Abstract：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.
