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International Journal of
eISSN: 2573-2889

Molecular Biology: Open Access

Opinion Volume 3 Issue 3

Molecular evidence not supporting theuse of Hirsutella sinensis strain EFCC7287 as the taxonomic standard for multiple Ophiocordyceps sinensis fungi

Jia Shi Zhu,1,2 Yu Ling Li,3 Yi Sang Yao,1 Wei Dong Xie1

1Tsinghua University Graduate School at Shenzhen, China
2The Hong Kong Polytechnic University, China
3Qinghai Academy of Animal Husbandry and Veterinary Sciences, State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, China

Correspondence: Jia-Shi Zhu, Tsinghua University Graduate School at Shenzhen, The Hong Kong Polytechnic University, Hong Kong, China

Received: April 27, 2018 | Published: May 11, 2018

Citation: Zhu JS, Li YL, Yao YS, et al. Molecular evidence not supporting the use of Hirsutella sinensis strain EFCC7287 as the taxonomic standard for multiple Ophiocordyceps sinensis fungi. Int J Mol Biol Open Access. 2018;3(3):114-115. DOI: 10.15406/ijmboa.2018.03.00062

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Opinion

Sung et al.1 reported the sequences of five EFCC7287 genes (nrSSU, nrLSU, tef1, rpb1, rpb2) in the taxonomic-nomenclature study and renamed Cordyceps sinensis (Berkeley) Saccardo to Ophiocordyceps sinensis (Berkeley), according to the molecular systematics rules for fungi. It seems that Hirsutella sinensis strain EFCC7287 became a taxonomic standard for studying O. sinensis,2although Dr. Hywel Jones1 believed in a Research Gate discussion the selection of strain EFCC7287 was arbitrary. Among the 5 genes examined by Sung et al.1 and Quandt et al.2 EF468827 (nrLSU) of 28S gene aligns with 99.5-99.7% homology to the ribosomal DNA segments (ANOV01021709, LKHE01000582, and LWBQ01000008) of the genome sequences of 3 H. sinensis strains: ANOV00000000 of Strain Co18,3 LKHE00000000 of Strain 1229,4 and LWBQ00000000 of Strain ZJB12195,5 while EF468971 (nrSSU) of 18S gene with 98.7-99.5% homology to the segments (ANOV01024851, LKHE01000582, LWBQ01000008) of the H. sinensis genome sequences. But EF468827 and EF468971 have low similarities to Genotypes#3-17 of O. sinensis; and no other segments with high similarity homology were identified within ANOV00000000, LKHE00000000, or LWBQ00000000.6–8 The genomic sequence analysis indicated that Sung et al.1 & Quandt et al.2 worked exclusively on H. sinensis, Genotype#1 of O. sinensis, without considering Genotypes#2-#17 of O. sinensis that have been deposited in GenBank and described in many research papers since 2002.6–13

Studies with using PCR amplicon-sequencing, cloning sequencing, Sothern-blotting and RFLP following EcoRI restrictive digestion, and SNP mass spectrometry genotyping reported that the GC-biased Genotype#1 H. sinensis was either non-detectable or a minor O. sinensis component within the C. sinensis insect-fungi complex, whereas the AT-biased genotypes of O. sinensis predominated.7,8,11,12 Molecular examinations demonstrated that the genotypes of O. sinensis, including Genotype#1 H. sinensis, are differentially present and quantitatively and asynchronously altered in the compartments of natural C. sinensis during maturation. The molecular data indicate that the sequences of Genotypes#2-#17 O. sinensis reside not in the genome of H. sinensis but rather in the genomes of other independent fungi.6–13 Bushley et al.14 demonstrated the multicellular heterokaryotic hyphae and ascospores of natural C. sinensis with mono-/bi-/tri-nucleate structures. Barseghyan et al.15 conclude that H. sinensis and Tolypocladium sinensis are “the anamorphs of Ophiocordyceps sinensis”. Close association of Paecilomyces hepiali with several genotypes of O. sinensis have been characterized in natural C. sinensis, forming species (fungal) complexes.6,8,11,12,16,17 Genotypes#13 and #14 of O. sinensis were identified from the heterokaryotic ascospores of natural C. sinensis as genetic variants (offspring) with large DNA segment reciprocal substitutions between 2 parental fungi, Genotype#1 H. sinensis and AB067719-type O. sinensis.6

The molecular evidence indicates that (1) the name O. sinensis represents a group of fungi, including the 17 mutant genotypes of O. sinensis and probably other C. sinensis associated fungi that have been considered as and biologically associated to the anamorphs and/or teleomorphs of O. sinensis, and (2) Strain EFCC7287 may be considered as the “taxonomic standard” solely of the GC-biased H. sinensis, but not of Genotypes#2-#17 O. sinensis or other C. sinensis associated fungi.6–8,11,12,15

Acknowledgements

None.

