Study On Metabolic Differences And Biosynthesis Of Ginsenosides From Vietnamese Ginseng Based On Multi-Omics Analysis

China is rich in medicinal plant resources,with 11,146 medicinal plants confirmed.The effective protection and rational utilization of many medicinal plant resources have always been the focus of botanists,evolutionary biologists and geneticists.Due to the individual differences and the complexity of plant introduction,as well as the blank stage in the research of some important species,the exploitation and utilization of medicinal plant resources are still limited.Panax vietnamensis Ha & Grushv.,the Panax plant of Araliaceae,mainly distributed in Vietnam province and Jinping County of Yunnan Province.In recent years,the high-priced “Vietnamese ginseng” has occupied a high share in the ginseng consumer market due to its high total ginsenoside content and anti-cancer effect.The overexploitation of native habitat species poses a serious threat to their survival.Due to the lack of information on the genetic variation of the entire genome,there is still a lot of blindness and randomness in the exploration and utilization of its natural resources.Studying the overall genetic variation level of important medicinal plants at the functional genomic level,which helps to fully understand the genetic relationship between related genera and species.This is the key to the effective protection of medicinal plant resources and the screening of "excellent germplasm resources" and "excellent alleles".At the same time,it is an important direction for modern medicinal plant resource evaluation and breeding.In this study,four parts of the main root,fibrous root,stem and leaf of Vietnamese ginseng at 2-5 years were analyzed.Based on UPLC-MS,the qualitative and quantitative comparative study of ginsenosides was carried out,and the metabolites with different growth years and tissue parts were screened out by multivariate statistical analysis.By constructing a visualized metabolic network of metabolites differences in tissue and growth years of Vietnamese ginseng,a new research idea can be provided for revealing the pathway of ginsenoside synthesis.In addition,in order to further explore the key genes for saponin synthesis and clarify the effective substances,high-throughput sequencing technology with metabolic pathways analysis of highly expressed genes was used to construct a transcriptome database of Vietnamese ginseng.The application of system biology to reveal the metabolic regulatory network of different tissues and growth years of Vietnamese ginseng is of great significance for understanding the metabolic network regulation and molecular mechanism of ginsenoside synthesis.The correlation analysis of gene expression profiles of P.vietnamensis showed that the gene expression patterns of roots and fibrils were similar,but significantly different from those of stems and leaves.Therefore,we speculated that the expression level of many genes in leaves is down regulated.Through further identification of ginsenoside biosynthesis related genes,we determined the candidate genes involved in MVA,MEP and triterpenoid saponins biosynthesis pathway.We identified 15 FPS,16 SE,and 9 β-As from the unigene dataset,all of which were highly expressed in roots.The 85 UGTs encoded transcripts may catalyze glycosylation in the last step of ginsenoside biosynthesis.In this study,we found that the upstream unigene(AACT,HMGs,NADPH,MVK,MVD)involved in MVA pathway showed high activity in 5-year-old roots,while the gene(DXS,DXR,Isp H,Isp G)encoding enzyme in MEP pathway had high expression in 2-year-old leaves.Most of the downstream genes(FPS,SE,β-As)were highly expressed in the roots of two years old,and the genes encoding UGTs enzyme were highly expressed in the leaves of two years old.These results showed that there were significant tissue-specific in the expression of key enzyme genes of P.vietnamensis.The biosynthesis of ginsenoside in roots and leaves tissue is coordinated by several key enzymes.The expression of key enzymes regulates the metabolic flow of ginsenoside,and ultimately guides the synthesis of a variety of monomeric saponins.The difference in expression profile may be the reason for the uneven distribution of ginsenoside in different parts.