Protective role of hydrogen sulfide(H2S) on seed germination and seedling growth was studied in wheat(Triticum) seeds subjected to aluminum(Al3+) stress.We show that germination and seedling growth of wheat is inhibited by high concentrations of AlCl3.At 30 mmol/L AlCl3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment.Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AlCl3-induced stress in a dose-dependant manner at an optimal concentration of 0.3 mmol/L.We verified that the role of NaHS in alleviating Al3+ stress could be attributed to H2S/HS-by showing that the level of endogenous H2S increased following NaHS treatment.Furthermore,other sodium salts containing sulfur were ineffective in alleviating Al3+ stress.NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3+ stress.Moreover,NaHS pretreatment increased the activities of guaiacol peroxidase,ascorbate peroxidase,superoxide dismutase and catalase and decreased that of lipoxygenase.NaHS pretreatment also decreased the uptake of Al3+ in AlCl3-treated seed.Taken together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3+ stress. Protective role of hydrogen sulfide (H2S) on seed germination and seedling growth was studied in wheat (Triticum) seeds subjected to aluminum (Al3 +) stress. We show that germination and seedling growth of wheat is inhibited by high concentrations of AlCl3.At 30 mmol / L AlCl3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment. Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AlCl3-induced stress in a dose- dependent manner at an optimal concentration of 0.3 mmol /L.We verified that the role of NaHS in alleviating Al3 + stress could be attributed to H2S / HS-by showing that the level of endogenous H2S Lightens following NaHS treatment. Fluorrthermore, other sodium salts containing sulfur were ineffective in alleviating Al3 + stress. NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3 + stress. Moreover, NaHS pretreatment increased t he activities of guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase and catalase and decreased that of lipoxygenase. NaHS pretreatment also decreased the uptake of Al3 + in AlCl3-treated seed. Straw together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3 + stress.