马铃薯sAGP基因表达对块茎淀粉和还原糖含量的影响

Expression of Potato sAGP Gene and Its Effects on Contents of Starch and Reducing Sugar of Transgenic Potato Tubers

通过根癌农杆菌(Agrobacteriumtumefaciens)介导将CaMV35S驱动的正/反义sAGP基因导入马铃薯(SolanumtuberosumL.)品种鄂马铃薯3号(E3)和南中552(N552)以研究sAGP基因对马铃薯块茎淀粉-糖代谢的影响。PCR扩增和Southern杂交证明正/反义sAGP基因已整合到马铃薯基因组中。Northern杂交分析表明,该正/反义基因在转基因植株中均能正常转录。转基因植株块茎分析显示,导入正义基因的株系中除4个与转反义基因表现相同外,其余19个株系AGPase酶活性平均上升约25%,还原糖含量下降20%左右,淀粉含量增加5%～6%。其中3个测定指标与各自对照相比,差异均达到显著水平的有A8、C1和C5,最大变化幅度分别为酶活性上升53.5%,还原糖含量下降60.1%,淀粉含量增加33.9%。转反义sAGP基因的15个株系中,AGPase酶活性平均下降约27%,还原糖含量上升近36%,淀粉含量下降亦达27%,其中株系B5、B6、B8和D7的这3个指标均与各自未转基因对照差异显著。本研究结果表明,sAGP基因与AGPase酶活性直接相关,而AGPase很大程度上调节着马铃薯块茎淀粉-糖代谢,通过增强sAGP表达,能有效改良块茎的加工品质。

sAGP gene with sense and antisense orientation under the control of CaMV 35S promoter were introduced into potato cultivars E-potato 3 and N552-potato by Agrobacterium-mediated transformation, aiming to elucidate the effects of sAGP gene on regulating metabolism of starch-sugar in potato tubers. The PCR amplification and Southern blot analysis proved the integration of sAGP into potato genome, and the Northern hybridization showed a normal transcription of the transformed gene. Although 4 out of transgenic lines with sense sAGP orientation showed conflict results, the AGPase activity and starch content of the tubers of the other 19 lines increased averagely by 25% and 5%–6%, respectively, and reducing sugar content decreased by around 20%, while lines A8, C1 and C5 had significant difference to the corresponding control. With the antisense transformation, all the 15 derived lines showed average decline in both AGPase activity and starch content by almost 27% and increase in reducing sugar content by about 36%. Among them, lines B5, B6, B8 and D7 were significantly different with the control. The present results suggested that sAGP may directly relate to AGPase activity that could regulate, to a certain extent, starch-sugar metabolism of potato tubers. Therefore increase in sAGP expression could be an efficient approach to improve the processing quality of potato tubers.