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Source-sink nitrogen dynamics and their response to variable nitrogen levels during rice grain filling
Xiao-Li Huang1,2,3, Yan Peng1,2,3, Zhi-Jun Xu1,2,3
1Hunan Provincial Key Laboratory of Rice Stress Biology, Hunan Agricultural University, Changsha, 410128, China.
BMC Plant Biology
|July 20, 2026
Summary
Rice grain filling depends on nitrogen remobilization from leaves. External nitrogen supply affects nitrogen dynamics in leaves and grains, impacting overall nitrogen metabolism and grain yield.
Area of Science:
- Agricultural Science
- Plant Physiology
- Biochemistry
Background:
- Rice grain yield relies heavily on nitrogen remobilization from leaves.
- Nitrogen dynamics within rice source (leaf) and sink (grain) tissues, especially under varying nitrogen supplies, are not fully understood.
Purpose of the Study:
- To investigate the dynamic changes and metabolic characteristics of major nitrogen fractions in rice flag leaves and grains.
- To understand the effects of high-nitrogen (HN) and low-nitrogen (LN) supply on nitrogen metabolism during grain filling.
Main Methods:
- Comparative analysis of nitrogen fractions (nitrate-N, ammonium-N, amino acid-N, total N) in flag leaves and grains under HN and LN conditions.
- Correlation analysis to determine relationships between different nitrogen fractions and total nitrogen.
- Enzyme activity assays (NiR, NR, GS) and transcriptomic analysis to explore regulatory mechanisms.
Main Results:
- Grain nitrate-N and amino acid-N decreased, while ammonium-N showed dynamic changes, increasing inorganic N proportion.
- Total grain nitrogen was positively correlated with ammonium-N and negatively with nitrate-N.
- Low nitrogen accelerated leaf nitrogen degradation and remobilization, while high nitrogen maintained leaf nitrogen assimilation enzyme activity.
Conclusions:
- Nitrogen dynamics in rice grains and leaves are complex and change during grain filling.
- Enzyme activity and gene expression differentially regulate nitrogen fractions under varying nitrogen supplies.
- Understanding these source-sink nitrogen dynamics is crucial for optimizing nitrogen management in rice production.
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