Gavrin, A.; Batista, M. B.; Evangelisti, E.; Dixon, R.; Schornack, S.

Through symbiosis with nitrogen-fixing bacteria, cultivated legumes provide themselves and subsequent crops with nitrogen, making genetic improvements of symbiotic efficiency particularly attractive. Here, we identify the symbiosis-specific GBP1 gene which negatively regulates nitrogen fixation by attenuating bacterial nitrogenase activity in Medicago truncatula nodules. GBP1 inactivation increases nitrogen fixation without affecting nodule development and numbers, providing inroads for engineering legumes with increased productivity for sustainable nitrogen provision.