title: Timing of plant immune responses by a central circadian regulator.
abstract: The principal immune mechanism against biotrophic pathogens in plants is the resistance (R)-gene-mediated defence. It was proposed to share components with the broad-spectrum basal defence machinery. However, the underlying molecular mechanism is largely unknown. Here we report the identification of novel genes involved in R-gene-mediated resistance against downy mildew in Arabidopsis and their regulatory control by the circadian regulator, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1). Numerical clustering based on phenotypes of these gene mutants revealed that programmed cell death (PCD) is the major contributor to resistance. Mutants compromised in the R-gene-mediated PCD were also defective in basal resistance, establishing an interconnection between these two distinct defence mechanisms. Surprisingly, we found that these new defence genes are under circadian control by CCA1, allowing plants to 'anticipate' infection at dawn when the pathogen normally disperses the spores and time immune responses according to the perception of different pathogenic signals upon infection. Temporal control of the defence genes by CCA1 differentiates their involvement in basal and R-gene-mediated defence. Our study has revealed a key functional link between the circadian clock and plant immunity.
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Jinyoung Yang
authors.initials: JY
authors.lastname: Barnaby
authors.forename: Yasuomi
authors.initials: Y
authors.lastname: Tada
authors.forename: Hairi
authors.initials: H
authors.lastname: Li
authors.forename: Mahmut
authors.initials: M
authors.lastname: Tör
authors.forename: Daniela
authors.initials: D
authors.lastname: Caldelari
authors.forename: Dae-un
authors.initials: DU
authors.lastname: Lee
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Fu
authors.forename: Xinnian
authors.initials: X
authors.lastname: Dong
mesh_terms: D017209:Apoptosis; D017360:Arabidopsis / Q000276:immunology* / Q000382:microbiology* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D057906:Circadian Clocks / Q000276:immunology*; D002940:Circadian Rhythm / Q000235:genetics / Q000276:immunology; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000276:immunology; D017343:Genes, Plant / Q000235:genetics / Q000276:immunology; D007113:Immunity, Innate / Q000276:immunology; D008027:Light; D009154:Mutation; D009868:Oomycetes / Q000276:immunology* / Q000472:pathogenicity; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity / Q000276:immunology*; D013172:Spores, Fungal / Q000276:immunology / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; C107295:RPP5 protein, Arabidopsis; D014157:Transcription Factors