Comparison of Major Bioactive Compounds of the Caterpillar Medicinal Mushroom, Cordyceps militaris (Ascomycetes), Fruiting Bodies Cultured on Wheat Substrate and Pupae

Transcriptome analysis of Ganoderma lingzhi (Agaricomycetes) response to Trichoderma hengshanicum infection

Green mold caused by Trichoderma spp. has become one of the most serious diseases which threatening the production of Ganoderma lingzhi. To understand the possible resistance mechanism of the G. lingzhi response to T. hengshanicum infection, we examined the G. lingzhi transcript accumulation at 0, 12, and 24 h after T. hengshanicum inoculation. The gene expression analysis was conducted on the interaction between G. lingzhi and T. hengshanicum using RNA-seq and digital gene expression (DGE) profiling methods. Transcriptome sequencing indicated that there were 162 differentially expressed genes (DEGs) at three infection time points, containing 15 up-regulated DEGs and 147 down-regulated DEGs. Resistance-related genes thaumatin-like proteins (TLPs) (PR-5s), phenylalanine ammonia-lyase, and Beta-1,3-glucan binding protein were significantly up-regulated. At the three time points of infection, the heat shock proteins (HSPs) genes of G. lingzhi were down-regulated. The down-regulation of HSPs genes led to the inhibition of HSP function, which may compromise the HSP-mediated defense signaling transduction pathway, leading to G. lingzhi susceptibility. Pathway enrichment analyses showed that the main enriched pathways by G. lingzhi after infection were sphingolipid metabolism, ether lipid metabolism, and valine, leucine and isoleucine degradation pathway. Overall, the results described here improve fundamental knowledge of molecular responses to G. lingzhi defense and contribute to the design of strategies against Trichoderma spp.

De novo Sequencing and Comparative Transcriptome Analyses Provide First Insights Into Polysaccharide Biosynthesis During Fruiting Body Development of Lentinula edodes

Polysaccharides separated from Lentinula edodes are well known for their medicinal properties. However, the precise molecular mechanisms of polysaccharide biosynthesis in L. edodes remain unclear. In this study, the fruiting bodies of L. edodes in four developmental stages with significant differences in polysaccharide yield were collected, and the characteristics of polysaccharides were studied. De novo sequencing and comparative transcriptomic analysis were performed by using high-throughput Illumina RNA-sequencing. KS1P30, KS2P30, KS3P30, and KS4P30 were obtained from the four developmental stages, respectively, by hot water extraction and 30% ethanol precipitation. These four polysaccharides had good immune activity in vitro; all of them were β-glucopyranose with a high molecular weight. Glucose was the main monosaccharide component of these polysaccharides. High-quality clean reads (57.88, 53.17, 53.28, and 47.56 million for different growth stages) and mapping ratios ranging from 84.75 to 90.11% were obtained. In total, 11,493 (96.56%) unigenes and 18,924 (97.46%) transcripts were successfully annotated in five public databases. The biosynthetic pathway and related genes of LEFP30 were mined. The molecular mechanism of LEFP30 yield change in the different developmental stages was predicted. The results provide some insights into the possible mechanisms involved in the biosynthetic pathway of this kind of polysaccharide in L. edodes fruiting bodies. They also indicate that candidate genes can be used as important resources for biotechnology and molecular breeding to regulate L. edodes fruiting body polysaccharide biosynthesis.

Identification of cordycepin biosynthesis-related genes through de novo transcriptome assembly and analysis in Cordyceps cicadae

Cordyceps cicadae (Chanhua) is a parasitic fungus that grows on Cicada flammata larvae and is used to relieve exhaustion and treat numerous diseases, in part through its active constituent, cordycepin. We used de novo Illumina HiSeq 4000 sequencing to obtain transcriptomes of C. cicadae mycelium, fruiting body, and sclerotium, and identify differentially expressed genes. In the mycelium versus sclerotium libraries, 1576 upregulated and 2300 downregulated genes were identified. In the mycelium versus fruiting body and fruiting body versus sclerotium body libraries, 1604 and 1474 upregulated and 1365 and 1320 downregulated genes, respectively, were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses identified 19 genes differentially expressed in mycelium versus fruiting body as related to the purine pathway, along with 28 and 16 genes differentially expressed in the mycelium versus sclerotium and fruiting body versus sclerotium groups, respectively. Gene expression of six key enzymes was validated by quantitative polymerase chain reaction. Specifically, 5'-nucleotidase (c62060g1) and adenosine deaminase (c35629g1) in purine nucleotide metabolism, which are involved in cordycepin biosynthesis, were significantly upregulated in the sclerotium group. These findings improved our understanding of genes involved in the biosynthesis of cordycepin and other characteristic secondary metabolites in C. cicadae.