Abstract
Background: Epigenetic regulation plays a significant role in the accumulation of plant secondary metabolites. The terpenoids are the most abundant in the secondary metabolites of plants, iridoid glycosides belong to monoterpenoids which is one of the main medicinal components of R.glutinosa. At present, study on iridoid glycosides mainly focuses on its pharmacology, accumulation and distribution, while the mechanism of its biosynthesis and the relationship between DNA methylation and plant terpene biosynthesis are seldom reports. Results: The research showed that the expression of DXS, DXR, 10HGO, G10H, GPPS and accumulation of iridoid glycosides increased at first and then decreased with the maturity of R.glutinosa, and under different concentrations of 5-azaC, the expression of DXS, DXR, 10HGO, G10H, GPPS and the accumulation of total iridoid glycosides were promoted, the promotion effect of low concentration (15μM-50μM) was more significant, the content of genomic DNA 5mC decreased significantly, the DNA methylation status of R.glutinosa genomes was also changed. DNA demethylation promoted gene expression and increased the accumulation of iridoid glycosides, but excessive demethylation inhibited gene expression and decreased the accumulation of iridoid glycosides. Conclusion: The analysis of DNA methylation, gene expression, and accumulation of iridoid glycoside provides insights into accumulation of terpenoids in R.glutinosa and lays a foundation for future studies on the effects of epigenetics on the synthesis of secondary metabolites.