植物失水将引起细胞伤害甚至死亡，植物种胚具有耐严重脱水且保持细胞活力的罕见特性。莲子寿命极长，莲胚具有强大的抗逆保护能力，申请人前期筛选到LEA家族脱水素DHN Rab18在成熟莲胚中显著富集，并发现此蛋白可显著提升离体细胞极度脱水后的细胞活性，但其保护机制尚不明确。本项目拟开展抗逆生理检测与蛋白组学技术，明确种胚脱水生理特征，构建蛋白调控网络；通过启动子转基因检测与酵母单杂技术，分析莲Rab18应答模式与转录调控机制；应用Rab18同源转化实验，根据基因定位、种子衰老检测、胁迫耐受评价等，确定Rab18的作用靶点与逆境保护功能；利用体外实验体系，明确Rab18对蛋白活性、质膜系统、离子平衡、ROS清除的调控作用，结合蛋白二级结构、胞质水合性质与热物性分析，阐明Rab18对生物大分子的保护机制。本项目可进一步完善植物脱水逆境生理的理论基础，为改善植物抗逆性、种质资源保存与创新提供科学依据。

Water is the most important element for any living organism. Dehydration of a living cell has great physical and chemical effects on cellular and macromolecular structures and usually causes irreparable changes, which ultimately lead to cell death. Most angiosperms do not survive when the relative cellular water content is below 60%. In higher plants, orthodox seeds or pollen grains with low water content can maintain germination ability for years or decades under favorable conditions, and desiccation tolerance is a prerequisite for seeds to acquire longevity. Recent studies found that late embryogenesis abundant (LEA) proteins were induced by dehydration and abscisic acid, and played an important role in desiccation tolerance during seed maturation. Lotus (Nelumbo nucifera) seed has the characteristic of longevity and can be stored for thousands of years. In our previous study, we used embryology and western blot technology to screen an important LEA family protein, dehydrin Rab18, which significant enriched in seed embryo and protected the cell during late embryogenesis. Dehydrin (DHN) can protect nucleic acids, protein and membrane structure, which is closely related to the stress tolerance in plants. This project intends to explore the protection mechanism of DHN Rab18 expression regulation by the promoter cloning and cis-acting element analysis; to determine the subcellular localization of the protein by immuno electron microscopy and protein transient expression technologies; furthermore, application of in vivo and in vitro protein function validation, proteomics, combined with biological physics, and molecular structure analyses reveal the protein protective effect on membrane system, ROS metabolism, antioxidant system, ion affinity, enzyme activity, and cell hydration characteristics. Elucidate the structural and functional differences and cell protective mechanism of DHN Rab18 under complex stress conditions. This study will provide a new insight for improving plant stress tolerance, and supplement theoretical foundation for plant desiccation tolerance regulation and utilization.