Retinoblastoma and its binding partner MSI1 control imprinting in Arabidopsis

PLoS Biol. 2008 Aug 12;6(8):e194. doi: 10.1371/journal.pbio.0060194.


Parental genomic imprinting causes preferential expression of one of the two parental alleles. In mammals, differential sex-dependent deposition of silencing DNA methylation marks during gametogenesis initiates a new cycle of imprinting. Parental genomic imprinting has been detected in plants and relies on DNA methylation by the methyltransferase MET1. However, in contrast to mammals, plant imprints are created by differential removal of silencing marks during gametogenesis. In Arabidopsis, DNA demethylation is mediated by the DNA glycosylase DEMETER (DME) causing activation of imprinted genes at the end of female gametogenesis. On the basis of genetic interactions, we show that in addition to DME, the plant homologs of the human Retinoblastoma (Rb) and its binding partner RbAp48 are required for the activation of the imprinted genes FIS2 and FWA. This Rb-dependent activation is mediated by direct transcriptional repression of MET1 during female gametogenesis. We have thus identified a new mechanism required for imprinting establishment, outlining a new role for the Retinoblastoma pathway, which may be conserved in mammals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / biosynthesis
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • DNA (Cytosine-5-)-Methyltransferases / biosynthesis
  • DNA Methylation
  • Down-Regulation
  • Epigenesis, Genetic
  • Gametogenesis
  • Gene Expression Regulation, Plant
  • Genomic Imprinting*
  • Homeodomain Proteins / biosynthesis
  • Humans
  • N-Glycosyl Hydrolases / genetics
  • N-Glycosyl Hydrolases / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Retinoblastoma Protein / genetics*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism
  • Transcription Factors / biosynthesis


  • Arabidopsis Proteins
  • FIS2 protein, Arabidopsis
  • FWA protein, Arabidopsis
  • Homeodomain Proteins
  • MEA protein, Arabidopsis
  • MSI1 protein, Arabidopsis
  • RBR1 protein, Arabidopsis
  • Retinoblastoma Protein
  • Trans-Activators
  • Transcription Factors
  • MET1 protein, Arabidopsis
  • DNA (Cytosine-5-)-Methyltransferases
  • DEMETER protein, Arabidopsis
  • N-Glycosyl Hydrolases