Differential transcription of mating-type genes during sexual reproduction of natural Cordyceps sinensis / 中国中药杂志

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.

Identification of Cordyceps cicadae and Tolypocladium dujiaolongae based on ITS sequences and chemical pattern recognition method / 中国中药杂志

Based on ITS sequences, the molecular identification of Cordyceps cicadae and Tolypocladium dujiaolongae was carried out, and high-performance liquid chromatography(HPLC) fingerprint combined with chemical pattern recognition method was established to differentiate C. cicadae from its adulterant T. dujiaolongae. The genomic DNA from 10 batches of C. cicadae and five batches of T. dujiaolongae was extracted, and ITS sequences were amplified by PCR and sequenced. The stable differential sites of these two species were compared and the phylogenetic tree was constructed via MEGA 7.0. HPLC was used to establish the fingerprints of C. cicadae and T. dujiaolongae, and similarity evaluation, cluster analysis(CA), principal component analysis(PCA), and partial least squares discriminant analysis(PLS-DA) were applied to investigate the chemical pattern recognition. The result showed that the sources of these two species were different, and there were 115 stable differential sites in ITS sequences of C. cicadae and T. dujiao-longae. The phylogenetic tree could distinguish them effectively. HPLC fingerprints of 18 batches of C. cicadae and 5 batches of T. dujiaolongae were established. The results of CA, PCA, and PLS-DA were consistent, which could distinguish them well, indicating that there were great differences in chemical components between C. cicadae and T. dujiaolongae. The results of PLS-DA showed that six components such as uridine, guanosine, adenosine, and N~6-(2-hydroxyethyl) adenosine were the main differential markers of the two species. ITS sequences and HPLC fingerprint combined with the chemical pattern recognition method can serve as the identification and differentiation methods for C. cicadae and T. dujiaolongae.

Identification of geographical origins of Cordyceps based on data of amino acids with self-organizing map neural network / 中国中药杂志

In this study, data of amino acids of Cordyceps samples from Qinghai and Tibet was analyzed with self-organizing map neural network. A model of XY-Fused network was established with the content of 8 major amino acids and total amino acids for the identification of geographical origins of Cordyceps from Qinghai and Tibet. It had the prediction accuracy of 83.3% for the test set. In addition, data mining indicated that methionine was a special kind of amino acid in Cordyceps which could serve as a marker to identify its geographical origins. On this basis, the content ratio of methionine to total amino acids was proposed to be a quantifiable indicator to distinguish Cordyceps from Qinghai and Tibet.

Comparison of endogenetic microbial community diversity between wild Cordyceps sinensis,artificial C. sinensis and habitat soil / 中国中药杂志

To obtain the difference of the fungal and bacterial community diversity between wild Cordyceps sinensis, artificial C. sinensis and their habitat soil, Illmina Hiseq high-throughput sequencing technology was applied. The results show that Proteobacteria was the dominant bacterial phylum in C. sinensis, Actinobacteria was the dominant bacterial phylum in soil microhabitat, Ophiocordyceps sinensis was the predominant dominant fungus of C. sinensis. The α diversity analysis showed that the fungal diversity of stroma was lower than other parts, and the fungal diversity of wild C. sinensis was lower than that of artificial C. sinensis. The β diversity analysis showed that the fungal and bacterial community diversity of soil microhabitat samples was significantly different from that of C. sinensis. The fungal community diversity was less different between wild and artificial C. sinensis, especially in sclerotia. LEfSe analysis showed a lot of species diversity between wild and artificial C. sinensis. Those different species between wild C. sinensis, artificial C. sinensis and their habitat soil provide ideas for further research on breed and components of C. sinensis.

Characterizations of a new Cordyceps cicadae isolate and production of adenosine and cordycepin

Cordyceps is a fastidious pathogenic fungus infecting insects, and recent years have witnessed rapid progress in its medical properties. In this study, a wild isolate, C. cicadae MP12, was characterized through in vitro cultivation and its nuclear small-subunit (SSU) ribosomal DNA (rDNA) data. In vitro culture of C. cicadae MP12 was established by growing its fruiting bodies in a solid matrix. C. cicadae MP12 was inoculated into Cryptotympana atrata cicada pupae for in vivo culture, where the fungi developed its fruiting body as well. The contents of adenosine and cordycepin in dried fruiting bodies after culture were 1421.45µg/g and 1398.12 µg/g, respectively. Therefore, the established cultures from this study could be used for the production of various medically important metabolic substances.