Exogenous hydrogen peroxide can enhance tolerance of wheat seedlings to salt stress

Hydrogen peroxide (H₂O₂), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In this study, we demonstrated that exogenous H₂O₂ was able to improve the tolerance of wheat seedlings to salt stress. Treatments with exogenous H₂O₂ for 2 days significantly enhanced salt stress tolerance in wheat seedlings by decreasing the concentration of malondialdehyde (MDA), the production rate of superoxide radical (O₂ ⁻), and increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and the concentration of glutathione (GSH) and carotenoids (CAR). To further clarify the role of H₂O₂ in preventing salt stress damage, CAT and ascorbate (AsA), the specific H₂O₂ scavengers, were used. The promoting effect of exogenous H₂O₂ on salt stress could be reversed by the addition of CAT and AsA. It was suggested that exogenous H₂O₂ induced changes in MDA, O₂ ⁻, antioxidant enzymes and antioxidant compounds were responsible for the increase in salt stress tolerance observed in the experiments. Therefore, H₂O₂ may participate in antioxidant enzymes and antioxidant compounds induced tolerance of wheat seedlings to salt stress. The results also showed that exogenous H₂O₂ had a positive physiological effect on the growth and development of salt-stressed seedlings.