Abstract
To clarify the role of hydroperoxides of unsaturated fatty acids in the resistant reaction of rice plants to blast infection, cytotoxicity to rice cells and anti-blast activity were examined using hydroperoxide of linolenic acid produced by the action of lipoxygenase. Three kinds of hydroperoxides were identified as a result of in vitro enzyme reaction using the homogenate of blast-infected rice leaves. The mixture of hydroperoxides showed a severe cytotoxicity to rice cells prepared from callus. The damage of rice cells was observed after 20-min incubation with ED50 around 1.0μg/ml. These metabolites also exhibited strong anti-blast activity to all the examined isolates of rice blast fungus. The evidence suggests that lipoxygenase products play an important role in the hypersensitive cell death of rice leaves and also the inhibition of growth of infection hyphae of the fungus at the site of the blast infection.
