Host genetic control of strain-specific nitrogen fixation in the legume-rhizobial symbiosis

Grants and Contracts Details


Legumes have the remarkable ability to establish a symbiotic relationship with nitrogen-fixing soil bacteria, known as rhizobia. This mutualism culminates in the formation of a new plant organ, called the root nodule, within which the bacteria convert atmospheric nitrogen into ammonia, a biological form that can be directly consumed by the plant. One striking feature of the symbiosis is its high level of specificity. Such specificity can occur at the early phase of the interaction that is associated with bacterial infection and nodulation as well as at the late phase of nodule development that is related to nitrogen fixation. Genetic control of symbiosis specificity is complex, involving complex signal communication between the symbiotic partners. Despite recent advances in our understanding of the signaling pathways leading to root nodule development, the molecular mechanisms underlying natural variation in nitrogen fixation efficiency/specificity are largely unknown. The goal of this proposal is to explore host genetic control mechanisms underlying strain-specific nitrogen fixation in the legume-rhizobial symbiosis using the Medicago-Sinorhizobium model. Specific objectives include: 1) Map-based cloning of Nfs1 (nitrogen fixation specificity 1), a host gene that regulates strain-specific nitrogen fixation in Medicago truncatula; 2) Molecular and biochemical characterization of Mt-Nfs1; and 3) Exploring genomic signatures of efficient nitrogen-fixing symbiosis. The knowledge gained from this project will greatly improve our ability to enhance the agronomic potential of the root nodule symbiosis in sustainable agriculture.
Effective start/end date12/1/1311/30/18


  • National Institute of Food and Agriculture: $500,000.00


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