Molecular taxonomic characterization and infra-specific diversity of entomopathogenic Beauveria bassiana fungi from Argentina

It has been the aim of this study to molecular-taxonomically identify 15 Beauveria isolates collected from different geographical regions and insect hosts in Argentina and to investigate the levels of inter- and intra-specific diversity across this set of isolates. Based on phylogenetic analyses of EF1A-RPB1-RPB2 concatenated genes and BLOC markers, all Beauveria strains were identify as B. bassiana. Within the B. bassiana clades of both phylogenies, isolates from Argentina were not clustered according to geographic origin or host. The 15 fungal isolates were further analyzed by PCR amplification of the intron insertion hot spot region of the nuclear 28S rRNA encoding sequence. By intron sequence and position, seven different group-I intron combinations termed variants A, B1, B2, C, D, E and F were found in the 15 isolates under study. Variants B1/B2 consisting of a single 28Si2 intron were found in ten isolates, whereas variant A occurred twice and variants C through F were unique across the set of isolates under study. The determination of the different introns and intron combinations in the 28S rRNA gene is a powerful tool for achieving infraspecific differentiation of B. bassiana isolates from Argentina.