Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea

Cereal/legume intercropping enhances legume nodulation and improves nitrogen use efficiency (NUE) in cereal crops. This facilitation of symbiotic nitrogen fixation (SNF) in intercropped legumes involves a complex eco-physiological mechanism driven by multiple factors. Among them, interspecific root...

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Main Authors: Yali Sun, Zefeng Wu, Falong Hu, Hong Fan, Wei He, Lianhao Zhao, Congcong Guo, Xiaoyuan Bao, Qiang Chai, Cai Zhao
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Agronomy
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Online Access:https://www.mdpi.com/2073-4395/15/7/1615
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author Yali Sun
Zefeng Wu
Falong Hu
Hong Fan
Wei He
Lianhao Zhao
Congcong Guo
Xiaoyuan Bao
Qiang Chai
Cai Zhao
author_facet Yali Sun
Zefeng Wu
Falong Hu
Hong Fan
Wei He
Lianhao Zhao
Congcong Guo
Xiaoyuan Bao
Qiang Chai
Cai Zhao
author_sort Yali Sun
collection DOAJ
description Cereal/legume intercropping enhances legume nodulation and improves nitrogen use efficiency (NUE) in cereal crops. This facilitation of symbiotic nitrogen fixation (SNF) in intercropped legumes involves a complex eco-physiological mechanism driven by multiple factors. Among them, interspecific root interactions (IRIs) are a key factor influencing SNF in intercropped legumes. Currently, it remains unclear whether and how IRIs modulate SNF to affect NUE and yield formation in legume species. In this study, maize/pea intercropping with different types of root separation [no barrier (NB) and plastic barrier (PB)] and pea monocropping (IP) were simulated in a nitrogen (N)-free nutrient matrix in pots, and the SNF, N metabolism, and N partitioning were investigated. We demonstrated that IRIs optimize SNF performance. N assimilation is positively regulated following increases in enzyme activity and gene expression in intercropped roots and nodules. Furthermore, IRIs facilitate amino acid (AA) export from nodules to roots and shoots, which is followed by an increase in AA levels in leaves (source) and leaf exudates (sink). Overall, intensive SNF drives N metabolism and alters source-to-sink N partitioning, thereby increasing NUE (by 23%) and yield (by 15%) in intercropped pea. This study reveals the positive roles of IRIs to the NUE and yield and provides useful reference material for increasing N contents derived from SNF to maximize NUE and crop yields in intercropped legumes.
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spelling doaj-art-0ee995d3ddc8426ea932e1367e3fbb6b2025-08-20T02:45:48ZengMDPI AGAgronomy2073-43952025-07-01157161510.3390/agronomy15071615Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped PeaYali Sun0Zefeng Wu1Falong Hu2Hong Fan3Wei He4Lianhao Zhao5Congcong Guo6Xiaoyuan Bao7Qiang Chai8Cai Zhao9State Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaState Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, ChinaCereal/legume intercropping enhances legume nodulation and improves nitrogen use efficiency (NUE) in cereal crops. This facilitation of symbiotic nitrogen fixation (SNF) in intercropped legumes involves a complex eco-physiological mechanism driven by multiple factors. Among them, interspecific root interactions (IRIs) are a key factor influencing SNF in intercropped legumes. Currently, it remains unclear whether and how IRIs modulate SNF to affect NUE and yield formation in legume species. In this study, maize/pea intercropping with different types of root separation [no barrier (NB) and plastic barrier (PB)] and pea monocropping (IP) were simulated in a nitrogen (N)-free nutrient matrix in pots, and the SNF, N metabolism, and N partitioning were investigated. We demonstrated that IRIs optimize SNF performance. N assimilation is positively regulated following increases in enzyme activity and gene expression in intercropped roots and nodules. Furthermore, IRIs facilitate amino acid (AA) export from nodules to roots and shoots, which is followed by an increase in AA levels in leaves (source) and leaf exudates (sink). Overall, intensive SNF drives N metabolism and alters source-to-sink N partitioning, thereby increasing NUE (by 23%) and yield (by 15%) in intercropped pea. This study reveals the positive roles of IRIs to the NUE and yield and provides useful reference material for increasing N contents derived from SNF to maximize NUE and crop yields in intercropped legumes.https://www.mdpi.com/2073-4395/15/7/1615interspecific root interactionssymbiotic nitrogen fixationN assimilationamino acid partitioning
spellingShingle Yali Sun
Zefeng Wu
Falong Hu
Hong Fan
Wei He
Lianhao Zhao
Congcong Guo
Xiaoyuan Bao
Qiang Chai
Cai Zhao
Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
Agronomy
interspecific root interactions
symbiotic nitrogen fixation
N assimilation
amino acid partitioning
title Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
title_full Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
title_fullStr Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
title_full_unstemmed Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
title_short Maize and Pea Root Interactions Promote Symbiotic Nitrogen Fixation, Thereby Accelerating Nitrogen Assimilation and Partitioning in Intercropped Pea
title_sort maize and pea root interactions promote symbiotic nitrogen fixation thereby accelerating nitrogen assimilation and partitioning in intercropped pea
topic interspecific root interactions
symbiotic nitrogen fixation
N assimilation
amino acid partitioning
url https://www.mdpi.com/2073-4395/15/7/1615
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