Mechanisms of salt tolerance in transgenic Arabidopsis thaliana constitutively overexpressing the tomato 14-3-3 protein TFT7

Abstract

Soil salinity is a major abiotic stress in reducing plant growth and agricultural productivity. In higher plants, 14-3-3 proteins are phosphoserine-binding proteins that regulate the activity of a wide array of targets via protein–protein interaction and play a key role in abiotic stress. We report here that CaMV 35S promoter driven overexpression of the TFT7 gene, one of tomato 14-3-3 proteins, improves plant salt tolerance in Arabidopsis thaliana. In response to salt stress, transgenic plants overexpressing TFT7 improved germination rate, dry mass, total chlorophyll concentration and root length. In contrast, the degree of hydrogen peroxide and malondialdehyde accumulation were more in wild-type plants than in transgenic plants. Therefore, the mechanisms of salt tolerance in transgenic plants can be explained by reduction of salt-induced oxidative stress damage. In addition, under normal growth condition or salt stress, the higher total ascorbate peroxidase (APX) activity in transgenic plants than in the wild-type plants indicates that TFT7 upregulates the activity of APX which plays the indispensable role in salt-induced oxidative stress. These results suggest that in higher plants, TFT7 plays an important role in salt tolerance and may be a candidate gene for developing salt-tolerant crop plants.