Molecular characterization of Pisolithos spp. isolates by rDNA PCR-RFLP

Variation within ribosomal DNA. (rDNA) genes of 19 isolates of Pisolithus f rom different geographic origins and hosts was examined by polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP ) analysis. The primers utilized amplify rDNA regions in a wide range of fu ngi. One amplified region includes the internal transcribed spacer (ITS), w hich has a low degree of conservation. The ITS amplification products (640- 750 bp) were digested with a variety of restriction endonucleases. Cluster analysis based on the restriction fragments grouped the isolates into three distinct groups: group I contained isolates collected in the northern hemi sphere, except Pt 1, group II contained those collected in Brazil and group III contained isolate Pt 1. Additional analysis of other rDNA regions, IGS , 17 S and 25 S rDNA, resulted in similar groups. The data suggest that the taxonomy and systematics of this ectomycorrhizal fungus should be revised.