title: An endogenous artificial microRNA system for unraveling the function of root endosymbioses related genes in Medicago truncatula.
abstract: BACKGROUND
  Legumes have the unique capacity to undergo two important root endosymbioses: the root nodule symbiosis and the arbuscular mycorrhizal symbiosis. Medicago truncatula is widely used to unravel the functions of genes during these root symbioses. Here we describe the development of an artificial microRNA (amiR)-mediated gene silencing system for M. truncatula roots.
  
  
  RESULTS
  The endogenous microRNA (miR) mtr-miR159b was selected as a backbone molecule for driving amiR expression. Heterologous expression of mtr-miR159b-amiR constructs in tobacco showed that the backbone is functional and mediates an efficient gene silencing. amiR-mediated silencing of a visible marker was also effective after root transformation of M. truncatula constitutively expressing the visible marker. Most importantly, we applied the novel amiR system to shed light on the function of a putative transcription factor, MtErf1, which was strongly induced in arbuscule-containing cells during mycorrhizal symbiosis. MtPt4 promoter driven amiR-silencing led to strongly decreased transcript levels and deformed, non-fully truncated arbuscules indicating that MtErf1 is required for arbuscule development.
  
  
  CONCLUSIONS
  The endogenous amiR system demonstrated here presents a novel and highly efficient tool to unravel gene functions during root endosymbioses.
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam-OT Golm, Germany.
authors.forename: Emanuel A
authors.initials: EA
authors.lastname: Devers
authors.forename: Julia
authors.initials: J
authors.lastname: Teply
authors.forename: Armin
authors.initials: A
authors.lastname: Reinert
authors.forename: Nicole
authors.initials: N
authors.lastname: Gaude
authors.forename: Franziska
authors.initials: F
authors.lastname: Krajinski
mesh_terms: D005658:Fungi / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D005821:Genetic Techniques; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D038821:Mycorrhizae / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics* / Q000378:metabolism; D013559:Symbiosis
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant