Genetic diversity of Ophiocordyceps sinensis, a medicinal fungus endemic to the Tibetan Plateau: Implications for its evolution and conservation
- Equal contributors
1 Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, No.3, 1st Beichen West Road, Chaoyang District, Beijing 100101, PR China
2 School of Life Sciences, Shanxi University, Wucheng Road, Xiaodian District, Taiyuan, Shanxi 030006, PR China
3 Graduate University, Chinese Academy of Sciences, Beijing 100049, PR China
4 Epitomics, Inc., 863 Mitten Road, Suite 103, Burlingame, CA 94010-1303, USA
5 School of Plant Science & Technology, Agriculture and Animal Husbandry College of Tibet, Nyingchi, Tibet 860000, PR China
BMC Evolutionary Biology 2009, 9:290 doi:10.1186/1471-2148-9-290Published: 16 December 2009
Ophiocordyceps sinensis (syn. Cordyceps sinensis), endemic to alpine regions on the Tibetan plateau, is one of the most valuable medicinal fungi in the world. Huge commercial demand has led to excessive harvest and a dramatic decline in its numbers. The diversity of terrains and climates on the Tibetan Plateau and the broad insect host range (more than 50 species in the family Hepialidae) may have resulted in substantial intraspecific genetic diversity for this fungus. The objective of this study was to evaluate the population distribution of O. sinensis from geographically diverse regions of the Tibetan Plateau based on nrDNA ITS and MAT1-2-1 gene sequences. Understanding of the genetic diversity and genesis of O. sinensis will provide important information for the evolution and conservation of this fungus.
Significant sequence variations in the ITS and MAT1-2-1 genes (27 and 23 informative sites, eight and seven haplotypes, respectively) were observed. Phylogenetic analysis based on ITS sequences, MAT1-2-1 sequences, or their combined data set, clustered isolates from northern regions in one clade (clade I), whereas isolates from southern regions were dispersed in all four clades (clade I-IV). Single-strand conformation polymorphism (SSCP) analyses of 2639 ITS clones from seven samples revealed 91 different SSCP patterns that were subsequently sequenced. ITS heterogeneity was found in XZ-LZ07-H1 (Nyingchi population), and 17 informative sites and five haplotypes were detected from 15 clones. The five haplotypes clustered into three clades (clade I, II, and IV).
Significant genetic divergence in O. sinensis was observed and the genetic diversification was greater among southern isolates than that among northern isolates. The polymorphism of nrDNA ITS sequences suggested that O. sinensis spread from a center of origin (the Nyingchi District) to southern regions and subsequently to northern areas. These results suggest that southern populations are important reservoirs of genetic diversity and should be taken into account in conservation programs.