Assistant Professor North Dakota State University Fargo, North Dakota
Biological nitrogen fixation from the symbiotic relationship between rhizobia and legume crops is a pillar of sustainable agriculture. We seek to understand how to maximize symbiotic nitrogen fixation in agricultural systems using rhizobial inoculants and to generate a translatable knowledge framework for engineering such a symbiosis in cereal crops. While we know much about the essential genes in rhizobia required to carry out the symbiosis (Nod Factor production, nitrogen fixation and microaerobic metabolism genes), comparatively less is known about agronomically important traits such as the effectiveness of nitrogen fixation and competition for root nodule occupancy. Concurrently, the required genetic components for invasion and intracellular accommodation in the appropriate legume host are not clearly understood and will be key towards facilitating colonization of cereals engineered with root nodule symbiosis capabilities. We are taking a synthetic genomics approach, experimentally engineering rhizobial symbiosis gene sets from the ground up in well-defined chassis, to explore the genetic basis of these traits. Our early experiments lend insight into the genomic and genetic basis of effective symbiotic nitrogen fixation, competition for root nodule occupancy, and genetic compatibility between rhizobia and their particular legume hosts.