Abstract: Glutathione transferase (GST) and cysteine synthase (CS) play an important role in plant elimination of active oxygen (reactive oxygen species, ROS). RT-PCR analysis of GST and CS in Polygonum sibiricum Laxm. showed remarkable change in expression induced by 3% NaHCO3 stress. We transformed GST, CS and the GST+CS combination into yeast cells(Saccharomyces cerevisiae), designated transgenic yeast (ty) ty-gst, ty-cs and ty-gc. The survival rate of ty-gst, ty-cs and ty-gc was higher than that of wild-type yeast (wy) under 1 mol.L-1 Na2CO3 and 5 mol.L-1 NaCl stress, with essentially no difference in rate between the three tys. With 0.4 mol.L-1 NaCl, the activity of superoxide dismutase 1 (SOD1), SOD2, glutathione peroxidase 1 (GPX1) and GPX3 were lower and that of catalase 1 (CTA1) higher in ty than in wy. However, the activity of the ty-cs SOD, CAT and GPX showed the highest with 0.4 mol.L-1 NaCl stress.