title: Specification of Arabidopsis floral meristem identity by repression of flowering time genes.
abstract: Flowering plants produce floral meristems in response to intrinsic and extrinsic flowering inductive signals. In Arabidopsis, the floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) are activated to play a pivotal role in specifying floral meristems during floral transition. We show here that the emerging floral meristems require AP1 to partly specify their floral identities by directly repressing a group of flowering time genes, including SHORT VEGETATIVE PHASE (SVP), AGAMOUS-LIKE 24 (AGL24) and SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1). In wild-type plants, these flowering time genes are normally downregulated in emerging floral meristems. In the absence of AP1, these genes are ectopically expressed, transforming floral meristems into shoot meristems. By post-translational activation of an AP1-GR fusion protein and chromatin immunoprecipitation assays, we further demonstrate the repression of these flowering time genes by induced AP1 activity and in vivo AP1 binding to the cis-regulatory regions of these genes. These findings indicate that once AP1 is activated during the floral transition, it acts partly as a master repressor in floral meristems by directly suppressing the expression of flowering time genes, thus preventing the continuation of the shoot developmental program.
authors.affiliation: Department of Biological Sciences and Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Keren
authors.initials: K
authors.lastname: Bracha-Drori
authors.forename: Shaul
authors.initials: S
authors.lastname: Yalovsky
authors.forename: Toshiro
authors.initials: T
authors.lastname: Ito
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D026161:MADS Domain Proteins / Q000235:genetics* / Q000502:physiology; D010641:Phenotype; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: C419046:AGL20 protein, Arabidopsis; C478065:AGL24 protein, Arabidopsis; C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; C407549:SVP protein, Arabidopsis; D014157:Transcription Factors