title: The MED12-MED13 module of Mediator regulates the timing of embryo patterning in Arabidopsis.
abstract: The Arabidopsis embryo becomes patterned into central and peripheral domains during the first few days after fertilization. A screen for mutants that affect this process identified two genes, GRAND CENTRAL (GCT)and CENTER CITY (CCT). Mutations in GCT and CCT delay the specification of central and peripheral identity and the globular-to-heart transition, but have little or no effect on the initial growth rate of the embryo. Mutant embryos eventually recover and undergo relatively normal patterning, albeit at an inappropriate size. GCT and CCT were identified as the Arabidopsis orthologs of MED13 and MED12 - evolutionarily conserved proteins that act in association with the Mediator complex to negatively regulate transcription. The predicted function of these proteins combined with the effect of gct and cct on embryo development suggests that MED13 and MED12 regulate pattern formation during Arabidopsis embryogenesis by transiently repressing a transcriptional program that interferes with this process. Their mutant phenotype reveals the existence of a previously unknown temporal regulatory mechanism in plant embryogenesis.
authors.affiliation: Department of Biological Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: C Stewart
authors.initials: CS
authors.lastname: Gillmor
authors.forename: Mee Yeon
authors.initials: MY
authors.lastname: Park
authors.forename: Michael R
authors.initials: MR
authors.lastname: Smith
authors.forename: Robert
authors.initials: R
authors.lastname: Pepitone
authors.forename: Randall A
authors.initials: RA
authors.lastname: Kerstetter
authors.forename: R Scott
authors.initials: RS
authors.lastname: Poethig
mesh_terms: D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C546592:CENTRAL CITY protein, Arabidopsis; C546591:GRAND CENTRAL protein, Arabidopsis; D056892:Mediator Complex; D012097:Repressor Proteins