title: Crosstalk between the circadian clock and innate immunity in Arabidopsis.
abstract: The circadian clock integrates temporal information with environmental cues in regulating plant development and physiology. Recently, the circadian clock has been shown to affect plant responses to biotic cues. To further examine this role of the circadian clock, we tested disease resistance in mutants disrupted in CCA1 and LHY, which act synergistically to regulate clock activity. We found that cca1 and lhy mutants also synergistically affect basal and resistance gene-mediated defense against Pseudomonas syringae and Hyaloperonospora arabidopsidis. Disrupting the circadian clock caused by overexpression of CCA1 or LHY also resulted in severe susceptibility to P. syringae. We identified a downstream target of CCA1 and LHY, GRP7, a key constituent of a slave oscillator regulated by the circadian clock and previously shown to influence plant defense and stomatal activity. We show that the defense role of CCA1 and LHY against P. syringae is at least partially through circadian control of stomatal aperture but is independent of defense mediated by salicylic acid. Furthermore, we found defense activation by P. syringae infection and treatment with the elicitor flg22 can feedback-regulate clock activity. Together this data strongly supports a direct role of the circadian clock in defense control and reveal for the first time crosstalk between the circadian clock and plant innate immunity.
authors.affiliation: Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.forename: Qiguang
authors.initials: Q
authors.lastname: Xie
authors.forename: Ryan G
authors.initials: RG
authors.lastname: Anderson
authors.forename: Gina
authors.initials: G
authors.lastname: Ng
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Seitz
authors.forename: Thomas
authors.initials: T
authors.lastname: Peterson
authors.forename: C Robertson
authors.initials: CR
authors.lastname: McClung
authors.forename: John M
authors.initials: JM
authors.lastname: McDowell
authors.forename: Dongdong
authors.initials: D
authors.lastname: Kong
authors.forename: June M
authors.initials: JM
authors.lastname: Kwak
authors.forename: Hua
authors.initials: H
authors.lastname: Lu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D057906:Circadian Clocks / Q000235:genetics / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology*; D009154:Mutation; D016958:Pseudomonas putida / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; D014157:Transcription Factors