Dissecting Metabolic Regulation in Mycelial Growth and Fruiting Body Developmental Stages of Cordyceps militaris through Integrative Transcriptome Analysis

Dissecting the cellular metabolism of Cordyceps militaris is important for the efficient production of bioactive compounds of a target with medicinal and industrial applications. However, the metabolic functions during developmental stages in this fungus at a system level are still unexplored. In this study, we aimed to reveal the metabolic functions and regulation of C. militaris TBRC6039 relevant to its developmental stages, including mycelial growth (MY) and fruiting body (FB) stages through integrative transcriptome analysis. The transcriptome analysis showed that 9,256 genes of C. militaris were expressed in both stages. Of them, 1,877 genes, residing primarily in the cell division cycle and amino acid, carbohydrate, and lipid metabolisms, exhibited significant differences in transcript levels between the MY and FB stages. Through integration with genome-scale networks analysis, the unique reporter metabolites ( e.g. , α-D-glucose, β-D-glucose, D-galactose, triacylglycerol, and diacylglycerol) and key regulators ( e.g. , AtfA, Atf2, and Yap1 transcription factors) were identified in C. militaris when grown at FB stage, linking to up-regulation of the metabolic genes involved in galactose and polysaccharide metabolisms, as well as glycerolipid and glycerophospholipid biosynthesis. Moreover, the high cordycepin content is related to the upregulated genes in lipid metabolism during the FB stage. Our findings suggest that the transcriptional regulation of these metabolic pathways played a crucial role in specific developmental stages of C. militaris . This study serves for cultivation process improvement for overproduction of valuable metabolites in C. militaris through an emerging systems and synthetic biology approach.