Increased maternal genome dosage bypasses the requirement of the FIS polycomb repressive complex 2 in Arabidopsis seed development

PLoS Genet. 2013;9(1):e1003163. doi: 10.1371/journal.pgen.1003163. Epub 2013 Jan 10.


Seed development in flowering plants is initiated after a double fertilization event with two sperm cells fertilizing two female gametes, the egg cell and the central cell, leading to the formation of embryo and endosperm, respectively. In most species the endosperm is a polyploid tissue inheriting two maternal genomes and one paternal genome. As a consequence of this particular genomic configuration the endosperm is a dosage sensitive tissue, and changes in the ratio of maternal to paternal contributions strongly impact on endosperm development. The fertilization independent seed (FIS) Polycomb Repressive Complex 2 (PRC2) is essential for endosperm development; however, the underlying forces that led to the evolution of the FIS-PRC2 remained unknown. Here, we show that the functional requirement of the FIS-PRC2 can be bypassed by increasing the ratio of maternal to paternal genomes in the endosperm, suggesting that the main functional requirement of the FIS-PRC2 is to balance parental genome contributions and to reduce genetic conflict. We furthermore reveal that the AGAMOUS LIKE (AGL) gene AGL62 acts as a dosage-sensitive seed size regulator and that reduced expression of AGL62 might be responsible for reduced size of seeds with increased maternal genome dosage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AGAMOUS Protein, Arabidopsis / genetics
  • AGAMOUS Protein, Arabidopsis / metabolism
  • Arabidopsis Proteins* / genetics
  • Arabidopsis Proteins* / metabolism
  • Arabidopsis* / genetics
  • Arabidopsis* / growth & development
  • Endosperm / genetics
  • Endosperm / growth & development
  • Gene Dosage
  • Gene Expression Regulation, Plant
  • Genome, Plant
  • Genomic Imprinting / genetics
  • Ovule / growth & development
  • Ovule / metabolism
  • Plants, Genetically Modified
  • Polycomb Repressive Complex 2
  • Polyploidy
  • Repressor Proteins* / genetics
  • Repressor Proteins* / metabolism
  • Seeds* / genetics
  • Seeds* / growth & development


  • AGAMOUS Protein, Arabidopsis
  • Arabidopsis Proteins
  • MEA protein, Arabidopsis
  • PRC2 protein, Arabidopsis
  • Repressor Proteins
  • Polycomb Repressive Complex 2

Grant support

This research was supported by Swiss National Science Foundation ( grants PP00P3_123362 and CRSI33_127506/1 to CK and by a fellowship of the Zurich-Basel Plant Science Center to DK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.