Natural Cordyceps sinensis as an insect-fungal complex, which is developed after Ophiocordyceps sinensis infects a larva of Hepialidae family. Seventeen genotypes of O. sinensis have been identified in natural C. sinensis. This paper summarized the literature reports and GenBank database regarding occurrence and transcription of the mating-type genes of MAT1-1 and MAT1-2 idiomorphs in natural C. sinensis, in Hirsutella sinensis(GC-biased Genotype #1 of O. sinensis), to infer the mating pattern of O. sinensis in the lifecycle of natural C. sinensis. The mating-type genes and transcripts of MAT1-1 and MAT1-2 idiomorphs were identified in the metagenomes and metatranscriptomes of natural C. sinensis. However, their fungal sources are unclear because of co-colonization of several genotypes of O. sinensis and multiple fungal species in natural C. sinensis. The mating-type genes of MAT1-1 and MAT1-2 idiomorphs were differentially present in 237 H. sinensis strains, constituting the genetic control of the O. sinensis reproduction. Transcriptional control of the O. sinensis reproduction includes: differential transcription or silencing of the mating-type genes of MAT1-1 and MAT1-2 idiomorphs, and the MAT1-2-1 transcript with unspliced intron I that contains 3 stop codons. Research on the H. sinensis transcriptome demonstrated differential and complementary transcriptions of the mating-type genes of MAT1-1 and MAT1-2 idiomorphs in Strains L0106 and 1229, which may become mating partners to accomplish physiological heterothallism. The differential occurrence and transcription of the mating-type genes in H. sinensis are inconsistent with the self-fertilization hypothesis under homothallism or pseudohomothallism, but instead indicate the need of mating partners of the same H. sinensis species, either monoecious or dioecious, for physiological heterothallism, or heterospecific species for hybridization. Multiple GC-and AT-biased genotypes of O. sinensis were identified in the stroma, stromal fertile portion(densely covered with numerous ascocarps) and ascospores of natural C. sinensis. It needs to be further explored if the genome-independent O. sinensis genotypes could become mating partners to accomplish sexual reproduction. S. hepiali Strain FENG experienced differential transcription of the mating-type genes with a pattern complementary to that of H. sinensis Strain L0106. Additional evidence is needed to explore a hybridization possibility between S. hepiali and H. sinensis, whether they are able to break the interspecific reproductive isolation. Genotypes #13～14 of O. sinensis feature large DNA segment reciprocal substitutions and genetic material recombination between 2 heterospecific parental fungi, H. sinensis and an AB067719-type fungus, indicating a possibility of hybridization or parasexuality. Our analysis provides important information at the genetic and transcriptional levels regarding the mating-type gene expression and reproduction physiology of O. sinensis in the sexual life of natural C. sinensis and offers crucial reproductive physiology evidence, to assist in the design of the artificial cultivation of C. sinensis to supplement the increasing scarcity of natural resource.
Cordyceps/genetics* ; Genes, Mating Type, Fungal/genetics* ; Reproduction/genetics*

To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield, it is important to identify molecular fingerprint of dominant O. sinensis. In the present study, we collected 3 batches of industrially cultivated O. sinensis product with higher yield than the others and compared their internal transcribed spacer (ITS) sequences with the wild and the reported. The ITS sequence was obtained by bidirectional sequencing and analyzed with molecular systematics as a DNA barcode for rapid and accurate identification of wild and cultivated O. sinensis collected. The ITS sequences of O. sinensis with detailed collection loci on NCBI were downloaded to construct a phylogenetic tree together with the sequences obtained from the present study by using neighbor-joining method based on their evolution relationship. The information on collection loci was analyzed with ArcGIS 10.2 to demonstrate the geographic distribution of these samples and thus to determine the origin of the dominant samples. The results showed that all wild and cultivated samples were identified as O. sinensis and all sequences were divided into seven phylogenetic groups in the tree. Those groups were precisely distributed on the map and the process of their system evolution was clearly presented. The three cultivated samples were clustered into two dominant groups, showing the correlation between the industrially cultivated samples and the dominant wild samples, which can provide references for its optimized breeding in the future.
Breeding ; DNA, Fungal ; genetics ; DNA, Intergenic ; genetics ; Genes, Mating Type, Fungal ; Hypocreales ; chemistry ; classification ; genetics ; growth & development ; Phylogeny