Electrophoretic Karyotypes Distinguish the Biological Species of Gibberella fujikuroi (Fusarium Section Liseola). Jin-Rong Xu . Department of Plant Pathology, Kansas State University, Manhattan 66506-5502 U.S.A. Keying Yan(2), Martin B. Dickman(2), and John F. Leslie(1). (1)Department of Plant Pathology, Kansas State University, Manhattan 66506-5502 USA (2) department of Plant Pathology, University of Nebraska, Lincoln 68583-0722 U.S.A. MPMI 8:74-84. Accepted 7 October 1994. Copyright 1995The American Phytopathological Society.

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 Schizo-saccharomyces pomhe (5.7 Mhp), and one of these bands is larger than the largest chromosome of Neurospora crassa (10 Mbp). AH strains from the same mating population have a similar electrophorelic karyotypc, regardless of geographic or host origin, but each mating population has a distinctive karyotype. Comparison of karyotype profiles following Southern analysis using homologous and het-erologous 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 field 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.