Genome-wide identification and integrated analysis of TCP genes controlling ginsenoside biosynthesis in Panax ginseng.

Panax ginseng is an important medicinal plant, and ginsenosides are the main bioactive molecules of ginseng. The TCP (TBI, CYC, PCF) family is a group of transcription factors (TFs) that play an important role in plant growth and development, hormone signalling and synthesis of secondary metabolites. In our study, 78 PgTCP transcripts were identified from the established ginseng transcriptome database. A phylogenetic tree analysis showed that the 67 PgTCP transcripts with complete open reading frames were classified into three subfamilies, including CIN, PCF, and CYC/TB1. Protein structure analysis showed that PgTCP genes had bHLH structures. Chromosomal localization analysis showed that 63 PgTCP genes were localized on 17 of the 24 chromosomes of the Chinese ginseng genome. Expression pattern analysis showed that PgTCP genes differed among different lineages and were spatiotemporally specific. Coexpression network analysis indicated that PgTCP genes were coexpressed and involved in plant activities or metabolic regulation in ginseng. The expression levels of PgTCP genes from class I (PCF) were significantly downregulated, while the expression levels of PgTCP genes from class II (CIN and CYC/TB1) were upregulated, suggesting that TCP genes may be involved in the regulation of secondary metabolism in ginseng. As the PgTCP26-02 gene was found to be related to ginsenoside synthesis, its predicted protein structure and expression pattern were further analysed. Our results provide new insights into the origin, differentiation, evolution and function of the PgTCP gene family in ginseng, as well as the regulation of plant secondary metabolism.

Functional Study of PgGRAS68-01 Gene Involved in the Regulation of Ginsenoside Biosynthesis in Panax ginseng.

Ginseng (Panax ginseng C. A. Meyer) is a perennial herb from the genus Panax in the family Araliaceae. It is famous in China and abroad. The biosynthesis of ginsenosides is controlled by structural genes and regulated by transcription factors. GRAS transcription factors are widely found in plants. They can be used as tools to modify plant metabolic pathways by interacting with promoters or regulatory elements of target genes to regulate the expression of target genes, thereby activating the synergistic interaction of multiple genes in metabolic pathways and effectively improving the accumulation of secondary metabolites. However, there are no reports on the involvement of the GRAS gene family in ginsenoside biosynthesis. In this study, the GRAS gene family was located on chromosome 24 pairs in ginseng. Tandem replication and fragment replication also played a key role in the expansion of the GRAS gene family. The PgGRAS68-01 gene closely related to ginsenoside biosynthesis was screened out, and the sequence and expression pattern of the gene were analyzed. The results showed that the expression of PgGRAS68-01 gene was spatio-temporal specific. The full-length sequence of PgGRAS68-01 gene was cloned, and the overexpression vector pBI121-PgGRAS68-01 was constructed. The ginseng seedlings were transformed by Agrobacterium rhifaciens-mediated method. The saponin content in the single root of positive hair root was detected, and the inhibitory role of PgGRAS68-01 in ginsenoside synthesis is reported.

Integrative transcriptome analysis identifies new oxidosqualene cyclase genes involved in ginsenoside biosynthesis in Jilin ginseng.

BACKGROUND: Jilin ginseng, Panax ginseng, is a valuable medicinal herb whose ginsenosides are its major bioactive components. The ginseng oxidosqualene cyclase (PgOSC) gene family is known to play important roles in ginsenoside biosynthesis, but few members of the gene family have been functionally studied. METHODS: The PgOSC gene family has been studied by an integrated analysis of gene expression-ginsenoside content correlation, gene mutation-ginsenoside content association and gene co-expression network, followed by functional analysis through gene regulation. RESULTS: We found that five of the genes in the PgOSC gene family, including two published ginsenoside biosynthesis genes and three new genes, were involved in ginsenoside biosynthesis. Not only were the expressions of these genes significantly correlated with ginsenoside contents, but also their nucleotide mutations significantly influenced ginsenoside contents. These results were further verified by regulation analysis of the genes by methyl jasmonate (MeJA) in ginseng hairy roots. Four of these five PgOSC genes were mapped to the ginsenoside biosynthesis pathway. These PgOSC genes expressed differently across tissues, but relatively consistent across developmental stages. These PgOSC genes formed a single co-expression network with those published ginsenoside biosynthesis genes, further confirming their roles in ginsenoside biosynthesis. When the network varied, ginsenoside biosynthesis was significantly influenced, thus revealing the molecular mechanism of ginsenoside biosynthesis. CONCLUSION: At least five of the PgOSC genes, including the three newly identified and two published PgOSC genes, are involved in ginsenoside biosynthesis. These results provide gene resources and knowledge essential for enhanced research and applications of ginsenoside biosynthesis in ginseng.

