Colletotrichum graminicola, the causal agent of anthracnose or stalk rot of corn (Zea mays), is an important pathogen with a high genetic variability. Nine isolates of this phytopathogen were compared by using isozyme analysis with polyacrylamide gel electrophoresis in three systems: proteins, esterase and acidic phosphatase. Analysis by each system showed variation in the number, intensity, and relative mobility of the bands in the gel of the pathogen population. For protein the analysis revealed polymorphism eventhough Cgr8 and Cgr9 isolates have shown the same pattern with six bands of relative position in the gel. For esterase activity, the same isolates showed a monomorphic behaviour while the other isolates revealed polymorphic phenotypes. In relation to acidic phosphatase, all isolates presented two bands, but differences in mobility of the molecules were observed, except between Cgr1 and Cgr2 and among Cgr6, Cgr7 and Cgr8. In general, the isolates produced bands in common, indicating that they are closely related to each other, and that the phenotypic variation observed, is probably the result of a nuclear condition, homozygous or heterozygous, for each enzyme system tested.
