title: Gibberellic acid signaling is required for ambient temperature-mediated induction of flowering in Arabidopsis thaliana.
abstract: Distinct molecular mechanisms integrate changes in ambient temperature into the genetic pathways that govern flowering time in Arabidopsis thaliana. Temperature-dependent eviction of the histone variant H2A.Z from nucleosomes has been suggested to facilitate the expression of FT by PIF4 at elevated ambient temperatures. Here we show that, in addition to PIF4, PIF3 and PIF5, but not PIF1 and PIF6, can promote flowering when expressed specifically in phloem companion cells (PCC), where they can induce FT and its close paralog, TSF. However, despite their strong potential to promote flowering, genetic analyses suggest that the PIF genes seem to have only a minor role in adjusting flowering in response to photoperiod or high ambient temperature. In addition, loss of PIF function only partially suppressed the early flowering phenotype and FT expression of the arp6 mutant, which is defective in H2A.Z deposition. In contrast, the chemical inhibition of gibberellic acid (GA) biosynthesis resulted in a strong attenuation of early flowering and FT expression in arp6. Furthermore, GA was able to induce flowering at low temperature (15°C) independently of FT, TSF, and the PIF genes, probably directly at the shoot apical meristem. Together, our results suggest that the timing of the floral transition in response to ambient temperature is more complex than previously thought and that GA signaling might play a crucial role in this process.
authors.affiliation: Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany.|Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH 1015, Lausanne, Switzerland.
authors.forename: Vinicius Costa
authors.initials: VC
authors.lastname: Galvão
authors.affiliation: Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany.
authors.forename: Silvio
authors.initials: S
authors.lastname: Collani
authors.affiliation: Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Horrer
authors.affiliation: Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany.|Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87, Umeå, Sweden.
authors.forename: Markus
authors.initials: M
authors.lastname: Schmid
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009707:Nucleosomes / Q000378:metabolism; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017440:Photoperiod; D010937:Plant Growth Regulators / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D005875:Gibberellins; D006657:Histones; D008840:Microfilament Proteins; D009707:Nucleosomes; D049488:Phosphatidylethanolamine Binding Protein; D010937:Plant Growth Regulators; C507995:ARP6 protein, Arabidopsis; C418905:FT protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis; C497729:PIF5 protein, Arabidopsis; C500577:TSF protein, Arabidopsis; C007842:gibberellic acid
keywords: ARP6; Arabidopsis thaliana; FLM; FT; H2A.Z; PIF; SVP; ambient temperature; flowering; gibberellin