Electrophoretic Karyotyping of Fusarium oxysporum

Abstract

Chromosome-sized DNAs of Fusarium species were prepared for pulsed-field gel electrophoresis without first generating protoplasts. The technique involves pre-treatment of intact, agarose-solidified microconidia with endo-β-1, 3-glucanase before treatment with protease in the presence of EDTA and SDS. By using four different electrophoretic conditions for the separation of four size ranges of chromosomes, we have succeeded in separating the chromosomes of 6 formae speciales (lycopersici, radicislycopersici, melonis, cucumerinum, fragariae and spinaciae) or Fusarium oxysporum in an agarose gel matrix by crossed field gel electrophoresis. The total number of chromosome-sized DNA molecules of these fungi varied from 9 to 15, depending on the formae speciales and, in some case, individual strains. The sizes of chromosomes ranged from 0.8 to approximately 7.4Mb which gave estimates of genome size of between 36.0 and 56.3Mb.