State Key Laboratory for Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China.
College of Plant Protection, Northwest Agriculture and Forestry University, Yangling, China.
Plant Biotechnol J. 2024 May;22(5):1335-1351. doi: 10.1111/pbi.14270. Epub 2023 Dec 15.
Thiamine (vitamin B1) biosynthesis involves key enzymes known as thiazole moieties (THI1/THI2), which have been shown to participate in plant responses to abiotic stress. However, the role of THI1/THI2 in plant immunity remains unclear. In this study, we cloned TaTHI2 from wheat and investigated its function in Chinese wheat mosaic virus (CWMV) infection. Overexpression of TaTHI2 (TaTHI2-OE) inhibited CWMV infection, while TaTHI2 silencing enhanced viral infection in wheat. Interestingly, the membrane-localized TaTHI2 protein was increased during CWMV infection. TaTHI2 also interacted with the Ca-dependent protein kinase 5 (TaCPK5), which is localized in the plasma membrane, and promoted reactive oxygen species (ROS) production by repressing TaCPK5-mediated activity of the catalase protein TaCAT1. CWMV CP disrupted the interaction between TaTHI2 and TaCAT1, reducing ROS accumulation and facilitating viral infection. Additionally, transgenic plants overexpressing TaTHI2 showed increased seed number per ear and 1000-kernel weight compared to control plants. Our findings reveal a novel function of TaTHI2 in plant immunity and suggest its potential as a valuable gene for balancing disease resistance and wheat yield. Furthermore, the disruption of the TaTHI2-mediated plant immune pathway by CWMV CP provides further evidence for the evolutionary arms race between plants and viruses.
硫胺素（维生素 B1）的生物合成涉及被称为噻唑部分（THI1/THI2）的关键酶，这些酶已被证明参与植物对非生物胁迫的反应。然而，THI1/THI2 在植物免疫中的作用尚不清楚。在这项研究中，我们从小麦中克隆了 TaTHI2，并研究了它在小麦花叶病毒（CWMV）感染中的功能。TaTHI2 的过表达（TaTHI2-OE）抑制了 CWMV 的感染，而 TaTHI2 的沉默增强了小麦中的病毒感染。有趣的是，在 CWMV 感染过程中，膜定位的 TaTHI2 蛋白增加。TaTHI2 还与钙依赖性蛋白激酶 5（TaCPK5）相互作用，TaCPK5 定位于质膜，通过抑制 TaCPK5 介导的过氧化氢酶蛋白 TaCAT1 的活性来促进活性氧（ROS）的产生。CWMV CP 破坏了 TaTHI2 与 TaCAT1 之间的相互作用，减少了 ROS 的积累，促进了病毒的感染。此外，过表达 TaTHI2 的转基因植物与对照植物相比，每穗种子数和千粒重增加。我们的研究结果揭示了 TaTHI2 在植物免疫中的新功能，并表明其作为平衡抗病性和小麦产量的有价值基因的潜力。此外，CWMV CP 破坏 TaTHI2 介导的植物免疫途径为植物和病毒之间的进化军备竞赛提供了进一步证据。
