Genetic variation of Cordyceps sinensis, a fruit-body-producing entomopathogenic species from different geographical regions in China.

Cordyceps sinensis is one of the most valuable medicinal fungi in the Orient. It is naturally distributed in the eastern extension area of the Qinghai-Tibet plateau, at an altitude over 4000 m high. In order to investigate genetic variation and evolutionary relationships of C. sinensis from different geographical regions, 17 isolates of C. sinensis were collected from different provinces and the complete sequences of rDNA ITS were determined. On the basis of 5.8S rDNA and ITS region analysis, it was clearly shown that the ITS sequences within C. sinensis are highly homologous regardless of geographical origin. The distance values between the sequences in this study were lower than 0.03. This implied that C. sinensis from different geographic regions are the same species; they are not different species or a species complex. The results also showed that distance values between C. sinensis and Hirsutella sinensis are of the same order as those within C. sinensis from different geographic regions. This confirmed our previous results that C. sinensis should only have H. sinensis as its asexual stage whatever the geographic region from which the samples were collected. An rDNA ITS clone library was established to obtain further evidence for the interpretation of the fungal community structure from C. sinensis and to confirm the accuracy of the taxonomic identities produced by directly sequencing the rDNA ITS region. The discrimination between intraspecies of C. sinensis might provide additional data for the authentication of medicinal material at the species or intraspecies level.