Detection of molecular variation in the insect pathogenic fungus Metarhizium using RAPD-PCR.

DNA polymorphism among isolates of the insect pathogenic fungus Metarhizium anisopliae and M. flavoviride was investigated by RAPD-PCR. DNA fragments of between 0.3 and 2.7 kb were obtained using eight 10-mer PCR primers of arbitrary nucleotide sequence, and each isolate differed in the size and number of RAPD products, indicating considerable polymorphism. Isolate-specific RAPD fingerprints were used to calculate relative genetic similarity; this differentiated isolates into two major groups, separating nine of the ten isolates of M. anisopliae from the two of M. flavoviride. However, an Australian M. anisopliae isolated from an Orthopteran host exhibited a higher degree of genetic similarity to the M. flavoviride group. M. anisopliae isolates were further segregated into three subgroups which were loosely related to their geographical origins, although considerable polymorphism was observed within these groups. There was no apparent association between genotype and original insect host.