SOD, CAT, GR and APX Enzyme Activities in Callus Tissues of Susceptible and Tolerant Eggplant Varieties under Salt Stress

When plants are subjected to environmental stresses such as temperature extremes, drought, salinity or heavy metal toxicity, they produce reactive oxygen species ROS causing oxidative damage. Plants with high levels of antioxidants, either constitutive or induced, have been reported to have greater resistance to the oxidative damage. In our previous studies, we examined the relationship between antioxidant enzymes and salt tolerance in the leaves of the eggplant seedlings of two salt-tolerant genotypes (Burdur Bucak-BB and Mardin Kiziltepe-MK) and two salt-sensitive genotypes (Giresun-GI and Artvin Hopa-AH) and we found that the salt-tolerant varieties contained significantly higher constitutive levels of catalase and induced levels of SOD, APX and GR. SOD, CAT, GR and APX enzyme activities were determined in callus tissues. Under salt stress at the 8th day, significant differences were found in the aspect of SOD activity between salt-tolerant and salt-sensitive eggplant varieties. Concerning CAT, GR and APX activities, it is found that the 4th day calculations were significant and gave a high correlation with the tolerance levels of genotypes. The data indicated a strong correlation between antioxidant enzyme activity and the ability of eggplant callus tissue to grow on media amended with NaCl. The salt-induced increase in antioxidant enzyme activities in callus tissue was found at the highest level in salt tolerant eggplant varieties. The genotypical differences in salt tolerance observed at whole plant level experiments were also apparent in callus cultures of eggplant. These results show that callus cultures can be useful for the screening programs to determine the salt tolerance level in eggplant.