Ribosomal DNA analysis for resolution of genotypic classes of Pleurotus

Pleurotus contains several species common to North America. Pleurotus is economically important worldwide, with many species commercially grown. Despite its commercial importance, however, the systematics of the genus is unclear. Previous phylogenetic analysis of the group has relied on allozyme analysis, mating types and morphological characters. Genotypic classification of Pleurotus spp. has utilized allozyme analysis. We present new methods of phylogenetic and genotypic classification based on RFLP analysis of PCR-amplified ribosomal DNA from 21 isolates of Pleurotus spp. Our techniques resulted in greater resolution of P. ostreatus genotypes than with previous methods. The resulting phylogenetic tree suggests several putative species of Pleurotus may be synonymous with P. ostreatus. In addition, there may be more variation between geographically isolated populations within a species than between different species of Pleurotus.