Enhancing polyphenol synthesis and antioxidant activity in <i>Camellia sinensis</i> using shikimic and salicylic acids

Abstract Background Camellia sinensis , widely consumed as tea, is the second most popular beverage globally and is valued for its health benefits. However, environmental stressors pose a significant challenge to the tea industry. This study investigates the potential of shikimic acid (ShA) and its derivative, salicylic acid (SA), as inducers to enhance polyphenol content and antioxidant activity across different growth stages. Results Experiments on Biclonal Tea Stock 1 (BTS1) family plants, including 4‐month‐old seedlings and 2‐year‐old plants, revealed significant increases in polyphenol levels and antioxidant activity following induction, though effects diminished over time. SA provided a stronger initial boost, whereas ShA sustained longer‐lasting effects. Two‐year‐old plants exhibited greater baseline polyphenol levels and a stronger response to induction than seedlings. A strong correlation between polyphenol accumulation and antioxidant activity was also observed. Molecular docking simulations suggested that SA signaling facilitates NPR1‐TGA and NPR1‐WRKY binding to the PAL promoter, enhancing PAL gene transcription. Additionally, polyphenols such as flavones, p‐coumaric acid, gallic acid, and caffeic acid were found to interact with the PAL enzyme through mechanisms similar to that of trans‐cinnamic acid and may, therefore, act as feedback inhibitors in a manner analogous to trans‐cinnamic acid. Conclusion These findings provide novel insights into optimizing tea plant defenses and enhancing polyphenol‐related health benefits, offering potential strategies for improving tea quality and resilience against environmental stress.