转铜/锌超氧化物歧化酶和抗坏血酸过氧化物酶基因甘薯的耐旱性

水分胁迫使转铜／锌超氧化物歧化酶基因（Cu／Zn SOD）和抗坏血酸过氧化物酶基因（APX）甘薯及未转基因甘薯中超氧阴离子（O2^-）、过氧化氢（H2O2）、丙二醛（MDA）含量和细胞膜相对透性增加，在相同条件下以上指标均为转基因甘薯低于未转基因甘薯；而叶片含水量、净光合速率（Pn）和气孔导度（Gs）均下降，SOD和APX酶活性随胁迫程度的加重先增大后减小，胞间CO2浓度（Ci）则先减小后增大，在相同条件下转基因甘薯中以上指标均高于未转基因甘薯。这些结果表明：转入Cu／Zn SOD和APX基因使转基因甘薯清除活性氧的能力增强，在水分胁迫下能保持较高的叶片含水量和Pn，耐旱性得到提高。

Drought Tolerance of Transgenic Sweet Potato Expressing Both Cu/Zn Superoxide Dismutase and Ascorbate Peroxidase

Two strains, Cu/Zn SOD and APX gene transferred sweet potato (TS) and non-transgenic sweet potato (Ipomoea batatas L.) (NT), were used as experimental materials to study the drought tolerance under three different degrees of water stress: 0, -0.44 MPa, -0.78 MPa. The results showed that activities of Cu/Zn SOD and APX increased under -0.44 MPa and decreased under -0.78 MPa (Fig. 2), P(n), G(s) and leaf water content decreased, C(i) increased, then decreased under water stress (Fig. 6), but under the same PEG concentration all these indexes in the TS were higher than those in NT. The accumulation of H(2)O(2) and O(-*)(2) (Fig. 1) increased the degree of lipid peroxidation of the plasma membrane (Fig. 4), prompted the accumulation of MDA (Fig. 3), and the accumulation of TS always lower than the NT at the same PEG concentration. All the results showed that the transgenic sweet potato has a stronger ability to clean up active oxygen than the non-transgenic one, and it can keep a higher leaf water content and P(n) under water stress, so it has a stronger tolerance to drought.