title: Nuclear small subunit rRNA group I intron variation among Beauveria spp provide tools for strain identification and evidence of horizontal transfer.
abstract: An optional group I intron was characterized at a single insertion point in nuclear small subunit rRNA (nuSSU rRNA) genes of the imperfect entomopathogenic fungi, Beauveria bassiana and B. brongniartii. Insertion points were conserved among nuSSU rRNA genes from 35 Beauveria isolates. PCR-RFLP and DNA sequencing identified 12 group I intron variants and were applied to the identification of strains isolated from insect hosts. Alignment of 383-404-nt subgroup IB3 group I introns indicated that four insertion/deletion (indel) mutations were the main basis of fragment length variation. Phylogeny reconstruction using parsimony and neighbor-joining methods suggested six lineages may be present among nuSSU rRNA group I intron sequences from Beauveria and related ascomycete fungi. Terminal node placement of Beauveria introns conflicted with previously published phylogenies constructed from gene sequences, suggesting horizontal transfer of group I introns. PCR-RFLP among introns provided a means for the differentiation of Beauveria isolates.
authors.affiliation: USDA-ARS, Corn Insect and Crop Genetics Research Unit, Genetics Laboratory, Iowa State University, Ames, IA 50011, USA. coates@iastate.edu
authors.forename: Brad S
authors.initials: BS
authors.lastname: Coates
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hellmich
authors.forename: Leslie C
authors.initials: LC
authors.lastname: Lewis
mesh_terms: D001483:Base Sequence; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D006999:Hypocreales / Q000145:classification* / Q000235:genetics; D007438:Introns; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004275:DNA, Ribosomal