Abstract

Tea (Camellia sinensis) contains bioactive metabolites such as catechins, amino acids, caffeine, and aroma compounds that contribute to characteristic tea function and flavor. Therefore, studies on biochemical formation pathways and occurrences of these characteristic specialized metabolites in tea plants are important, providing essential information for the regulation and improvement of tea quality and function. Owing to the lack of a stable genetic transformation system, obtaining direct in vivo evidence of the formation of characteristic tea specialized metabolites is difficult. Herein, we review potential strategies for studying in vivo biochemical formation pathways and multilevel distributions of specialized metabolites in tea. At the individual plant level, stable isotope-labeled precursor tracing is an approach to discovering the pathways of some specialized metabolites specifically occurring in tea and elucidating the formation of tea specialized metabolites in response to stresses. At the within-tissue level, imaging mass spectrometry can be used to investigate the in situ localization of characteristic specialized metabolites within tea tissue without sample destruction. At the cellular or subcellular level, nonaqueous fractionation is a feasible method for characterizing the distributions of nonvolatile metabolites in subcellular organs. These approaches will help explain the characteristic scientific problems in tea secondary metabolism and provide more precise information to improve tea quality or function.

茶（Camellia sinensis）含有生物活性代谢物，如儿茶素、氨基酸、咖啡因和香气化合物，这些物质有助于构成茶特色的功能和风味。因此，研究茶树特有代谢产物的生化形成途径及其在茶树中的发生规律，可以为茶叶品质和功能的调控和改良提供必要的信息。由于缺乏稳定的遗传转化系统，很难在体内直接获得茶叶特有代谢物形成的证据。在此，我们综述了研究茶叶体内生化形成途径和特殊代谢物多层次分布的潜在策略。在植物个体水平上，稳定同位素标记的前体示踪技术是一种发现茶叶中某些特殊代谢物的途径和阐明茶树特异代谢物在逆境中形成的一种方法。在组织内水平上，成像质谱技术可用于在不破坏样品的情况下，研究茶叶组织内特征性代谢产物的原位定位。在细胞或亚细胞水平上，非水分馏是明确非挥发性代谢物在亚细胞器官中分布的一种可行方法。这些方法将有助于解释茶叶次生代谢中特有的科学问题，为改善茶叶品质或功能提供更精确的信息。【百度翻译，仅供参考】