Nitrogen Metabolism and Use Efficiency in Plants

Plants depend on nitrogen for vital processes such as amino acid synthesis, chlorophyll formation and nucleic acid production. In nature, nitrogen is available in organic and inorganic forms, of which ammonium and nitrate are the principal sources. Uptake is mediated by specialised transporters that harness electrochemical gradients and metabolic energy to accumulate nitrogen in the root. Once inside, nitrate is reduced to ammonium by nitrate reductase and nitrite reductase, and subsequent assimilation via the glutamine synthetase–glutamate synthase cycle produces amino acids. Excess nitrogen is recycled during senescence, redistributed through vascular tissues and stored in vacuoles. Nitrogen use efficiency (NUE) reflects a plant’s ability to convert available nitrogen into biomass or yield. High NUE is essential for sustainable agriculture, as it reduces fertiliser inputs, mitigates environmental pollution and enhances food security. Recent advances have revealed complex regulatory networks that integrate nutrient signalling, epigenetic marks and cross-talk between nitrogen and other mineral pathways. Breeding strategies increasingly target key transporters, transcription factors and epigenetic regulators to optimise uptake, assimilation and allocation under variable soil conditions.

Research from Nature Portfolio

Recent studies have identified a transcription factor in rice that orchestrates nitrogen uptake and productive tiller formation through coordinated regulation of ammonium transport and tillering genes, leading to a high-NUE haplotype adapted to fertile soils. Investigations into wheat cultivars have uncovered how histone modifications underpin cultivar-specific root architecture and metabolic adaptation to low nitrogen, demonstrating that epigenetic reprogramming can shift preference between root growth and uptake strategies. Genome-wide analyses have further revealed an elite allele of a nitrate transporter in rice that enhances uptake and yield under nitrogen limitation by interacting with a key transcriptional regulator, offering a blueprint for marker-assisted breeding.

Nitrogen Metabolism and Use Efficiency in Plants publication trend

The graph below shows the total number of articles in nitrogen metabolism and use efficiency in plants across all publications each year (not limited to Nature Index journals).

Technical terms

Nitrogen use efficiency (NUE): The ratio of biomass or grain yield produced per unit of nitrogen available.

Assimilation: The enzymatic incorporation of inorganic nitrogen into organic molecules such as amino acids.

Transporter: A membrane protein that mediates the uptake or movement of nutrients across cellular membranes.

Haplotype: A combination of alleles at adjacent loci that are inherited together and may confer distinct traits.

Epigenetic modification: A heritable change in gene expression without alteration of DNA sequence, often via histone acetylation or methylation.

Tiller: A branch arising from the base of a grass plant that can bear grain and contribute to yield.

Xylem: Vascular tissue responsible for long-distance transport of water and minerals from roots to shoots.

Phloem: Vascular tissue that distributes photoassimilates and nutrients from source to sink tissues.

References

1. The elite haplotype OsGATA8-H coordinates nitrogen uptake and productive tiller formation in rice. Nature Genetics (2024).
2. Epigenetic modifications regulate cultivar-specific root development and metabolic adaptation to nitrogen availability in wheat. Nature Communications (2023).
3. Genome-wide associated study identifies NAC42-activated nitrate transporter conferring high nitrogen use efficiency in rice. Nature Communications (2019).
4. Knockdown of a Rice Stelar Nitrate Transporter Alters Long-Distance Translocation But Not Root Influx. Plant Physiology (2012).
5. Two Phloem Nitrate Transporters, NRT1.11 and NRT1.12, Are Important for Redistributing Xylem-Borne Nitrate to Enhance Plant Growth. Plant Physiology (2013).
6. Agronomic nitrogen‐use efficiency of rice can be increased by driving OsNRT2.1 expression with the OsNAR2.1 promoter. Plant Biotechnology Journal (2016).
7. Improving Nitrogen Use Efficiency in Crops for Sustainable Agriculture. Sustainability (2011).