Functional Analysis of Sterol O-Acyltransferase Involved in the Biosynthetic Pathway of Pachymic Acid in .

Pachymic acid from possesses important medicinal values including anti-bacterial, anti-inflammatory, anti-viral, invigorating, anti-rejection, anti-tumor, and antioxidant activities. However, little is known about the biosynthetic pathway from lanostane to pachymic acid. In particular, the associated genes in the biosynthetic pathway have not been characterized, which limits the high-efficiency obtaining and application of pachymic acid. To characterize the synthetic pathway and genes involved in pachymic acid synthesis, in this study, we identified 11 triterpenoids in using liquid chromatography tandem mass spectrometry (LC-MS/MS), and inferred the putative biosynthetic pathway from lanostane to pachymic acid based on analyzing the chemical structure of triterpenoids and the transcriptome data. In addition, we identified a key gene in the biosynthetic pathway encoding sterol O-acyltransferase (), which catalyzes tumolusic acid to pachymic acid. The results show that silence of gene in strain led to reduction of pachymic acid production, whereas overexpression of this gene increased pachymic acid production, indicating that is involved in pachymic acid synthesis in and the biosynthesis of pachymic acid is closely dependent on the expression of gene. In summary, the biosynthetic pathway of pachymic acid and the associated genes complement our knowledge on the biosynthesis of pachymic acid and other triterpenoids, and also provides a reference for target genes modification for exploring high-efficiency obtaining of active components.