Responses of Protective Enzymes and Reactive Oxygen Species to Crude Toxin Produced by Sclerotium cepivorum Berk.in Garlic Leaves

The dynamic changes in activities of defensive enzymes,the content of superoxide radical (O-·2) and malonaldehyde (MDA) in leaf of resistant cultivar ‘Hanzhong Red Skin’ and susceptible cultivar ‘Gailiang’ treated by crude toxin produced by Sclerotium cepivorum Berk.were tested in seedling stage.The results suggested that the activities of superoxide dismutase (SOD) and peroxidase (POD) were stimulated and increased,and the activities of catalase (CAT) were lower after treating by crude toxin.The enzyme activities in resistant cultivar ‘Hanzhong Red Skin’ were higher than that of susceptible cultivar ‘Gailiang’.The peaks of the activities of SOD and POD in the resistant cultivar appeared earlier than that of the susceptible cultivar,and POD is the most sensitive one among them to the toxin coercion.The results also showed that the content of O-·2 in resistant cultivar was lower than that in susceptible cultivar,after treating 24 hours.The dynamic changes of the content of MDA were basically in conformity with that of O-·2.These results indicated that the content of reactive oxygen species (ROS) and activities of protection enzymes in leaf had a close relationship with disease resistance in garlic.