Overexpression of glutathione S-transferase gene increases salt tolerance of arabidopsis

The Suaeda salsa glutathione S-transferase gene (GST) was introduced into arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Transformants were selected for their ability to grow on medium containing kanamycin. Southern and northern blot analyses confirmed that GST was transferred into the arabidopsis genome, and the GST and GPX activities in transgenic plants (GT) were much higher than in wild-type plants (WT). There were no obvious morphological or developmental differences between transgenic and wild-type plants. One transgenic homozygous line (GT(6-8)) and WT plants were evaluated for salt tolerance and gene expression. Seed germination and seedling salt tolerance were improved after overexpression of GST in arabidopsis; the photosynthesis rate and the fresh weight of the GT(6-8) line were distinctly higher than those of WT plants after NaCl treatment. Glutathione content increased substantially in salt-stressed arabidopsis plants of both genotypes, and the glutathione pool in GT(6-8) plants was more oxidized than in WT plants under both control and stressful conditions. The MDA content, an indicator of lipid peroxidation, increased in WT plants but was not affected distinctly in GT(6-8) seedlings after NaCl treatment. Results from different tests indicated that the expression of the GST gene promoted a higher level of salt tolerance in vivo in transgenic arabidopsis plants.