Multiple Gene Analyses are Necessary to Understand Accurate Phylogenetic Relationships among Trichophyton Species

Abstract

Phylogenetic relationships among 34 isolates from 11 Trichophyton and 3 Arthroderma species were investigated using the nucleotide sequences from 4 DNA regions: internal transcribed spacers(ITS)1 and 2 including the 5.8S rRNA gene, and the actin(ACT), DNA topoisomerase(TOP)2 and glyceraldehyde-3-phosphate dehydrogenase(GPD)genes. All four phylogenetic trees showed that the 34 isolates can be divided into 3 clades, the Arthroderma simii, A. benhamiae and Trichophyton rubrum clades. The Shimodaira-Hasegawa test(SH test)revealed significant topological incongruities within the A. benhamiae and A. simii clades. Although branching patterns of the 3 clades were inconsistent among the four trees, the SH test did not support these differences except that the best tree topology according to ACT sequences was significantly rejected by the TOP data set. These results show that multiple gene analyses are necessary to more precisely understand the phylogenetic relationships among these fungi.