Genetically related isolates of the entomopathogenic fungus Metarhizium anisopliae harbour homologous dsRNA viruses

Several isolates of the entomopathogenic Metarhizium anisopliae that harbou red dsRNA viruses of similar electrophoretic band sizes (1.8 and 2.0 kbp) w ere assessed for homologies of the dsRNA by Northern analysis. The isolates were also characterised genetically by RAPD and VCG. Similarly sized dsRNA , as visualised by electrophoresis, were not always homologous, suggesting that the comparison of dsRNA based solely on electrophoretic banding patter ns is an unreliable method of dsRNA characterisation. Several isolates, but not all, harbouring multiple dsRNA patterns, including a 1.8 and 2.0 kbp d oubler, also showed homologies to strains harbouring only the dsRNA banding doubler. This suggests that mixed infections of different dsRNA elements a re found in M. anisopliae. Genetically similar fungi, based on RAPD banding patterns and vegetative compatibility, were more likely to harbour genetic ally related dsRNA. The findings suggested that dsRNA elements in M. anisop liae are horizontally transferred to genetically related isolates or are ma intained through clonal lineages.