Transcriptomic analysis of the orchestrated molecular mechanisms underlying fruiting body initiation in Chinese cordyceps.

Abstract Chinese cordyceps, the fruiting body of the Chinese caterpillar fungus (Ophiocordyceps sinensis, syn. Cordyceps sinensis), is among the most valuable traditional Chinese medicine fungi. Transcriptomic analysis of O. sinensis has revealed several aspects of its life cycle and ecological importance. However, the molecular mechanisms involved in fruiting body initiation remain unclear. The developmental transcriptomes were analyzed from three tissues at the fruiting body initiation stage, namely, the mycelium, sclerotium and primordium. Principal component analysis showed that in the three tissues, the gene expression patterns differed from each other. The functional analysis of differentially expressed genes showed that DNA synthesis and cell division were active in the primordium. In addition, the function of the mycelium was to absorb certain substances from the environment and the sclerotium was the metabolism center of O. sinensis. Genes participating in the mitogen-activated protein kinase (MAPK) signal pathway were involved in fruiting body initiation. Two environmental sensing genes, including a pheromone receptor gene (OSIN6252) and an amino acid sensing gene (OSIN6398), were highly expressed in the primordium, suggesting their important roles in initiation. These results provided insights into the orchestrated functions and gene profiles of different O. sinensis tissues at the key stage. These findings will aid in revealing the underlying mechanisms of fruiting body initiation, which will further benefit artificial cultivation.