Evolutionary relationships among members of the genus Lentinula and other selected basidiomycetes based on beta-tubulin and ribosomal DNA sequences

Four primer pairs comprising six individual primers were used to amplify regions of {dollar}beta{dollar}-tubulin genes from members of the Basidiomycotina. A region of 500 bp, spanning two introns and 133 codons, was amplified and sequenced from isolates of Lentinula spp., Pleurotus spp., and several related taxa. Intronic regions were highly polymorphic among Pleurotus spp. and between Pleurotus and Lentinula. Two L. lateritia isolates were 99% similar to each other and 80.7%-82.8% similar to Pleurotus species. Sufficient polymorphism existed within protein coding regions to differentiate among species of Pleurotus. Lentinus tigrinus and Ganoderma lucidum shared a unique evolutionary lineage, supporting the hypothesis that the gilled hymenial structure is a product of convergent evolution. The phylogenetic analysis provided evidence for an ancient gene duplication among ascomycete genes. The basidiomycete lineage is attached at a point near the Aspergillus nidulans ben a/Colletotrichum graminicola tub 2 cluster, after the divergence of the gene duplication, suggesting that the {dollar}beta{dollar}-tubulin genes sequenced here are related to A. nidulans ben a and C. graminicola tub 2 by orthology.; Based on ribosomal DNA and {dollar}beta{dollar}-tubulin phylogenies, we suggest that there are at least two major lineages of L. boryana in Mexico and South America. A neighbor-joining tree of combined ribosomal DNA and {dollar}beta{dollar}-tubulin sequences supports the monophyly of the L. boryana isolates. This close relationship between L. boryana and C. dryophila was not supported in the analysis of morphological traits. Pleurotus spp., C. dryophila, and Flammulina velutipes formed a cluster that was supported in 43% of bootstrap replications.; Most of the DNA sequences obtained from polymerase chain reactions of 118 year-old L. guarapiensis herbarium specimens appear to be contaminants of DNA from other species of Lentinula, as well as other sources. A single ITS 1 sequence and a single ITS 2 sequence were obtained that do not match any previously reported sequences. These may be the true sequences of L. guarapiensis, however, failure to reproduce these results and the constant presence of contaminating sequences confounded further investigation. We concluded that the L. guarapiensis specimens were too highly degraded and too highly contaminated to include this species in DNA based studies.