An ultrastructural investigation of pathological alterations induced by Macrophomina phaseolina (Tassi) Goid in seedlings of soybean, Glycine max (L.) Merrill

Abstract

An ultrastructural investigation of seedling soybean root tissue infected by the charcoal rot fungus indicated that during the initial stages of pathogenesis, the fungus appears to be restricted mostly to the intercellular spaces and that penetration of interior cell walls occurred as a result of both mechanical pressure and chemical softening. Subsequently, the middle lamella disintegrates, the plasmalemma is separated from the cell wall, the cytoplasm becomes highly vesiculated and the mitochondria disorganized. In later stages of pathogenesis, the fungus becomes intracellular and recognizable cytoplasmic organelles disappear.