title: Repression of AGAMOUS-LIKE 24 is a crucial step in promoting flower development.
abstract: Flower development begins as floral meristems arise in succession on the flank of the inflorescence meristem. Floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) promote establishment and maintenance of floral identity in newly formed floral primordia. Without their activity, the floral primordia develop with inflorescence characteristics. The underlying molecular-genetic mechanism is unknown. Here we show that these phenotypes are due in large part to the ectopic expression of AGAMOUS-LIKE 24 (AGL24), a central regulator of floral meristem identity. We present evidence that AGL24 is an early target of transcriptional repression by LFY and AP1. Without such repression, continued AGL24 expression in floral meristems is sufficient to cause floral reversion regardless of the activation of floral organ identity genes. This indicates that LFY and AP1 promote floral development not only by positively regulating genes activated in flower development, but also by repressing AGL24, a promoter of inflorescence fate.
authors.affiliation: Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
authors.forename: Toshiro
authors.initials: T
authors.lastname: Ito
authors.forename: Frank
authors.initials: F
authors.lastname: Wellmer
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Meyerowitz
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D015536:Down-Regulation; D035263:Flowering Tops / Q000254:growth & development / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D026161:MADS Domain Proteins / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C478065:AGL24 protein, Arabidopsis; C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D010940:Plant Proteins; D014157:Transcription Factors