Abstract
BACKGROUND: Epigallocatechin gallate (EGCG) imparts unique health benefits and flavour to tea. Photosynthesis plays a crucial role in modulating secondary metabolite production in plants, and this study investigated its impact on the biosynthesis of EGCG in tea plants under different ecological conditions. RESULTS: Enhanced photosynthetic activity and the increased EGCG content, total esterified catechins (TEC), total catechins (TC) responded synchronously to changes in ecological factors. The photosynthetic capacity of tea plants and the EGCG content fit surface model equations (Extreme 2D and Polynomial 2D) and multiple regression equations (R(2) > 70%). Additionally, logistic regression and ROC curves revealed that photosynthetic capacity was related to EGCG accumulation patterns in response to ecological variations. Upon perceiving ecological changes, the response of photosynthesis-related genes (CspsaA from photosystem I, CspsbB, CspsbC from photosystem II, and CsLHCB3 from the antenna protein pathway) was associated to carbon cycle-related genes (CsALDO, CsACOX, CsICDH, Csrbcs), which mediated the expression of CsPAL in the phenylalanine pathway; CsaroDE in the shikimate pathway; and CsCHS, CsF3H, CsF3'H, and CsANS in the flavonoid pathway. Eventually, this influenced the accumulation of EGCG and its precursors (gallic acid and epigallocatechin) in tea plants. CONCLUSIONS: This study reveals the effects of photosynthesis on EGCG biosynthesis in response to ecological factors, providing insights for optimizing tea cultivation and quality.