Researchers Unlock Genetic Switch to Enhance Nitrogen Fixation in Plants

Researchers at Aarhus University have made a significant breakthrough in understanding how certain plants can thrive without nitrogen fertilizers. Their findings, published in the journal Nature on November 6, 2025, could pave the way for more sustainable agricultural practices, potentially reducing reliance on artificial fertilizers in key crops like wheat, maize, and rice.

Professors Kasper Røjkjær Andersen and Simona Radutoiu led the study, which identified critical genetic mechanisms that enable specific plants to form symbiotic relationships with nitrogen-fixing bacteria. These bacteria convert atmospheric nitrogen into a usable form for plants, allowing certain species, such as peas, clover, and beans, to grow without additional nitrogen inputs.

Understanding Plant-Bacteria Symbiosis

Currently, most crops depend on fertilizers for nitrogen, which contributes to approximately 2% of global energy consumption and substantial carbon dioxide emissions. The research team focused on the receptors in plant cells that communicate with soil microorganisms. These receptors can distinguish between harmful bacteria and beneficial ones, triggering either an immune response or a welcoming environment for symbiotic partners.

Through their research, the team discovered that two specific amino acids within a protein in the roots of plants play a crucial role in this process. They identified an area within the protein termed Symbiosis Determinant 1, which acts as a switch controlling the plant’s response to bacteria.

“This is a remarkable and important finding,” said Radutoiu. They demonstrated that by altering just two amino acids, they could convert a receptor that would typically signal an immune response into one that promotes symbiosis with nitrogen-fixing bacteria.

“We have shown that two small changes can cause plants to alter their behavior on a crucial point—from rejecting bacteria to cooperating with them,” said Radutoiu.

Implications for Major Crops

The researchers successfully modified the plant Lotus japonicus in the laboratory, and the same genetic principles were found to apply to barley. Røjkjær Andersen noted, “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 profound. If these modifications can be extended to other major crops, it could lead to the development of cereals like wheat, corn, or rice that can naturally fix nitrogen, similarly to legumes.

However, Radutoiu emphasizes that further research is necessary to identify additional essential genetic components. “Only very few crops can perform symbiosis today. If we can extend that to widely used crops, it can really make a big difference in how much nitrogen needs to be used,” she stated.

This innovative research not only contributes to the scientific understanding of plant biology but also holds the potential for a more sustainable agricultural future, reducing both environmental impact and production costs for farmers worldwide.

For more information, see the study by Radutoiu and Andersen, titled “Two residues reprogram immunity receptors for nitrogen-fixing symbiosis,” published in Nature.