Cold stress significantly limits the yield and quality of tomato. Deciphering the key genes related to cold tolerance is important for selecting and breeding superior cold-tolerant varieties. γ-aminobutyric acid (GABA) responds to various types of stress by rapidly accumulating in plant. In this study, glutamic acid decarboxylase (GAD2) was a positive regulator to enhance cold stress tolerance of tomato. Overexpression of SlGAD2 decreased the extent of cytoplasmic membrane damage and increased the endogenous GABA content, antioxidant enzyme activities, and reactive oxygen species (ROS) scavenging capacity in response to cold stress, whereas Slgad2 mutant plants showed the opposite trend. In addition, SlGAD2 induced anthocyanin biosynthesis in response to cold stress by increasing the content of endogenous GABA. Further study revealed that SlGAD2 expression was negatively regulated by the transcription factor SlTHM27. However, the transcript levels of SlTHM27 were repressed under cold stress. Antioxidant enzyme activities, SlGAD2 transcript levels, GABA and anthocyanin contents were significantly increase in Slthm27 mutant plants. Further, our study demonstrated that SlTHM27 decreases SlGAD2-promoted cold resistance in tomato by repressing SlGAD2 transcription. Overall, our results showed that the SlTHM27-SlGAD2 model regulates the cold tolerance in tomato by regulating GABA and anthocyanin.

中文翻译：

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SlGAD2 是 SlTHM27 的靶标，通过介导番茄花青素生物合成来正向调节耐寒性

冷胁迫严重限制了番茄的产量和品质。破译与耐寒相关的关键基因对于选育优良耐寒品种具有重要意义。 γ-氨基丁酸（GABA）通过在植物中快速积累来响应各种类型的胁迫。在本研究中，谷氨酸脱羧酶（GAD2）是增强番茄冷胁迫耐受性的正调节因子。 SlGAD2的过表达降低了细胞质膜损伤的程度，增加了内源GABA含量、抗氧化酶活性和应对冷胁迫的活性氧（ROS）清除能力，而Slgad2突变体植物则表现出相反的趋势。此外，SlGAD2通过增加内源GABA的含量来诱导花青素生物合成以应对冷应激。进一步的研究表明，SlGAD2的表达受到转录因子SlTHM27的负调控。然而，SlTHM27 的转录水平在冷应激下受到抑制。 Slthm27突变体植株的抗氧化酶活性、SlGAD2转录水平、GABA和花青素含量显着增加。此外，我们的研究表明，SlTHM27 通过抑制 SlGAD2 转录来降低 SlGAD2 促进的番茄耐寒性。总的来说，我们的结果表明SlTHM27-SlGAD2模型通过调节GABA和花青素来调节番茄的耐冷性。