Harnessing atmospheric nitrogen for cereal crop production.

While synthetic nitrogen fuels modern agriculture, its production is energy-intensive, and its application leads to aquatic pollution and greenhouse gas emissions. Sustainable intensification of agriculture to provide both food for humans and feedstocks for bio-based fuels and materials requires alternative options for nitrogen management. For nearly fifty years, nitrogen fixation in cereal crops has been pursued to address this challenge. Efforts to engineer plants for nitrogen fixation have made strides through eukaryotic nitrogenase expression and a deepened understanding of root nodulation pathways, but deployment of transgenic nitrogen fixing cereals may be outpaced by population growth. By contrast, a root-associated bacterium that can fix and supply nitrogen to cereals could offer a sustainable solution for nitrogen management on a shorter timescale.