Structural dissection of unnatural ginsenoside-biosynthetic UDP-glycosyltransferase Bs-YjiC from Bacillus subtilis for substrate promiscuity.

Glycosylation catalyzed by uridine diphosphate-dependent glycosyltransferases (UGT) contributes to the chemical and functional diversity of a number of natural products. Bacillus subtilis Bs-YjiC is a robust and versatile UGT that holds potentials in the biosynthesis of unnatural bioactive ginsenosides. To understand the molecular mechanism underlying the substrate promiscuity of Bs-YjiC, we solved crystal structures of Bs-YjiC and its binary complex with uridine diphosphate (UDP) at resolution of 2.18 Å and 2.44 Å, respectively. Bs-YjiC adopts the classical GT-B fold containing the N-terminal and C-terminal domains that accommodate the sugar acceptor and UDP-glucose, respectively. Molecular docking indicates that the spacious sugar-acceptor binding pocket of Bs-YjiC might be responsible for its broad substrate spectrum and unique glycosylation patterns toward protopanaxadiol-(PPD) and PPD-type ginsenosides. Our study reveals the structural basis for the aglycone promiscuity of Bs-YjiC and will facilitate the protein engineering of Bs-YjiC to synthesize novel bioactive glycosylated compounds.

Characteristics of RNA alternative splicing and its potential roles in ginsenoside biosynthesis in a single plant of ginseng, Panax ginseng C.A. Meyer.

RNA alternative splicing (AS) is prevalent in higher organisms and plays a paramount role in biology; therefore, it is crucial to have comprehensive knowledge on AS to understand biology. However, knowledge is limited about how AS activates in a single plant and functions in a biological process. Ginseng is one of the most widely used medicinal herbs that is abundant in a number of medicinal bioactive components, especially ginsenosides. In this study, we sequenced the transcripts of 14 organs from a 4-year-old ginseng plant and quantified their ginsenoside contents. We identified AS genes by analyzing their transcripts with the ginseng genome and verified their AS events by PCR. The plant had a total of 13,863 AS genes subjected to 30,801 AS events with five mechanisms: skipped exon, retained intron, alternative 5'splice site, alternative 3' splice site, and mutually exclusive exon. The genes that were more conserved, had more exons, and/or expressed across organs were more likely to be subjected to AS. AS genes were enriched in over 500 GO terms in the plant even though the number of AS gene-enriched GO terms varied across organs. At least 24 AS genes were found to be involved in ginsenoside biosynthesis. These AS genes were significantly up-enriched and more likely to form a co-expression network, thus suggesting the functions of AS and correlations of the AS genes in the process. This study provides comprehensive insights into the molecular characteristics and biological functions of AS in a single plant; thus, helping better understand biology.

Changes in the physiological characteristics of Panax ginseng embryogenic calli and molecular mechanism of ginsenoside biosynthesis under cold stress.

MAIN CONCLUSION: Short-term cold stress can induce the increased expression of key enzyme-encoding genes involved in secondary metabolite synthesis, thereby increasing secondary metabolite concentration. Cold stress is an ecologically limiting factor that strongly affects the physiological and biochemical properties of medicinal plants often resulting in changes of the secondary metabolic process. Ginsenosides are the main active ingredients in medicinal ginseng yet few studies exist on the effect of cold stress on the expression of ginsenosides or the molecular mechanism underlying its regulation. Here, we evaluated the effects of cold stress on the physiological characteristics and secondary metabolism of P. ginseng embryogenic calli. Physiological measurements and RNA-Seq analysis were used to dissect the metabolic and molecular responses of P. ginseng to cold conditions. We found that the dynamic accumulation of ginsenoside and various physiological indicators leads to homogenous adaptation to cold stress. Secondary metabolism of ginseng could be a compensation mechanism to facilitate its adaptation to cold stress. Combined with the changes in the endogenous hormone content, 9-cis-epoxycarotenoid dioxygenase (NCED), zeaxanthin epoxidase (ZEP), and short chain dehydrogenase (SDR) from the abscisic acid (ABA) synthesis pathway were identified as key mediators of this response. Thus, an appropriate degree of cold stress may promote accumulation of ginsenosides. Moreover, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR2), squalene epoxidase (SE1), squalene synthase (SS), dammarenediol synthase (DS-II), and ß-alanine C-28 hydroxylase (CYP716A52v2) should be considered key mediators of the cold stress response and ginsenoside biosynthesis. During industrial production, short-term cold stress should be carried out on ginseng calli to improve the quality of its medicinal materials.

[Expression analysis of transcription factor ERF gene family of Panax ginseng].

