SDE5, the putative homologue of a human mRNA export factor, is required for transgene silencing and accumulation of trans-acting endogenous siRNA.
Post-transcriptional gene silencing (PTGS) is a sequence-specific RNA degradation process conserved in fungi, plants and animals. The trigger of the mechanism is double-stranded RNA derived from transgenic or endogenous loci and formed by intra- or inter-molecular interactions of single-stranded RNAs or the action of RNA-dependent RNA polymerases (RDRs). Double-stranded RNA from various sources is processed by one of the four Dicer-like (DCL) proteins in Arabidopsis, and the resulting short RNAs enter into at least four different pathways, one of which involves the production of trans-acting short interfering RNAs (tasiRNAs). We report here a novel gene (SDE5) that is required for transgene silencing and the production of tasiRNAs. Mutation in SDE5 also results in hyper-susceptibility to cucumber mosaic virus but not turnip mosaic virus. However, like RDR6, SDE5 is not involved in inverted repeat-induced transgene silencing or the biogenesis of microRNAs and 24 nt siRNAs produced by DCL3. Based on these results, we propose that SDE5 acts together with RDR6 in generating double-stranded RNA from specific single-stranded RNAs. As the sequence of SDE5 has sequence features shared by TAP, a human mRNA export factor, we propose that its role could be in the transport of RNA molecules that are converted into a double-stranded form by RDR6.
Hernandez-Pinzon
Inmaculada
I
School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
Yelina
Nataliya E
NE
Schwach
Frank
F
Studholme
David J
DJ
Baulcombe
David
D
Dalmay
Tamas
T
D017360:Arabidopsis / Q000235:genetics / Q000821:virology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D017799:Cucumovirus / Q000254:growth & development; D005816:Genetic Complementation Test; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D009029:Mosaic Viruses / Q000254:growth & development; D009154:Mutation; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D019076:Transgenes / Q000235:genetics*
D029681:Arabidopsis Proteins; D035683:MicroRNAs; D029543:Nucleocytoplasmic Transport Proteins; D012330:RNA, Double-Stranded; D018749:RNA, Plant; D034741:RNA, Small Interfering; C522029:SDE5 protein, Arabidopsis