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

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 Ó2 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 Ó2 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 thatCte level is one of the essential factors responsible for the difference in the interactions between bean plant and compatible and incompatible pathogens.