title: Differential control of pre-invasive and post-invasive antibacterial defense by the Arabidopsis circadian clock.
abstract: Plants show a suite of inducible defense responses against bacterial pathogens. Here we investigate in detail the effect of the circadian clock on these reactions in Arabidopsis thaliana. The magnitude of immune responses elicited by flg22, by virulent and by avirulent Pseudomonas syringae strains depends on the time of day of inoculation. The oxidative burst is stronger when flg22 is infiltrated in the morning in wild-type plants but not in the arrhythmic clock mutant lux arrhythmo/phytoclock1 (pcl1), and thus is controlled by the endogenous clock. Similarly, when bacteria are syringe-infiltrated into the leaf, defense gene induction is higher and bacterial growth is suppressed more strongly after morning inoculation in wild-type but not in pcl1 plants. Furthermore, cell death associated with the hypersensitive response was found to be under clock control. Notably, the clock effect depends on the mode of infection: upon spray inoculation onto the leaf surface, defense gene induction is higher and bacterial growth is suppressed more strongly upon evening inoculation. This different phasing of pre-invasive and post-invasive defense relates to clock-regulated stomatal movement. In particular, TIME FOR COFFEE may impact pathogen defense via clock-regulated stomata movement apart from its known role in time-of-day-dependent jasmonate responses. Taken together, these data highlight the importance of the circadian clock for the control of different immune responses at distinct times of the day.
authors: Molecular Cell Physiology, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany Institute for Genome Research and Systems Biology, CeBiTec, Bielefeld University, Bielefeld, Germany.
authors: Christin
authors: C
authors: Korneli
authors: Molecular Cell Physiology, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany.
authors: Selahattin
authors: S
authors: Danisman
authors: Molecular Cell Physiology, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany Institute for Genome Research and Systems Biology, CeBiTec, Bielefeld University, Bielefeld, Germany dorothee.staiger@uni-bielefeld.de.
authors: Dorothee
authors: D
authors: Staiger
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D016923:Cell Death; D057906:Circadian Clocks / Q000502:physiology*; D005408:Flagellin / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000502:physiology / Q000528:radiation effects; D054046:Plant Stomata / Q000235:genetics / Q000276:immunology / Q000502:physiology / Q000528:radiation effects; D044224:Pseudomonas syringae / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C504848:Lux Arrhythmo protein, Arabidopsis; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D005408:Flagellin
keywords: Circadian; Flg22; Immunity; LUX/PCL; ROS; TIC