Identification of Molecular Variants in Mitochondrial DNAs of Members of the Genera Beauveria, Verticillium, Paecilomyces, Tolypocladium, and Metarhizium.

A set of five mitochondrial (mt) probes derived from a strain of Beauveria bassiana was used to evaluate the similarity of mtDNAs from 15 additional isolates of this fungus and five genera of other entomopathogenic fungi. The probes and genes encoded for (shown in parentheses) were pBbmtE2 (NADI, ATP6), pBbmtE3 (ATP6, small rRNA [srRNA]), pBbmtE4 (srRNA, CO3, NAD6), pBbSE1 (NAD6, tRNA, large rRNA [lrRNA]), and pBbXS1 (lrRNA). The probes produced identical hybridization patterns in EcoRI-digested DNA from nearly all isolates of B. bassiana and Beauveria caledonica. Similar patterns were also observed with Beauveria densa. The isolates of B. caledonica and B. densa DNAs could be differentiated from each other and from B. bassiana on the basis of a HindIII digestion and probing with pBbmtE3. Probe pBbmtE2 produced either a 5.0-kb or a 4.1-kb band in all of the B. bassiana isolates. This observation was used to categorize the mtDNA of B. bassiana into two types, designated A and B. Hybridization of the five probes produced distinct banding patterns in Beauveria brongniartii, Tolypocladium cylindrosporum, Tolypocladium nivea, Metarhizium anisopliae, Verticillium lecanii, and Paecilomyces farinosus. Hybridizations carried out with multiple probes simultaneously present produced unique patterns which characterized the B. bassiana group from all other fungi tested. These results are discussed in terms of how mtDNA polymorphisms in B. bassiana may relate to natural population structures, mt transmission in deuteromycetes, and the use of mtDNA polymorphisms in structural analysis of mtDNA.