TY - JOUR T1 - In plants, decapping prevents RDR6-dependent production of small interfering RNAs from endogenous mRNAs JF - bioRxiv DO - 10.1101/013912 SP - 013912 AU - Angel Emilio Martínez de Alba AU - Ana Beatriz Moreno AU - Marc Gabriel AU - Allison C. Mallory AU - Aurélie Christ AU - Rémi Bounon AU - Sandrine Balzergue AU - Sebastien Aubourg AU - Daniel Gautheret AU - Martin D. Crespi AU - Hervé Vaucheret AU - Alexis Maizel Y1 - 2015/01/01 UR - http://biorxiv.org/content/early/2015/01/18/013912.abstract N2 - Cytoplasmic degradation of endogenous RNAs is an integral part of RNA quality control (RQC) and often relies on the removal of the 5′ cap structure and their subsequent 5’ to 3’ degradation in cytoplasmic processing (P-)bodies. In parallel, many eukaryotes degrade exogenous and selected endogenous RNAs through post-transcriptional gene silencing (PTGS). In plants, PTGS depends on small interfering (si)RNAs produced after the conversion of single-stranded RNAs to double-stranded RNAs by the cellular RNA DEPENDENT RNA POLYMERASE 6 (RDR6) in cytoplasmic siRNA-bodies. PTGS and RQC compete for transgene-derived RNAs, but it is unknown whether this competition also occurs for endogenous transcripts. We show that the lethality of decapping mutants is suppressed by impairing RDR6 activity. We establish that upon decapping impairment hundreds of endogenous mRNAs give rise to a new class of rqc-siRNAs, that over-accumulate when RQC processes are impaired, a subset of which depending on RDR6 for their production. We observe that P- and siRNA-bodies often are dynamically juxtaposed, potentially allowing for crosstalk of the two machineries. Our results suggest that the decapping of endogenous RNA limits their entry into the PTGS pathway. We anticipate that the rqc-siRNAs identified in decapping mutants represent a subset of a larger ensemble of endogenous siRNAs. ER -