Changes in transcriptomic and metabolomic profiles of morphotypes of Ophiocordyceps sinensis within the hemocoel of its host larvae, Thitarodes xiaojinensis

Abstract

Background Ophiocordyceps sinensis (Berk.) is a well-known entomopathogenic and medicinal fungus. It parasitizes and mummifies the underground ghost moth larvae to produce a fruiting body named Chinese cordyceps. Specific for the fungus, O. sinensis experiences a biotrophic vegetative growth period spanning over 5 months. During this vegetative growth, it appears successively in the host hemocoel in three/four morphotypes, namely, the yeast-like blastospores (subdivided into proliferative (BP) and stationary phase (BS)), prehyphae (PreHy) and the hyphae (Hy). This peculiar morphogenesis has been elucidated through morphological and ultrastructural observations, but its molecular basis remains cryptic. In this study, transcriptome and metabolome profiling of BP, BS, PreHy and Hy stages were performed to characterize the key genes, metabolites, and signaling pathways that regulated the vegetative development of O. sinensis in Thitarodes xiaojinensis larva. Results The molecular events and metabolic pathways that regulated different intracellular processes at various stages were examined. Cluster analyses of differentially expressed genes across the four stages revealed the stage specifically enriched pathways. Analysis of metabolome profiles showed that carbon metabolism and several amino acids biosynthesis were significantly perturbed during the tested development stages of O. sinensis in the host hemocoel. Genes homologous to Saccharomyces cerevisiae MAPK cascade were significantly up-regulated during the transition from blastospore to hypha. The up-regulation of Sho1, a regulator protein, suggested nutrient starvation act a role in activation of MAPK pathway and filamentous growth. In addition, up-regulation of several fatty acid synthesis genes and their corresponding products accumulation in the samples of BS might explain more lipid droplets were observed in BS than in BP. Coupled with the up-regulation of fatty acid degradation during PreHy and Hy stages, it is presumed that lipid accumulation and mobilization play important roles in filamentous development. Conclusions This is the first report comprehensively describing developmental transcriptomics and metabolomics of O. sinensis in vivo. Our findings provide new perspectives into the key pathways and hub genes involved in morphological changes of fungus developed in the hemocoel of its host, and are expected to guide future studies on morphogenesis and morphotype changes of entomopathogenic fungi in vivo.

Metabolomics approach to assess the effect of siphonal autotomy on metabolic characteristics of razor clam Solen grandis

“…Additionally, there is a shortage of intermediate compounds and energy caused by the downregulation of succinate. The relatively low carbohydrate content observed in this study can be attributed to the glucose and glucose conjugates that break down maltose being converted into TCA cycle intermediates 41 . Therefore, such changes in sugar levels are expected to affect the generation of energy and intermediate compounds in order to maintain normal biological processes 21 .…”

Stable reference gene selection for Ophiocordyceps sinensis gene expression studies under different developmental stages and light-induced conditions

“…sinensis mainly propagates asexually in the form of hyphal bodies [ 28 ]. At the subsequent stage, the hyphal bodies are induced by certain signal substances to transform by hyphae proliferation [ 29 ]. Our results revealed that, as the content of O .…”

“…sinensis in liquid fermentation and host hemolymph was the same, the similar morphological changes can also provide a reference for studying the dimorphic transition of O . sinensis [ 29 ]. Our findings provide a tool for future research on morphogenesis and morphological changes of O .…”

Stage- and Rearing-Dependent Metabolomics Profiling of Ophiocordyceps sinensis and Its Pipeline Products

“…A few works have focused on development or infection influences. It was revealed that the main life activity metabolism was consistent across O. sinensis morphotypes, but each morphotype adopted a different metabolic pattern [55]. It was observed that metabolic changes of C. militaris could increase and reach maximal after inoculation with germinated soybean during rearing [56].…”