## 3 Results
### RNA-Sequencing Based Transcriptome Analysis of the Strain CPCC 401429  
To further investigate and evaluate the differently expressed genes (DEGs), we constructed three DEGs libraries to compare YMEG to F1, PDB to YMEG, and PDB to F1 (Figures S1-S3, supporting information I). Overall, there are 10,003, 10,623, and 9895 genes which were transcribed in F1, PDB, and YMEG fermentation broth, respectively. Among the transcribed genes, 9367 genes were commonly shared (Figure 6A). Additionally, we detected 1721, 1531, and 1616 up-regulated genes, and 1948, 2271, and 2026 down-regulated genes between PDB and YMEG libraries, PDB and YMEG libraries, PDB and F1 libraries, respectively (Figures 6B, S3 and S4, supporting information I). In organisms, different genes accomplish in a synchronizing mode to perform the biological functions. Pathway-directed analysis supports to further characterize the molecular functions of genes. Functional enrichment analysis was conducted using all DEGs against the GO database to investigate DEGs involved in metabolism and development. The enrichment data supports the hypothesis that the DEGs are approximately related to glycoside metabolism, fruiting body formation, membrane transporters, and secondary metabolites (SMs) production (Tables S3-S6, supporting information I). The latter includes SMs biosynthesis, exemplified as merotterpenoid melleolides, polyketides, and sesquiterpenes. It is worth noting that the DEGs functioning in the basal metabolic process, e.g., glycoside metabolism and transmembrane transport, which could promote the biological process of secondary metabolism  
Figure 5: Phylogeny and distribution of sesquiterpene synthases obtained from _D. tabescens_ CPCC 401429 with other basidiomycetous STSs. Rooted phylogenetic tree was constructed using MrBayes v3.2.6 [49]. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (10,000,000 replicates) are shown next to the branches. The selected STSs were obtained from _C. pseudopinsitus_ (CpSTS), _O. olearius_ (Omp), _C. aegerita_ (Agr), _C. puteana_ (Copu), _C. cinerea_ (Cop), _L. rhincerotus_ (GME), _S. hirsutum_ (ShSTS), protoilludene synthases described from _A. ostogue_ (PROI_ARMOS) and _A. gallia_ (Pro1).  
(Tables S3 and S4, Supplementary Information I). Moreover, KEGG pathway analysis indicated that mevalonate and acetyl-CoA and metabolic pathways were also up-regulated, which facilitate the biosynthesis of sesquiterpenes and melleolides. Ten genes associated with GO terms related to sesquiterpene biosynthesis were identified. Among them, one gene _DtSTS3_ exhibited up-regulation in F1 fermentation broth, which is responsible for melleolides biosynthesis. While five genes (_DtSTS4_, _DtSTS7_, _DtSTS9_, _DtSTS11_, _DtSTS12_) and four genes (_DtSTS2_, _DtSTS5_, _DtSTS8_, and _DtSTS10_) showed up-regulated expression in PDB broth and YMEG broth, respectively (Figure 6C). We envisage that these transcriptome analysis results would be conductive to the further study of STSs characterization in _Desramillaria_ or close affinities.  
Figure 6: Mining transcriptome data for sesquiterpene synthases encoding genes in _D. tabescens_ CPCC 401429. (**A**) Venn analysis of DEGs in three fermentation media. (**B**) Differentiated expression statistics of the transcriptome data of the strain CPCC 401429 in three fermentation media. (**C**) Heatmap of three samples including F1, YMEG, and PDB fermentation broth obtained by RNA\(-\)seq. F1\(-\)1, F1\(-\)2, and F1\(-\)3 are samples of F1 fermentation medium; YMEG\(-\)1, YMEG\(-\)2, and YMEG\(-\)3 are samples of YMEG fermentation medium; PDB\(-\)1, PDB\(-\)2, and PDB\(-\)3 are samples of PDB fermentation medium.