Involved in RNA-directed DNA methylation (RdDM). Required for the silencing of some endogenous RdDM targets and accumulation of 24-nt siRNAs, but not for the production of Pol V-dependent transcripts. Functions in transcriptional silencing through both DNA methylation-dependent and -independent pathways. Required for both maintenance and de-novo DNA methylation. Plays a role in the recruitment of Pol IV to genomic regions associated with K9 methylated histone H3 that are targets for RdDM. Associates with the RNA polymerase IV (Pol IV) complex. Interacts with NRPD1, NRPD2, NRPD3, NRPD3B, CLSY1 and CLSY2. The SAWADEE domain (138-244) binds to mono-, di-, or trimethylated H3K9 histone peptides, but this interaction is impaired if H3K4me2/3 methylation is present (PubMed:23637343 PubMed:23636332). Loss of DRM2 controlled DNA methylation, but no effect on CMT3 or MET1 controlled methylation. Associates in vivo with Pol IV but not with Pol V (PubMed:23637343) and this interaction is not dependent on its H3K9me binding activity (PubMed:23636332). Glu-130 and Asp-141 interact with the H3K4 side chain while the H3K9me1/2/3 side chains insert into a hydrophobic aromatic cage formed by Tyr-140, Phe-162 and Phe-165 (PubMed:23636332).