转基因纯合四倍体马铃薯多酚氧化酶活性及同工酶谱的变异

Variation of Polyphenol Oxidase Activity and Isozyme in Transgenic Homozygous Tetraploid Potato (Solanum tuberosum L.)

选择14个已插入反义PPO基因的纯合四倍体马铃薯“GD-9-qc”系列,进行叶片、微型薯PPO活性检测和同工酶分析。结果表明,不同品系间的叶片、微型薯PPO活性存在极显著差异,其中2个品系的叶片及8个品系的微型薯PPO活性明显低于对照;供试转基因品系间的叶片PPO同工酶谱带的颜色深浅表现差异,所示结果与PPO活性检测基本一致;而不同品系间微型薯PPO同工酶谱带除颜色表现不同外,其中4个品系的同工酶主带消失,推测是由反义PPO基因直接抑制的结果。此外,在某些品系中,叶片与微型薯PPO活性增减趋势不同。实验获得了叶片PPO活性较高、块茎PPO活性低的目标转基因品系。

The technology of antisense RNA is used more and more to improve the disadvantageous characters and enhance quality of crop. The plant expression vector with antisense polyphenol oxidase （PPO） gene has been constructed and transformed into potato in order to regulate the expression of PPO gene and the enzymatic browning of potato tuber . In this paper, the PPO activity and isozyme were tested using 14 transgenic homozygous tetraploid potatoes of GD-9-qc series by spectrophotometer and polyacrylamide gel electrophoresis. The results showed that the PPO activity had extremely significant differences in leaves and minitubers among different strains（Table 1 ）. The PPO activity was obviously lower than control in the leaves of 2 strains and the minitubers of 8 transgenic potatoes ones（Table 1 ）. The color intensity of isozyme bands of leaves changed among the transgenic potato strains （ Fig. 1, Fig. 2 ） . Furthermore, not only the isozyme bands color of minituber changed among the different series but also the main bands of isozyme disappeared in 4 transgenic potato strains （Fig.3）. It was indicated that their PPO gene is repressed directly by anti-sense PPO gene. In addition, in some strains, the PPO activity increased in leaves but decreased in minitubers （Table 1 ）. The target transgenic potato with high PPO activity in leaves and low activity in tubers has been obtained.