Generation of superoxide anion and induction of superoxide dismutase and peroxidase in bean leaves infected with pathogenic fungi.

Abstract

Generation of superoxide anion (O2-.) and peroxidase activity were significantly increased in bean leaves infected with incompatible and compatible pathogens: Botrytis fabae and Botrytis cinerea, respectively, but the induction was greater on direct inoculation with B. fabae, than with B. cinerea. A slightly higher O2-. level was also detected in the parts of leaves surrounding the inoculation side. Overproduction of O2-. was observed earlier than the increase in peroxidase activity. Pretreatment of the leaves with methyl jasmonate enhanced both O2-. production and peroxidase activity following inoculation with B. cinerea. Induction of superoxide dismutase activity after the infection was less pronounced than changes in O2-. level. The differences in the rate of NADH oxidation in the extracts from control and inoculated leaves, correlated with the differences in the rate of O2-. production. The results indicate that O2-. level is one of the essential factors responsible for the difference in the interactions between bean plant and compatible and incompatible pathogens.