Researchers Identify Genetic Switch for Nitrogen-Fixing Bacteria in Plants

Researchers from Aarhus University have made a significant breakthrough in understanding how certain plants can thrive without artificial nitrogen fertilizers. Their findings, published in the journal Nature on November 6, 2025, could lead to more sustainable agricultural practices by reducing reliance on chemical fertilizers in crops such as wheat, maize, and rice.

Kasper Røjkjær Andersen and Simona Radutoiu, both professors of molecular biology, led the study that reveals the genetic mechanisms enabling plants to form beneficial partnerships with nitrogen-fixing bacteria. Most crops depend on fertilizers to obtain nitrogen, a crucial nutrient for growth, while a select few, like peas and clover, have developed the ability to engage in symbiosis with these bacteria, converting atmospheric nitrogen into a usable form.

The research team identified specific changes in plant receptors that allow them to deactivate their immune responses, thereby facilitating a symbiotic relationship with nitrogen-fixing bacteria. This process is essential for legumes, which can thrive without the additional input of fertilizers.

Mechanisms of Symbiosis

Plants utilize surface receptors to interpret signals from surrounding microorganisms. Some bacteria send out signals indicating they are harmful, prompting plants to activate their defenses. Conversely, beneficial bacteria signal their presence as allies, leading to nutrient exchange. The researchers discovered that two amino acids play a pivotal role in this process.

Radutoiu highlighted the significance of their findings, stating, “This is a remarkable and important finding.” The protein responsible for these receptor functions acts as a decision-maker, determining whether the plant should initiate an immune response or welcome the symbiotic bacteria. The team pinpointed a specific region within this protein, termed Symbiosis Determinant 1, which functions as a switch. By altering just two amino acids in this switch, researchers were able to transform a receptor that typically triggers an immune response into one that promotes symbiosis.

“Two small changes can cause plants to alter their behavior on a crucial point—from rejecting bacteria to cooperating with them,” Radutoiu explained.

Future Implications for Crop Production

The study’s laboratory results indicate that the researchers successfully modified the plant Lotus japonicus to enhance nitrogen fixation. They also found similar success with barley, which Røjkjær Andersen described as “quite remarkable.” The ability to adapt such receptors may pave the way for creating cereal crops, including wheat, corn, and rice, capable of fixing nitrogen independently.

Yet, despite the promising results, Radutoiu cautioned that more research is necessary. “We have to find the other, essential keys first. Only very few crops can perform symbiosis today,” she noted. Expanding this capability to widely cultivated crops could significantly reduce the nitrogen inputs required in agriculture, which currently contributes to about 2% of global energy consumption and emits substantial carbon dioxide.

The potential impact of this research is significant, offering a path toward more environmentally sustainable food production practices. As the scientific community continues to explore these genetic mechanisms, the transition to nitrogen self-sufficient crops may soon become a reality, promising a greener future for global agriculture.

For further details, refer to the study titled “Two residues reprogram immunity receptors for nitrogen-fixing symbiosis,” published in Nature (2025).