title: A Medicago truncatula rdr6 allele impairs transgene silencing and endogenous phased siRNA production but not development.
abstract: RNA-dependent RNA polymerase 6 (RDR6) and suppressor of gene silencing 3 (SGS3) act together in post-transcriptional transgene silencing mediated by small interfering RNAs (siRNAs) and in biogenesis of various endogenous siRNAs including the tasiARFs, known regulators of auxin responses and plant development. Legumes, the third major crop family worldwide, has been widely improved through transgenic approaches. Here, we isolated rdr6 and sgs3 mutants in the model legume Medicago truncatula. Two sgs3 and one rdr6 alleles led to strong developmental defects and impaired biogenesis of tasiARFs. In contrast, the rdr6.1 homozygous plants produced sufficient amounts of tasiARFs to ensure proper development. High throughput sequencing of small RNAs from this specific mutant identified 354 potential MtRDR6 substrates, for which siRNA production was significantly reduced in the mutant. Among them, we found a large variety of novel phased loci corresponding to protein-encoding genes or transposable elements. Interestingly, measurement of GFP expression revealed that post-transcriptional transgene silencing was reduced in rdr6.1 roots. Hence, this novel mis-sense mutation, affecting a highly conserved amino acid residue in plant RDR6s, may be an interesting tool both to analyse endogenous pha-siRNA functions and to improve transgene expression, at least in legume species.
authors: CNRS, Institut des Sciences du Végétal (ISV), UPR2355, Labex SPS Saclay Plant Sciences, Gif-sur-Yvette Cedex, France.
authors: Pilar
authors: P
authors: Bustos-Sanmamed
authors: Elodie
authors: E
authors: Hudik
authors: Carole
authors: C
authors: Laffont
authors: Christelle
authors: C
authors: Reynes
authors: Erika
authors: E
authors: Sallet
authors: Jiangqi
authors: J
authors: Wen
authors: Kirankumar S
authors: KS
authors: Mysore
authors: Anne-Claude
authors: AC
authors: Camproux
authors: Caroline
authors: C
authors: Hartmann
authors: Jérome
authors: J
authors: Gouzy
authors: Florian
authors: F
authors: Frugier
authors: Martin
authors: M
authors: Crespi
authors: Christine
authors: C
authors: Lelandais-Brière
mesh_terms: D000483:Alleles; D020868:Gene Silencing; D056426:Genetic Loci; D046913:Medicago truncatula / Q000235:genetics* / Q000254:growth & development; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D063245:Plant Development / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics; D034741:RNA, Small Interfering / Q000096:biosynthesis*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D014158:Transcription, Genetic; D019076:Transgenes / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D034741:RNA, Small Interfering; D012324:RNA-Dependent RNA Polymerase
keywords: RDR6; RNA silencing; SGS3; legumes; pha-siRNA; small RNAs; ta-siRNA