Overexpression of tomato SlTpx improves salt stress tolerance in transgenic tobacco plants by scavenging H2O2

Hydrogen peroxide (H2O2) is an important signaling molecule that involved in multiple physiological metabolic processes in plants. Excess H2O2 can destroy biological macromolecules to poison the cell. Thioredoxin peroxidase (Tpx) plays an important role in protecting plants from oxidative damage by clearing H2O2. In this study, tomato Tpx (SlTpx) gene was cloned and bioinformatic analysis was done. The mRNA transcript level of SlTpx in tomato root and leaf was increased significantly after NaCl stress treatment for 12 h. SlTpx overexpression transgenic tobacco plants were obtained to study its function under NaCl stress. The seed germination rate of SlTpx overexpression plants was higher than that in wild type (WT) plants under NaCl treatment. The malondialdehyde (MDA) content and reactive oxygen species (ROS) accumulation in transgenic tobacco were less than in WT under NaCl stress. Transgenic plants had significantly higher antioxidant enzyme activities, proline and total soluble sugar contents, and expression of Na+ metabolism genes in transgenic plants than the WT. Moreover, The SlTpx transgenic seeds showed higher tolerance to H2O2 and methyl viologen (MV) treatment, compared with the WT. Besides, the growth of prokaryotic strain of pET-28a-SlTpx was better than the pET-28a strain with H2O2 treatment. The above results indicate that the SlTpx gene improves the plant salt tolerance by scavenging H2O2.