Abstract: With the enhancement of copper (Cu) stress, the germination percentage of wheat seeds decreased gradually. Pretreatment with NaHS, hydrogen sulfide (H2S) donor alleviated the inhibitory effect of Cu stress in a dose dependent manner; while little visible symptom was observed in germinating seeds and radicle tips cultured in NaHS solutions. It was verified that H2S or HS- rather than other sulfur-containing components derived from NaHS attribute to the potential role in promoting seed germination against Cu stress. Further studies showed that NaHS could promote amylase and esterase activities, reduce Cu-induced disturbance of plasma membrane integrity in the radicle tips, and sustain lower levels of MDA and H2O2 in germinating seeds. Furthermore, NaHS pretreatment increased activities of superoxide dismutase (SOD) and catalase (CAT) and decreased that of lipoxygenase (LOX), but showed no significant effect on ascorbate peroxidase (APX). Alternatively, NaHS prevented the uptake of Cu and promoted the accumulation of free amino acids in seeds exposure to Cu. In addition, a rapid accumulation of endogenous H2S in seeds was observed at the early stage of germination, and higher level of H2S in NaHS-pretreated seeds. These data indicated that H2S was involved in the mechanism of germinating seeds’responses to Cr stress.

Key words: Antioxidant enzymes, Copper stress, Hydrogen sulfide, Seed germination, Wheat (Triticum)