1997 Volume 63 Issue 2 Pages 69-77
Magnaporthe grisea produces a toxin(s) which is important in the establishment of basic compatibility at the species level between fungus and plant. The effects of the toxin(s) on host (rice and barley) and non-host (finger millet) plants were examined by ultrastructural observation and morphometric measurement. The first ultrastructural changes observed after 1 hr of toxin(s) treatment were a decrease in the number of mitochondrial cristae and in the electron density of the mitochondrial matrix in rice leaf cells. Further, such modifications were observed in both compatible and incompatible inoculated with the fungal strain used for preparation of the toxin(s). However, morphological and ultrastructural changes were not observed in other organelles. Such phenomena were observed in all leaf tissues (epidermis, mesophyll and vascular bundle) of host plants. On the other hand, the effects of toxin(s) were not observed in leaves of the non-host plant. These results suggested that the mitochondrial modifications induced by the toxin(s) were a host-specific phenomenon and possibly, on essential event for M. grisea to establish basic compatibility with host plants at the species level.