title: Tissue-specific clocks in Arabidopsis show asymmetric coupling.
abstract: Many organisms rely on a circadian clock system to adapt to daily and seasonal environmental changes. The mammalian circadian clock consists of a central clock in the suprachiasmatic nucleus that has tightly coupled neurons and synchronizes other clocks in peripheral tissues. Plants also have a circadian clock, but plant circadian clock function has long been assumed to be uncoupled. Only a few studies have been able to show weak, local coupling among cells. Here, by implementing two novel techniques, we have performed a comprehensive tissue-specific analysis of leaf tissues, and show that the vasculature and mesophyll clocks asymmetrically regulate each other in Arabidopsis. The circadian clock in the vasculature has characteristics distinct from other tissues, cycles robustly without environmental cues, and affects circadian clock regulation in other tissues. Furthermore, we found that vasculature-enriched genes that are rhythmically expressed are preferentially expressed in the evening, whereas rhythmic mesophyll-enriched genes tend to be expressed in the morning. Our results set the stage for a deeper understanding of how the vasculature circadian clock in plants regulates key physiological responses such as flowering time.
authors.affiliation: 1] Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto 606-8501, Japan [2] Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Motomu
authors.initials: M
authors.lastname: Endo
authors.affiliation: Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto 606-8501, Japan.
authors.forename: Hanako
authors.initials: H
authors.lastname: Shimizu
authors.affiliation: University of Southern California Molecular and Computational Biology, Department of Biology, Dana and David Dornsife College of Letters, Arts and Sciences, Los Angeles, California 90089, USA.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Nohales
authors.affiliation: Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto 606-8501, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Araki
authors.affiliation: University of Southern California Molecular and Computational Biology, Department of Biology, Dana and David Dornsife College of Letters, Arts and Sciences, Los Angeles, California 90089, USA.
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D057906:Circadian Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D020869:Gene Expression Profiling; D058503:Mesophyll Cells / Q000378:metabolism; D009928:Organ Specificity; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology