088137:aminoethoxyvinylglycine; D005998:Glycine