Carbon allocation and carbohydrate dynamics in tea plants regulating source sink relationships stress adaptation and quality

Carbohydrates play a fundamental role in regulating growth, carbon allocation, and stress resilience in tea (Camellia sinensis L.), a perennial crop subjected to continuous biomass removal through plucking. Structural carbohydrates, including cellulose, hemicellulose, and pectins, contribute to cell wall integrity, tissue stability, and processing-related biochemical transformations, while Non-structural carbohydrates (NSCs), including starch and soluble sugars, function as dynamic reserves that mediate source–sink interactions, seasonal growth patterns, and recovery processes. This review integrates recent advances in carbohydrate metabolism with physiological, biochemical, and molecular mechanisms governing carbon partitioning, providing a comprehensive perspective on how carbohydrate dynamics influence growth, productivity, stress adaptation, and tea quality. Particular emphasis is placed on photosynthetic regulation, enzymatic control, hormonal interactions, and seasonal fluctuations in NSCs that determine shoot development, yield stability, and environmental responses. The review further examines the role of carbohydrate metabolism in mediating plant responses to abiotic stresses, including drought and temperature extremes, and discusses its interaction with secondary metabolite biosynthesis underlying tea quality. Key research gaps are identified, including limited understanding of whole-plant carbon budgeting, root–shoot carbon fluxes, stable isotope-based carbon tracing, genotype-specific carbon allocation, and the integration of multi-omics approaches. Future research directions highlight system-level strategies to improve carbon economy, strengthen climate resilience, and support the development of sustainable tea production systems. Carbohydrate dynamics regulate growth, yield, and resilience in Camellia sinensis L. NSCs control source–sink balance and seasonal carbon allocation. Photosynthetic, enzymatic, and hormonal networks coordinate carbon metabolism in tea. Carbon allocation influences tea quality via secondary metabolite biosynthesis. Stress and agronomic practices modulate carbohydrate partitioning and productivity.