title: Phytochrome-mediated agravitropism in Arabidopsis hypocotyls requires GIL1 and confers a fitness advantage.
abstract: Plants use specialized photoreceptors to detect the amount, quality, periodicity and direction of light and to modulate their growth and development accordingly. These regulatory light signals often interact with other environmental cues. Exposure of etiolated Arabidopsis seedlings to red (R) or far-red (FR) light causes hypocotyls to grow in random orientations with respect to the gravitational vector, thus overcoming the signal from gravity to grow upwards. This light response, mediated by either phytochrome A or phytochrome B, represents a prime example of cross-talk between environmental signalling systems. Here, we report the isolation the mutant gil1 (for gravitropic in the light) in which hypocotyls continue to grow upwards after exposure of seedlings to R or FR light. The gil1 mutant displays no other phenotypic alterations in response to gravity or light. Cloning of GIL1 has identified a novel gene that is necessary for light-dependent randomization of hypocotyl growth orientation. Using gil1, we have demonstrated that phytochrome-mediated randomization of Arabidopsis hypocotyl orientation provides a fitness advantage to seedlings developing in patchy, low-light environments.
authors.affiliation: Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK. ta16@le.ac.uk
authors.forename: Trudie
authors.initials: T
authors.lastname: Allen
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Ingles
authors.forename: Uta
authors.initials: U
authors.lastname: Praekelt
authors.forename: Harry
authors.initials: H
authors.lastname: Smith
authors.forename: Garry C
authors.initials: GC
authors.lastname: Whitelam
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D018522:Gravitropism / Q000235:genetics* / Q000502:physiology; D018546:Hypocotyl / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D018524:Phototropism / Q000235:genetics / Q000502:physiology; D010834:Phytochrome / Q000502:physiology*; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C511864:GIL1 protein, Arabidopsis; D010834:Phytochrome