Effect of Salicylic Acid on Enzyme Activity in Wheat in Immediate Early Time after Infection with Mycosphaerella graminicola

The effect of salicylic acid (SA) on antioxidant enzymes activities in wheat infected with Mycosphaerella graminicola was investigated. Different concentrations of SA (0 and 2mM) were sprayed on susceptible and tolerant cultivars of wheat at a two-leaf stage. Enhanced activities of peroxidase, catalase, phenylalanine ammonia lyase, and polyphenoloxidase were determined in two wheat SA-treated cultivars in the presence or absence of pathogen. The results showed that the application of SA was more effective on antioxidant activities than pathogen. However, the highest activities of all tested enzymes were detected in cultivars treated both with SA and pathogen. Although in the earliest time of infection the antioxidant enzymes activities in susceptible cultivar were weaker than in the tolerant cultivar, the enzymes activity enhancement by SA in susceptible cultivar was observable, too. These results suggest SA as plant defense inducer could be an effective agent against M. graminicola in wheat.