[Effects of antisense acid invertase gene on reducing sugar and starch contents of potato (Solanum tuberosum L.) tuber stored at low temperature].

Two transgenic potato lines with antisense AcInv gene and the non-transgenic varieties were used to test the reducing sugar and starch contents. The results indicated that the reducing sugar content increased and total starch content decreased in all samples after tubers were stored at 4 degrees C for 40 d. The reducing sugar content in tubers of transgenic line "Anti-AcInv Atlantic" and "Anti-AcInv Gannongshu No.2" were lower about 23% and 18% than those of Atlantic and Gannongshu No.2 (Table 1). The total starch and the amylopectin were also decreased by 1% and 1.3% in "Anti-AcInv Atlantic" and 1.4% and 1.7% in "Anti-AcInv Gannongshu No.2" respectively (Table 2). The proportions of amylose and amylopectin were lower in the transgenic lines than the non-transgenic varieties (Figs. 1 and 2). It was only 0.29 for "Anti-AcInv Atlantic" and 0.38 for "Anti-AcInv Gannongshu No.2". Meanwhile, there are fewer dark blue starch particles in transgenic tuber, which is less than in tuber of the non-transgenic varieties by paraffin-cut section method (Fig. 3). After the tubers were transferred to the storage temperature 15-17 degrees C for 20 d, the reducing sugar contents in tubers of the two transgenic lines were significantly lower than that of non-transgenic varieties. It was 0.23% for "Anti-AcInv Atlantic" and 0.24% for "Anti-AcInv Gannongshu No.2" (Table 1). It is suggested that the trans-antisense AcInv gene in the transgenic potato down-regulates the AcInv gene expression after the tubers were stored under low temperature.