By using the tobacco (Nicotiana tabacum L. cv. Bright Yellow) cell culture, the effects of the cyanide-resistant respiration on the cell viability and hydrogen peroxide production under ZnCl2 stress were studied. The results showed that with the increase of the concentrations of ZnCl2, the level of cell viability is decreased, while the level of the cyanide-resistant respiration is increased. A higher level of ZnCl2 (150 mmol/L) stress caused a significant decrease of cell viability and a significant increase of the hydrogen peroxide(H2O2) production. Treatment with exogenous H2O2 also caused a decrease of cell viability, and application of the scavenger of H2O2 alleviated the decrease of cell viability under ZnCl2 stress. The effects of the cyanide-resistant respiration on the cell viability and hydrogen peroxide production under ZnCl2 stress were further studied.The ZnCl2-stressed (150 mmol/L) cells pretreated with salicylhydroxamic acid (an inhibitor of the cyanide-resistant respiration) had lower cell viability but higher H2O2 production than the cells exposed to 150 mmol/L ZnCl2 stress only. These results suggest that the cyanide-resistant respiration can function in alleviating the decrease of cell viability and oxidative stress under ZnCl2 stress and thus could be involved in the tolerance of plants to ZnCl2 stress.

cyanide-resistant respiration; cell viability; hydrogen peroxide; ZnCl2 stress