title: BR-SIGNALING KINASE1 physically associates with FLAGELLIN SENSING2 and regulates plant innate immunity in Arabidopsis.
abstract: Pathogen-associated molecular pattern (PAMP)-trigged immunity (PTI) is the first defensive line of plant innate immunity and is mediated by pattern recognition receptors. Here, we show that a mutation in BR-SIGNALING KINASE1 (BSK1), a substrate of the brassinosteroid (BR) receptor BRASSINOSTEROID INSENSITIVE1, suppressed the powdery mildew resistance caused by a mutation in ENHANCED DISEASE RESISTANCE2, which negatively regulates powdery mildew resistance and programmed cell death, in Arabidopsis thaliana. A loss-of-function bsk1 mutant displayed enhanced susceptibility to virulent and avirulent pathogens, including Golovinomyces cichoracearum, Pseudomonas syringae, and Hyaloperonospora arabidopsidis. The bsk1 mutant also accumulated lower levels of salicylic acid upon infection with G. cichoracearum and P. syringae. BSK1 belongs to a receptor-like cytoplasmic kinase family and displays kinase activity in vitro; this kinase activity is required for its function. BSK1 physically associates with the PAMP receptor FLAGELLIN SENSING2 and is required for a subset of flg22-induced responses, including the reactive oxygen burst, but not for mitogen-activated protein kinase activation. Our data demonstrate that BSK1 is involved in positive regulation of PTI. Together with previous findings, our work indicates that BSK1 represents a key component directly involved in both BR signaling and plant immunity.
authors.affiliation: State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Shi
authors.forename: Qiujing
authors.initials: Q
authors.lastname: Shen
authors.forename: Yiping
authors.initials: Y
authors.lastname: Qi
authors.forename: Haojie
authors.initials: H
authors.lastname: Yan
authors.forename: Haozhen
authors.initials: H
authors.lastname: Nie
authors.forename: Yongfang
authors.initials: Y
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Zhao
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Katagiri
authors.forename: Dingzhong
authors.initials: D
authors.lastname: Tang
mesh_terms: D019943:Amino Acid Substitution; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota / Q000276:immunology / Q000472:pathogenicity; D060406:Brassinosteroids / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D016922:Cellular Senescence; D060467:Disease Resistance; D004789:Enzyme Activation; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity; D017354:Point Mutation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; C423568:EDR1 protein, Arabidopsis; C560397:EDR2 protein, Arabidopsis; D005030:Ethylenes; D046912:Multiprotein Complexes; D017382:Reactive Oxygen Species; C036216:ethylene; D011494:Protein Kinases; C411853:FLS2 protein, Arabidopsis; C108270:BRI1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; C530518:brassinosteroid-signaling kinase1, Arabidopsis; D020156:Salicylic Acid