Preinfectional interactions between M. grisea spores and resistant and susceptible rice plants were investigated by the scanning electron microscope. At 2 hr after inoculation, germ tubes emerged mostly from top cells of spores and elongated on cell junctures between the papillae. At this stage, mucilage-like substances which contacted with the cuticle surface were observed on both resistant and susceptible cultivars. Mucilages were observed
on the undersides of germ tubes and were often attached to papillae on the leaf surface. Most of immuture appressoria of M. grisea were formed 6 hr after inoculation and secreted the mucilages. The wax crystals around appressoria of M. grisea disappeared. Above phenomena were observed regardless of the compatibility between M. grisea and rice cultivars used. The present study showed that the mucilage and enzyme productions might enable the fungus to attach to the leaf surface and facilitate.
Key words: Magnaporthe grisea; rice plant; rice blast; SEM.