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 effects of water stress and rewatering on photosynthetic characteristics of sweet potatoes.The result showed that the activities of SOD of both TS and NT first increased and then decreased under water stress

but the activity of SOD of TS was always higher than that of NT

under 24 h water stress

the activity of SOD of TS was 20% higher than that of NT.The activities of SOD of TS and NT both decreased after rewatering.Under water stress

the activity of APX of TS firstly increased and then decreased;in NT it firstly decreased and then increased.After rewatering

the activity of APX of both TS and NT firstly increased and then decreased

after 12 h rewatering

the activity of APX of TS was 50% higher than it of NT.Under water stress

the membrane structural stability of TS was better than it of NT

after 24 h water stress and 12 h rewatering

the MDA content of NT were 20% more than it of TS. At the beginning of the water stress

pn decreased in both TS and NT

when stress time became longer

pn in TS increased

in NT pn almost keep the same level

after 36 h stress

pn in TS is 50% higher than it in NT

after rewatering

pn in both TS and NT began to increased

after 12 h rewatering

pn in TS was 1 times higher than it in NT.Under water stress

Ci increased in both TS and NT.After 36 h water stress

Ci in NT was 40% higher than it in TS

after rewatering

Ci in both TS and NT decreased.The result showed that transferred both Cu/Zn SOD and APX gene

the antioxidative system of the transgenic sweet potato had a higher ability to protect and recover the photosynthetic system of the plant.