title: Gibberellin acts positively then negatively to control onset of flower formation in Arabidopsis.
abstract: The switch to reproductive development is biphasic in many plants, a feature important for optimal pollination and yield. We show that dual opposite roles of the phytohormone gibberellin underpin this phenomenon in Arabidopsis. Although gibberellin promotes termination of vegetative development, it inhibits flower formation. To overcome this effect, the transcription factor LEAFY induces expression of a gibberellin catabolism gene; consequently, increased LEAFY activity causes reduced gibberellin levels. This allows accumulation of gibberellin-sensitive DELLA proteins. The DELLA proteins are recruited by SQUAMOSA PROMOTER BINDING PROTEIN-LIKE transcription factors to regulatory regions of the floral commitment gene APETALA1 and promote APETALA1 up-regulation and floral fate synergistically with LEAFY. The two opposing functions of gibberellin may facilitate evolutionary and environmental modulation of plant inflorescence architecture.
authors.affiliation: Department of Biology, University of Pennsylvania, 415 South University Avenue, Philadelphia, PA 19104-6018, USA.
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: Cara M
authors.initials: CM
authors.lastname: Winter
authors.forename: Miin-Feng
authors.initials: MF
authors.lastname: Wu
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kanno
authors.forename: Ayako
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Seo
authors.forename: Doris
authors.initials: D
authors.lastname: Wagner
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D000075065:Elongin; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D026161:MADS Domain Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D000075065:Elongin; C109555:GAI protein, Arabidopsis; D005875:Gibberellins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D014157:Transcription Factors; C007842:gibberellic acid