investigation of catalase, proxidase and total protein level in some cold treated grapevine cultivars cold stress response

chilling is an important environmental stress that influences the yield and quality of many agricultural crops. different plants use different systems to endure this stress and minimize its effects. one of these systems is enzymatic reaction. to find out more about responses of different grapevine species and cultivars to the low temperature conditions, their enzymatic changes were evaluated in a factorial experiment based on randomized complete design with 3 replication during different periods after chilling stress. leaf samples of plants under cold stress had been taken and maintained in -80 °c until enzyme extraction. low temperature around 4 °c is sufficient to induce genes that produce chilling acclimatization proteins. in the present study, leaf samples were collected from the plants that were kept at 4 °c during different time intervals, and then total proteins as well as two main antioxidant enzymes (catalase and guaiacolperoxidase) activities were measured. results showed that as temperature decreased, enzymatic activities were increased in six iranian grapevine cultivars (‘atabaki’, ‘khalili-danedar’, ‘shahroodi’, ‘rajabi-siah’, ‘askari’ and ‘bidane-sefid’) as well as ‘riparia’, an american species. the highest enzymatic activities of catalase and ceroxidase were recorded in ‘khalili-danedar’ and ‘riparia’. however,the lowest activities were recorded in ‘rajabi-siah’, ‘bidane-sefid’ and ‘shahroodi’. for all studied cultivars, peroxidase showed its highest activity at 12 h after chilling stress, then remained constant, while, the highest activity of catalase were recorded at 8 h. in addition, cold stress increased the total protein content for all studied cultivars, in which ‘khalili-danedar’ had the highest protein content amongstudied cultivars. also, the highest proteins content were recorded at 12 h after exposing plants to cold.