title: The apoplastic oxidative burst peroxidase in Arabidopsis is a major component of pattern-triggered immunity.
abstract: In plants, reactive oxygen species (ROS) associated with the response to pathogen attack are generated by NADPH oxidases or apoplastic peroxidases. Antisense expression of a heterologous French bean (Phaseolus vulgaris) peroxidase (FBP1) cDNA in Arabidopsis thaliana was previously shown to diminish the expression of two Arabidopsis peroxidases (peroxidase 33 [PRX33] and PRX34), block the oxidative burst in response to a fungal elicitor, and cause enhanced susceptibility to a broad range of fungal and bacterial pathogens. Here we show that mature leaves of T-DNA insertion lines with diminished expression of PRX33 and PRX34 exhibit reduced ROS and callose deposition in response to microbe-associated molecular patterns (MAMPs), including the synthetic peptides Flg22 and Elf26 corresponding to bacterial flagellin and elongation factor Tu, respectively. PRX33 and PRX34 knockdown lines also exhibited diminished activation of Flg22-activated genes after Flg22 treatment. These MAMP-activated genes were also downregulated in unchallenged leaves of the peroxidase knockdown lines, suggesting that a low level of apoplastic ROS production may be required to preprime basal resistance. Finally, the PRX33 knockdown line is more susceptible to Pseudomonas syringae than wild-type plants. In aggregate, these data demonstrate that the peroxidase-dependent oxidative burst plays an important role in Arabidopsis basal resistance mediated by the recognition of MAMPs.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom.
authors.forename: Arsalan
authors.initials: A
authors.lastname: Daudi
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Cheng
authors.forename: Jose A
authors.initials: JA
authors.lastname: O'Brien
authors.forename: Nicole
authors.initials: N
authors.lastname: Mammarella
authors.forename: Safina
authors.initials: S
authors.lastname: Khan
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Ausubel
authors.forename: G Paul
authors.initials: GP
authors.lastname: Bolwell
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D057865:Plant Immunity / Q000235:genetics / Q000502:physiology*; D018515:Plant Leaves / Q000201:enzymology / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D044224:Pseudomonas syringae / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005936:Glucans; D017382:Reactive Oxygen Species; C048306:callose; D010544:Peroxidases; C553803:PRX34 protein, Arabidopsis