title: Failure of self-control: defense-like reactions during legume/rhizobia symbiosis.
abstract: Medicago truncatula and Sinorhizobium meliloti form a symbiotic association resulting in the formation of nitrogen-fixing nodules. In this organ, symbiotic cells contain large numbers of bacteroids. Remarkably, this chronic infection does not trigger visible defense reactions. Despite the importance of this phenomenon for potential transfer of the symbiotic capacity to non-legume plants, the molecular mechanisms underlying this tolerance are not understood. We have characterized the dnf2 M. truncatula mutant blocked in the symbiotic process after bacterial infection of the symbiotic cells. Nodules formed by the mutant contain only few layers of infected cells. Furthermore, they exhibit defense-like reactions which clearly contrast with premature senescence frequently observed during inefficient symbioses. This atypical phenotype raises DNF2 as an exciting starting point to investigate the molecular basis of symbiotic repression of plant defenses.
authors: Institut des Sciences du Végétal; CNRS; Gif-sur-Yvette, France.
authors: Marie
authors: M
authors: Bourcy
authors: Fathi
authors: F
authors: Berrabah
authors: Pascal
authors: P
authors: Ratet
authors: Benjamin
authors: B
authors: Gourion
mesh_terms: D016922:Cellular Senescence; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology; D009154:Mutation; D009584:Nitrogen; D009586:Nitrogen Fixation; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D055170:Plant Root Nodulation / Q000235:genetics*; D053204:Root Nodules, Plant / Q000382:microbiology; D016962:Sinorhizobium meliloti; D013559:Symbiosis / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D009584:Nitrogen
keywords: Medicago truncatula; Sinorhizobium; defense reaction; immune status; symbiosis