Molecular mechanisms controlling functional association between Arabidopsis thaliana and Sinorhizobium meliloti bacterium

KRAISER T; GRAS DE; GONZÁLEZ B; GUTIÉRREZ RG

Puerto Varas

Simposio; Second International Symposium on the Nitrogen Nutrition of Plants; 2013

Nitrogen acquisition in plants by the association with nitrogen fixing bacteria (NFB) have been mostly studied in legumes. In those plants, regulatory mechanisms are essential for a successful association and nodule development. In the case of non-legume plants unable to form nodules, it is unknown the extent to which they can or cannot establish functional associations with NFB and the molecular regulatory mechanisms involved. Our goal was to evaluate a functional association between Arabidopsis thaliana and NFB to develop a model system in which to study and identify molecular mechanisms underlying non-legumes and NFB association. We found A. thaliana can functionally associate with Sinorhizobium meliloti RMP110 contributing to plant growth under N-limiting conditions. We showed the growth-promoting effect to be at least partly dependent on nitrogen fixation by genetically inactivating the nitrogenase complex in the bacterium. Analysis of plant gene expression under different nitrogen regimes in the presence or absence of NFB identified candidate plant genes. Arabidopsis mutant lines verified the importance of these genes for NFB-mediated plant growth promotion. We propose Arabidopsis and S. meliloti as an excellent model system to identifying key regulatory networks in non-legumes and NFB association.