title: Biochemical and genetic requirements for function of the immune response regulator BOTRYTIS-INDUCED KINASE1 in plant growth, ethylene signaling, and PAMP-triggered immunity in Arabidopsis.
abstract: Arabidopsis thaliana BOTRYTIS-INDUCED KINASE1 (BIK1) regulates immune responses to a distinct class of pathogens. Here, mechanisms underlying BIK1 function and its interactions with other immune response regulators were determined. We describe BIK1 function as a component of ethylene (ET) signaling and PAMP-triggered immunity (PTI) to fungal pathogens. BIK1 in vivo kinase activity increases in response to flagellin peptide (flg22) and the ET precursor 1-aminocyclopropane-1-carboxylic acid (ACC) but is blocked by inhibition of ET perception. BIK1 induction by flg22, ACC, and pathogens is strictly dependent on EIN3, and the bik1 mutation results in altered expression of ET-regulated genes. BIK1 site-directed mutants were used to determine residues essential for phosphorylation and biological functions in planta, including PTI, ET signaling, and plant growth. Genetic analysis revealed flg22-induced PTI to Botrytis cinerea requires BIK1, EIN2, and HUB1 but not genes involved in salicylate (SA) functions. BIK1-mediated PTI to Pseudomonas syringae is modulated by SA, ET, and jasmonate signaling. The coi1 mutation suppressed several bik1 phenotypes, suggesting that COI1 may act as a repressor of BIK1 function. Thus, common and distinct mechanisms underlying BIK1 function in mediating responses to distinct pathogens are uncovered. In sum, the critical role of BIK1 in plant immune responses hinges upon phosphorylation, its function in ET signaling, and complex interactions with other immune response regulators.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Laluk
authors.forename: Hongli
authors.initials: H
authors.lastname: Luo
authors.forename: Maofeng
authors.initials: M
authors.lastname: Chai
authors.forename: Rahul
authors.initials: R
authors.lastname: Dhawan
authors.forename: Zhibing
authors.initials: Z
authors.lastname: Lai
authors.forename: Tesfaye
authors.initials: T
authors.lastname: Mengiste
mesh_terms: D000595:Amino Acid Sequence; D000598:Amino Acids, Cyclic / Q000494:pharmacology; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020171:Botrytis / Q000276:immunology / Q000502:physiology; D017124:Conserved Sequence; D003517:Cyclopentanes / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism*; D005408:Flagellin / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism; D057865:Plant Immunity; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000502:physiology; D020156:Salicylic Acid / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000598:Amino Acids, Cyclic; D029681:Arabidopsis Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D010937:Plant Growth Regulators; D005408:Flagellin; C023863:1-aminocyclopropane-1-carboxylic acid; C011006:jasmonic acid; C036216:ethylene; C509522:BIK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D020156:Salicylic Acid