Pleurotus contains several species common to North America. Pleurotus
is economically important worldwide, with many species commercially gr
own. Despite its commercial importance, however, the systematics of th
e genus is unclear. Previous phylogenetic analysis of the group has re
lied on allozyme analysis, mating types and morphological characters.
Genotypic classification of Pleurotus spp. has utilized allozyme analy
sis. We present new methods of phylogenetic and genotypic classificati
on based on RFLP analysis of PCR-amplified ribosomal DNA from 21 isola
tes of Pleurotus spp. Our techniques resulted in greater resolution of
P. ostreatus genotypes than with previous methods. The resulting phyl
ogenetic tree suggests several putative species of Pleurotus may be sy
nonymous with P. ostreatus. In addition, there may be more variation b
etween geographically isolated populations within a species than betwe
en different species of Pleurotus.