title: The microRNA miR171h modulates arbuscular mycorrhizal colonization of Medicago truncatula by targeting NSP2.
abstract: Most land plants live symbiotically with arbuscular mycorrhizal fungi. Establishment of this symbiosis requires signals produced by both partners: strigolactones in root exudates stimulate pre-symbiotic growth of the fungus, which releases lipochito-oligosaccharides (Myc-LCOs) that prepare the plant for symbiosis. Here, we have investigated the events downstream of this early signaling in the roots. We report that expression of miR171h, a microRNA that targets NSP2, is up-regulated in the elongation zone of the root during colonization by Rhizophagus irregularis (formerly Glomus intraradices) and in response to Myc-LCOs. Fungal colonization was much reduced by over-expressing miR171h in roots, mimicking the phenotype of nsp2 mutants. Conversely, in plants expressing an NSP2 mRNA resistant to miR171h cleavage, fungal colonization was much increased and extended into the elongation zone of the roots. Finally, phylogenetic analyses revealed that miR171h regulation of NSP2 is probably conserved among mycotrophic plants. Our findings suggest a regulatory mechanism, triggered by Myc-LCOs, that prevents over-colonization of roots by arbuscular mycorrhizal fungi by a mechanism involving miRNA-mediated negative regulation of NSP2.
authors: Université de Toulouse, UMR 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan Cedex, France.
authors: Dominique
authors: D
authors: Lauressergues
authors: Pierre-Marc
authors: PM
authors: Delaux
authors: Damien
authors: D
authors: Formey
authors: Christine
authors: C
authors: Lelandais-Brière
authors: Sébastien
authors: S
authors: Fort
authors: Sylvain
authors: S
authors: Cottaz
authors: Guillaume
authors: G
authors: Bécard
authors: Andreas
authors: A
authors: Niebel
authors: Christophe
authors: C
authors: Roux
authors: Jean-Philippe
authors: JP
authors: Combier
mesh_terms: D001665:Binding Sites; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D055137:Glomeromycota / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D007783:Lactones / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D046913:Medicago truncatula / Q000166:cytology / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D038821:Mycorrhizae / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013559:Symbiosis; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D007783:Lactones; D008070:Lipopolysaccharides; D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; C023023:lipid-linked oligosaccharides