Unique among crop species, legumes produce their own nitrogen nutrient through a symbiosis with nitrogen-fixing bacteria collectively known as rhizobia. This nitrogen-fixing symbiosis is a complex system, and currently we know too few of the molecular players involved. This project will optimize two methods to reduce the activity of a given gene, and use these methods to screen for legume genes required for the function of the nitrogen-fixing symbiosis. The result of such endeavors should be a comprehensive list of legume genes playing critical roles in interacting with their rhizobial symbionts, and help unveil crucial biological processes in the interaction between plants and beneficial microbes.