Updated project metadata. Legumes establish nitrogen-fixing symbiosis with beneficial rhizobia. On the other hand, they might be attacked concomitantly by pathogens raising the question of potential trade-off between mutualism and immunity. Here, using a tripartite system involving the model legume Lotus japonicus, its rhizobial symbiont Mesorhizobium loti and the soil-borne pathogen Ralstonia solanacearum we investigated such trade-offs. We found that interaction with M. loti increases plant resistance against the pathogen without impairing mutualism. Genetic and proteomics characterisation indicate that Lotus resistance is mediated by Effector Triggered Immunity and is associated with distinct proteome modifications in roots and nodules. The inoculation of rhizobia, even if they are not mutualist, increases plant resistance. Our results question the concept of interference between efficient defense reactions and mutualistic interactions and is of great interest for agricultural purposes as it not only restricts pathogen colonisation but would also preserve nitrogen fixation and yield.