过表达IbOr基因甘薯增强抗旱性的生理机制

以超表达甘薯橙色基因(IbOr)的转基因甘薯(TS)以及非转基因甘薯(NT)为实验材料,通过15%聚乙二醇6000(PEG-6000)模拟干旱条件,研究转基因与非转基因甘薯幼苗在水分胁迫不同时间的光合系统,膜脂过氧化及抗氧化防御系统中主要指标的变化情况,探讨转基因甘薯耐旱性的生理机制。结果显示:(1)随PEG-6000胁迫时间延长,甘薯叶片的叶绿素、类胡萝卜素含量及其叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率都显著降低,但转基因株系降低幅度小于非转基因植株。(2)在正常供水和水分胁迫下,超表达IbOr基因甘薯叶片中O-·2、MDA含量均低于非转基因甘薯,即转基因甘薯具有较低的活性氧水平且脂膜受损伤较小。(3)PEG-6000胁迫24h后,甘薯叶片中SOD、POD酶活性均增加,48h达到最大值,且转基因甘薯中2种酶活性显著高于非转基因甘薯。研究表明,过表达IbOr基因可以有效减轻甘薯在水分胁迫条件下受损害的程度,且可能主要通过提高甘薯的抗氧化胁迫能力来完成。

Overexpression of IbOr Gene Confers Enhanced Tolerance to Water Stress in Sweet Potato (Ipomoea batatas L.)

Transgenic and non-transgenic sweet potatoes were used as experimental material under 15% PEG-6000 simulated water stress condition.Response of lipid peroxidation,photosynthetic and antioxidative system during water stress in transgenic sweet potato lines (TS) overexpressing IbOr and non-transgenic line (NT),were studied to explore the physiological mechanism of transferring gene increase the drought stress tolerance of sweet potato.The results showed that:(1) As water stress time extended,chlorophyll,carotenoids,photosynthetic parameters such as:Photosynthetic net rate (P_n),Stomatal conductance (G_s),Intercellular CO₂ concentration (C_i),Transpiration rate (T_r) in TS lines and NT plants decreased obviously,while,transgenic sweet potato lines keep higher level than that of NT plants.(2)O^-·₂ and malondialdehyde (MDA) contents of NT were higher than that of TS under normal condition and water stress.The results indicate that transgenic lines have lower reactive oxygen species (ROS) level and smaller lipid membrane damage than that of NT plants.(3)After 24 h water stress,the activities of SOD and POD enzyme increased,and 48 h later,the enzyme activities reached the maximum,while,which in TS lines is significantly higher than that in NT plants.So we can conclude that overexpression IbOr gene could effectively reduce damage degree of sweet potato under the condition of water stress.The tolerance to water deficit may be achieved mostly by improving the antioxidant ability of sweet potato.