title: Circadian rhythms of ethylene emission in Arabidopsis.
abstract: Ethylene controls multiple physiological processes in plants, including cell elongation. Consequently, ethylene synthesis is regulated by internal and external signals. We show that a light-entrained circadian clock regulates ethylene release from unstressed, wild-type Arabidopsis (Arabidopsis thaliana) seedlings, with a peak in the mid-subjective day. The circadian clock drives the expression of multiple ACC SYNTHASE genes, resulting in peak RNA levels at the phase of maximal ethylene synthesis. Ethylene production levels are tightly correlated with ACC SYNTHASE 8 steady-state transcript levels. The expression of this gene is controlled by light, by the circadian clock, and by negative feedback regulation through ethylene signaling. In addition, ethylene production is controlled by the TIMING OF CAB EXPRESSION 1 and CIRCADIAN CLOCK ASSOCIATED 1 genes, which are critical for all circadian rhythms yet tested in Arabidopsis. Mutation of ethylene signaling pathways did not alter the phase or period of circadian rhythms. Mutants with altered ethylene production or signaling also retained normal rhythmicity of leaf movement. We conclude that circadian rhythms of ethylene production are not critical for rhythmic growth.
authors.affiliation: Unit Plant Hormone Signaling and Bio-Imaging, Department of Molecular Genetics, University of Ghent, Belgium.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Thain
authors.forename: Filip
authors.initials: F
authors.lastname: Vandenbussche
authors.forename: Lucas J J
authors.initials: LJ
authors.lastname: Laarhoven
authors.forename: Mandy J
authors.initials: MJ
authors.lastname: Dowson-Day
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Wang
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Tobin
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Harren
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Millar
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
mesh_terms: D000598:Amino Acids, Cyclic / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000502:physiology; D002940:Circadian Rhythm; D005030:Ethylenes / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D008190:Lyases / Q000378:metabolism; D009154:Mutation; D036226:Seedlings / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000502:physiology
chemical_list: D000598:Amino Acids, Cyclic; D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D005030:Ethylenes; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase