title: Mediator subunit18 controls flowering time and floral organ identity in Arabidopsis.
abstract: Mediator is a conserved multi-protein complex that plays an important role in regulating transcription by mediating interactions between transcriptional activator proteins and RNA polymerase II. Much evidence exists that Mediator plays a constitutive role in the transcription of all genes transcribed by RNA polymerase II. However, evidence is mounting that specific Mediator subunits may control the developmental regulation of specific subsets of RNA polymerase II-dependent genes. Although the Mediator complex has been extensively studied in yeast and mammals, only a few reports on Mediator function in flowering time control of plants, little is known about Mediator function in floral organ identity. Here we show that in Arabidopsis thaliana, MEDIATOR SUBUNIT 18 (MED18) affects flowering time and floral organ formation through FLOWERING LOCUS C (FLC) and AGAMOUS (AG). A MED18 loss-of-function mutant showed a remarkable syndrome of later flowering and altered floral organ number. We show that FLC and AG mRNA levels and AG expression patterns are altered in the mutant. Our results support parallels between the regulation of FLC and AG and demonstrate a developmental role for Mediator in plants.
authors: Department of Biology, University of Florida, Gainesville, Florida, United States of America. patrickz@ufl.edu
authors: Zhengui
authors: Z
authors: Zheng
authors: Hexin
authors: H
authors: Guan
authors: Francisca
authors: F
authors: Leal
authors: Paris H
authors: PH
authors: Grey
authors: David G
authors: DG
authors: Oppenheimer
mesh_terms: D026342:AGAMOUS Protein, Arabidopsis / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D056892:Mediator Complex / Q000235:genetics*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D012319:RNA Polymerase II / Q000235:genetics*; D015533:Transcriptional Activation
chemical_list: D026342:AGAMOUS Protein, Arabidopsis; D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; D026161:MADS Domain Proteins; C582268:MED18 protein, Arabidopsis; D056892:Mediator Complex; D046912:Multiprotein Complexes; D012319:RNA Polymerase II