RDR6

RDR6, or RNA-dependent RNA polymerase 6, is a plant enzyme that belongs to the family of RNA-dependent RNA polymerases. In Arabidopsis thaliana and other plants, RDR6 plays a central role in RNA silencing pathways, particularly post-transcriptional gene silencing (PTGS) and the biogenesis of trans-acting short interfering RNAs (ta-siRNAs). The enzyme synthesizes complementary RNA using aberrant RNA as a template, generating double-stranded RNA that is subsequently cleaved by Dicer-like enzymes into small interfering RNAs. These siRNAs are incorporated into Argonaute-containing effector complexes to guide targeted transcript silencing.

RDR6 often works with SGS3, a stabilizing factor that binds aberrant RNAs and supports dsRNA production. Through this collaboration, RDR6 amplifies silencing signals and reinforces transgene silencing and antiviral defense. In ta-siRNA pathways, RDR6 contributes to production of phased siRNAs that regulate endogenous genes during development and stress responses.

Mutants deficient in RDR6 exhibit compromised PTGS, reduced ta-siRNA production, and increased susceptibility to RNA viruses, illustrating its importance in RNA-mediated defense and gene regulation. While best characterized in Arabidopsis thaliana, RDR6 and its functional equivalents are conserved across many plant species, though redundancy with other RdRPs varies among taxa.

Discovery and naming vary by species, with RDR6 studied primarily in model plants and crop relatives. RDR6 remains a focus of research on how plants regulate gene expression and defend against viral pathogens through RNA silencing pathways.