Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice

Ammonium and nitrate nitrogen are the two main forms of inorganic nitrogen (N) available to crops. However, it is not clear how mixtures of ammonium and nitrate N affect N uptake and partitioning in major rice cultivars in southern China. This study investigated the effects of different ammonium nit...

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Main Authors: Xianting Fan, Chusheng Lu, Zaid Khan, Zhiming Li, Songpo Duan, Hong Shen, Youqiang Fu
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/4/611
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author Xianting Fan
Chusheng Lu
Zaid Khan
Zhiming Li
Songpo Duan
Hong Shen
Youqiang Fu
author_facet Xianting Fan
Chusheng Lu
Zaid Khan
Zhiming Li
Songpo Duan
Hong Shen
Youqiang Fu
author_sort Xianting Fan
collection DOAJ
description Ammonium and nitrate nitrogen are the two main forms of inorganic nitrogen (N) available to crops. However, it is not clear how mixtures of ammonium and nitrate N affect N uptake and partitioning in major rice cultivars in southern China. This study investigated the effects of different ammonium nitrogen and nitrate nitrogen mixture treatments (100:0, 75:25, 50:50, 25:75, and 0:100) on the growth, photosynthetic characteristics, nitrogen uptake, gene expression, and yield of different rice cultivars (Mei Xiang Zhan NO. 2: MXZ2; Nan Jing Xiang Zhan: NJXZ). Rice root biomass, tiller number, and yield were increased by 69.5%, 42.5%, and 46.8%, respectively, in the 75:25 ammonium-nitrate mixed treatment compared to the 100:0 ammonium-nitrate mixed treatment. The nitrogen content in rice roots, stems, leaves, and grains increased by 69.5%, 64.0%, 65.5%, and 17.5%, respectively. In addition, compared with MXZ2, NJXZ had a greater proportion of N allocated to leaves and grains. Analysis of root enzyme activities revealed that the 75:25 ammonium-nitrate mixed nutrient treatment increased rice root glutamine synthetase activity by an average of 35.0% and glutamate synthetase activity by an average of 52.0%. Transcriptome analysis revealed that the 75:25 mixed ammonium-nitrate nutrient treatment upregulated the expression of genes related to the nitrogen metabolism transporter pathway. Weighted correlation network analysis revealed that some differentially expressed genes (<i>HISX</i> and <i>RPAB5</i>) regulated the activities of nitrogen-metabolizing enzymes in rice and some (<i>SAT2</i>, <i>CYSKP</i>, <i>SYIM</i>, <i>CHI1</i>, and <i>XIP1</i>) modulated amino acid synthesis; greater expression of these genes was detected in the 75:25 ammonium-nitrate mixed nutrient treatment. The expression characteristics of the above genes were further confirmed by RT‒qPCR. Interestingly, the expression levels of the above genes were significantly correlated with the glutamate synthase activity, photosynthetic rate, and root volume. It is noteworthy that increasing the expression of the aforementioned genes coupled with nitrogen uptake was observed in the three main rice cultivars. These results suggest that the 75:25 ammonium-nitrate mixture may have increased nitrogen-metabolizing enzyme activities and promoted nitrogen uptake through the upregulated expression of nitrogen metabolism-related genes, thereby increasing tiller number and improving rice yield.
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spelling doaj-art-0c4bb246751b4e0584dfc6d8710f9fce2025-08-20T02:44:56ZengMDPI AGPlants2223-77472025-02-0114461110.3390/plants14040611Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in RiceXianting Fan0Chusheng Lu1Zaid Khan2Zhiming Li3Songpo Duan4Hong Shen5Youqiang Fu6College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaCollege of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaCollege of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaCollege of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaCollege of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaCollege of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, ChinaRice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaAmmonium and nitrate nitrogen are the two main forms of inorganic nitrogen (N) available to crops. However, it is not clear how mixtures of ammonium and nitrate N affect N uptake and partitioning in major rice cultivars in southern China. This study investigated the effects of different ammonium nitrogen and nitrate nitrogen mixture treatments (100:0, 75:25, 50:50, 25:75, and 0:100) on the growth, photosynthetic characteristics, nitrogen uptake, gene expression, and yield of different rice cultivars (Mei Xiang Zhan NO. 2: MXZ2; Nan Jing Xiang Zhan: NJXZ). Rice root biomass, tiller number, and yield were increased by 69.5%, 42.5%, and 46.8%, respectively, in the 75:25 ammonium-nitrate mixed treatment compared to the 100:0 ammonium-nitrate mixed treatment. The nitrogen content in rice roots, stems, leaves, and grains increased by 69.5%, 64.0%, 65.5%, and 17.5%, respectively. In addition, compared with MXZ2, NJXZ had a greater proportion of N allocated to leaves and grains. Analysis of root enzyme activities revealed that the 75:25 ammonium-nitrate mixed nutrient treatment increased rice root glutamine synthetase activity by an average of 35.0% and glutamate synthetase activity by an average of 52.0%. Transcriptome analysis revealed that the 75:25 mixed ammonium-nitrate nutrient treatment upregulated the expression of genes related to the nitrogen metabolism transporter pathway. Weighted correlation network analysis revealed that some differentially expressed genes (<i>HISX</i> and <i>RPAB5</i>) regulated the activities of nitrogen-metabolizing enzymes in rice and some (<i>SAT2</i>, <i>CYSKP</i>, <i>SYIM</i>, <i>CHI1</i>, and <i>XIP1</i>) modulated amino acid synthesis; greater expression of these genes was detected in the 75:25 ammonium-nitrate mixed nutrient treatment. The expression characteristics of the above genes were further confirmed by RT‒qPCR. Interestingly, the expression levels of the above genes were significantly correlated with the glutamate synthase activity, photosynthetic rate, and root volume. It is noteworthy that increasing the expression of the aforementioned genes coupled with nitrogen uptake was observed in the three main rice cultivars. These results suggest that the 75:25 ammonium-nitrate mixture may have increased nitrogen-metabolizing enzyme activities and promoted nitrogen uptake through the upregulated expression of nitrogen metabolism-related genes, thereby increasing tiller number and improving rice yield.https://www.mdpi.com/2223-7747/14/4/611riceammonium-nitrate mixed nutritionnitrogen metabolism enzymestranscriptomicsroot morphology
spellingShingle Xianting Fan
Chusheng Lu
Zaid Khan
Zhiming Li
Songpo Duan
Hong Shen
Youqiang Fu
Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
Plants
rice
ammonium-nitrate mixed nutrition
nitrogen metabolism enzymes
transcriptomics
root morphology
title Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
title_full Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
title_fullStr Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
title_full_unstemmed Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
title_short Mixed Ammonium-Nitrate Nutrition Regulates Enzymes, Gene Expression, and Metabolic Pathways to Improve Nitrogen Uptake, Partitioning, and Utilization Efficiency in Rice
title_sort mixed ammonium nitrate nutrition regulates enzymes gene expression and metabolic pathways to improve nitrogen uptake partitioning and utilization efficiency in rice
topic rice
ammonium-nitrate mixed nutrition
nitrogen metabolism enzymes
transcriptomics
root morphology
url https://www.mdpi.com/2223-7747/14/4/611
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