超积累植物东南景天根系细胞壁多糖修饰对镉积累的影响及机制

项目名称： 超积累植物东南景天根系细胞壁多糖修饰对镉积累的影响及机制

项目编号： No.21477104

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 化学工业

项目作者： 李廷强

作者单位： 浙江大学

项目金额： 86万元

中文摘要： 细胞壁是金属离子进入细胞质的第一道屏障，在植物抵抗金属离子毒害的过程中发挥着重要作用。尽管围绕植物金属诱导的细胞壁多糖修饰机制做了大量工作，然而目前有关超积累植物根系细胞壁多糖修饰特征还未见报道，其在植物重金属超积累中的作用机制也不清楚。该项目以镉超积累植物东南景天（Sedum alfredii）为材料，综合应用稳定同位素示踪、LA-ICP-MS、非损伤微测技术、同步辐射、免疫荧光及分子生物学等技术手段，研究东南景天根系镉的区隔特征及其向木质部的转运特点，分析东南景天根系细胞壁多糖组成及其对镉的结合特性，研究镉对东南景天根系细胞壁果胶多糖组成、甲基化程度的影响，以及镉对根系细胞壁XET和XEH活性、XTH基因表达水平的影响，揭示超积累植物东南景天根系细胞壁多糖修饰特征及其对镉积累的影响及机制。研究结果对于揭示超积累植物重金属超积累机理、完善植物修复理论具有重要意义。

中文关键词： 超积累植物；镉；细胞壁；多糖修饰；土壤重金属污染

英文摘要： Cell wall is the first barrier for any ions to enter the cell, which play a key role in resisting metal toxicity in plant. Although extensive efforts have been directed to uncover the mechanisms of metal-induced cell wall modification in tolerant plant, little is known concerning the structural modifications of root cell walls in hyperaccumulator. Sedum alfredii (Crassulaceae), a species native to China, has been characterized as a Zn/Cd cohyperaccumulator. To date, studies on the mechanism of metal tolerance and hyperaccumulation of S. alfredii were mainly focused on the uptake and subcellular distribution characteristics, while no information is available about the root cell wall polysaccharide modifications of this plant. In this project, hydroponic experiments, as well as new techniques such as stable isotope tracing, LA-ICP-MS, scanning ion-selected electrode technique (SIET), synchrotron radiation techniques, immunofluorescence and RT-PCR were used to (1) investigate the compartmention of Cd in root cell and it efflux to the xylem; (2) investigate the polysaccharide content (cellulose, hemicellulose and pectin) of root cell walls of S. alfredii tereated with different Cd and Cd content in different components of root cell walls; (3) study the influence of Cd on the components of root cell wall pectin, as well was the degree of pectin methylation; (4) investigate the influence of Cd on the activity of XET and XEH, as well as the XTH gene expression in the root cell wall of S. alfredii. Results of this project will contribute to reveal the polysaccharides modification features of root cell wall and its influence on cadmium accumulation and will help to understand the mechanisms of metal hyperaccumulation in S. alfredii and will optimize the management practices for maximum metal phytoextraction, and it is of great importance for protecting soil ecosystem health.

英文关键词： hyperaccumulator;cadmium;cell wall;polysaccharide modification;soil heavy metal pollution