The Arabidopsis floral meristem identity genes AP1, AGL24 and SVP directly repress class B and C floral homeotic genes

Plant J. 2009 Nov;60(4):626-37. doi: 10.1111/j.1365-313X.2009.03985.x. Epub 2009 Jul 25.


During the initial stages of flower development, floral meristems increase in size without the formation of floral organs. When a critical meristem size is reached, the floral meristem begins to develop the floral organs. The first stages of flower development are characterized by the expression of genes such as Apetala 1 (AP1), cauliflower (CAL), AGAMOUS-LIKE 24 (AGL24) and short vegetative phase (SVP). We have shown that AP1, AGL24 and SVP act redundantly to control the identity of the floral meristem and to repress expression of class B, C and E genes. Recently, it was shown that class E gene repression was direct and established by two independent pathways. We show here that repression of class B and C genes is also directly established by a co-repressor complex that comprises LEUNIG (LUG), SEUSS (SEU) and the MADS box dimers AP1-AGL24 and AP1-SVP. Furthermore, we show that the distantly related suppressor of overexpression of CO 1 (SOC1) MADS box gene can complement for the loss of AGL24 and SVP activity; however, under normal conditions, this transcription factor does not play a role during the early stages of flower development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Chromatin Immunoprecipitation
  • DNA, Plant / genetics
  • Flowers / genetics
  • Flowers / growth & development*
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • MADS Domain Proteins / genetics
  • MADS Domain Proteins / metabolism*
  • Meristem / genetics
  • Meristem / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • AGL20 protein, Arabidopsis
  • AGL24 protein, Arabidopsis
  • AP1 protein, Arabidopsis
  • Arabidopsis Proteins
  • DNA, Plant
  • MADS Domain Proteins
  • SVP protein, Arabidopsis
  • Transcription Factors