Salicylic acid-induced upregulation of AtAACT and AtMVD expression enhances triterpene biosynthesis in Athelia termitophila.

Triterpenoids exhibit great potential in the food and pharmaceutical industries and are the predominant secondary metabolites of Athelia termitophila (TMB). AtAACT catalyzes the conversion of acetyl-CoA and acetoacetate in mevalonate biosynthesis, while AtMVD catalyzes the decarboxylation of mevalonate diphosphate, producing key precursors essential for triterpenoid synthesis. To augment the biosynthesis of TMB triterpenes, we cloned the AtAACT and AtMVD genes into plasmids, which were subsequently used to transform Escherichia coli. The resulting bacterial strains were used for sequencing and bioinformatic analyses to elucidate the encoded amino acid sequences. Furthermore, salicylic acid (SA) was employed as an elicitor to enhance triterpene biosynthesis in TMB. The SA treatment was initiated on the 6th day of incubation and maintained continuously across all time points (36, 48, and 60 h and others), achieving a maximal triterpene concentration of 41.83 ± 0.5 mg/100 mL, corresponding to a 26% increase compared to the uninduced group. Comparative transcriptomic analysis showed that the expression of AtAACT and AtMVD was significantly upregulated in the SA-treated group compared to the control. This upregulation underscores the crucial roles of these genes in facilitating triterpene biosynthesis in TMB. Furthermore, qPCR temporal profiling revealed that AtAACT achieved peak transcript levels at 36 h post-induction, whereas AtMVD peaked at 48 h. This study provides an effective strategy to enhance TMB triterpene content and offers new insights into the mechanisms of SA-treated triterpene biosynthesis.