Danish researchers say that a tiny protein tweak could unlock nitrogen-fixing super-crops that slash global fertilizer demand.

Danish scientists have discovered a small protein region that determines whether plants reject or welcome nitrogen-fixing bacteria. By tweaking only two amino acids, they converted a defensive receptor into one that supports symbiosis. Early success in barley hints that cereals may eventually be engineered to fix nitrogen on their own. Such crops could dramatically reduce fertilizer use and emissions. It's hard to overstate how vast a win this could be. Firstly, strongly yielding cereal crops that don't need fertilizers would be a huge benefit to food security in the world's poorest and most marginalized places. Eliminating or drastically reducing the need for nitrogen fertilizers would be a huge win for the environment. Not only does their production and transportation account for at least 2% of global C02 emissions, but their runoff pollution of water bodies is a huge cost, too. Two residues reprogram immunity receptors for nitrogen-fixing symbiosis