Under low-nitrogen conditions, tea shoots shifted away from growth- and quality-related compounds such as theanine, caffeine, and several catechins, while increasing stress-related metabolites including jasmonoyl-L-isoleucine (JA-Ile), luteolin, and γ-aminobutyric acid (GABA). The work shows that nitrogen shortage does not simply reduce tea quality; it also activates a coordinated defense strategy. These findings offer potential molecular targets for breeding tea varieties with improved nitrogen-use efficiency and more stable quality under nutrient-limited cultivation conditions.
Nitrogen plays a central role in tea plant growth, photosynthesis, stress resistance, and the formation of flavor-related compounds. Earlier studies have shown that low nitrogen can alter root development, suppress amino acid synthesis, and promote the accumulation of some secondary metabolites. Yet most previous work has focused on roots rather than the commercially important new shoots used for tea production. As a result, the quality-related consequences of prolonged nitrogen deficiency in fresh tea shoots, as well as the key biomarkers and regulatory pathways involved, have remained unclear. This knowledge gap is especially important because improper nitrogen supply can change the balance between amino acids and polyphenols, directly affecting tea taste and aroma.
A study (DOI: 10.48130/bpr-0025-0041) published in Beverage Plant Research on 16 March 2026 by Shaoqun Liu’s & Peng Zheng’s team, South China Agricultural University, reveals that nitrogen deficiency drives a phased acclimation strategy in tea shoots, causing major quality trade-offs while activating gene–metabolite networks linked to stress adaptation.
To investigate this process, the team grew two-year-old clonal tea plants hydroponically and then transferred them to a nitrogen-free nutrient solution, collecting new shoots after 0, 7, 15, and 30 days. They combined physiological measurements, biochemical assays, volatile profiling by GC–MS, widely targeted metabolomics by UPLC-MS/MS, transcriptome sequencing, co-expression network analysis, and qRT-PCR validation. The results showed that nitrogen content in the shoots fell early, while the carbon-to-nitrogen ratio rose sharply, indicating resource reallocation under stress. Chlorophyll content declined, signaling reduced photosynthetic capacity, but carotenoids increased later, suggesting photoprotective adjustment. At the same time, major quality components dropped: theanine decreased dramatically, falling by 66.67% at the latest stage, and caffeine and total catechins were also reduced, while the phenol-to-amino acid ratio rose continuously. The aroma profile also changed. Nitrogen-deficient shoots accumulated more aldehydes, especially (E)-2-hexenal and decanal, producing a stronger “green” character and reducing some floral notes such as linalool and geraniol. Metabolomic and transcriptomic integration further revealed large-scale reorganization of primary and secondary metabolism. Among the most notable changes, JA-Ile increased more than 20-fold, luteolin rose roughly eightfold, and GABA increased more than threefold. Network analysis identified candidate regulatory modules linking transcription factors and metabolic outputs, including bZIP11/23/bHLH149-HCT for luteolin-related regulation, bZIP11/23/bHLH149-MYC2-JAZ for JA-Ile accumulation, and RAV2/bZIP53/ATH7-ASNS for GABA production. Together, these pathways suggest that tea shoots under nitrogen shortage redirect resources from flavor formation toward defense and homeostasis.
Overall, the study presents nitrogen deficiency as a trigger for a sophisticated survival program in tea shoots rather than a simple nutrient stress effect. By revealing how low nitrogen reshapes both tea quality traits and defensive metabolism, the work provides a framework for improving fertilization strategies and developing tea cultivars better suited to low-input, sustainable production systems.
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References
DOI
10.48130/bpr-0025-0041
Original Source URL
https://doi.org/10.48130/bpr-0025-0041
Funding Information
This work was supported by the Innovative Team Construction Project of the Modern Agricultural Industrial Technology System in Guangdong Province with agricultural products as the unit (tea industry technology system) (2024CXTD11).
About Beverage Plant Research
Beverage Plant Research (e-ISSN 2769-2108) is the official journal of Tea Research Institute, Chinese Academy of Agricultural Sciences and China Tea Science Society. Beverage Plant Research is an open-access, online-only journal published by Maximum Academic Press. Beverage Plant Research publishes original research, methods, reviews, editorials, and perspectives that advance the biology, chemistry, processing, and health functions of tea and other important beverage plants.