功能分析H2S调控拟南芥过氧化物酶体H2O2介导的防御响应

Unlike animals, plants cannot move to a more comfortable location to escape stresses of external origin. Instead, plants have developed coping mechanisms that allow them to withstand environmental fluctuations. Emerging evidence implicates hydrogen sulfide (H2S) in cellular acclimation to abiotic stress as well as resistance to pathogens. It has been suggested that H2S functions in the alleviation of enviromental factors triggered oxidative damage through detoxification of hydrogen peroxide (H2O2) via the up-regulation of antioxidant systems. However, the relationship between H2O2, H2S and antioxidant systmes is not yet clearly established in plants. In order to directly investigate the possible effect of H2S on the metabolism of H2O2, a Arabidopsis mutant, cat2, which has a defect in metabolism of peroxisomal H2O2, has been used as a stress mimic tool to assess the importance of H2S that could be important in oxidative stress. On the other hand, although the 'antioxidative role' of this signaling compound has been proposed, the importance of H2S in signaling remains unclear. H2S may a candidate for transmission of signals in plant responses to oxidative stress but identification of signaling roles is complicated by its 'antioxidant function'. Thus, this study aims to establish if H2S plays an important functional role in the transmission of signals downstream of H2O2.Taken together, the overall goal of this research is to exploit model study systems to investigate the potential interaction between intracellular H2O2 and H2S in the regulation of downstream responses. Studying their cross-talk may contribute to understanding and optimizing the stress responses of plants growing in a variable environment.

植物受其移动性的限制，它通过开发自身多重应对机制来抵御环境波动。研究暗示，硫化氢（H2S）可能通过上调抗氧化系统，加速过氧化氢（H2O2）的代谢，进而调控植物对胁迫适应性与抗病性。然而H2O2、H2S与抗氧化系统之间直接的互作关系尚未明确。为解决上述问题，我们利用拟南芥过氧化氢酶缺失突变体cat2作为氧化胁迫模拟工具，研究H2S对过氧化物酶体H2O2诱导的氧化胁迫的调控作用。另一方面，尽管H2S可能被认为是一种抗氧化信号分子，但是，相关研究暗示其可能信号机制不仅于此。并且受其可能的抗氧化机制干扰，鉴定H2S作为氧化信号传递子的证据一直不是十分清晰。因此，我们将研究H2S是否能够传递H2O2信号去激活其下游防御途径。总之，本项目将利用模式研究系统去揭示植物细胞内H2O2与H2S的互作对下游防御信号途径的调控机制，为理解与优化植物响应外界胁迫干扰提供理论依据。

H2O2被广泛地认为是调控植物抗病激素与衰老的关键信号分子。相关研究暗示硫化氢（H2S）参与H2O2的代谢调控，但是H2S如何调控H2O2介导的信号转导还不是很清楚。本项目以模式植物拟南芥为材料，综合采用药理学、生理学、遗传学、分子生物学、转录组学和代谢组学等多种技术手段，分析了H2S在H2O2信号转导中的调控作用。我们发现了（1）H2S是过氧化物酶体H2O2信号转导的下游负调控因子；（2）H2S负调控H2O2诱导的水杨酸途径不是通过增强抗氧化能力或清除H2O2的水平；（3）H2S通过调控细胞自噬途径抑制H2O2诱导的水杨酸信号转导途径; （4）H2S在H2O2诱导叶片衰老程序中的正调控作用；（5）H2S通过调控GSNOR1介导植物衰老基因的表达。总之，本项目建立起H2O2、H2S、细胞自噬以及水杨酸这四者之间的信号网络关系图，为进一步精细解析H2S负调控H2O2诱导的水杨酸途径提供了坚实理论依据和重要的遗传材料。同时，我们也初步建立了H2O2、H2S与一氧化氮之间在调控叶片衰老过程的关系，为深入解析H2O2或H2S以及二者之间互作调控植物衰老的分子机制提供了重要的线索和依据。