It is all about balance. The balance between the production of soybean, one of the most important crops worldwide, and a sustainable environment. Also, the balance maintained by the soybean itself between its nitrogen needs and the energy costs during nodulation, the symbiotic interaction with nitrogen-fixing rhizobia. The key component of that balance is the protein kinase, NARK. NARK acts in the shoots to regulate nodulation in response to rhizobia and in the roots to restrict this process if nitrate is available. Despite long-lasting research efforts, the signaling pathway downstream of NARK remains elusive. My project aims to reveal how NARK regulates nodulation, possibly by interacting with distinct protein partners in response to rhizobia and nitrate. I will use phosphoproteomics to explore NARK-dependent protein phosphorylation in roots and shoots, identifying putative NARK targets. This will be complemented by proximity labeling to reveal NARK’s interaction network. Novel NARK signaling components will be functionally characterized to define their role in the control of nodulation. As a methodological advance, I will establish virus-induced gene editing as a novel functional genomics tool in soybean. Discovering the unique downstream interactors of NARK and shared components of nitrate- and rhizobia-regulated nodulation will direct future research in optimizing nitrogen fixation for more sustainable agriculture.