patatin启动子调控烟草液泡转化酶抑制子在马铃薯抗低温糖化中的作用

为了降低马铃薯(Solanum tuberosum )块茎低温贮藏下还原糖的积累，实验构建了马铃薯块茎特异性启动子（CIPP）调控的烟草液泡转化酶抑制子Nt-VIF基因表达载体pBICNI，并转化马铃薯植株。PCR、Northern杂交和Southern杂交分析结果显示，CIPP调控的Nt-VIF基因全长cDNA成功地导入鄂马铃薯3号（E-3）植株。14个转基因株系块茎分别贮藏在4℃和20℃条件下，贮藏1个月后进行还原糖含量和液泡酸性转化酶（VI）活性测定。结果表明，在20℃条件下转基因株系块茎还原糖（RS）含量与对照相比差异不明显，在4℃条件下RS含量则显著下降，与对照相比下降幅度从34%（株系B-13）至76.8%（株系B-1），说明Nt-VIF cDNA在马铃薯中的表达，成功地抑制了液泡酸性转化酶的活性，导致还原糖含量降低。进一步分析表明，转基因块茎低温贮藏其液泡转化酶活性与还原糖含量呈显著的正直线相关（VI = 0.3084RS + 0.0673）。实验获得的B-1、B-2、B-6、B-9、B-14等5个转基因株系，块茎低温贮藏后能直接满足炸片加工对还原糖含量的要求。

Role of Tobacco Vacuolar Invertase Regulated by patatin Promoter in Resistance of Potato Tubers to Cold-sweetening

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.