GENERATION OF SUPEROXIDE ANION AND INDUCTION OF SUPEROXIDE-DISMUTASE AND PEROXIDASE IN BEAN-LEAVES INFECTED WITH PATHOGENIC FUNGI

Generation of superoxide anion (O-2(-.)) and peroxidase activity were significantly increased in bean leaves infected with incompatible and compatible pathogens: Botrytis fabae and Botrytis cinerea, respectivel y, but the induction was greater on direct inoculation with B. fabae, than with B. cinerea. A slightly higher O-2(-.) level was also detecte d in the parts of leaves surrounding the inoculation side. Overproduct ion of O-2(-.) was observed earlier than the increase in peroxidase ac tivity. Pretreatment of the leaves with methyl jasmonate enhanced both O-2(-.) production and peroxidase activity following inoculation with B. cinerea. Induction of superoxide dismutase activity after the infe ction was less pronounced than changes in O-2(-.) level. The differenc es in the rate of NADH oxidation in the extracts from control and inoc ulated leaves, correlated with the differences in the rate of O-2(-.) production. The results indicate that O-2(-.) level is one of the esse ntial factors responsible for the difference in the interactions betwe en bean plant and compatible and incompatible pathogens.