RNA polymerase IV and V in plants are mainly involved in
Nuclear polymerases IV and V drive RNA-directed DNA methylation pathway RdDM essential for heterochromatin formation. Pol IV is recruited to repetitive and transposon regions by CLSY chromatin remodelers and SHH1 reading H3K9 methylation, producing short single-stranded RNAs converted to double-stranded RNAs by RNA-dependent RNA polymerase RDR2, then diced by Dicer-like 3 into twenty-four nucleotide siRNAs loaded into Argonaute4. Pol V transcribes long noncoding scaffold RNAs at target loci that base-pair with AGO4-siRNA, recruiting de novo methyltransferase DRM2 to methylate cytosine in all s
Ref: PNAS 2011: Pol IV-RDR2 coupling generates dsRNA for siRNA biogenesis; Cell 2005 Plant Pol IV mediates DNA methylation
