Variation in electrophoretic karyotype among Mexican isolates of Mycosphaerella fijiensis

The electrophoretic karyotype of the filamentous fungus Mycosphaerella fijiensis was determined using contour-clamped homogenous electric field (CHEF) gel electrophoresis. Among 10 isolates from different geographical areas, the highest variation in the banding profiles was found in the chromosomes with sizes below 1.5 megabases pairs (Mbp). The minimal genome size was estimated to range from 27 to 35 Mbp. Eight to 13 chromosomal bands, ranging approximately from 0.5 to 8.6 Mbp in size, were separated. These results open perspectives for the physical mapping of specific genes, such as those associated with avirulence, pathogenicity, and fungicide resistance, and for the construction of chromosome-specific libraries.