Molecular analyses of Cordyceps gunnii in China

Abstract

Cordyceps gunnii Berk., originally named for a specimen discovered in Tasmania, Australia, is commonly reported in China as an adulterant of the valuable Chinese medicinal fungus, Cordyceps sinensis. Correct identification of this adulterant species bears close relevance to herb control, legal disputes and forensic measures. Analyses of the internal transcribed spacers of the nuclear ribosomal DNA repeats (ITS) and three loci [nuclear ribosomal large subunit (nrLSU), elongation factor 1α (EF-1α) and the largest subunit of RNA polymerase II (rpbl)] of C. gunnii from China and from Tasmania revealed that they are not conspecific. The Cordyceps species recognized as C. gunnii in China is clustered with those species that are regarded as belonging to the genus Metacordyceps and placed in the Clavicipitaceae family. Tasmanian samples, however, are closer to C. sinensis and belong to the genus Ophiocordyceps in the Ophiocordycipitaceae family. Re-investigation of the taxonomic status of this adulterant fungus is urgently needed to avoid unnecessary dispute. At this stage, reference to the Chinese samples of Cordyceps gunnii can be tentatively labeled as Cordyceps gunnii auctorum non Berkeley (Cordyceps gunnii auct. non Berk.). The tested sequences can also be useful for differentiating the adulterant 'Cordyceps gunnii' from genuine samples of Cordyceps sinensis.