Amino acid transporter CsBAT links GABA accumulation to flavonoid metabolism in Camellia sinensis

Abstract

γ-Aminobutyric acid (GABA), a four-carbon non-protein amino acid functions as a key signaling molecule in plants. As a signature bioactive compound in tea, GABA plays a crucial role in determining both flavor profile and health-promoting properties. Despite its importance, the molecular regulation of GABA accumulation in tea plants—especially its metabolic crosstalk with key quality determinants like flavonoids—remains elusive. While amino acid transporters are known to mediate source-sink allocation in plants, the functional characterization of GABA transporters in Camellia sinensis has been lacking. In this study, we identified and functionally characterized the bidirectional amino acid transporter CsBAT in tea plants. Through a comprehensive multiplatform validation system encompassing yeast heterologous expression, Arabidopsis genetic transformation, and tea transgenic system, we revealed that CsBAT shows vascular-specific expression and facilitates directional amino acid transport from source (mature leaves) to sink (young shoots), thereby significantly boosting GABA accumulation in buds and young leaves. Importantly, we discovered that CsBAT functionally interacts with key flavonoid biosynthetic enzymes (LAR, 4CL, C4H) within secondary metabolic networks. Our findings provide the first mechanistic link between CsBAT-mediated amino acid transport and tea quality formation, establishing both theoretical frameworks and practical tools for molecular breeding of premium tea cultivars.

Acknowledgements

We thank Prof. Wan’s and Prof. Li’s laboratory for their assistance with the yeast strains and vector plasmids used in the study. This work was supported by grants from the Hubei Provincial Key Research and Development Program (2024BBB080, 2024BBB081); the Hubei Provincial Natural Science Foundation (2019CFB178, 2022CFB472); Wuhan Industry University Research Special Project (2023110201030668); and the Earmarked Fund for China Agriculture Research System (CARS-19).

Data availability

The data underlying this article are available in the article and in its online supplementary material.

Conflicts of interest statement

Authors declare no conflicts of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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