Keissar, H.T., Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel
Bashan, B., Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel
Levy, Y., Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel
Kenigsbuch, D., Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel

Exserohilum turcicum is the fungal agent that causes northern leaf blight disease in maize. Spores of E. turcicum can germinate in water containing up to 15 mM hydrogen peroxide. Initially the catalase isoform activities from E. turcicum cultured on artificial medium were analysed by polyacrylamide gel electrophoresis. Seven different catalase isoform activities were detected during a 72-hour time course from spore germination to young hyphal formation. During the time period studied the activity levels of each isoform varied independently. In two-week-old E. turcicum mycelia, only the activities of catalase isoforms #2 and #3 were detected. During a compatible interaction on maize leaves, plant catalases were suppressed with E. turcicum isoform #3 being detected from 72 h after inoculation onwards. E. turcicum #2 was the predominant isoform detected in necrotic lesions. Salicylic acid was not found to effect fungal or maize catalase activities. E. turcicum isoform #3 activity was found to be strongly induced by hydrogen peroxide and by the herbicide 3-amino-l,2,4-triazole (AT), while the activity of all other isoforms was suppressed by AT. © 2002 Published by Elsevier Science Ltd.