RNA-binding protein required for DNA demethylation and to eluviate siRNA-mediated transcriptional gene silencing (TGS), probably by guiding ROS1 (PubMed:18815596). Can bind specifically single stranded G-rich RNAs of 21-, 24- or 26-nt corresponding to promoter sequence of target genes; this interaction directs demethylation of target sequences (PubMed:18815596). Localized in discrete foci dispersed throughout the nucleus. Ubiquitously expressed. The RRM domain is required for single stranded RNA binding. DNA hypermethylation (at CpG, CpNpG and CpNpN sites, N is A, T or C) leading to increased siRNA-mediated transcriptional gene silencing (TGS) (PubMed:18815596). Narrow and slightly lobed second and third pairs of true leaves (PubMed:18815596). Disrupted ROS1 subcellular localization in the nucleolus (PubMed:18815596).