烟草细胞壁DUF642蛋白在授粉受精中的功能及作用机制研究

授粉受精是植物繁衍的重要环节，花粉管生长受自身和雌蕊细胞壁特性的高度调节。DUF642蛋白可能通过增强PME活性或结合多糖调节细胞壁特性，但其在授粉受精中的功能及作用机制不清楚，其N端结构域功能也未知。我们研究发现，定位于细胞壁的烟草DUF642成员XP 177在授粉亲和性不同的雌蕊中表达差异显著，其在雌蕊的花粉管生长通道中、花粉管顶端及花粉发育成熟期表达；其同源基因XP 117仅在雌蕊表达，推测它们功能相关但存在差异，在花粉发育，花粉管生长和授粉过程中发挥功能。免疫共沉淀表明，XP 177和PGIP互作。本项目拟构建突变体鉴定XP 177和XP 117在授粉受精中的功能及其作用机制；验证XP 177与细胞壁多糖、PME及PGIP的互作，探明其N端结构域的功能，解析其结构与细胞壁特性调节功能的关系。本项目的实施将增进对花粉-雌蕊互作调控机制的认识，对植物繁衍和育种有重要意义。

Pollination and fertilization are the key steps in plant reproduction. The growth of pollen tube is highly regulated by the cell wall characteristics of itself and the pistil. The DUF642 protein may regulate the cell wall characteristics through pectin methylesterase (PME) or binding to the cell wall polysaccharides, but its function and the regulatory mechanism in pollination and fertilization are unclear, and the function of its N-terminal DUF642 domain is unknown. Our previous work has shown that the cell wall XP 177 protein,a member of DUF642 family in Nicotiana tabacum, was differentially expressed between self-compatible and cross-incompatible pistils, and was expressed in the pollen tube growth path of the pistil, and at the tip of growing pollen tubes and in the maturing pollen grains. XP 117, the homologous DUF 642 member of XP 177, was only expressed in the pistil, indicating that their functions are related but different. Co-IP analysis showed that XP 177 may interact with the polygalacturonase inhibitor (PGIP). This project is intended to explore the function and regulatory mechanisms of XP 177 in pollination and fertilization. Furthermore, we will verify whether XP 177 binds to the cell wall polysaccharides, or interacts with PME and PGIP, study the function of the N-terminal DUF642 domain of XP 177 protein, in order to know about how the structure of XP 177 was related to its function in regulating cell wall characteristics. This project will improve our understanding on the regulatory mechanisms of pollen-pistil interaction, which is of great significance to plant reproduction and breeding.