Enhancement and Mechanism of Ergosterol Biosynthesis in Termite Ball Fungus Athelia termitophila by Methyl Jasmonate

Ergosterol is a component of fungal cell membranes that has physiological functions and applications in drugs, such as anti-inflammatory, anti-tumor, anti-fungal, and other immunosuppressive activities. The fungus Athelia termitophila, also known as the termite ball fungus, primarily contains secondary metabolites (like active ingredients) that are similar to ergosterol. To enhance the synthesis of ergosterol and mycelial biomass in termite ball fungus, methyl jasmonate and salicylic acid were used to stimulate the biosynthesis of ergosterol compounds during the growth of TMB mycelium and relative quantitative levels of gene transcripts. The conditions of the inducers were optimized. Under 80 mu mol/L MJ incubation conditions, the content of ergosterol compounds in TMB was increased by 2.23-fold compared with the wild-type strain. RT-qPCR results at the transcriptional level of ergosterol synthesis pathway genes showed that MJ significantly induced the expression of HMGR (3-Hydroxy-3-Methylglutaryl-Coa Reductase), HMGS (3-Hydroxy-3-Methylglutaryl-Coa Synthase), SE (Squalene Epoxidase), and FPS (Farnesyl Diphosphate Synthase) genes in the ergosterol synthesis pathway. For expression levels at different induction days, we collected 7/10 d and 4/6/8 d samples with similar expression patterns, as well as SS (Squalene Synthase)/FPS (Farnesyl Diphosphate Synthase), SE (Squalene Epoxidase)/MVD (Mevalonate Diphosphate Decarboxylase), and HMGS (3-Hydroxy-3-Methylglutaryl-Coa Synthase)/HMGR (3-Hydroxy-3-Methylglutaryl-Coa Reductase) genes with similar expression patterns, which resulted in gene transcription data during ergosterol content synthesis. The current study provides an effective method to increase the ergosterol contents in termite ball fungus and a new idea for the mechanism of MJ-induced ergosterol compound biosynthesis.