Involved in sense transgene post-transcriptional gene silencing (S-PTGS). Not involved in repeat-induced transgene silencing (IR-PTGS). Essential component of the trans-acting short interfering RNA (tasiRNA) pathway. Required for the production of tasiRNAs (PubMed:17397509, PubMed:20798330). Acts together with RDR6 in generating double-stranded RNA from specific single-stranded RNAs. May be involved in the transport of RNA molecules that are converted into a double-stranded form by RDR6. Involved in virus-induced silencing. Not involved in the biogenesis of microRNAs and 24 nt siRNAs produced by DCL3 (PubMed:17397509). A number of isoforms are produced. According to EST data. Elongated and curled downward leaves. Upon infection, over-accumulation of cucumber mosaic virus (CMV) RNA and enhanced susceptibility to CMV.