马铃薯淀粉合成酶融合基因植物表达载体构建

Fusion of the Fragments cDNA from Potato Starch Synthases and Construction of the Plant Expression Vector

通过反义抑制马铃薯（Solanum tuberosumL．）块茎淀粉合成酶GBSS、SSⅡ和ssⅢ基因的表达，可降低淀粉中直链淀粉含量和改变分支链的长度，从而降低马铃薯淀粉糊化温度、改善其抗凝沉性。依据GBSS、SSⅡ和SSⅢ基因的cDNA序列分析，从各基因中筛选和克隆了一段同源性极低、约500～600bp的片段；通过PCR技术实现了3个片段的融合，得到了1671bp的融合基因GS：S3；将GS：S3反向连接在GBSS5′侧翼序列之后，构建了由GBSS5′侧翼序列驱动的GS2S3反义基因的植物表达载体pBI-GS2S3，并进行了初步转化。

The contents of amylose and the length of branch chains of potato starch were changed by inhibi- ting the expression of the potato tuber starch synthase genes （GBSS,SS Ⅱ and SSⅢ ）. Thereby the gelati- nization temperature was degraded and the anti-retrogradation of potato starch was improved. Based on the cDNA sequences of GBSS,SS Ⅱ and SSⅢ genes,three fragments about 500-600 bp from each gene with lower identity among them were cloned. The fusion gene GS2S3 （1 671 bp） is fused by the PCR technique. Then the fusion gene was inversely ligated by T4 ligase with the pBIGG which have the GBSS 5′ flanking sequence. Finally the plant anti-sense expression vector pBI-GS2S3 was constructed.