Electrophoretic karyotyping from Tolypocladium inflatum and six related strains allows differentiation of morpologically similar species

Summary The electropheretic karyotype for the imperfect filamentous fungus Tolypocladium inflatum and for six related strains is presented. Pulsed-field gel electrophoresis was used with improved separation conditions to separate DNA from 6.6 Mb to 1.05 Mb in size. Using probes encoding rRNA or the -tubulin gene from T.iinflatum the corresponding genes were detected on designated chromosomes. In addition, two recombinant lambda clones, carrying T. inflatum chromosomal DNA, were used as chromosome-specific probes. Although all strains investigated are very similar in their morphology, significant chromosome-lengt polymorphisms were detected, allowing easy strain differentiation. The polymorphism was confirmed using an rRNA probe for genomic mapping. All strains contain a homologous minichromosome of 1.05 Mb. Finally, the resolution of very large DNA enabled us to separate a 6.6-Mb DNA band that specifically hybridizes with mitochondrial gene probes. The electrophoretic karyotyping presented here may be regarded as a reliable molecular tool to differentiate morphologically very similar filamentous fungi. Correspondence to: U. Kück