Enzyme Activity and Isozymic Profile of Peroxidase Induced by Elicitors andErysiphe polygoniin Pea (Pisum sativumL.)

A significant increase in peroxidase (PO) activity of powdery mildew (Erysiphe polygoni DC) in the susceptible garden pea (Pisum sativum L.), cv. ‘Arkel’, was observed after treatment with 5 mM salicylic acid (SA). The increase in PO activity after inoculation with spores of E. polygoni was highly significant. Treatment with SA (1 mM) and 4-aminobutyric acid (1 and 5 mM) did not produce significant change in PO activity as compared to water treated control plants in both the resistant (‘JP-179’), and susceptible cultivars. In the resistant cultivar, treatment with 5 mM SA produced significant increase in PO activity after 120 h. The isozymic profile of peroxidase showed additional bands in both cultivars after treatment with 5 mM SA and inoculation with E. polygoni. The additional increase in the activity and number of isoforms of peroxidase in the powdery mildew resistant cultivar may be a limiting factor for the growth of the pathogen.