IDN1 and IDN2 are required for de novo DNA methylation in Arabidopsis thaliana

DNA methylation is an epigenetic mark affecting genes and transposons. Screening for mutants that fail to establish DNA methylation yielded two we termed involved in de novo (idn) 1 and 2. IDN1 encodes DMS3, an SMC-related protein, and IDN2 encodes a previously unknown double-stranded RNA-binding protein with homology to SGS3. IDN1 and IDN2 control de novo methylation and small interfering RNA (siRNA)-mediated maintenance methylation and are components of the RNA-directed DNA methylation pathway.