Researchers Uncover Genetic Switch for Nitrogen-Fixing Plants

A team of researchers from Aarhus University has made significant strides in understanding how some plants can thrive without external nitrogen sources. Their study, published in the journal Nature, could pave the way for reducing reliance on artificial fertilizers for major crops such as wheat, maize, and rice.

In their research, professors Kasper Røjkjær Andersen and Simona Radutoiu have identified crucial genetic mechanisms that enable certain plants, like legumes, to engage in symbiotic relationships with nitrogen-fixing bacteria. This discovery holds promise for enhancing sustainable agriculture practices and decreasing the environmental impact of fertilizer use.

Plants require nitrogen to grow, a nutrient typically supplied through fertilizers. However, only a select group of plants, including peas, clover, and beans, can thrive without it by forming partnerships with specific bacteria that convert atmospheric nitrogen into a usable form for the plants. As the global agricultural sector aims to minimize its carbon footprint, understanding these relationships is essential.

The researchers focused on the genetic receptors in plants that determine whether to accept or reject microbial partners. They found that minor changes in these receptors can influence a plant’s immune response and its ability to establish beneficial relationships with nitrogen-fixing bacteria.

Radutoiu highlighted the importance of their findings, stating, “This is a remarkable and important finding.” The study reveals that two specific amino acids play a pivotal role in the receptor proteins located in the roots of these plants. This protein acts as a decision-maker, determining whether the plant’s immune system should trigger a defensive response or open the door for cooperation with beneficial bacteria.

A critical component of their research is the identification of a region in the receptor protein, termed Symbiosis Determinant 1. This area functions like a switch, regulating the plant’s internal response to bacterial signals. By altering just two amino acids in this switch, the researchers successfully converted a receptor that triggers an immune response into one that fosters symbiosis with nitrogen-fixing bacteria.

In laboratory tests, the team successfully modified the plant Lotus japonicus, demonstrating that the principles of their findings can also apply to barley. Røjkjær Andersen remarked, “It is quite remarkable that we are now able to take a receptor from barley, make small changes in it, and then nitrogen fixation works again.”

The implications of this research are significant. If these genetic modifications can be applied to other cereal crops such as wheat, corn, or rice, it may eventually lead to the development of self-sufficient plants that do not require artificial fertilizers. Radutoiu expressed optimism, stating, “If we can extend that to widely used crops, it can really make a big difference in how much nitrogen needs to be used.”

While the potential for transforming crops is evident, the researchers recognize that further exploration is necessary to uncover additional genetic keys essential for establishing such symbiotic relationships. Currently, very few crops possess this ability, and broadening this capacity could revolutionize agricultural practices.

With this groundbreaking work, the researchers are moving closer to a future where sustainable food production is not just aspirational but achievable. By reducing dependence on artificial fertilizers, the agricultural sector can contribute to a greener, more climate-friendly world.

For more information on this study, refer to the publication by Simona Radutoiu in Nature, titled “Two residues reprogram immunity receptors for nitrogen-fixing symbiosis” (2025).