A Link Between mRNA Turnover and RNA Interference in Arabidopsis

• DOI: 10.1126/science.1101092
• Publication Date: 2004-11-04T22:23:52Z
• Authors: S. Gazzani; T. Lawrenson; C. Woodward; D. Headon; R. Sablowski
• Keywords: Homeodomain Proteins; RNA Caps; 0303 health sciences; Arabidopsis Proteins; Recombinant Fusion Proteins; Arabidopsis; Plants, Genetically Modified; RNA-Dependent RNA Polymerase; Rats; 03 medical and health sciences; RNA, Plant; Exoribonucleases; Mutation; Animals; RNA Interference; Gene Silencing; RNA, Messenger; Plant Proteins

In RNA interference (RNAi), double-stranded RNA (dsRNA) triggers degradation of homologous messenger RNA. In many organisms, RNA-dependent RNA polymerase (RdRp) is required to initiate or amplify RNAi, but the substrate for dsRNA synthesis in vivo is not known. Here, we show that RdRp-dependent transgene silencing in Arabidopsis was caused by mutation of XRN4, which is a ribonuclease (RNase) implicated in mRNA turnover by means of decapping and 5′-3′ exonucleolysis. When both XRN4 and the RdRp were mutated, the plants accumulated decapped transgene mRNA. We propose that mRNAs lacking a cap structure become exposed to RdRp to initiate or maintain RNAi.