SGS3 and RDR6 interact and colocalize in cytoplasmic SGS3/RDR6-bodies.

Suppressor of gene silencing 3 (SGS3) is involved in RNA-dependent RNA polymerase 6 (RDR6)-dependent small-interfering RNA (siRNA) pathways in Arabidopsis. However, the roles of SGS3 in those pathways are unclear. Here, we show that SGS3 interacts and colocalizes with RDR6 in cytoplasmic granules. Interestingly, the granules containing SGS3 and RDR6 (named SGS3/RDR6-bodies) were distinct from the processing bodies where mRNAs are decayed and/or stored. Microscopic analyses and complementation experiments using SGS3-deletion mutants suggested that proper localization of SGS3 is important for its function. These results provide novel insights into RDR6-dependent siRNA formation in plants.