Intraspecific polymorphism in Metarhizium anisopliae var. anisopliae revealed by analysis of rRNA gene complex and mtDNA RFLPs

Sequence analysis of the rDNA intergenic spacer of Metarhizium strains isolated in Brazil

“…The variability in length of IGS amplicons observed among the isolates sampled in this 118 Metarhizium strains rDNA intergenic spacer study has also been observed in other studies with Metarhizium strains (Mavridou and Typas, 1998;Pantou et al, 2003) and other fungi in the Hypocreales (Mishra et al, 2002). Including all insertion sites, we obtained a final aligned data set of 983 bp.…”

“…The utilization and the improvement of mycoinsecticides could be an alternative tool to overcome the considerable environmental impact and high economical costs posed by conventional insecticides (Roberts and St. Leger, 2004). The non-transcribed intergenic region (IGS) and the internal transcribed spacers (ITS) located in the nuclear ribosomal DNA (rDNA) gene cluster evolve rapidly and have been widely used as a tool to evaluate the genetic diversity within populations of fungi (Mavridou and Typas, 1998;Pantou et al, 2003;Hughes et al, 2004;Velásquez et al, 2007) and to resolve problems regarding the identification of species and isolates based on morphological characters (Milner et al, 1994;Driver et al, 2000;Iwen et al, 2002).…”

“…The utilization and the improvement of mycoinsecticides could be an alternative tool to overcome the considerable environmental impact and high economical costs posed by conventional insecticides (Roberts and St. Leger, 2004). The non-transcribed intergenic region (IGS) and the internal transcribed spacers (ITS) located in the nuclear ribosomal DNA (rDNA) gene cluster evolve rapidly and have been widely used as a tool to evaluate the genetic diversity within populations of fungi (Mavridou and Typas, 1998;Pantou et al, 2003;Hughes et al, 2004;Velásquez et al, 2007) and to resolve problems regarding the identification of species and isolates based on morphological characters (Milner et al, 1994;Driver et al, 2000;Iwen et al, 2002).Even though Metarhizium strains have been used in Brazil against a number of insect pests since the 1980s (Garcia et al, 1984), an evaluation on the intraspecific genetic variability of Metarhizium isolates from Brazil has not so far been performed. Since better characterization of the genetic variation within an entomopathogenic fungus population could be useful for the selection of more efficient isolates for biological control, the aim of this study was to assess the extent of genetic variability in the IGS region of Metarhizium strains with special attention placed on the Brazilian isolates.…”

Identification of Group-I Introns at Three Different Positions within the 28S rDNA Gene of the Entomopathogenic Fungus Metarhizium anisopliae var. anisopliae

“…Using RFLP analysis, several research groups have shown recently that the rRNA gene block of M. anisopliae isolates is rather conserved with complete absence of variation in the ITS1-5.8S-ITS2 region (Bridge et al, 1993;Pipe et al, 1995;Mavridou and Typas, 1998). This is in contrast to results from other related fungal species such as the entomopathogens B. brongniatii (Neuveglise et al, 1997) and V. lecanii (Zare et al, 1999), where great variability has been observed within the above gene region.…”

“…All these approaches undoubtedly helped to detect some polymorphism among isolates of the species and the genus, but in general, it was evident that the rRNA gene complex repeat region was rather conserved. In a very recent report it was shown that a combination of rDNA and mtDNA RFLP analysis can lead to maximum isolate differentiation (Mavridou and Typas, 1998). Additionally, evidence was provided that the ITS1-5.8S-ITS2 region was extremely conserved among the 25 Metarhizium anisopliae isolates tested, whereas RFLP analysis of the entire rDNA region using a heterologous gene probe provided some levels of polymorphism indicating size differences in this region.…”