Antioxidative enzyme activity, lipid peroxidation, and proline accumulation in the callus tissues of salt and drought tolerant and sensitive pumpkin genotypes under chilling stress

In this study, the effects of chilling stress were studied on 2 salt- and drought-tolerant and 2 sensitive pumpkin genotypes in callus culture. Growth inhibition occurred in the callus tissues when exposed to 4°C for 8 days. The tolerant genotypes showed lower increase in lipid peroxidation and a greater increase in superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase than the tolerant genotypes under stress conditions. The proline, glucose, and fructose contents continued to increase with progression in the chilling in the pumpkin genotypes. However, this increase was more significant in the tolerant genotypes than in the sensitive ones. These results indicate that chilling stress leads to the production of reactive oxygen radicals, resulting in increased lipid peroxidation and oxidative stress in pumpkin genotypes. The increase of antioxidant enzyme activities is associated with a tolerance to chilling stress.