盾叶薯蓣根状茎甾体皂苷转化分子机制研究

项目名称： 盾叶薯蓣根状茎甾体皂苷转化分子机制研究

项目编号： No.31470388

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生物科学

项目作者： 李家儒

作者单位： 武汉大学

项目金额： 85万元

中文摘要： 盾叶薯蓣是世界上最重要的甾体皂苷资源植物。依甾体皂苷分子结构中F环环合状态，将其分为呋甾皂苷与螺甾皂苷，二者生物活性相差炯异。呋甾皂苷普遍存在于含甾体皂苷植物体内，在采后干燥、贮存过程中，呋甾皂苷在F26G酶解作用下，转化为相应的螺甾皂苷。迄今，关于甾体皂苷转化机制研究报道不多，盾叶薯蓣根状茎甾体皂苷转化分子机制仍为空白。基于对这一科学问题的认识现状和工作基础，拟通过构建盾叶薯蓣DzF26G基因过表达、反义表达及RNAi工程株，研究根状茎干燥过程中呋甾皂苷、螺甾皂苷与F26G变化时间进程与亚细胞分布变化；采用丙氨酸扫描定点突变方法，确定F26G关键功能残基，揭示F26G酶与呋甾皂苷作用的细胞、生化与分子生物学机制，阐明盾叶薯蓣根状茎甾体皂苷转化分子机制，使定向调控盾叶薯蓣根状茎甾体皂苷的合成与积累成为可能。项目预期成果具有重要学术价值和实践意义。

中文关键词： 盾叶薯蓣；根状茎；甾体皂苷；分子机制

英文摘要： Dioscorea zingiberensis C.H.Wright, an endemic species of China, is the world's most important resource plants of steroidal saponins. According to the open or close state of F ring in the molecular structure of steroidal saponins, steroidal saponins are divided into two types, called furostanol glycosides and spirostanol glycosides. And these two types of steroidal saponins have a clear difference in their bioactivities. In plant, furostanol glycosides are enzymatically converted into the corresponding spirostanol glycosides during postharvest treatment and storage by furostanol glycoside 26-O-β-glucosidase (F26G). So far, little is known about the conversion mechanism from furostanol glycosides to spirostanol glycosides. It is still unknown about the molecular mechanisms of the steroidal saponins conversion in the rhizome of Dioscorea zingiberensis. Based on the current understanding and research status of this scientific issue, we aim to uncover the cellular, biochemical and molecular mechanisms. To this end, we will investigate the temporal and spatial subcellular localization and time course of furostanol glycosidesm, spirostanol glycosides and F26G in rhizomes drying process by constructing overexpression, antisense expression and RNAi plants. After that, we will determine the key functional residues of F26G with the method of Alanine Scanning Mutagenesis. The accomplishment of this project will elucidate the molecular mechanisms of the conversion from furostanol glycosides to spirostanol glycosides in the rhizome of Dioscorea zingiberensis, and will make directional regulation of steroid saponins synthesis and accumulation possible. Obviously, our expected outcomes should be important for both science and practice.

英文关键词： Dioscorea zingiberensis;rhizome;steroidal saponins;molecular mechanism