ARABIDOPSIS TRITHORAX1 dynamically regulates FLOWERING LOCUS C activation via histone 3 lysine 4 trimethylation

Plant Cell. 2008 Mar;20(3):580-8. doi: 10.1105/tpc.108.058172. Epub 2008 Mar 28.


Trithorax function is essential for epigenetic maintenance of gene expression in animals, but little is known about trithorax homologs in plants. ARABIDOPSIS TRITHORAX1 (ATX1) was shown to be required for the expression of homeotic genes involved in flower organogenesis. Here, we report a novel function of ATX1, namely, the epigenetic regulation of the floral repressor FLOWERING LOCUS C (FLC). Downregulation of FLC accelerates the transition from vegetative to reproductive development in Arabidopsis thaliana. In the atx1 mutant, FLC levels are reduced and the FLC chromatin is depleted of trimethylated, but not dimethylated, histone 3 lysine 4, suggesting a specific trimethylation function of ATX1. In addition, we found that ATX1 directly binds the active FLC locus before flowering and that this interaction is released upon the transition to flowering. This dynamic process stands in contrast with the stable maintenance of homeotic gene expression mediated by trithorax group proteins in animals but resembles the dynamics of plant Polycomb group function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / physiology*
  • Chromatin / metabolism
  • Chromatin Immunoprecipitation
  • Gene Expression Regulation, Plant
  • Histone-Lysine N-Methyltransferase
  • Histones / metabolism*
  • In Situ Hybridization
  • Lysine / metabolism*
  • MADS Domain Proteins / genetics*
  • Methylation
  • Models, Biological
  • Plants, Genetically Modified
  • Protein Binding
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics
  • Transcription Factors / physiology*


  • Arabidopsis Proteins
  • Chromatin
  • FLF protein, Arabidopsis
  • Histones
  • MADS Domain Proteins
  • Transcription Factors
  • At2g31650 protein, Arabidopsis
  • Histone-Lysine N-Methyltransferase
  • Lysine