中文摘要：

利用基因重组技术．分别克隆木薯SBEI基因ORF中的494bp的片段和SBEII基因ORF中的340bp的片段；并通过重叠延伸PCR方法，扩增融合SBEI、SBEII基因片段的大片段SⅢ，将其正向、反向插入植物RNAi表达载体pART27中，同时克隆块根特异性启动子取代原来载体上自有的35S启动子，构建块根特异启动的可编码发夹结构的RNAi表达载体Sp—pRNAiSⅢ．为后续培育高直链淀粉含量的木薯新品种等实验打下基础。

英文摘要：

A 494 bp fragment named SI from the Open Reading Frame（ORF）of SBE I and a 340 bp fragment named S II from the ORF of SBE II were cloned from cassava and fused into a larger fragment named SIII with Overlap Extension PCR（SOE PCR）. The SⅢ fragment was inserted into the plant expression vector pART27 RNAi in forward and reverse direction; Also the original 35S promotor in the vector was replaced with a root specific promotor Sporamin, and then a coding hairpin RNAi expression vector Sp-pRNAiS Ⅲ was constructed, which could, lay a foundation to breed new cassava varieties with high amylase content.