College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China.
Plant Physiol Biochem. 2021 Feb;159:363-371. doi: 10.1016/j.plaphy.2021.01.003. Epub 2021 Jan 7.
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可以显著增加植物中多酚的含量。γ-氨基丁酸（GABA）是一种天然的功能性氨基酸，本研究旨在探讨外源 GABA 是否可以在热胁迫条件下增加茶树中多酚的含量并增强其抗氧化活性。结果表明，GABA 含量与多酚含量呈正相关（r=0.649），尤其是与总儿茶素含量呈正相关（r=0.837）。大多数编码类黄酮代谢（PAL、C4H、4CL、CHS、CHI、F3H、F3’H、F3’5’H、DFR、LAR、ANS、ANR 和 FLS）以及酶活性（PAL、C4H 和 4CL）的相关基因都被上调。此外，在热胁迫条件下，抗氧化酶的活性也被诱导。然而，GABA 合成抑制剂 3-巯基丙酸（3-MPA）在热胁迫条件下的表现与 GABA 处理的结果相反。这些结果表明，GABA 在热胁迫条件下，在茶树中多酚的积累和抗氧化系统的上调中起关键作用。
