State Vegetable Improvement Central (Certral China ) , Key Laboratory of Horticultural Plant Biology, Huazhong Agricultural University, Ministry of Education, Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University Wuhan, 430070, China
Abstract：To slow down reducing sugar accumulation of potato tubers exposed to low temperature storage, an expression vector pBICNI of Nt-VIF gene, a vacuolar invertase inhibitor from Nicotiana tabacum, regulated by the potato tuber specific promoter CIPP was contructed and transformed into potato(Solanum tuberosum) cv. E-potato 3 (E3). Detections by the PCR, Northern and Southern hybridizations indicated that the full longth Nt-VIF Nt-VIF cDNA was successfully transformed into cv. E3. After storing potato tubers of 14 transgenic lines in 4 ℃ or 20 ℃ for 30 d, the activities of vaculoar invertase (VI) and reducing sugar(RS) content were analysed. The results showed that there were no significant differences in RS content between transgenic and untransformed(control) tubers stored in 20℃. However, compared to the control, RS content of transgenic lines reduced obviously in 4 ℃ from 34.0% (line B-13) to 76.8% (line B-1), implying inhibition of VI activity by Nt-VIF cDNA expression resulted in RS content reduction. Further analysis revealed a positive linear relationship between IV activity and RS content (VI = 0.308RS + 0.067). Lines B-1, B-2, B-6, B-9 and B-14 can meet the requirements of potato fries in terms of their low RS content after the cold-storage.
