The Effect of Piriformospora indica and Salicylic Acid on the Activity of Antioxidant Enzymes in the Wheat Sensitive to Powdery Mildew Fungus

Use of fungicides against wheat powdery mildew disease caused by biotrophic Blumeria graminis f. sp. tritici (Bgt)), is not taken into consideration. Therefore, employment of artificial activator of defense mechanism that can induce resistance in plants, is very important. For this purpose, Falat cultivar as a susceptible genotype to powdery mildew, was inoculated with B. graminis after colonizing with endomycorrhizal fungus, Piriformospora indica, together with control plants. In another experiment, two weeks old Falat plants were treated with salicylic acid after 48h and then, were inoculated with the pathogen. Then, the pattern of catalase, peroxidase and ascorbate peroxidase antioxidant enzymes were compared at 0, 12, 24 and 48 hours after infection in three replications. The results of this study showed that the enzyme activity of the Falat treated with SA were less than the control plant before and after the disease (except peroxidase enzyme, which increased before and after infection). In symbiont plants, there was no significant difference in the amount of enzyme activities than control plants, except overexpression of peroxidase enzyme. Therefore, it seems that the symbiotic fungi is hot effect for inducing resistance via enzymatic pathway. Probably these fungi can play an important role through the activation of other pathways such as activation of pathogens related proteins. While, SA can suppress the biotrophic pathogen by reducing the capacity of the antioxidant enzymes and inducting the rapid cell death. Therefore, the application of SA against powdery mildew is recommended.