Spatial metabolic heterogeneity in tea shoots underpins tea flavor and sensory quality

Tea (Camellia sinensis L.) flavor is a major determinant of consumer preference and market value, yet the heterogeneous metabolic profiles of tea shoot tissues complicate quality prediction and limit precision control in production. This review systematically proposes a spatial flavor metabolism framework for the tea shoot, with the aim of elucidating coordinated metabolic mechanisms among its different tissues. By integrating cutting-edge empirical evidence from plant physiology and flavor chemistry, we map the tissue-specific metabolic roles of trichomes, buds, leaves, and stems within the tea flavor network, and illustrate how their interactions shape the overall sensory profile. Tea shoots exhibit pronounced spatial metabolic specialization. Buds function as key metabolic hubs, accumulating aroma glycosides, amino acids, and galloylated catechins that contribute to the fresh and floral flavor profile of tea. Leaves modulate bitterness and aroma with maturity, while purple and albino phenotypes alter anthocyanin and catechin fluxes, generating distinct flavors. Trichomes contain lower levels of flavonol and flavone glycosides but are rich in free amino acids (e.g., L-theanine, glutamic acid, and asparagine), which reduce bitterness while enhancing umami taste. Stems are often regarded as by-products; however, they play important roles in the transport and storage of L-theanine and are rich in soluble sugars and pectin. During thermal processing, these compounds participate in Maillard reactions, generating roasted aromas as well as a sweet and mellow taste. Understanding this spatial heterogeneity informs precision harvesting, tissue-targeted processing, and intelligent quality evaluation, providing a scientific basis for optimized tea production and high-quality flavor consistency.