Effect of Drought Stress on Antioxidant Activity in Two Sensitive and Tolerant Rapeseed (Brassica napus) Cultivars in Cell Suspension Culture

This research was conducted to evaluate drought stress effect on the activity of antioxidant enzymes Catalase, Polyphenol oxidase, and Ascorbate peroxidase in sensitive Hyola308 and resistant SLM046 cultivars of canola (Brassica napus). Factorial experiment was carried out in a completely randomized design with three replications. Seedlings were cultured in liquid MS medium supplimented with different amounts (0%, 3%, 6%, 12% and 15%) of PEG 6000. Leaf discs were collected at 3, 6, 12, 24, 48 and 72 hours after stress. Results showed that drought stress made significant changes in enzymatic antioxidants activity. In comparison with Hyola308, Catalase activity in SLM046 increased at lower amounts of PEG after 48 hours. Polyphenol oxidase activity in SLM046 cultivar reduced in medium containing 12% and 15% PEG. Polyphenol oxidase activity in Hyola308 was higher than SLM046 cultivar. Ascorbate peroxidase activity increased in media containing PEG after 48 hours, in both cultivars.