Constitutive expression of the wheat TaSOD5 gene enhances salinity tolerance of Arabidopsis thaliana

Superoxide dismutase is a crucial reactive oxygen species (ROS) scavenger and converts the superoxide radical (O2-) to H2O2, so it is thought to enhance abiotic stress tolerance by reducing ROS accumulation and so avoiding oxidative damage. In this study, we isolated a salt- and oxidative stress-responsive Cu/Zn SOD gene TaSOD5 from wheat. The ectopic overexpression of TaSOD5 in Arabidopsis increased total and Cu/Zn SOD activities, and offered the plant tolerance to salt stress. Arabidopsis ectopically expressing TaSOD5 possessed a superior resistance to oxidative stress induced H2O2. The TaSOD5 ectopic overexpression elevated the activities of both ROS scavengers and O2- producer NADPH oxidase. These findings show that Cu/Zn SOD enhances salt tolerance via regulating the machinery of redox homeostasis rather than improving SOD activity alone.