Integrated Metabolome and Transcriptome Analyses of the Effects of Elicitors Treated on Triterpene Accumulation in Sanghuangporus sanghuang

Abstract

Background: Sanghuangporus sanghuang (S. sanghuang) is a large wood-decaying mushroom that is considered a traditional Chinese herbal medicine because of its high medicinal value. The fundamental bioactive substances produced mainly include flavonoids, triterpenoids, and others. The expression of some specific genes in fungi can be effectively and selectively induced by fungal elicitors. Methods: To investigate the mechanism of fungal elicitors on the metabolites of S. sanghuang, we performed the metabolic and transcriptional profiling with elicitor treatment (ET) and without elicitor treatment (WET). A correlation analysis showed significant differences in triterpenoid biosynthetic pathways in the ET and WET groups. In addition, the structural genes associated with triterpenoids and metabolites of different triterpenoids in both groups were verified using quantitative real-time polymerase chain reaction (qRT-PCR) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Results: The results displayed that three triterpenoids betulinol, betulinic acid, and 2-hydroxyoleanolic acid were detected. After the excitation treatment, the level of betulinic acid reached 2.62 times that in the WET and that of 2-hydroxyoleanolic acid increased 114.67 times that in the WET. The qRT-PCR results of the expressions of the four genes related to secondary metabolic pathways, defense gene activation, and signal transduction showed significant variations between the ET and WET groups. Conclusions: the fungal elicitors have great potential to aggregate pentacyclic triterpenoid secondary metabolites in S. sanghuang.