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Open Access Research article

Recent dermatophyte divergence revealed by comparative and phylogenetic analysis of mitochondrial genomes

Yuan Wu12, Jian Yang2, Fan Yang2, Tao Liu2, Wenchuan Leng2, Yonglie Chu1* and Qi Jin2*

Author Affiliations

1 Department of Microbiology and Immunology, Medical School of Xi'an Jiaotong University, Shaanxi, 710061, PR China

2 State Key Laboratory for Molecular Virology and Genetic Engineering, Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Beijing 100730, PR China

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BMC Genomics 2009, 10:238  doi:10.1186/1471-2164-10-238

Published: 21 May 2009

Abstract

Background

Dermatophytes are fungi that cause superficial infections of the skin, hair, and nails. They are the most common agents of fungal infections worldwide. Dermatophytic fungi constitute three genera, Trichophyton, Epidermophyton, and Microsporum, and the evolutionary relationships between these genera are epidemiologically important. Mitochondria are considered to be of monophyletic origin and mitochondrial sequences offer many advantages for phylogenetic studies. However, only one complete dermatophyte mitochondrial genome (E. floccosum) has previously been determined.

Results

The complete mitochondrial DNA sequences of five dermatophyte species, T. rubrum (26,985 bp), T. mentagrophytes (24,297 bp), T. ajelloi (28,530 bp), M. canis (23,943 bp) and M. nanum (24,105 bp) were determined. These were compared to the E. floccosum sequence. Mitochondrial genomes of all 6 species were found to harbor the same set of genes arranged identical order indicating that these dermatophytes are closely related. Genome size differences were largely due to variable lengths of non-coding intergenic regions and the presence/absence of introns. Phylogenetic analyses based on complete mitochondrial genomes reveals that the divergence of the dermatophyte clade was later than of other groups of pathogenic fungi.

Conclusion

This is the first systematic comparative genomic study on dermatophytes, a highly conserved and recently-diverged lineage of ascomycota fungi. The data reported here provide a basis for further exploration of interrelationships between dermatophytes and will contribute to the study of mitochondrial evolution in higher fungi.