Intraspecific differentiation of Chilean isolates of the entomopathogenic fungi Metarhizium anisopliae var. anisopliae as revealed by RAPD, SSR and ITS markers

Abstract

The genus Metarhizium consists of a diverse group of asexual entomopathogenic fungi, which have a wide geographical distribution. The Chilean National Agricultural Research Institute (Instituto de Investigaciones Agropecuarias - INIA, Quilamapu Chile) has collected about 350 isolates of Metarhizium anisopliae var. anisopliae from central and southern Chile. These isolates have been partially characterized using morphological traits such as conidia size and shape, colony color, growth pattern and the efficiency of the isolates in controlling specific pests. However, further characterization with molecular markers could detect differences in DNA which could help to better understand the genetic diversity and structure of Chilean populations of this fungus. We analyzed approximately 10% of the INIA collection (39 isolates selected at random) collected from different geographical origins using the polymerase chain reaction (PCR)-random amplified polymorphic DNA (RAPD) method, simple sequences repeat (SSR or microsatellites) analysis and the PCR-restriction fragment length polymorphism (RFLP) assay of internal transcribed spacer (ITS)-rDNA sequences. The RAPD data revealed high genetic diversity in this fungus and an average of 41% of similarity while SSR analysis detected 45.2% similarity and the ITS markers 70.2% similarity. For the three molecular markers, this diversity was not associated with the geographical origin of these isolates.