title: Circadian regulation of sunflower heliotropism, floral orientation, and pollinator visits.
abstract: Young sunflower plants track the Sun from east to west during the day and then reorient during the night to face east in anticipation of dawn. In contrast, mature plants cease movement with their flower heads facing east. We show that circadian regulation of directional growth pathways accounts for both phenomena and leads to increased vegetative biomass and enhanced pollinator visits to flowers. Solar tracking movements are driven by antiphasic patterns of elongation on the east and west sides of the stem. Genes implicated in control of phototropic growth, but not clock genes, are differentially expressed on the opposite sides of solar tracking stems. Thus, interactions between environmental response pathways and the internal circadian oscillator coordinate physiological processes with predictable changes in the environment to influence growth and reproduction.
authors: Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
authors: Hagop S
authors: HS
authors: Atamian
authors: Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
authors: Nicky M
authors: NM
authors: Creux
authors: Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA.
authors: Robin Isadora
authors: RI
authors: Brown
authors: Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA.
authors: Austin G
authors: AG
authors: Garner
authors: Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA. Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA.
authors: Benjamin K
authors: BK
authors: Blackman
authors: Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA. slharmer@ucdavis.edu.
authors: Stacey L
authors: SL
authors: Harmer
mesh_terms: D000818:Animals; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006368:Helianthus / Q000235:genetics / Q000254:growth & development*; D018524:Phototropism / Q000235:genetics / Q000502:physiology*; D054817:Pollination; D013472:Sunlight