PossibleContributionofBlastSpores totheOxidativeBurst intheInfectionDropletonRiceLeaf

–was found after their germination, and H 2O2 was found after appressorium formation. Various fungal strains differed in ROS production. The results suggest that spores of the blast inocu lum may contribute significantly to ROS production on rice leaves, at least, at early stages of the disease. This might be a factor of incompatibility suppressing a parasite and/or inducing defense responses of a host.