title: Differentially phased leaf growth and movements in Arabidopsis depend on coordinated circadian and light regulation.
abstract: In contrast to vastly studied hypocotyl growth, little is known about diel regulation of leaf growth and its coordination with movements such as changes in leaf elevation angle (hyponasty). We developed a 3D live-leaf growth analysis system enabling simultaneous monitoring of growth and movements. Leaf growth is maximal several hours after dawn, requires light, and is regulated by daylength, suggesting coupling between growth and metabolism. We identify both blade and petiole positioning as important components of leaf movements in Arabidopsis thaliana and reveal a temporal delay between growth and movements. In hypocotyls, the combination of circadian expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5 and their light-regulated protein stability drives rhythmic hypocotyl elongation with peak growth at dawn. We find that PIF4 and PIF5 are not essential to sustain rhythmic leaf growth but influence their amplitude. Furthermore, EARLY FLOWERING3, a member of the evening complex (EC), is required to maintain the correct phase between growth and movement. Our study shows that the mechanisms underlying rhythmic hypocotyl and leaf growth differ. Moreover, we reveal the temporal relationship between leaf elongation and movements and demonstrate the importance of the EC for the coordination of these phenotypic traits.
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Tino
authors.initials: T
authors.lastname: Dornbusch
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Michaud
authors.affiliation: SIB-Swiss Institute of Bioinformatics, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Xenarios
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland christian.fankhauser@unil.ch.
authors.forename: Christian
authors.initials: C
authors.lastname: Fankhauser
mesh_terms: D000465:Algorithms; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D057906:Circadian Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D018546:Hypocotyl / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009154:Mutation; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014743:Videotape Recording
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D051939:Phytochrome B; D014157:Transcription Factors; C432430:At2g25930 protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis; C497729:PIF5 protein, Arabidopsis