木薯是广泛种植于世界热带和亚热带地区的一种重要经济作物，其薯块形成和淀粉积累与光合产物的卸载密切相关。质膜单糖转运蛋白在库器官中参与质外体卸载途径，能将胞外单糖分子转运进入胞内从而增加库细胞合成淀粉的能力。然而对木薯质膜单糖转运蛋白基因及其功能的研究尚未报导。通过对已发表的木薯全基因组测序数据进行生物信息学分析，推测到木薯基因组中包含20个质膜单糖转运蛋白基因(STP)。本项目拟利用分子生物学和生物化学方法对这些重要的功能基因进行分离和表达分析，并在酵母突变体中异源表达验证其单糖转运能力，进而选择参与糖卸载的质膜单糖转运蛋白基因，通过构建STP超表达或敲除载体转入木薯，对转基因木薯进行单糖转运蛋白基因功能的全面研究，从而解析木薯块根发育和淀粉积累机制，最终为木薯品种改良提供分子依据。

Cassava is an important economic crop which is grown in tropical and subtropical areas. Cassava storage-tuber formation and starch accumulation are closely related with the unloading of photosynthetic products. The uptake of monosaccharides from the apoplastic space across the plasma membrane is mediated by monosaccharide transporters named as STPs (sugar transport proteins) in storage roots (sink). It leads to the increase of starch synthesis. However, these transport genes were poorly reported. A total of 20 STP genes were captured in a genome-wide survey of the cassava genome database. This study will carry out the isolation identification, and expression of these STP genes using the methods of molecular biotechnology. Their functional characterization will be determined by heterologous expression in the hexose transport-deficient yeast mutant EBY.VW4000. The candidate STP genes, which may play important roles in sugar accumulation during the tubers development, will be found out in combination with all the previous reports. In addition, the transformed cassavas with over-expression or knockout of STPs will be used to fully analyze the functions of these genes in cassava. It might be helpful to understand the formation and development of cassava storage roots, and clarify the mechanism of starch accumulation, and ultimately provide molecular basis for the variety improvement of cassava.