اثر سرما روی تخریب اکسیداتیو و فعالیت آنزیم های آنتی اکسیدانت در برگ چای شمال ایران

Tea was planted in Lahijan by Kashefalsataneh in 1930. The main concern about important commercial plants such as tea is the formation of ice crystals in low temperatures. This can damage the live cells leading to lowering the quality of the plant and eventually its death. Formation of reactive oxygen species (ROS) and oxidative stress is the result of various environmental stresses leading to freezing. Investigating the variations in any of these factors could help to understand the mechanism of freeze resistance in ever-green plants. The aim of the present research was to investigate lipid peroxidation, the presence of antifreeze protein and variations in the activity of some antioxidant enzymes, including superoxide dismutase (SOD), ascorbate peroxidize (APX) and catalyse (CAT) in tea leaves subjected to 20, 0, -2, -5 and -8°C in tea leaves from the north of Iran. The results showed formation of an antifreeze protein with MW of about 20 KD in response to cold stress. It was also found that the activity of SOD, APX and CAT increased in tea leaves due to cold stress. The activity of SOD increased down to -8°C. APX and CAT increased their activity down to -5°C. On the other hand, the lipid per oxidation factor, MDA, was also elevated in response to the cold stress.