Soybeans are plants that need a lot of nitrogen to grow well because their seeds are packed with high content of proteins. Instead of just relying on nitrogen from the soil, soybeans can team up with helpful bacteria called rhizobia to get the nitrogen they need. These bacteria live in small bumps on the soybean roots called nodules and can turn nitrogen from the air into a form the plant can use – a process called symbiotic nitrogen fixation. Despite of this unique capability, the nitrogen fixation process alone cannot meet the nitrogen demands for the host plant to be productive. The main goal of this project is to enhance the capability of soybean plants to utilize the nitrogen from the air, through manipulate the expression of genes associated with nodule formation and nitrogen fixation processes, for enhanced soybean yields without supply of nitrogen fertilizers under nitrogen-deficient conditions. In this first year of a three-year project, we performed evaluation of agronomic traits of genetically manipulated (transformation and gene-editing) soybean lines of an old variety Williams 82 for each of two genes previously identified to be associated with soybean nodulation and created new lines of the same genetic manipulation using two high-yielding elite soybean varieties. In addition, we have identified two new genes associated with nodule formation and senescence in soybean and created new, early-generation lines for each of these two genes for seed advancement and field tests.

We anticipate that this project, upon completion, will deliver high-yielding soybean elite lines, as pre-breeding lines, for further enhancement or for direct deployment of enhanced elite varieties for soybean production, making the US soy production more economical, profitable, and sustainable, and greener.