硫化氢（H2S）是一种新发现的植物成熟与衰老调控因子，最近我们发现，H2S通过拮抗乙烯延缓果实的成熟与衰老进程，基于半胱氨酸（Cys）同时是H2S与乙烯的直接或间接的生物合成前体，我们推测，Cys与H2S信号的动态平衡，是调控果实成熟与衰老进程去向的分子开关。本项目拟以番茄为主要材料，构建“H2S↔Cys”代谢通路中关键基因（SiR、LCD、CAS等）的番茄超表达和缺失突变体；采用免疫组化、原位杂交与激光共聚焦技术，实时监测果实成熟衰老进程中Cys与H2S的消长规律和时序变化，探查调控H2S↔Cys动态平衡的关键基因的时空表达模式；利用Biotin Switch方法，解析受H2S信号激活的H2S↔Cys关键酶的巯基化修饰位点及生理作用；通过转录组和代谢组分析，构建野生型与突变体果实转录和代谢水平的差异网络图谱；从而系统阐明H2S↔Cys动态平衡调控果实成熟与衰老进程的分子机制与生理意义。

Hydrogen sulfide (H2S) is a newly discovered regulator of plant ripening and senescence. Our recent research revealed that H2S delayed fruit ripening and senescence by antagonizing the effect of ethylene. Based on the fact that cysteine (Cys) is the direct or indirect precursor of both H2S and ethylene biosynthesis, we speculate that the dynamic balance between Cys and H2S signal is the molecular switch in regulating fruit ripening and senescence. In this project, tomato (Solanum lycopersicum) will be used as the experimental material, and the over-expression and deletion mutants of the key genes (SiR, LCD, CAS etc) involved in the metabolic pathway of “H2S↔Cys” will be constructed. The immunohistochemical technologies in combination with in-situ hybridization and laser confocal microscopy will be used to monitor the real-time changes of subcellular Cys and H2S, and the spatiotemporal expression patterns of the key genes involved in the metabolic pathway of “H2S↔Cys” during fruit ripening and senescence. The Biotin switch method will be used to analyze the thiolation modification sites and physiological functions of the “H2S↔Cys” metabolism-related enzymes activated by H2S signal in the process of fruit ripening and senescence. By transcriptome sequencing and metabolomics assay, the differential network map of transcriptome and metabolome will be constructed in the wild type tomato and mutants, thereby systematically elucidating the molecular mechanism and physiological significance of H2S↔Cys dynamic homeostasis in regulating fruit ripening and senescence.