The effect of salt stress on antioxidative enzymes and proline content of two Turkish tobacco varieties

The aim of this study was to compare the salinity tolerances of 2 oriental tobacco varieties (Izmir Ozbas and Akhisar 97). Salinity stress experiments were performed under both in vitro and in vivo conditions. Seedlings of each variety were subjected to 0, 50, 100, 150, 200, 250, 300, and 350 mM NaCl. Photosynthetic pigment levels, lipid peroxidation rate, total protein content, antioxidant enzyme activities, and proline concentrations were determined for seedlings treated with salt for 14 days. The Akhisar 97 variety was found to be more sensitive to salinity stress than the Izmir Ozbas variety. Although proline is thought to accumulate in salt-tolerant plants, we found a negative correlation between salinity tolerance and proline accumulation in the plants. According to biochemical analyses, there were no differences in SOD, APX, GPX, or CAT activity levels between the 2 varieties, either in vivo or in vitro. However, differences in glutathione reductase (GR) activity between control plants and plants under NaCl stress were statistically significant in both varieties, both in vitro and in vivo. Our results support the hypothesis that GR is a key element in the evaluation of salinity tolerance of tobacco varieties.