ELECTROPHORETIC KARYOTYPES DISTINGUISH THE BIOLOGICAL SPECIES OF GIBBERELLA-FUJIKUROI (FUSARIUM SECTION LISEOLA)

Using pulsed field gel electrophoresis, we resolved the chromosomes of strains belonging to six different mating populations (biological species) of the ascomycete fungus Gibberella fujikuroi (anamorph Fusarium section Liseola), In all 34 strains examined, gross karyotypes suggest a haploid number of 12 chromosomes in all of the mating populations, although in some strains chromosomes 4 and 5 appear as a doublet band with an obviously higher density, All strains have two chromosome bands that are as large or larger than the largest chromosome of Schizosaccharomyces pombe (5.7 Mbp), and one of these bands is larger than the largest chromosome of Neurospora crassa (10 Mbp), All strains from the same mating population have a similar electrophoretic karyotype, regardless of geographic or host origin, but each mating population has a distinctive karyotype, Comparison of karyotype profiles following Southern analysis using homologous and heterologous nuclear gene probes and single-copy restriction fragment length polymorphism probes revealed some differences in hybridization between, but not within, biological species, Estimated genome sizes are 45-50 Mbp for mating populations A, B, D, and F, and 50-55 Mbp for mating populations C and E, The smallest of the 12 chromosomes varies the most between mating populations and was present in all of the held strains examined, but it can be lost following meiosis, Thus, karyotype analysis is a useful tool for the study of taxonomy, genome organization, and evolution of this group of fungi.