针对性rDNA-ITS序列分析不支持冬虫夏草复合种假设

冬虫夏草是有名的中药材,作为滋补药物已有数百年历史。它主要分布于亚洲高纬度草甸地带,寄主为蝙蝠蛾幼虫。目前有许多证据尤其是在rDNA-ITS水平上支持中国被毛孢Hirsutella sinensis是冬虫夏草的唯一无性型。然而,除了那些属于明显的错误注册的序列以外,从NCBI数据库检索得到的多个已注册为"冬虫夏草"的序列彼此之间的差异十分显著。基于这些有差异的GenBank序列,有些作者提出了冬虫夏草种复合群体及其包含的三个隐存种的假设。为检验该假设,我们以单株冬虫夏草子实体为材料,开展了rDNA-ITS序列分析研究。冬虫夏草样品分别采自中国的四川和青海两省。结果显示只有‘冬虫夏草A组’应为真正的冬虫夏草,而B组和C组很有可能属于其他真菌,而非冬虫夏草的隐存种。

Non-support of species complex hypothesis of Cordyceps sinensis by targeted rDNA-ITS sequence analysis

Cordyceps sinensis is a well-known traditional Chinese herb commonly used as a tonic drug for hundreds of years. It is mainly distributed in Asian high-altitude grasslands, growing parasitically on buried larvae of Lepidoptera. Hirsutella sinensis is the only anamorph of C. sinensis that has been supported by several reports especially at rDNA-ITS level. However, the rDNA-ITS sequences of C. sinensis available from the NCBI database are still significantly divergent, except for the apparently erroneous-accessioned sequences. Based on the GenBank sequences, a hypothesis of three cryptic species involved in C. sinensis species complex was proposed before. In order to examine this hypothesis, we carried out the experiment by designing specific primers for targeted rDNA-ITS sequences using the DNA sample from individual C. sinensis fruiting body. Specimens of C. sinensis were collected from Sichuan and Qinghai of China, respectively. Our results suggested that only the C. sinensis-group A is the authentic C. sinensis. The so-called C. sinensis-group B and C. sinensis-group C are most likely different fungal species rather than the cryptic species of C. sinensis.