Polyphenols are important active components in tea plants, which have strong biological activity and antioxidant activity. A certain degree of stress or exogenous substances can significantly increase the content of polyphenols in plants. γ-Aminobutyric acid (GABA), a natural functional amino acid, was used to study whether exogenous GABA can increase the content of polyphenols and enhance antioxidant activity in tea plants under heat-stress conditions. The results showed that the content of GABA was positively correlated with the content of polyphenols (r = 0.649), especially with the content of total catechins (r = 0.837). Most of the related genes encoding flavonoid metabolism (PAL, C4H, 4CL, CHS, CHI, F3H, F3′H, F3′5′H, DFR, LAR, ANS, ANR and FLS) as well as enzyme activities (PAL, C4H and 4CL) were upregulated. In addition, the activities of antioxidant enzymes were induced under heat-stress conditions. However, 3-mercaptopropionic acid (3-MPA), an inhibitor of GABA synthesis, exhibited opposite results under heat-stress conditions compared with GABA treatment. These results indicated that GABA plays a key role in the accumulation of polyphenols and the upregulation of the antioxidant system in tea plants under heat-stress conditions.

多酚是茶树中重要的活性成分，具有很强的生物活性和抗氧化活性。一定程度的胁迫或外源物质会显着增加植物中多酚的含量。γ-氨基丁酸（GABA）是一种天然功能氨基酸，用于研究外源GABA是否可以增加茶树在热胁迫条件下的多酚含量并增强其抗氧化活性。结果表明，GABA的含量与多酚的含量呈正相关（r = 0.649），特别是与儿茶素总含量（r = 0.837）呈正相关。大多数相关的编码类黄酮代谢的基因（PAL，C4H， 4CL ，CHS，CHI，F3H，F3'H，F3'5'H，DFR，LAR，ANS，ANR和FLS和酶活性（PAL，C4H和4CL）均被上调。另外，在热应激条件下诱导了抗氧化酶的活性。然而，与GABA处理相比，GABA合成抑制剂3-巯基丙酸（3-MPA）在热应激条件下表现出相反的结果。这些结果表明，在热胁迫条件下，GABA在茶树中多酚的积累和抗氧化系统的上调中起关键作用。