The Effect of Methylation Modification of MDD on the Expression of Key Genes in the Process of Saponin Synthesis in Eleutherococcus senticosus

Abstract

Mevalonate pyrophosphate decarboxylase is a kind of key enzyme in the terpenoid synthesis pathway in Eleutherococcus senticosus. The results of bisulfite sequencing showed that there were three kinds of samples with a low (0.68%), medium (0.72%) and high (0.79%) DNA methylation ratio in the promoter of MDD in E. senticosus, respectively. The transcriptome sequencing results showed that the expression of MDD in E. senticosus was significantly up-regulated in the types with low DNA methylation ratios of MDD (P < 0.05). There was a significant negative correlation between the saponin content in E. senticosus and the DNA methylation ratio of MDD promoter (P < 0.05). The screening results of differentially expressed transcription factors among the three groups with different DNA methylation ratio showed that a total of 4 transcription factors could bind to 6 CpG sites. Protein-protein interaction analysis showed that E. senticosus MDD could interacted with other key enzymes in the process of terpenoid synthesis. In addition, it was found that the DNA methylation of MDD promoter was mainly regulated by DNA methyltransferase. These results demonstrated that under the action of DNA methyltransferase, the changes of DNA methylation of MDD promoter could regulate its own expression level by affecting the combination ability of transcription factors, and then affected the expression of other genes in terpenoid synthesis pathway. The synthesis and accumulation of saponins in E. senticosus was also changed.

DNA methylation regulates the secondary metabolism of saponins to improve the adaptability of Eleutherococcus senticosus during drought stress

“…The unigene was created by splicing, assembling, and hierarchical clustering of high-quality data. Using HMMER software, the annotation information for unigene was retrieved by comparing it with the Pfam database after predicting the amino acid sequence [ 19 , 23 ].…”

“…A method based on the literature was used to extract the metabolites of E. senticosus [ 18 – 19 ]. For E. senticosus , the metabolome analysis was carried out using a UPLC-ESI-MS/MS system (UPLC, SHIMADZU Nexera X2, https://www.shimadzu.com.cn/ ; MS, Applied Biosystems 4500 Q TRAP, https://www.thermofisher.cn/cn/zh/home/brands/applied-biosystems.html ).…”

“…Using the literature as a guide, the total saponin content of E. senticosus was extracted [ 19 ]. Accurately weigh 2.6 mg of oleanolic acid standards (Solarbio, China) and place them in a 10 mL volumetric flask.…”

“…et Maxim) Maxim, sometimes called Siberian ginseng and a member of the Araliaceae family, is an invaluable medicinal plant [ 16 ]. Its primary active components, triterpenoid saponins, are critical metrics for assessing its therapeutic quality [ 17 – 19 ]. Recent studies on E. senticosus show the plant thrives in moist soil environments for growth and photosynthesis, and it accumulates secondary metabolites, such as triterpenoid saponins, under moderate drought stress [ 20 ].…”

“…Furthermore, site-specific DNA methylation significantly impacted gene expression, with secondary metabolism being more significant than the DNA methylation ratio [ 18 ]. The findings above indicate that DNA methylation involved in saponin synthesis can directly impact the level of secondary metabolites that accumulate [ 18 – 19 ]. Therefore, it is crucial to investigate how drought stress affects the DNA methylation state of E. senticosus and regulates saponin metabolism to improve the resistance of plants to drought stress and better understand the mechanisms by which plants adapt to drought.…”