My goal is to understand the interaction between multicellular hosts and their microbial partners, with a focus on symbiotic associations.
The living world is shaped by complex networks of interactions between organisms, some antagonistic and others beneficial. Symbioses allow diverse species to achieve feats unattainable by individual members. These collaborations frequently reflect elegant co- evolution; some are so successful as to have global-scale effects.
We aim to illuminate the molecular basis of highly evolved and intimate forms of symbiosis. Our system is the association between legume plants and nitrogen-fixing bacteria. The two species undergo a complex series of developmental changes, resulting in a specialized symbiotic organ, the root nodule. Within the nodule, bacteria are transformed into intracellular organelles – called symbiosomes – dedicated to converting (fixing) molecular nitrogen into ammonia for the host plant. Because fixed nitrogen is frequently the scarcest soil nutrient for plants, this symbiosis has significant economic and ecological impacts: legume crops provide a large portion of the protein in the human diet without nitrogen fertilizers. Globally, biologically fixed nitrogen constitutes a major component of the nitrogen cycle.