ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Metabolism and Chemodiversity
Integrated Transcriptomic and Metabolic Profiling Reveals the Molecular Mechanism of Improved Nitrogen Metabolism in Walnut (Juglans regia L.) Roots Mediated by Soybean Intercropping
Provisionally accepted
- 1CAAS Gansu Academy of Agricultural Sciences, Lanzhou, China
- 2Longnan Normal University, Longnan, China
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The practice of intercropping young walnut orchards with soybeans has emerged as a promising approach within the framework of sustainable agricultural management. However, the precise impacts of soybean intercropping on nitrogen metabolism in walnut roots remain insufficiently elucidated. This study systematically investigated the regulatory mechanisms of nitrogen metabolism in the walnut-soybean intercropping system using metabolomics and RNA-seq analysis. By determination relevant indicators, we observed that the dry matter accumulation of both aboveground tissues and roots in intercropped walnuts was significantly higher than that in monocropped walnuts, with the root system had a distinct vertical growth advantage. The nitrogen content in aboveground portions during dormancy and in roots during the hard kernel stage and dormancy was markedly elevated compared to monoculture systems. Metabolomics analysis revealed that differential metabolites in walnut under intercropping are significantly enriched in the carbon-nitrogen metabolic pathways and nitrogen transmembrane transport pathways. RNA-seq analysis identified 3,978 differentially expressed genes (DEGs), with significantly enrichment in the “nitrogen utilization” pathway. Furthermore, integrated analysis indicated that nitrogen metabolites may play a significant role in the walnut intercropping system. Key genes associated with nitrogen metabolism (NR, NIR, GOGAT, GDH, NRT, and AMT) exhibited significant alterations under the intercropping system. Enzyme activity validation demonstrated that intercropping substantially enhanced the activities of GS, GOGAT, and other enzymes, thereby strengthening the GS/GOGAT cycle responsible for converting inorganic nitrogen into organic nitrogen. This study confirms that walnut-soybean intercropping promotes dry matter accumulation and nitrogen allocation by activating root carbon-nitrogen metabolic pathways and the expression of nitrogen metabolism-related genes. These findings provide critical metabolic and transcriptional evidence supporting the sustainable development of intercropping systems in dryland orchards.
Keywords: walnut and soybean intercropping, nitrogen metabolism, transcriptome analysis, metabolomics analysis, multi-omics
Received: 03 Jul 2025; Accepted: 08 Dec 2025.
Copyright: © 2025 Ren, Liu, Wang, Jiang and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jing Ren
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