Bioengineering nitrogen fixation in plants

Our laboratory aims to increase cereal crop productivity by enabling plants to acquire nitrogen from the atmosphere instead of synthetic fertilizers. Engineering active nitrogenase in plants requires managing many genetic parts for nitrogenase assembly and function, as well as addressing nitrogenase sensitivity to O2. Here we explore the feasibility of this transgenic approach by expressing two critical genes (nifH and nifB) in rice. The nifH gene encodes the nitrogenase Fe protein, the obligate electron donor to NifDK for the nitrogen fixation reaction. NifB catalyzes the first committed step in the biosynthesis of the FeMo-cofactor located at the active-site of the nitrogenase of MoFe protein (NifDK). We use yeast and tobacco as model organisms and employ a combination of synthetic biology and biochemical complementation assays to investigate the functionality of nitrogenase parts in eukaryotes. The validated components are subsequently integrated into the rice genome with the goal of assembling the complete nitrogenase pathway step-by-step.