Effects of exogenous spermidine on ROS content and antioxidant enzyme activities in root of cucumber seedlings under root-zone hypoxia stress

The effects of exogenous Spermidine on antioxidant enzyme activities and ROS content in root of cucumber under hypoxia-stress were investigated. The results showed that under hypoxia stress, MDA content obviously increased, ROS content and antioxidant enzyme activities in cucumber seedlings roots increased significantly in the early period of treatment and then decreased in the later period. Exogenous Spd treatment could decrease MAD and ROS contents, maintain greater activities of superoxide dismutase (SOD), peroxidase (POD), while lower catlase (CAT) activity. It indicate the relation between O^-₂ productive rate and SOD activity (R²=0.643～0.7532), as well as H₂O₂ content and POD activity(R²=0.384～0.7705).