Assistant Professor University of Minnesota St. Paul, Minnesota
Nitrogen is often a limiting nutrient in agriculture. While legumes get the nitrogen fixed by rhizobia residing inside the root nodules, non-legumes rely either on associative nitrogen-fixing bacteria or chemical inputs of nitrogen. Arbuscular mycorrhizal (AM) fungi form symbiotic relationships with the vast majority of the land plants, including staple crops such as wheat, corn, soybean, rice, and potato. Growing evidence points to its role in acquiring and transferring nitrogen to plants in concert with other soil microbes. Our work focuses on the role of mycorrhizal fungi in transferring bacterial fixed nitrogen to crop plants. Our preliminary 15N dilution experiments show that bacterial fixed nitrogen uptake is better in the presence of mycorrhizal fungus when compared to non-mycorrhized maize plants. This leads to our central hypothesis that mycorrhizal fungi mediate the transfer of bacterial fixed nitrogen more efficiently than a direct transfer from bacteria to plants. To further understand the mechanism and optimize the synergistic potential of the diazotrophs and mycorrhizal fungi, we are studying the interactions of microbial symbionts and their impact on nitrogen benefits to cereal crops.