马铃薯Sgt1基因启动子的结构及功能分析

糖苷生物碱(steroidal glycoalkaloids，SGAs)是一类存在于茄科和某些百合科植物的重要次生代谢物，与植物的抗逆性和产品品质有密切关系．茄啶半乳糖基转移酶（solanidine galactosyltransferases,SGT1）是SGAs合成代谢途径的末端关键酶之一，研究其编码基因的启动子序列对于SGAs生物合成代谢调控有重要的作用和意义．研究采用染色体步移技术(Genome walking)，首次克隆到马铃薯Sgt1基因起始密码子上游2 183 bp的启动子序列，已注册到GenBank（注册号：KC759163）．构建该启动子驱动融合报告基因gfp::gus的植物双元表达载体p1304Sgt1p，转化野生型烟草获得Sgt1p::gfp::gus转基因植株，通过GUS组织化学染色分析Sgt1p::gfp::gus转基因植株中Sgt1p启动子的活性．结果表明，gus基因在转基因烟草的根、茎和叶中均表达，在叶中Sgt1p启动子的活性低于CaMV35S启动子，而在根和茎中二者基本相同；光诱导结果显示，光照处理明显增强了Sgt1p::gfp::gus转基因烟草叶片中Sgt1p启动子的活性，表明庄薯3号马铃薯 Sgt1p启动子是一种光诱导型启动子．

Promoter Analysis of Potato Sgt1 Gene

Steroidal glycoalkaloids (SGAs) is an important secondary metabolite in Solanaceae and certain Liliaceae. SGA closely related to stress resistance and plant productivity quality. Solanidine galactosyltransferases（SGT1）is a key terminases for SGAs biosynthesis that catalyzes solanidine to solanine. The function of SGTpromoter is important for the SGAs biosynthesis in plant. We obtained a 2183 bp sequence (KC759163 in GenBank) upstream of Sgt1 ORF from a light-sensitive “Zhuangshu 3” (solanum tuberosum L.) strain by chromosome walking. The promoter was fused with a gfp∷gus reporter in pCAMBIA1304 and constructed a plant binary expression vector p1304Sgt1p. The reporter vector was introduced into wild type tobacco (Nicotina tobacum L.) through Arobacterium-mediated transformation to generate Sgt1p∷gfp∷gus transgenic plants. The Sgt1 promoter activity in the transgenic tobacco was determined by GUS histochemical staining in the root, stem and leaves. We found that the Sgt1 promoter activity was weaker than that of CaMV35S promoter in the leaves, and nearly the same in root and stem. Photoinduced experiment showed that light exposure significantly enhanced the Sgt1 promoter activity in leaves, which verified its nature of a light-inducible promoter.