甲基化修饰对硫化氢信号分子调控大白菜花期的影响

Chinese Cabbage (Brassica rapa L. ssp. pekinesis) is one of the favorare vegetables in China. Research on its regulation of bolting and flowering is a hot topic. However, the regulation mechanism is largely unknown. Hydrogen sul?de (H2S) has been proposed as the third gasotransmitter after nitric oxide (NO) and carbon monoxide (CO), whose physiological functions in mammals have been fully confirmed, thus making it a hot research area. In recent years, great improvement has also been achieved with respect to the studies on H2S function in plants. LCD（L-cysteine desulphydrase）is a key gene encoding the endogenous H2S-generating enzyme in plant. Protein arginine methylation is one of the most important posttranslational modifications. AtPRMT5 is an Arabidopsis homolog of human PRMT5 which was a type II protein arginine methyltransferase. AtPRMT5 deficiency causes pleiotropic phenotypes, including delayed flowering, growth retardation, and so on. However, how AtPRMT5 impacts these biological processes is largely unknown. In previous studies, we found that H2S treatment in physiological concentrations can significantly promote bolting and flowering in Chinese cabbage. In this process, the expression of the major flowering repressor FLOWERING LOCUS C (FLC), a MADS-box transcription factor that quantitatively blocks the floral transition in plant was repressed. The simulation analysis on this phenomenon in Arabidopsis Thaliana revealed that H2S treatment can really promote flowering through inhibit the expression of FLC. The activity of LCD was modulated significantly by AtPRMT5 through methylation. In this project, taking the effect that H2S can regulate the flowering time in Chinese Cabbage as the clue, keeping the modulation of PRMT5 on LCD as the core issues, using the experimental evidences in Arabidopsis as references (for there is a perfect linear relationship between the genes in Chinese Cabbage and that in Arabidopsis), we plan to research on the regulation mechanisim of flowering time in Chinese Cabbage in physiology, cell biology, molecular biology and biochemistry level to explore the more simple, rapid and effective way of flowering regulation, and apply to the breeding and producing on Chinese cabbage.

大白菜(Brassica rapa L. ssp. pekinesis)作为重要的蔬菜作物，其花期调控机理研究有重要理论意义和应用价值。H2S是继NO、CO之后第三种气体信号分子，在植物中的重要生理作用日渐引起重视，而LCD是一个植物内源H2S产生的关键酶。PRMT5是一种重要的II型精氨酸甲基转移酶，缺失突变可引起植物晚花、发育迟缓等表型。前期试验我们证实，生理浓度的H2S可以使大白菜花期显著提前。以拟南芥为材料对这一现象模拟实验表明：AtPRMT5可甲基化AtLCD从而影响其活性，调节内源H2S释放；H2S对植物花期的影响依赖于转录因子FLC。本研究以H2S对大白菜花期的调控作用为线索，以PRMT5对LCD的甲基化修饰及活性调节为核心，以拟南芥中的实验证据为参考（二者基因组有良好的线性对应关系），从一个新的视角进行大白菜花期调节机制的探索，从而发掘简单快速有效的大白菜花期调节方式。

大白菜(Brassica rapa L. ssp. pekinesis)作为重要的蔬菜作物，其花期调控机理研究有重要理论意义和应用价值。H2S是继NO、CO之后第三种气体信号分子，在植物中的重要生理作用日渐引起重视，而LCD是一个植物内源H2S产生的关键酶。PRMT5是一种重要的II型精氨酸甲基转移酶，缺失突变可引起植物晚花、发育迟缓等表型。本研究以H2S对大白菜花期的调控作用为线索，以PRMT5对LCD的甲基化修饰及活性调节为核心从一个新的视角进行大白菜花期调节机制的探索，从而发掘简单快速有效的大白菜花期调节方式。.我们证实，生理浓度的H2S可以使大白菜花期显著提前。研究证实： PRMT5和LCD定位于细胞核，双分子荧光实验证实了二者的互作。同位素实验证实PRMT5可甲基化LCD，甲基化后的LCD活性明显提高，体内产生H2S的能力增强。进一步的研究表明，H2S信号可以通过弥补植物春化不足，从而促进植物提前开花。这个过程依赖于FLC途径，这个过程可能是H2S对FLC蛋白产生了巯基化修饰造成的。.以上研究结果为我们从新视角了解植物开花调控机制以及开发植物花期调节剂应用于蔬菜生产提供了理论基础。