title: Circadian Stress Regimes Affect the Circadian Clock and Cause Jasmonic Acid-Dependent Cell Death in Cytokinin-Deficient Arabidopsis Plants.
abstract: The circadian clock helps plants measure daylength and adapt to changes in the day-night rhythm. We found that changes in the light-dark regime triggered stress responses, eventually leading to cell death, in leaves of Arabidopsis thaliana plants with reduced cytokinin levels or defective cytokinin signaling. Prolonged light treatment followed by a dark period induced stress and cell death marker genes while reducing photosynthetic efficiency. This response, called circadian stress, is also characterized by altered expression of clock and clock output genes. In particular, this treatment strongly reduced the expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). Intriguingly, similar changes in gene expression and cell death were observed in clock mutants lacking proper CCA1 and LHY function. Circadian stress caused strong changes in reactive oxygen species- and jasmonic acid (JA)-related gene expression. The activation of the JA pathway, involving the accumulation of JA metabolites, was crucial for the induction of cell death, since the cell death phenotype was strongly reduced in the jasmonate resistant1 mutant background. We propose that adaptation to circadian stress regimes requires a normal cytokinin status which, acting primarily through the AHK3 receptor, supports circadian clock function to guard against the detrimental effects of circadian stress.
authors.affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany.
authors.forename: Silvia
authors.initials: S
authors.lastname: Nitschke
authors.affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Cortleven
authors.affiliation: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Iven
authors.affiliation: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors.forename: Ivo
authors.identifier: 0000-0002-9888-7003
authors.initials: I
authors.lastname: Feussner
authors.affiliation: Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et de Biotechnologies, CNRS UMR7265, Aix-Marseille Université, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Havaux
authors.affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany.
authors.forename: Michael
authors.identifier: 0000-0002-6299-347X
authors.initials: M
authors.lastname: Riefler
authors.affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany thomas.schmuelling@fu-berlin.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmülling
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000235:genetics / Q000502:physiology*; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008027:Light; D054883:Oxylipins / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D003517:Cyclopentanes; D003583:Cytokinins; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; D054883:Oxylipins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C011006:jasmonic acid