Component of the RNA-directed DNA methylation (RdDM) machinery, probably by facilitating an RNAi-mediated epigenetic modification involving secondary siRNAs and spreading of DNA methylation, thus leading to gene silencing. Involved in the assembly of RNA polymerase V (Pol V) transcription initiation or elongation complexes at the chromatin, as a component of the DDR complex. Required for de novo DNA methylation. Homodimer. Part of the chromatin-remodeling complex (DDR complex) that contains at least DRD1, DMS3 and RDM1. Interacts with CPL1. The DDR complex recruits/activates the RNA polymerases V and acts during siRNA-directed DNA methylation (RdDM) (PubMed:18541146, PubMed:20409711, PubMed:22560611). Interacts with SUVH2 (PubMed:24465213). Binds to DMS11 and stimulates its ATPase activity (PubMed:22560611). Very low levels of RNAi-mediated methylation and derepression of silenced genes. Impaired RNA polymerase V-chromatin associations (Pol V). The mutant idn1-1 fails to establish DNA methylation and exhibits a late-flowering phenotype.