and Are Redundant Genes That Encode Epigenetic Machinery Components in Arabidopsis.

All critical developmental and physiological events in a plant's life cycle depend on the proper activation and repression of specific gene sets, and this often involves epigenetic mechanisms. Some mutants with disorders of the epigenetic machinery exhibit pleiotropic defects, including incurved leaves and early flowering, due to the ectopic and heterochronic derepression of developmental regulators. Here, we studied one such mutant class, the () loss-of-function mutants. We have identified as the founding member of a small gene family that we have named (). This family is part of the 2-oxoglutarate/Fe(II)-dependent dioxygenase superfamily. and its closest paralog, have unequally redundant functions: although mutants are phenotypically wild type, double mutants skip vegetative development and flower upon germination. This phenotype is reminiscent of loss-of-function mutants of the Polycomb-group genes () and Double mutants harboring alleles and loss-of-function alleles of genes encoding components of the epigenetic machinery exhibit synergistic, severe phenotypes, and some are similar to those of mutants. Hundreds of genes are misexpressed in plants, including (), and derepression of causes the leaf phenotype of ICU11 and CP2 are nucleoplasmic proteins that act as epigenetic repressors through an unknown mechanism involving histone modification, but not DNA methylation.