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 spe cies) of the ascomycete fungus Gibberella fujikuroi (anamorph Fusarium section Liseola), In all 34 strains examined, gross karyotypes sugges t 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 ban ds that are as large or larger than the largest chromosome of Schizosa ccharomyces pombe (5.7 Mbp), and one of these bands is larger than the largest chromosome of Neurospora crassa (10 Mbp), All strains from th e same mating population have a similar electrophoretic karyotype, reg ardless of geographic or host origin, but each mating population has a distinctive karyotype, Comparison of karyotype profiles following Sou thern analysis using homologous and heterologous nuclear gene probes a nd single-copy restriction fragment length polymorphism probes reveale d some differences in hybridization between, but not within, biologica l 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 sma llest of the 12 chromosomes varies the most between mating populations and was present in all of the held strains examined, but it can be lo st following meiosis, Thus, karyotype analysis is a useful tool for th e study of taxonomy, genome organization, and evolution of this group of fungi.