[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.