Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2001
Publication Date: N/A
Interpretive Summary: The fungus, Beauveria bassiana, is a significant pathogen of European corn borer and corn rootworm, and has been used in biological control of these important corn pests. Studies were conducted to evaluate genetic differences between fungal isolates obtained from these two insects. Mutations were found that allow scientists to distinguish between several types of Beauveria. This identification method will help scientists to screen for better strains of this pathogen. This information is useful for scientists and growers interested in sustainable methods for controlling European corn borer and corn rootworm.
Technical Abstract: DNA sequence alignment of the ribosomal RNA (rRNA) internal transcribed spacers (ITS) and the 5.8 S gene from Beauveria bassiana (Bals.) isolates Bb153, Bb501, Bb726, Bb1022, Bb1149, Bb1155, Bb2515, Bb3113, and Bb3167 demonstrated that 6.62% sequence variation exists between isolates. A higher level of mutation was observed within the ITS regions, where 8.39% divergence occurred. Beauveria amorpha (Hohnel) isolate Ba2251 sequence data were aligned with that of B. bassiana, indicating 11.11% variation between species. Polymerase chain reaction restriction fragment length polymorphism, PCR-RFLP, and DNA sequence alignment of the ITS1 and ITS2 regions identified ten polymorphic restriction endonuclease sites Alu I, Hae III, Hha I, Hinf I, Msp I, Tha I (2), Sin I, Sau 3AI, and Tru 9AI. The allelic frequency for each genetic marker was determined within 45 B. bassiana isolates. Seven polymorphic B. bassiana intraspecies markers are comprised of Alu I, Hha I, Hinf I, Sin I, Tru 9AI and two Tha I restrictio sites. In total, PCR-RFLP defined 11 distinct genotypes within the sample set, whereupon the frequency of each was calculated. Analysis revealed a correlation between fungal genotypes and insect host. Beauveria interspecies variation was detectable by Hae III, Msp I and Sau 3AI PCR- RFLP, and PAGE separation of a 7 nucleotide B. amorpha ITS2 insertion.