biostudies-literatureUnknown36(18)Shivaprasad PVSeveral RNA silencing pathways in plants restrict viral infections and are suppressed by distinct viral proteins. Here we show that the endogenous trans-acting (ta)siRNA pathway, which depends on Dicer-like (DCL) 4 and RNA-dependent RNA polymerase (RDR) 6, is suppressed by infection of Arabidopsis with Cauliflower mosaic virus (CaMV). This effect was associated with overaccumulation of unprocessed, RDR6-dependent precursors of tasiRNAs and is due solely to expression of the CaMV transactivator/viroplasmin (TAV) protein. TAV expression also impaired secondary, but not primary, siRNA production from a silenced transgene and increased accumulation of mRNAs normally silenced by the four known tasiRNA families and RDR6-dependent secondary siRNAs. Moreover, TAV expression upregulated DCL4, DRB4 Nucleic acids research5896-909https://www.ebi.ac.uk/biostudies/studies/S-EPMC2566869biostudies-literatureThe CaMV transactivator/viroplasmin interferes with RDR6-dependent trans-acting and secondary siRNA pathways in Arabidopsis.PMC2566869Rajeswaran RShivaprasad PVBlevins TMeins FPooggin MMHohn TSchoelz JfalseThe CaMV transactivator/viroplasmin interferes with RDR6-dependent trans-acting and secondary siRNA pathways in Arabidopsis.Several RNA silencing pathways in plants restrict viral infections and are suppressed by distinct viral proteins. Here we show that the endogenous trans-acting (ta)siRNA pathway, which depends on Dicer-like (DCL) 4 and RNA-dependent RNA polymerase (RDR) 6, is suppressed by infection of Arabidopsis with Cauliflower mosaic virus (CaMV). This effect was associated with overaccumulation of unprocessed, RDR6-dependent precursors of tasiRNAs and is due solely to expression of the CaMV transactivator/viroplasmin (TAV) protein. TAV expression also impaired secondary, but not primary, siRNA production from a silenced transgene and increased accumulation of mRNAs normally silenced by the four known tasiRNA families and RDR6-dependent secondary siRNAs. Moreover, TAV expression upregulated DCL4, DRB4 2008-01-01T00:00:00Z2008 Oct2025-04-25T20:54:12.543Z2019-03-27T00:18:52ZS-EPMC25668691880184610.1093/nar/gkn590