H2S介导CAT2硫巯基化修饰提高植物耐盐性的分子机制

Hydrogen sulfide（H2S）, a newfound gaseous signaling molecule, has been widely reported to play crucial roles in plants resistance under stress conditions, while the underlying mechanism is poorly understood. Recently, S-sulfhydration of proteins, which is directly regulated by H2S has been reported as a primary post-translational modification for H2S to exert its effects. We previously found that H2S content and its synthetase LCD and DCD activity were increased under salt stress in Arabidopsis. The H2S biosynthesis mutants (lcd, dcd and lcd dcd) shown more sensitive to salt stress than the wild type. The modified biotin‐switch method (MBST) evidence confirmed that salt stress and H2S could significantly induce S-sulfhydration of total proteins in vivo. Furthermore, in vitro results indicated that H2S induced S-sulfhydration of CAT2 (catalase2) in a dose-dependent manner and that S-sulfhydration was abolished by the application of DTT. The cat2 mutant displayed hypersensitive to salt stress compared with the wild type. Above data suggested that H2S signaling might participated in plants response to salt stress by mediating CAT2 S-sulfhydration. In this project, we will uncovers a mechanism by which H2S modulates ROS homemostatisis, through regulating the activity of CAT2 by S-sulfhydration in enhancing salt tolerance in Arabidopsis. The prospective results of this project would provide a new research view to clarify the mechanism of plant in response to salt stress.

硫化氢 (H2S) 作为一种新型气体信号分子，在调控植物响应逆境胁迫中的作用已有很多报道，但是具体的分子机制还有待探究。最近研究表明，H2S介导的蛋白硫巯基化修饰是其发挥生理作用的主要方式。我们前期以拟南芥为材料，研究发现盐胁迫能够诱导H2S含量及其合成酶LCD和DCD活性增加，LCD和DCD表达量升高；H2S合成突变体表现出盐胁迫敏感表型；盐胁迫和H2S处理均能够增强拟南芥总蛋白硫巯基化水平；H2S可以在体外硫巯基化修饰CAT2 (catalase2)；与野生型相比，cat2突变体表现出更强的盐胁迫敏感表型。这些结果强烈暗示H2S可能通过介导CAT2硫巯基化修饰参与植物响应盐胁迫。本项目将在前期基础上，深入探究H2S通过介导CAT2硫巯基化修饰，精确调控CAT2活性，维持植物体内ROS动态平衡，从而增强植物盐胁迫抗性的分子机制。为阐明植物响应盐胁迫的分子机制提供新的研究方向。

土壤盐渍化是制约现代粮食产业可持续发展的主要环境障碍之一，是全球广泛关注的农业问题。因此探究植物响应盐胁迫的分子调控机理，具有重要的研究意义和应用价值。H2S作为新兴的气体信号分子，在调控植物响应盐胁迫中的作用已有很多报道，但是具体的分子机制还有待探究。最近研究表明，H2S介导的蛋白硫巯基化修饰是其发挥生理作用的主要方式。拟南芥蛋白质硫巯基化修饰组学显示，CAT2可能是H2S硫巯基化修饰的靶蛋白。由此，我们推测，在盐胁迫下，H2S通过介导CAT2硫巯基化修饰，增强CAT2的活性，清除过量积累的ROS，减弱盐胁迫对植物造成的氧化损伤，从而增强植物对盐胁迫的耐受能力。基于以上假设，本项目以拟南芥为材料，综合利用多种生物学研究手段和技术方法，深入探究H2S参与盐胁迫应答的分子机制，通过体内和体外实验验证H2S通过介导CAT2硫巯基化修饰，增强盐胁迫下CAT2的活性；进而构建CAT2的相关遗传材料，进行盐胁迫表型观察，生理指标测定以及CAT2硫巯基化修饰水平和酶活性检测，最终阐明了H2S通过硫巯基化修饰CAT2参与植物响应盐胁迫的分子机制，揭示了植物应答非生物逆境的生理、代谢及其信号转导通路，有助于发展调控植物抗盐性的技术手段和相关产品的开发，为作物抗逆品种选育和精准栽培提供分子靶标，具有较好的理论创新和应用潜力。