Legume Genomics and Genetics 2025, Vol.16, No.3, 108-127 http://cropscipublisher.com/index.php/lgg 108 Research Insight Open Access Discussion on the Symbiotic Relationship between Legume Crops and Soil Microorganisms and Their Ecological Benefits Ming Li, Fumin Gao Tropical Microbial Resources Research Center, Hainan Institute of Tropical Agricultural Resources, Sanya, 572025, Hainan, China Corresponding email: fumin.gao@hitar.org Legume Genomics and Genetics, 2025 Vol.16, No.3 doi: 10.5376/lgg.2025.16.0012 Received: 22 Mar., 2025 Accepted: 08 May, 2025 Published: 26 May, 2025 Copyright © 2025 Li and Gao, 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. Preferred citation for this article: Li M., and Gao F.M., 2025, Discussion on the symbiotic relationship between legume crops and soil microorganisms and their ecological benefits, Legume Genomics and Genetics, 16(3): 108-127 (doi: 10.5376/lgg.2025.16.0012) Abstract Leguminous crops form a unique symbiotic system with soil microorganisms (especially nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi), which plays an important role in agricultural ecosystems. This study reviews the biological basis of leguminous crop-microorganism symbiosis and its significance to soil microecology and agricultural sustainable development, introduces the mechanism of symbiotic nitrogen fixation, discusses how leguminous crops promote soil microecological balance by increasing soil organic matter, improving soil enzyme activity and improving soil physical and chemical properties, and explains the supporting role of microbial symbiosis on nutrient absorption and stress resistance of leguminous plants, such as improving nitrogen fixation efficiency, enhancing plant drought and salt tolerance, inducing plant immunity and biological control potential. Furthermore, from the perspective of ecological benefits, the contribution of leguminous-microorganism symbiosis in reducing fertilizer dependence and greenhouse gas emissions, restoring degraded soil functions and enhancing the stability of agricultural ecosystems is analyzed, and illustrated by cases such as soybean-rhizobium, peanut inoculants and leguminous rotation. This study hopes to provide a theoretical basis and practical reference for the role of leguminous crops and soil microbial symbiosis in sustainable agriculture. Keywords Legume crops; Soil microorganisms; Symbiotic nitrogen fixation; Ecological benefits; Sustainable agriculture 1 Introduction Symbiotic nitrogen fixation between legumes and soil microorganisms is an important source of nitrogen supply in agricultural ecosystems and has the potential to replace some chemical nitrogen fertilizers. It is estimated that the symbiosis between legumes and rhizobia can fix a large amount of nitrogen for terrestrial ecosystems every year, thereby reducing dependence on chemical fertilizers. However, environmental problems caused by long-term excessive application of chemical fertilizers are becoming increasingly prominent, such as increased greenhouse gas emissions, eutrophication of water bodies, and soil degradation. Therefore, making full use of the mutualistic symbiotic relationship between legumes and soil microorganisms to achieve the biological cycle of nutrients in the soil is of great practical significance for the development of sustainable agriculture. In addition, legumes are rich in protein and bioactive substances, and they also play a key role in ensuring food security and nutrition. Their symbiotic nitrogen fixation ability enables them to survive in poor environments and improve soil fertility (Fahde et al., 2023). Legumes have outstanding value in ecological agriculture. On the one hand, legumes provide nitrogen sources for subsequent crops through symbiotic nitrogen fixation, reduce the application of chemical fertilizers, and realize the green cycle of agricultural production (Mahama et al., 2020). For example, the introduction of leguminous crops into the crop rotation system of corn and other food crops can increase crop yields and nitrogen use efficiency, and reduce nitrogen fertilizer input and nitrogen loss (Yu et al., 2021). On the other hand, leguminous crops are often used as green manure and cover crops to improve soil, increase soil organic matter and nutrient content, promote soil microbial diversity, and thus improve the biological cycle function of farmland ecosystems. Leguminous crops have well-developed root systems and extensive symbiosis with mycorrhizal fungi, and also play a positive role in improving soil structure, preventing soil erosion, and restoring degraded soils. Therefore,
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