Identification of a unique tea germplasm exhibiting hyperaccumulation of trans-catechins and its molecular regulatory mechanism

Catechins are the principal bioactive components in tea, and their trans-isomers offer superior benefits such as tea quality, and support human health when compared with their predominant cis-forms. This study aims to identify natural tea germplasm that is rich in trans-catechins and hypothesizes that such a unique catechin composition can broadly reshape the metabolism of other flavor compounds. Herein, a unique germplasm, Y5, was identified and comprehensively profiled. Metabolomic and quantitative analysis revealed that Y5 preferentially hyperaccumulates trans-catechins over cis-catechins, with gallocatechin gallate (GCG) reaching 70.1 ± 0.3 mg/g (over 50-fold higher than controls). Moreover, Y5 exhibited rare co-accumulation of theobromine and caffeine, along with increased levels of specific proanthocyanidins and anthocyanin derivatives. The amino acid profiles changed accordingly as well. Molecular investigation revealed a coordinated regulatory network that redirects biosynthetic flux toward the trans-catechins pathway. The redirection of metabolic flux was largely affected by the late biosynthetic genes and transporters rather than the early biosynthetic genes. Serine carboxypeptidase-like acyltransferases (SCPLs) and multidrug and toxic extrusion transporters (MATEs) were identified as the key genes that facilitate GCG hyperaccumulation. This study provides a valuable resource for catechin research and a foundation for the development of GCG-rich natural tea beverages.