The Study On Gene Expression Differences Of Wild Panax Ginseng And Cultivated P.ginseng With Different Ages

Panax ginseng C.A.Meyer belongs to genus Panax,Araliaceae.It is a perennial herb with important medicinal and economic value,which is now mostly distributed in Jilin and Liaoning provinces of China.Its main effective biologically active ingredient is a triterpenoid compound,namely ginsenoside.Wild ginsengs refer to ginsengs that grow in the natural environment,not by artificial control and management.It is a treasure among Chinese herbal medicines with high medicinal efficacy and adversarial ability.However,due to slow growth and severe damage,wild ginseng germplasm resources are extremely rare,which makes cultivated ginsengs become the main source of ginseng market.Cultivated ginsengs are a group domesticated from wild ginsengs.Since cultivated ginsengs are susceptible to disease from the sixth year of growth,they are generally harvested in the sixth year.Growth year is an important factor affecting the development and the content of active components such as ginsenoside of cultivated ginsengs.This study is based on the whole genome data of ginseng published by Kim et al.in 2018,using transcriptome sequencing technology to screen and analyze the differentially expressed genes in roots,stems and leaves of wild ginsengs and cultivated ginsengs with different ages,so as to comprehensively explore the differences in gene expression in different tissues of wild ginsengs and cultivated ginsengs with different ages.(1)The gene expression of wild ginsengs was little affected by the ages.After the statistics of the number of differentially expressed genes in wild ginsengs and cultivated ginsengs with different ages,it is found that there was a significant difference in the number of differentially expressed genes between the two,that is,the number of differentially expressed genes in cultivated ginsengs with different ages was far more than that in wild ginsengs.The differentially expressed genes in roots,stems and leaves of wild ginsengs were very few.(2)The effect of ages on the gene expression level of cultivated ginsengs was different among different tissues.For cultivated ginsengs,there were more differentially expressed genes between one-year-old and six-year-old cultivated ginsengs.The number of differentially expressed genes was similar in roots and leaves,and the least in stems.In contrast,the number of differentially expressed genes between six-year-old and fifteen-year-old cultivated ginsengs was relatively small,and the proportion of differentially expressed genes was the highest in leaves and the lowest in roots.(3)The ages had an impact on the gene expression levels in some important metabolic pathways of cultivated ginsengs.The GO enrichment analysis and weighted gene co-expression network analysis of these differentially expressed genes showed the ages of cultivated ginsengs could affect the gene expression involved in metabolism pathways,such as stress and resistance,photosynthesis and terpenoid backbone biosynthesis.Due to the low number of differentially expressed genes in wild ginsengs,significantly enriched GO terms and metabolic pathways were not obtained.(4)The effect of ages on the related enzymes involved in ginsenoside biosynthesis in cultivated ginsengs was greater than that in wild ginsengs.Differentially expressed genes involved in ginsenoside biosynthesis pathway were also analyzed in this study.It was also found that the ages had little effect on the expression levels of related enzymes involved in ginsenoside biosynthesis of wild ginsengs but had a greater effect on that of cultivated ginsengs.(5)The ages also had an effect on the sites of ginsenoside biosynthesis in cultivated ginsengs.The differentially expressed genes involved in ginsenoside biosynthesis between one-year-old and six-year-old cultivated ginsengs were mostly distributed in roots,and the expression level of most enzymes was higher in the roots of six-year-old cultivated ginsengs.While the differentially expressed genes involved in ginsenoside biosynthesis between six-year-old and fifteen-year-old cultivated ginsengs were mostly distributed in leaves,and the expression level in fifteen-year-old cultivated ginsengs was lower than that in 6-year-old cultivated ginseng.This study is helpful to determine the differences in expression of genes with important biological functions and involved in important metabolic pathways in wild ginsengs and cultivated ginsengs of different ages,especially the expression differences in genes related to ginsenoside biosynthesis and stress resistance.This research provides information resources for improving transcriptome data of ginseng,and also provides a theoretical basis for further research on ginseng cultivation,breeding and related functional candidate genes.