Transcriptome and Differentially Expressed Gene Profiles in Mycelium, Primordium and Fruiting Body Development in Stropharia rugosoannulata

Stropharia rugosoannulata uses straw as a growth substrate during artificial cultivation and has been widely promoted in China. However, its fruiting body formation and development processes have not been elucidated. In this study, the developmental transcriptomes were analyzed at three stages: the mycelium (G-S), primordium (P-S) and fruiting body (M-F) stages. A total of 9690 differentially expressed genes (DEGs) were identified in the different developmental stages. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that these DEGs were involved mainly in hydrolase activity, structural molecule activity and oxidoreductase activity as well as xenobiotic biodegradation and metabolism and energy metabolism pathways. We further found that the higher expression of most carbohydrate enzyme (i.e., GH, CE, CBM, AA and PL) genes in the hyphal (i.e., G-S) stage was related mainly to substrate degradation, while the upregulation of glycosyltransferase (GT) gene expression in the P-S and M-F stages may be related to cell wall synthesis. In addition, we found that CO(2)-sensing-related genes (i.e., CA-2, CA-3, PKA-1 and PKA-2) were upregulated in the P-S and M-F stages, heat shock protein genes (HSP60 and HSP90) were significantly downregulated in the P-S stage and upregulated in the M-F stage and the transcription factors (i.e., steA, MYB, nosA, HAP1, and GATA-4/5/6) involved in growth and development were significantly upregulated in the P-S stage. These results suggest that environmental factors (i.e., CO(2) and temperature) and transcription factors may play a key role in primordium formation. In short, this study provides new insights into the study of stimulating primordia formation affecting the development of fruiting bodies of S. rugosoannulata.