Abstract: 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.

Key words: potato, sAGP, gene expression, starch, reducing sugar