Simultaneous overexpression of CuZnSOD and cAPX from Arachis hypogaea leads to salinity stress tolerance in tobacco

Abstract

Stress leads to generation of reactive oxygen species in living cells, which are scavenged by antioxidant enzymes. In the present study, genes encoding for two different antioxidant enzymes, namely cytosolic superoxide dismutase and cytosolic ascorbate peroxidase isolated from salt-tolerant cell lines of Arachis hypogaea, were simultaneously overexpressed in tobacco (Nicotiana tabacum cv. Xanthi) and the effect of their overexpression on alleviation of salinity stress was evaluated. The co-expression of AhCuZnSOD and AhcAPX in tobacco plants helped the resulting transgenic plants in overcoming salt stress. Compared to the wild-type plants, transgenic plants survived longer periods of salinity stress and displayed improved recovery after removal of the stress. The transgenic tobacco plants exhibited better photosynthetic efficiency, higher germination rate, more chlorophyll content, higher levels of total antioxidant enzyme activities, greater water retention capacity, higher proline accumulation, lower level of malondialdehyde content, and reactive oxygen species accumulation under stress conditions in comparison to the WT plants. Our analysis revealed that combined overexpression of the two antioxidant enzymes improved the salinity tolerance in transgenic plants.