中國古尼蟲草的分子分析   全文下載

Molecular Analyses of Cordyceps gunnii in China

古尼蟲草（Cordyceps gunnii）以澳洲塔斯馬利亞首次發現的標本命名，但中國大陸的文獻將之歸類於與中藥冬蟲夏草（Cordyceps sinensis）同屬的一種常見偽品。由於鑒定冬蟲夏草品種對中藥管理和相關執法有著關鍵作用，此實驗以分子鑒定方法透過核ITS（ITS）、核糖體大亞基（nrLSU）、轉譯因子1α片段（EF-1α）和RnA聚合?大亞基I（rpb1）序列來鑒定中國和塔斯馬利亞的古尼蟲草，發現兩地的樣品並不隸屬同一品種；中國稱為「古尼蟲草」的樣品實為Clavicipitaceae科Metacordyceps屬真菌，而塔斯馬利亞的古尼蟲草則與冬蟲夏草菌較相近，應歸入Ophiocordycipitaceae科Ophiocordyceps屬。研究結果顯示此偽品的分類地位有待釐清；在中國謂之「古尼蟲草」的品種可暫時標記為Cordyceps gunnii auctorum non Berkeley（Cordyceps gunnii auct. non. Berk.）。此外，本研究中所利用的基因序列亦證明有效分辨蟲草真偽。

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 (rpb1)] of C. gunnii from China and from Tasmania revealed that they are not conspecific. The Cordy-ceps species recognized as C. gunnii in China is clustered with those species that are regarded as belonging to the genus Meta-cordyceps 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 differ-entiating the adulterant ‘Cordyceps gunnii’ from genuine samples of Cordyceps sinensis.