Development of a soybean–bradyrhizobium symbiotic system with greenhouse gas reduction

September 5, 2025

An innovative technology to suppress nitrous oxide emissions from agricultural fields

Nitrous oxide (N₂O), a potent greenhouse gas contributing to global warming, is emitted from agricultural soils, and strategies to mitigate its release are being actively pursued worldwide. Researchers at the RIKEN CSRS, in collaboration with the National Agriculture and Food Research Organization (NARO), Tohoku University, and Obihiro University of Agriculture and Veterinary Medicine, have developed a technology that enables preferential nodulation of soybean roots by Bradyrhizobium strains with high N₂O-reducing activity. This approach is expected to contribute to climate change mitigation.

Previous efforts to reduce N₂O emissions by inoculating soybeans with high N₂O-reducing Bradyrhizobium strains have been hindered by competitive nodulation with diverse indigenous strains present in the soil, limiting the effectiveness of the introduced strains. To address this challenge, the research group focused on symbiotic incompatibility, a phenomenon observed in legume–rhizobia interactions, to increase the nodule occupancy of the desired N₂O-reducing strains. By combining soybean lines engineered to carry two symbiotic incompatibility genes with Bradyrhizobium mutants that, due to natural mutations, no longer produce the effector protein, the researchers established a system in which the effector-deficient Bradyrhizobium strains preferentially colonize the soybean nodules. Field trials confirmed that this system significantly reduces N₂O emissions during the senescence and degradation of root nodules following soybean harvest. This host–microbe engineering strategy offers a promising solution for reducing greenhouse gas emissions from agricultural ecosystems.

 

Original article

Nature Communications　doi: 10.1038/s41467-025-63223-6

H. Nishida, M. Itakura, K. T. Win, F. Li, K. Kakizaki, A. Suzuki, S. Ohkubo, L. V. Duc, M. Sugawara, K. Takahashi, M. Shenton, S. Masuda, A. Shibata, K. Shirasu, Y. Fujisawa, M. Tsubokura, H. Akiyama, Y. Shimoda, K. Minamisawa, H. Imaizumi-Anraku,

"Genetic design of soybean hosts and bradyrhizobial endosymbionts reduces N₂O emissions from soybean rhizosphere".

Contact

Ken Shirasu; Group Director
Sachiko Masuda; Research Scientist
Arisa Shibata; Technical Staff
Plant Immunity Research Group