Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Yangling, Shaanxi, China.
Key Laboratory of Economic Plant Resources Development and Utilization in Shaanxi Province, College of Forestry, Northwest A & F University, Yangling, Shaanxi, China.
Physiol Plant. 2019 Jul;166(3):748-761. doi: 10.1111/ppl.12833. Epub 2018 Oct 2.
Glutathione S-transferases (GSTs) are important plant proteins involved in biotic and abiotic stress responses. A gene from Juglans regia, JrGSTTau1 was previously cloned and functionally characterized as an enzyme involved in improving cold tolerance in plants. To clarify the functional mechanism of JrGSTTau1 and its role in stress response, here, the JrGSTTau1 promoter including the up-stream regulators was examined using yeast one-hybrid together with transient expression assays, and the osmotic stress response ability was confirmed by comparing with wild-type plants. The 1500 bp JrGSTTau1 promoter displayed high GUS expression activity and was enhanced by mannitol stress. The promoter is composed of abundant cis-elements, some of which were osmotic stress response-related motifs, such as ABRE, DRE and MYB, indicating that the expression of JrGSTTau1 is regulated by potential up-stream regulators under abiotic stress. The transcription factors (TFs) of JrDREB2A, JrMYC2, JrMYB44, JrDof1 and JrWRKY7 were identified, which shared a similar response with JrGSTTau1 when exposed to PEG in walnut leaf and root. These results implied that JrDREB2A, JrMYC2, JrMYB44, JrDof1 and JrWRKY7 may act as up-stream regulators of JrGSTTau1 to regulate or combine functionality with JrGSTTau1 in osmotic stress response. Furthermore, compared with the WT plants, the transgenic tobacco plants that overexpress JrGSTTau1 showed improved tolerance to drought induced by osmotic stress, in which antioxidant enzymes, proline and reactive oxygen species (ROS) are involved. Our results demonstrated the positive role played by JrGSTTau1 in osmotic tolerance, which is regulated by multiple up-stream regulators.
谷胱甘肽 S-转移酶（GSTs）是参与生物和非生物胁迫反应的重要植物蛋白。先前已经克隆了来自核桃的一个基因，JrGSTTau1，并将其功能表征为参与提高植物耐冷性的酶。为了阐明 JrGSTTau1 的功能机制及其在应激反应中的作用，本文使用酵母单杂交和瞬时表达分析研究了JrGSTTau1 启动子及其上游调控元件，并通过与野生型植物比较来验证其渗透胁迫响应能力。1500bp 的 JrGSTTau1 启动子显示出较高的 GUS 表达活性，并受到甘露醇胁迫的增强。该启动子由丰富的顺式元件组成，其中一些是与渗透胁迫反应相关的元件，如 ABRE、DRE 和 MYB，表明 JrGSTTau1 的表达受到潜在的上游调控元件在非生物胁迫下的调控。鉴定了 JrDREB2A、JrMYC2、JrMYB44、JrDof1 和 JrWRKY7 等转录因子（TFs），它们在核桃叶片和根中受到 PEG 胁迫时与 JrGSTTau1 表现出相似的响应。这些结果表明，JrDREB2A、JrMYC2、JrMYB44、JrDof1 和 JrWRKY7 可能作为 JrGSTTau1 的上游调控因子，通过调节或与 JrGSTTau1 在渗透胁迫反应中结合功能。此外，与 WT 植物相比，过表达 JrGSTTau1 的转基因烟草植物对渗透胁迫诱导的干旱表现出更好的耐受性，其中涉及抗氧化酶、脯氨酸和活性氧（ROS）。我们的研究结果表明，JrGSTTau1 在渗透胁迫耐受性中发挥了积极作用，该作用受到多个上游调控因子的调控。