Conflict of interest

Authors declare that there is no conflict of interest.

References

  1. Sung GH, Hywel Jones NL, Sung JM, et al. Phylogenetic classification of Cordyceps and the clavicipitaceous fungi. Stud Mycology. 2007;57:5–59.
  2. Quandt CA, Kepler RM, Gams W, et al. Phylogenetic-based nomenclatural proposals for Ophiocordycipitaceae (Hypocreales) with new combinations in Tolypocladium. IMA Fungus. 2014;5(1):121–134.
  3. Hu X, Zhang YJ, Xiao GH, et al. Genome survey uncovers the secrets of sex and lifestyle in caterpillar fungus. Chinese Science Bulletin. 2013;58(23):2846–2854.
  4. Li Yi, Hsiang T, Yang RH, et al. Comparison of different sequencing and assembly strategies for a repeat-rich fungal genome, Ophiocordyceps sinensis. J Microbiol Methods. 2016;128:1–6.  
  5. Liu ZQ, Lin S, Zheng YG. Genome sequencing and analysis of anamorphic strain (Hirsutella sinensis) from traditional medicine Ophiocordyceps sinensis. GenBank; 2016.
  6. Zhu JS, Yao YS, Li YL, et al. Hereditary variations with DNA segment substitution between fungi in the two types of Cordyceps sinensis ascospores suggest fungal chromosomal fusions. Proceedings of the 11th National Conference of Medicinal Mycology, Shimla, India. 2016. p. 92–103.
  7. Li YL, Yao YS, Xie WD, et al. The Molecular heterogeneity of naturalCordyceps sinensis with multipleOphiocordyceps sinensis fungi challenges the anamorph-teleomorph connection hypotheses. American Journal of Biomedical Sciences 2016;8(2):123–159.
  8. Zhu JS, Li YL. A Precious Transitional Chinese Medicine, Cordyceps sinensis: Multiple heterogeneous Ophiocordyceps sinensis in the insect-fungi complex. Germany: Lambert Academic Publishing; 2017.
  9. Stensrud Ø, Schumacher T, Shalchian Tabrizi K, et al. Accelerated nrDNA evolution and profound AT bias in the medicinal fungus Cordyceps sinensis. Mycological Research. 2007;111(4):409–415.
  10. Xiao W, Yang JP, Zhu P, et al. Non-support of species complex hypothesis of Cordyceps sinensis by targeted rDNA-ITS sequence analysis. Mycosystema. 2009;28:724–730.
  11. Zhu JS, Gao L, Li XH, et al. Maturational alterations of oppositely orientated rDNA and differential proliferations of CG:AT-biased genotypes of Cordyceps sinensis fungi and Paecilomyces hepiali in natural Cordyceps sinensis. American Journal of Biomedical Sciences. 2010;2(3):217–238.
  12. Mao XM, Zhao SM, Cao L, et al. The Morphology observation of Ophiocordyceps sinensis from different origins. Journal of Environmental Entomology. 2013;35:343–353.
  13. Wei JC, Wei XL, Zheng WF, et al. Species identification and component detection of Ophiocordyceps sinensis cultivated by modern industry. Mycosystema. 2016;35(4):404–410.
  14. Bushley KE, Li Y, Wang WJ, et al. Isolation of the MAT1-1 mating type idiomorph and evidence for selfing in the Chinese medicinal fungus Ophiocordyceps sinensis. Fungal Biol. 2013;117(9):599–610.               
  15. Barseghyan GS, Holliday JC, Price TC, et al. Growth and cultural-morphological characteristics of vegetative mycelia of medicinal caterpillar fungus Ophiocordyceps sinensis G.H. Sung et al. (Ascomycetes) isolates from Tibetan plateau (P.R.China). Int J Medi Mushrooms. 2011;13(6):565–581.
  16. Zhu JS, Guo YL, Yao YS, et al. Maturation of Cordyceps sinensis associates with co-existence of Hirsutella sinensis and Paecilomyces hepiali DNA and dynamic changes in fungal competitive proliferation predominance and chemical profiles. Journal of Fungal Research. 2007;5:214–224.
  17. Li YL, Yao YS, Zhang ZH, et al. Synergy of fungal complexes isolated from the intestines of Hepialus armoricanus larvae containing multiple fungi increases infection potency. Journal of Fungal Research. 2016;14:96–112.
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