Differential display reverse transcription PCR (DDRT-PCR) analysis was performed on lily 'Marcopolo' bulb scale for isolation of expressed genes during bulblet formation. Cu/Zn lily-superoxide dismutase (LSOD) of 872 bp gene, with ability to scavenge reactive oxygen in stress environment, was isolated. Northern blot analysis showed expression levels of LSOD maximized 12 days after bulblet formation. Ti plasmid vectors were constructed with sense and antisense expressions of LSOD gene and transformed into potato. Southern blot analysis of transgenic potatoes revealed different copies of T-DNA were incorporated into potato genome. In transgenic potatoes, lily SOD gene was overexpressed in sense lines and not in antisense lines. In native polyacrylamide gel electrophoresis analysis, additional engineered LSOD was detected in sense overexpressed transgenic line only. Transgenic potatoes were subjected to oxidative stress, such as herbicide methyl viologen (MV). Transgenic potato lines with sense orientation exhibited increased tolerance to MV, whereas in antisense lines exhibited decreased tolerance. In vitro tuberization of transgenic potato with sense orientation was promoted, but was inhibited in transgenic potato with antisense orientation.