Enhanced tolerance of the transgenic potato plants overexpressing Cu/Zn superoxide dismutase to low temperature

Low temperature stress is one of the major factors for damage in plants, especially in food crops. Cu/Zn superoxide dismutase plays an important role in the processes of scavenging reactive oxygen species (ROS) caused by environmental stresses. In order to study transgenic potato plants whether improved tolerance to low temperature, in this research, StSOD1 gene was overexpressed under the control of CaMV 35S promoter through Agrobacterium tumefaciens-mediated transformation in potato. The results showed that after 4 degrees C treatment for 48 h, superoxide dismutase (SOD) activity of the transgenic potato lines (OE lines) overexpressing StSOD1 was 1.38-fold enhanced compared to the non-transgenic plants (NT lines). On the other hand, the activity of the transgenic potato lines (RNAi lines) that inhibiting expression of StSOD1 decreased compared with NT lines. In addition, the effect of increased SOD activity on lipid peroxidation was determined by measuring malondialdehyde (MDA) contents in plants during cold treatment. The result showed that MDA content increased by 2.02-fold and 1.78-fold in NT lines and RNAi lines after 4 degrees C treatment for 48 h, respectively. In contrast, the OE lines showed only small changes and were lower than the NT lines. Meanwhile, the activity of peroxidase (POD) and catalase (CAT) were also enhanced in OE lines compared with NT lines after cold treatment. Through observing the phenotype, importantly, this research found that the leaves of NT lines and RNAi lines have wilted severely while the OE lines were slightly affected. In all, these results indicated that genetic engineering technology could be used to regulate the antioxidant enzymes activity in plants to improve tolerance to cold stress.