DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Component of RNA polymerase V involved in RNA-directed DNA methylation-dependent (RdDM) silencing of endogenous repeated sequences, including transposable elements. Component of the RNA polymerase V complex. Expressed in flower buds and siliques. Belongs to the archaeal Rpo5/eukaryotic RPB5 RNA polymerase subunit family.