Microbial Genetics Group - Xavier PERRET

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Genetics of symbioses between Sinorhizobium fredii NGR234 and legumes

Soil bacteria collectively known as rhizobia form together with leguminous plants nitrogen-fixing symbioses in which the chemically inert atmospheric nitrogen becomes available to other living forms. By providing the reduced nitrogen that lacks in nitrate-poor soils, rhizobia foster legume growth in areas where other plants cannot develop. In agriculture, rhizobia-legume symbiosis helps preserve water resources from being polluted by nitrates found in fertilizers. Thus, rhizobia and legumes play a critical role in the global nitrogen cycle that is essential to our survival. Our group investigates the molecular mechanisms that allow the promiscuous bacterium S. fredii NGR234 to fix nitrogen in association with more than 135 legume species.



Legumes growing in a field in presence (left) or absence (right) of symbiotic rhizobia.