农杆菌介导的辽宁碱蓬胆碱单氧化酶基因CMO转化烟草提高抗氧化胁迫的研究

通过农杆菌介导的遗传转化，将来自辽宁碱蓬的甜菜碱合成关键基因－胆碱单氧化酶基因CMO 转入烟草，以提高烟草耐受氧化胁迫的能力，并对得到抗生素抗性植株进行了分子检测和百草枯诱导 的氧化胁迫。Southern 和Northern 检测表明CMO 已经整合到烟草基因组中，并得到了正确的表达，但 不同转基因株系中的拷贝数不同，株系T1、T2、T6 为单拷贝；株系T4、T5 为双拷贝；株系T3 为3 个拷 贝。在10 μM 和20 μM百草枯胁迫24 h 的情况下，转基因植株表现了较强的耐受氧化胁迫能力，各转 基因株系和野生型相比具有较低的丙二醛含量和较高的超氧化物歧化酶活性。这可能是转基因植物 中甜菜碱的积累诱导或保护了抗氧化酶的活性，使得转基因植株受到的氧化胁迫较低，转基因植株中 较低的电导率也证明了这一点。转CMO 基因烟草耐氧化胁迫能力的提高，说明CMO 基因可以进一步 在玉米、水稻等重要农作物中应用以提高其耐受干旱、低温等非生物胁迫的能力。

Improving Tobacco Oxidative Stress by Agrobacterium Mediated Transformation of Choline Monooxygenase Gene from Suaeda liaotungensis

Suaeda liaotungensis choline monooxygenase CMO, a key gene in betaine biosynthesis, was introduced into tobacco genome by Agrobacterium tumefaciens mediated transformation. Molecular test showed that CMO had been integrated into tobacco genome and expressed properly. However, different transgenic lines showed different CMO copies, with lines of T1 、 T2 、 T6 being 1 copy, lines of T4 、 T5 being 2 copies and line T3 being 3 copies. And this might be a result of various insert sites of CMO in the tobacco genome. All the transgenic lines acquired enhanced oxidative stress induced by paraquat. When stressed with 10 μ M and 20 μ M paraquat for 24 h, the transgenic lines had significant lower malondialdehyde content and higher superoxide dismutase activity compared with wild type plants. In contrast, no significant difference of malondialdehyde content and superoxide dismutase activity was found between the transgenic lines and wild type plants under normal conditions. The accumulation of betaine in the transgenic lines might induced or protected the activities of the antioxidant enzymes, which makes the transgenic plants suffered less from oxidative stress as evidenced by lower electric conductivity. In conclusion, the overexpression of choline monooxygenase gene CMO in tobacco plants enhanced its oxidative stress tolerance ability, and gene CMO canbe further used in some important crop plants such as corn and rice to improve their abiotic stress.