Overexpression of the sweetpotato peroxidase gene swpa4 enhances tolerance to methyl viologen-mediated oxidative stress and dehydration in Arabidopsis thaliana

We previously reported that transgenic Arabidopsis thaliana plants overexpressing the sweet potato peroxidase gene swpa4 under the control of the cauliflower mosaic virus (CaMV) 35 s promoter showed increased levels of reactive oxygen species (ROS) and nitric oxide (NO), and higher expression of ROS and NO related genes than control plants. Here, we investigated the effect of swpa4 overexpression on the abiotic and biotic stress tolerance levels of Arabidopsis plants. Methyl viologen (MV) treatment-induced oxidative stress caused visible damage to the seedlings and rosette leaves of all Arabidopsis plants, although the symptoms were more severe in control plants than in transgenic lines. Additionally, survival rates and ion leakage showed a slight decline in transgenic lines but a more severe decline in control plants after MV treatment. Transgenic plants also showed enhanced tolerance to drought stress. Dehydration treatment, followed by rehydration, resulted in a greater change in the relative water content and lipid peroxidation of control plants than in that of transgenic lines. However, transgenic plants did not show enhanced resistance to biotic stresses such as bacterial and fungal pathogens. These results indicate that transgenic Arabidopsis plants can efficiently regulate defense levels during oxidative stress via the overexpression of swpa4.