title: Circadian control of root elongation and C partitioning in Arabidopsis thaliana.
abstract: Plants grow in a light/dark cycle. We have investigated how growth is buffered against the resulting changes in the carbon supply. Growth of primary roots of Arabidopsis seedlings was monitored using time-resolved video imaging. The average daily rate of growth is increased in longer light periods or by addition of sugars. It responds slowly over days when the conditions are changed. The momentary rate of growth exhibits a robust diel oscillation with a minimum 8-9 h after dawn and a maximum towards the end of the night. Analyses with starch metabolism mutants show that starch turnover is required to maintain growth at night. A carbon shortfall leads to an inhibition of growth, which is not immediately reversed when carbon becomes available again. The diel oscillation persists in continuous light and is strongly modified in clock mutants. Central clock functions that depend on CCA1/LHY are required to set an appropriate rate of starch degradation and maintain a supply of carbon to support growth through to dawn, whereas ELF3 acts to decrease growth in the light period and promote growth in the night. Thus, while the overall growth rate depends on the carbon supply, the clock orchestrates diurnal carbon allocation and growth.
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Am Mühlenberg 1, GermanyDepartment of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4/UH, UK.
authors.forename: Nima
authors.initials: N
authors.lastname: Yazdanbakhsh
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Am Mühlenberg 1, GermanyDepartment of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4/UH, UK.
authors.forename: Ronan
authors.initials: R
authors.lastname: Sulpice
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Am Mühlenberg 1, GermanyDepartment of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4/UH, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Graf
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Am Mühlenberg 1, GermanyDepartment of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4/UH, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Stitt
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Am Mühlenberg 1, GermanyDepartment of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4/UH, UK.
authors.forename: Joachim
authors.initials: J
authors.lastname: Fisahn
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002244:Carbon / Q000378:metabolism*; D057906:Circadian Clocks / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D003624:Darkness; D007700:Kinetics; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D017440:Photoperiod; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D013395:Sucrose; D002244:Carbon; D013213:Starch