乙烯和一氧化氮信号协同调控盐胁迫条件下拟南芥种子萌发的作用机制

It has been demonstrated that the gaseous plant hormone ethylene and signaling molecule nitric oxide (NO) were both tightly related to seed germination. Our previous studies have revealed that ethylene could antagonize the inhibition of germination in Arabidopsis induced by salinity by modulating the concentration of hydrogen peroxide (H2O2). In addition, exogenous SNP, an NO donor, could also promote seed germination under salinity, and its effects were largely dependent on the presence of ethylene. Our emerging results indicated that ethylene and NO were coordinately involved in modulating seed germination events under salinity, which is remained to be investigated. Regarding this issue, the organic, cellular and molecular events during seed germination process, including endogenous ethylene and NO responses at levels of signaling and synthesis, ROS production, the tissue-specific programmed cell death (PCD) localized at the adjacent transition zone and lower hypocotyl of the germinating seeds under control and salinity condition will be comparatively investigated. The techniques of histochemical dying, transmission electron microscope, in situ hybridization (ISH) and LC－MS will be employed to facilitate demonstration. Based on the above-mentioned results, we construct genetic accessions of Arabidopsis with loss-of-function or gain-of-function of ET and NO signaling to reveal the cascaded effects of them, combined with using exogenous stimulators and signaling inhibitors. We ultimately attempt to illustrate the underlying mechanisms of ET and NO governing seed germination when plants were grown in saline condition in a coordinated means.

植物气态激素乙烯（ET）与信号小分子一氧化氮（NO）在植物种子萌发进程中发挥着重要调控作用。申请人前期青年基金研究发现在盐胁迫条件下外源ET和NO均具有减少内源H2O2水平和提高种子萌发的能力，并且此过程中NO功能的产生部分依赖于ET信号。此现象表明乙烯和NO两种信号分子在此过程中存在着相互作用，但目前内在作用机制还不清楚。围绕该问题，本项目以拟南芥为对象，利用组织化学、植物解剖学、液相质谱、荧光定量PCR等技术，分别从组织、细胞和分子水平上对比阐明种子萌发进程、内源ET和NO在合成和信号层次上的响应、种子胚胎特定区域程序化死亡发生、氧化分子产生等生物学过程在对照和盐胁迫条件下的差异及关联；根据上述差异特征，借助构建的ET和NO信号增加或缺失遗传学材料，结合外源诱导、信号抑制等手段，确证ET和NO在调控种子萌发进程中信号级联效应，以期揭示ET与NO协同调控盐胁迫下种子萌发的机制。

植物气态激素乙烯（ET）与信号小分子一氧化氮（NO）在植物种子萌发进程中发挥着重要调控作用。申请人前期青年基金研究发现在盐胁迫条件下外源ET和NO均具有减少内源H2O2水平和提高种子萌发的能力，并且此过程中NO功能的产生部分依赖于ET信号。通过本项目的研究，我们利用乙烯（ET）和一氧化氮（NO）信号增加或缺失的拟南芥遗传材料，结合外源诱导、信号抑制等手段，揭示了ET和NO在调控盐胁迫条件下拟南芥种子萌发进程中信号关联效应和协调调控作用机制，为揭示植物抗盐机制及耐盐基因工程提供了理论基础。项目组已完成全部既定的研究任务。项目主要研究结果包括：1）外源NO具有促进盐胁迫下乙烯生物合成、提高乙烯反应的功能,二者可形成一个相互作用的网络，彼此促进对方的生物合成，共同参与调控萌发过程；二是NO和乙烯协调提高种子萌发和生长的耐盐性主要依赖乙烯信号组分EIN3蛋白的稳定以及乙烯合成释放；三是乙烯调控拟南芥种子胚胎细胞凋亡与油脂代谢来缓解盐胁迫伤害。总体上，本项目分别从组织、细胞和分子水平上阐明揭示了ET和NO两种信号分子共同调控盐胁迫条件下拟南芥种子萌发进程的功能及作用机制，包括调控内源ET和NO合成和信号响应、种子胚胎特定区域程序化死亡发生、氧化分子产生等生理生化过程。研究结果已发表6篇项目标注的SCI收录学术论文，影响因子合计20。分别发表在Plant Physiology and Biochemistry/Frontiers in Plant Science等国际本领域学术期刊上。