Triterpenoid content and expression of triterpenoid biosynthetic genes in birch (Betula platyphylla Suk) treated with 5-azacytidine

DNA methylation is widespread in plants and associated with plant development and defense mechanisms. However, the relationship between DNA methylation and plant secondary metabolism has rarely been reported. Here, when birch suspension cells were treated with 5-azacytidine (5-azaC), which blocks DNA methylation, triterpenoid accumulation was significantly promoted and antioxidant and defense enzymatic activity changed. For studying triterpenoid accumulation, 0.1 mM azaC was optimal. A qRT-PCR assay revealed increased expression of genes encoding key triterpenoid biosynthetic enzymes. Evaluation of methylation polymorphisms at CCGG sites showed that the methylation level was lower in cells treated with 5-azaC. These results demonstrated that 5-azaC treatment led to an increase in the production of triterpenoids in cell cultures through a mechanism that involved in DNA methylation, which resulted in the induction of genes encoding the key enzymes. The study provides evidence of a relationship between DNA methylation and regulation of secondary metabolism.