title: Age-associated circadian period changes in Arabidopsis leaves.
abstract: As most organisms age, their appearance, physiology, and behaviour alters as part of a life history strategy that maximizes their fitness over their lifetime. The passage of time is measured by organisms and is used to modulate these age-related changes. Organisms have an endogenous time measurement system called the circadian clock. This endogenous clock regulates many physiological responses throughout the life history of organisms to enhance their fitness. However, little is known about the relation between ageing and the circadian clock in plants. Here, we investigate the association of leaf ageing with circadian rhythm changes to better understand the regulation of life-history strategy in Arabidopsis. The circadian periods of clock output genes were approximately 1h shorter in older leaves than younger leaves. The periods of the core clock genes were also consistently shorter in older leaves, indicating an effect of ageing on regulation of the circadian period. Shortening of the circadian period with leaf age occurred faster in plants grown under a long photoperiod compared with a short photoperiod. We screened for a regulatory gene that links ageing and the circadian clock among multiple clock gene mutants. Only mutants for the clock oscillator TOC1 did not show a shortened circadian period during leaf ageing, suggesting that TOC1 may link age to changes in the circadian clock period. Our findings suggest that age-related information is incorporated into the regulation of the circadian period and that TOC1 is necessary for this integrative process.
authors.affiliation: Department of Life Sciences, POSTECH, Hyojadong, Pohang, Gyeongbuk 37673, Republic of Korea.
authors.forename: Hyunmin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of New Biology, DGIST, Daegu 42988, Republic of Korea Max-Planck Institute for Biology of Ageing, D-50931 Cologne, Germany nam@dgist.ac.kr kimyumi@dgist.ac.kr.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Life Sciences, POSTECH, Hyojadong, Pohang, Gyeongbuk 37673, Republic of Korea.
authors.forename: Miji
authors.initials: M
authors.lastname: Yeom
authors.affiliation: Integrative Biosciences & Biotechnology, POSTECH, Hyojadong, Pohang, Gyeongbuk 37673, Republic of Korea.
authors.forename: Junhyun
authors.initials: J
authors.lastname: Lim
authors.affiliation: Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu 42988, Republic of Korea Department of New Biology, DGIST, Daegu 42988, Republic of Korea nam@dgist.ac.kr kimyumi@dgist.ac.kr.
authors.forename: Hong Gil
authors.initials: HG
authors.lastname: Nam
mesh_terms: D000375:Aging / Q000502:physiology*; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D017440:Photoperiod; D018515:Plant Leaves / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D012333:RNA, Messenger; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors
keywords: Arabidopsis; TOC1.; circadian clock; day length; leaf age; plant life history