Fusarium oxysporum affects differently the hydrogen peroxide levels and oxidative metabolism in susceptible and resistant bean roots

Abstract This study aimed at investigating the role of enzymes related to the oxidative metabolism and hydrogen peroxide in susceptible and resistant plants of common bean to Fusarium oxysporum f. sp. phaseoli ( Fop ). Fop inoculation increased H 2 O 2 levels only in roots of resistant plants. Despite this, no hypersensitive cells were induced. In the enzymatic metabolism, two distinct phases were observed in resistant roots; the first one at 1 day after inoculation (dai) characterized by an increase in guaiacol peroxidase, superoxide dismutase and ascorbate peroxidase, and decrease in catalase and lipoxygenase activities, and the second one at 3–4 dai characterized by activity peaks of NADPH oxidase, superoxide dismutase and ascorbate peroxidase. Overall, the metabolism oxidative was more drastically modified in resistant roots than in susceptible ones. Our results demonstrate that Fop infection affects differently the oxidative metabolism in a genotype-dependent manner.