Yuping  Huang , Yunxia  Chen , Hangming Lin  Lin

Tropical Legume Research Center, Hainan Institute of Tropical Agricultural Resources, Sanya, 572025, Hainan, China
Author    Correspondence author
Legume Genomics and Genetics, 2026, Vol. 17, No. 1   
Received: 10 Feb., 2026    Accepted: 12 Feb., 2026    Published: 22 Mar., 2026

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Leguminous plants are capable of achieving biological nitrogen fixation through symbiotic relationships with rhizobia, thereby holding significant ecological and economic value in agricultural production. With the completion of genome sequencing for various legume crops, the systematic elucidation of the structural characteristics, evolutionary patterns, and functional divergence of nitrogen fixation-related genes-utilizing comparative genomics approaches-has emerged as a key direction in current plant molecular biology and crop genetic improvement research. Focusing on major legume crops such as soybean, pea, peanut, and alfalfa, this review systematically summarizes the molecular mechanisms underlying nitrogen fixation in legumes and the key genes regulating this process. Particular emphasis is placed on analyzing recent progress in identifying genes associated with nitrogen fixation signal recognition, nodule development regulation, and nitrogen metabolism. Building upon this foundation and integrating findings from comparative genomics studies, a comprehensive analysis is conducted regarding the evolutionary characteristics of nitrogen fixation-related genes in major legume crops, examining aspects such as gene family structure, sequence conservation, gene duplication, and phylogenetic relationships. Furthermore, using the NIN gene family-a key regulator of nitrogen fixation in soybean-as a case study, the review explores its evolutionary patterns across different legume species and its potential value for improving nitrogen fixation efficiency. Finally, this paper discusses the future prospects for applying comparative genomics in the mining of nitrogen fixation genes, the development of molecular markers, and molecular design breeding, while also offering perspectives on future directions for multi-omics integration research. The findings indicate that comparative genomics provides a crucial theoretical foundation for unraveling the mechanisms of nitrogen fixation in legumes and facilitating their genetic improvement, thereby holding significant importance for advancing the development of green agriculture.

Legume crops; Biological nitrogen fixation; Comparative genomics; Nodule formation; Nitrogen fixation genes