Integrated Metabolomic and Transcriptomic Analyses Provide New Perspectives into the Discoloration of Hawk Tea Tender Leaves

Background Litsea coreana (commonly known as hawk tea) is a spring-color foliage plant within the Lauraceae family. Its leaves are processed into “hawk tea” a distinctive traditional beverage in Southwest China that serves as a vital cultural and socio-economic resource within local communities. Its leaves typically exhibit red or green coloration, gradually transitioning to common green during maturation. In recent years, non-conventional tea cultivars with high anthocyanin content, particularly those displaying atypical leaf colors, have gained significant agricultural attention due to their potential advantages in tea quality. Investigating the overall pigment metabolism characteristics and associated biosynthetic pathways in hawk tea leaves exhibiting different initial colors across various maturation stages holds strong research significance and substantial application value. Results This study applied both targeted metabolomics and transcriptomics to investigate the metabolite accumulation and molecular mechanisms in the leaves of L. coreana with different leaf colors. Three anthocyanins, namely cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, and pelargonidin-3-O-glucoside significantly accumulated in the red tender leaves of L. coreana. Metabolic pathways of the various pigments were mapped, and through the combined analysis of metabolomics and transcriptomics, key enzymes involved in their synthesis were identified. Additionally, nine transcription factors, including 3 MYB, 2 bHLH, 3 C2C2 zinc finger proteins, and 1 GRAS, were predicted to directly or indirectly regulate anthocyanin biosynthesis in response to endogenous substances such as nitrogen, hormones, and sugars. Conclusion Our data reveal the core metabolites and regulatory networks involved in the coloration of L. coreana tender leaves, providing new insights for the comprehensive utilization of this resource.