Cellular antisilencing factor and regulator of genome DNA methylation patterns involved in the regulation of chromatin states. Together with SUVH4, monitors repressive epigenetic marks H3K27me1, H3K9me2, and prevents DNA-methylation at CHG sites, affecting especially the expression of transposons and developmentally important genes (PubMed:21830950, PubMed:23609044, PubMed:24248388). Regulates alternative RNA processing such as distal 3' polyadenylation by intronic heterochromatin (PubMed:24248388). Epigenetic reader that binds DNA and contributes to transcriptional transposable element (TE) silencing by modulating levels of the repressive post-translational histone modifications (PHM) H3K9me2 (PubMed:23609044). In cv. Columbia, required for RPP7-dependent disease resistance against the Hyaloperonospora arabidopsidis isolate Hiks1, by promoting levels of RPP7 via alternative polyadenylation (APA), resulting from cooption of epigenetic information at the TE insertion locus COPIA-R7 (PubMed:23940361, PubMed:17253987, PubMed:20149132). Regulates development processes such as the formation of leaf pavement cells, leaf expansion, fertility and flowering (PubMed:20840782, PubMed:20149132, PubMed:23609044). Prevents FLC accumulation to control flowering (PubMed:23976921). Modulates stomatal development by regulating the methylation-mediated silencing of ERECTA receptor genes (e.g. ER, ERL1 and ERL2) and preventing cell divisions (PubMed:27697902). Interacts with WNK8 in nucleus; this interaction is involved in developmental processes regulation but not in RPP7-dependent disease resistance (PubMed:20149132). Interacts with EML1 and EML2 in nucleus (PubMed:21830950). The PHD domains recognize both active and repressive histone methylation marks at the intronic repeat elements in genes. Phosphorylated by WNK8. Strong reduction in RPP7 levels due to altered H3K9me2 levels in COPIA-R7 (PubMed:23940361, PubMed:17253987). Impaired resistance against the Hyaloperonospora arabidopsidis isolate Hiks1 (PubMed:17253987). Abnormal leaf development and flowering time (PubMed:20840782, PubMed:20149132). Enhanced accumulation of FLC (PubMed:23976921). Altered silencing states of several transposons associated with reduced histone methylation at H3K27me1 and H3K9me2 (PubMed:23609044). Hypermethylation of DNA at CHG sites (PubMed:24248388). Reduced fertility (PubMed:23609044). Overproduction of stomatal lineage cells due to increased cell divisions and associated with DNA hypermethylation and silencing of ERECTA receptor genes such as ER, ERL1 and ERL2 (PubMed:27697902).