title: Overexpression of phosphomimic mutated OsWRKY53 leads to enhanced blast resistance in rice.
abstract: WRKY transcription factors and mitogen-activated protein kinase (MAPK) cascades have been shown to play pivotal roles in the regulation of plant defense responses. We previously reported that OsWRKY53-overexpressing rice plants showed enhanced resistance to the rice blast fungus. In this study, we identified OsWRKY53 as a substrate of OsMPK3/OsMPK6, components of a fungal PAMP-responsive MAPK cascade in rice, and analyzed the effect of OsWRKY53 phosphorylation on the regulation of basal defense responses to a virulence race of rice blast fungus Magnaporthe oryzae strain Ina86-137. An in vitro phosphorylation assay revealed that the OsMPK3/OsMPK6 activated by OsMKK4 phosphorylated OsWRKY53 recombinant protein at its multiple clustered serine-proline residues (SP cluster). When OsWRKY53 was coexpressed with a constitutively active mutant of OsMKK4 in a transient reporter gene assay, the enhanced transactivation activity of OsWRKY53 was found to be dependent on phosphorylation of the SP cluster. Transgenic rice plants overexpressing a phospho-mimic mutant of OsWRKY53 (OsWRKY53SD) showed further-enhanced disease resistance to the blast fungus compared to native OsWRKY53-overexpressing rice plants, and a substantial number of defense-related genes, including pathogenesis-related protein genes, were more upregulated in the OsWRKY53SD-overexpressing plants compared to the OsWRKY53-overexpressing plants. These results strongly suggest that the OsMKK4-OsMPK3/OsMPK6 cascade regulates transactivation activity of OsWRKY53, and overexpression of the phospho-mimic mutant of OsWRKY53 results in a major change to the rice transcriptome at steady state that leads to activation of a defense response against the blast fungus in rice plants.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Chujo
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Miyamoto
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Masuda
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Kishi-Kaboshi
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nishizawa
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Minami
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nojiri
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, Japan.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yamane
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
mesh_terms: D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors