Phylogenetic analysis of oyster mushrooms (Pleurotus spp.) based on restriction fragment length polymorphisms of the 5′ portion of 26S rDNA

Polymorphism analysis of the 5' portion of 26S rDNA from 34 Pleurotus strains (12 intersterility groups) collected mainly from Asia was performed. By combining the restriction fragment length polymorphism (RFLP) patterns obtained from digestions with seven restriction enzymes, the 34 Pleurotus strains were assigned to 11 RFLP types. Ten RFLP patterns corresponded with biological species, but one pattern was found in intersterility groups I (P. ostreatus complex), II (P. pulmonarius complex), and VIII (P. eryngii). The phylogenetic tree suggests that Pleurotus species have evolved in two patterns based on 26S rDNA RFLP data. One major cluster comprising the "P. ostreatus clade" is separated by relatively short branches, suggesting that the P. ostreatus complex, the P. pulmonarius complex, P. eryngii, and P. nebrodensis (intersterility groups I, II, VIII, and IX, respectively), share a recent common ancestor. RFLP data did not distinguish the species in the intersterility groups I, II, and VIII. The other major cluster apparently divided into five sublevel clusters in early stages of evolution and these clades split into terminal nodes in late stages of evolution: the P. calyptratus-salmoneostramineus Blade, the P. cornucopiae-ulmarius clade, the P. dryinus clade, the P. corticatus clade, and the P. cystidiosus-smithii clade.