Atypical rhizobia trigger nodulation and pathogenesis on the same legume hosts.

The emergence of commensalism and mutualism often derives from ancestral parasitism. However, in the case of rhizobium-legume interactions, bacterial strains displaying both pathogenic and nodulation features on a single host have not been described yet. Here, we isolated such a bacterium from Medicago nodules.

Medicago truncatula SOBIR1 controls pathogen immunity and specificity in the Rhizobium-legume symbiosis.

Medicago truncatula Nod Factor Perception (MtNFP) plays a role in both the Rhizobium-Legume (RL) symbiosis and plant immunity, and evidence suggests that the immune-related function of MtNFP is relevant for symbiosis. To better understand these roles of MtNFP, we sought to identify new interacting partners. We screened a yeast-2-hybrid cDNA library from Aphanomyces euteiches infected and noninfected M.

A dual legume-rhizobium transcriptome of symbiotic nodule senescence reveals coordinated plant and bacterial responses.

Senescence determines plant organ lifespan depending on aging and environmental cues. During the endosymbiotic interaction with rhizobia, legume plants develop a specific organ, the root nodule, which houses nitrogen (N)-fixing bacteria. Unlike earlier processes of the legume-rhizobium interaction (nodule formation, N fixation), mechanisms controlling nodule senescence remain poorly understood.

Role of Nitric Oxide of Bacterial Origin in the Symbiosis.

Nitric oxide (NO) is a small ubiquitous gaseous molecule that has been found in many host-pathogen interactions. NO has been shown to be part of the defense arsenal of animal cells and more recently of plant cells. To fight this molecular weapon, pathogens have evolved responses consisting of adaptation to NO or degradation of this toxic molecule.

The Nitrate Assimilatory Pathway in : Contribution to NO Production.

The interaction between rhizobia and their legume host plants culminates in the formation of specialized root organs called nodules in which differentiated endosymbiotic bacteria (bacteroids) fix atmospheric nitrogen to the benefit of the plant. Interestingly, nitric oxide (NO) has been detected at various steps of the rhizobium-legume symbiosis where it has been shown to play multifaceted roles. It is recognized that both bacterial and plant partners of the - symbiosis are involved in NO synthesis in nodules.