RNA干涉对马铃薯内源酸性转化酶活性的影响

酸性转化酶是植物体内降解蔗糖为还原糖（葡萄糖、果糖）的关键酶，而还原糖在马铃薯（Solanum tuberosum L.）低温贮藏中的快速积累是影响油炸加工品质的重要因素。为了实现对马铃薯块茎低温糖化的品质改良，本研究利用所克隆的酸性转化酶基因构建了RNA干涉载体，并转化马铃薯品种N2。经PCR、Northern鉴定，酸性转化酶基因的干涉片段已经成功导入马铃薯植株中。对干涉转基因株系的试管苗和试管薯的酸性转化酶活性进行测定，结果显示，植株的酸性转化酶的活性平均下降69.8%（Ni-1除外），最大降幅为78%（Ni-4），而试管薯的酶活性最大降幅为68%。与反义RNA的表现较好的转基因株系进行比较，RNA干涉对酶活的调节作用与之相当。研究结果表明，RNA干涉对马铃薯内源酸性转化酶活性的调节作用显著，这种转录表达的调控技术对马铃薯低温糖化改良具有良好的应用前景。

Effects of RNAi on Regulation of Endogenous Acid Invertase Activity in Potato (Solanum tuberosum L.) Tubers

In plants, acid invertases are known to be the key enzymes cleaving sucrose into reducing sugars (RS) (glucose and fructose). To improve quality of potato (Solanum tuberosum L.) fries which is largely influenced by accumulation of RS in tubers stored at low temperature, a part of acid invertase cDNA with hpRNA structure was transformed into potato cv N2. Detections of PCR amplification and Northern Hybridization suggested that the RNAi vector was successfully transformed into cv N2. Analysis of acid invertase activity of the plantlets and microtubers of RNAi transgenic lines indicated that expression of the interference RNA repressed significantly the activity of acid invertase of plantlets by an average 69.8% (excepted with Line Ni-1) and led to the best decrease of 78% (Line Ni-4), and the highest decrease of that of microcoubers by 68%. Compared with that of well inhibited antisense inv transgenic plants, the comparative downregulation of RNAi suggested a distinct alteration on endogenous acid invertase and a potential strategy of PTGS in modulation of cold-sweetening in potato.