Ethylene responsive factor(ERF), one of the largest families of transcriptional factors in plants, plays a key role in se-condary metabolism of herbal plants. To analyze the expression of ERF family genes, the heat map clustering method was used by analyzing the ginseng transcriptomes of different parts and different growth years. The contents of ginsenosides Rg_1, Re and Rb_1 in various concentrations of MeJA-treated ginseng adventitious roots were determined by UPLC-MS/MS method. The expression of key genes of ginsenoside biosynthesis(DDS, CYP716A47, CYP716A53v2) and ERF family genes in MeJA-treated ginseng adventitious roots were determined by using real-time quantitative PCR. Pearson correlation was adopted to analyze the gene expression pattern of DDS, CYP716A47, CYP716A53v2 gene and ERF family. The results showed that the content of ginseng diol ginsenoside Rb_1 in ginseng adventitious roots treated with different concentrations of MeJA increased, and the content of ginseng triol ginsenoside Rg_1 and Re decreased. It is consistent with the increase of DDS and CYP716A47 expression and the decrease of CYP716A53v2 gene expression. The expression of ERF003, ERF118 and ERF012 genes was significantly positively correlated with CYP716A53v2, but negatively correlated with DDS. While the expression of ERF1B was significantly negatively correlated with CYP716A47.It is proved that ERF003, ERF118 and ERF012 were likely to inhibit the expression of DDS and promote the expression of CYP716A53v2, and ERF1B was likely to inhibit CYP716A47. This work could provide theoretical basis of ERF functional verification of regulating the biosynthesis of ginsenosides.

Advances in ginsenoside biosynthesis and metabolic regulation.

In this paper, we reviewed the advances in ginsenoside biosynthesis and metabolic regulation. To begin with, the application of elicitors in the ginsenoside biosynthesis was discussed. Methyl jasmonate (MJ) and analogues have the best effect on accumulation of ginsenoside compared with other elicitors, and few biotic elicitors are applied in Panax genus plants tissue culture. In addition, so far, more than 40 genes encoding ginsenoside biosynthesis related enzymes have been cloned and identified from Panax genus, such as UDP-glycosyltransferases (UGT) genes UDPG, UGTAE2, UGT94Q2, UGTPg100, and UGTPg1. However, the downstream pathway of the ginsenoside biosynthesis is still not clear. Moreover, some methods have been used to increase the expression of functional genes and ginsenoside content in the ginsenoside synthesis pathway, including elicitors, overexpression, RNAi, and transcription factors. The ginsenoside biosynthesis pathway should be revealed so that ginsenoside contents can be regulated.

[Expression of saponin biosynthesis related genes in different tissues of Panax quinquefolius].

The relationship between saponin content of Panax quinquefolius in different parts of the organization and expression of ginsenoside biosynthesis related gene was obtained by the correlation analysis between saponin content and gene expression. The 14 tissue parts of P. quinquefolius were studied, six saponins in P. quinquefolius. Samples (ginsenoside Rg1, Re, Rb1, Rc, Rb2 and Rd), group saponins and total saponins were determined by high performance liquid chromatography and vanillin-sulfuric acid colorimetric method. Simultaneously, the expression levels of 7 ginsenoside biosynthesis related genes (SQS, OSC, DS, ß-AS, SQE, P450 and FPS) in different tissues of P. quinquefolius were determined by Real-time fluorescence quantitative PCR. Although 7 kinds of ginsenoside biosynthesis related enzyme gene in the P. quinquefolius involved in ginsenoside synthesis, the expression of ß-AS and P450 genes had no significant effect on the content of monosodium saponins, grouping saponins and total saponins, FPS, SQS, OSC, DS and SQE had significant or extremely significant on the contents of single saponins Re, Rg1, Rb1, Rd, group saponin PPD and PPT, total saponin TMS and total saponin TS (P<0.05 or P<0.01). The biosynthesis of partial saponins, grouping saponins and total saponins in P. quinquefolius was affected by the interaction of multiple enzyme genes in the saponin synthesis pathway, the content of saponins in different tissues of P. quinquefolius was determined by the differences in the expression of key enzymes in the biosynthetic pathway. Therefore, this study further clarified that FPS, SQS, OSC, DS and SQE was the key enzyme to control the synthesis of saponins in P. quinquefolius by correlation analysis, the biosynthesis of ginsenosides in P. quinquefolius was regulated by these five kind of enzymes in cluster co-expression of interaction mode.

Production of a bioactive unnatural ginsenoside by metabolically engineered yeasts based on a new UDP-glycosyltransferase from Bacillus subtilis.

Ginsenosides are the main bioactive constituents of Panax species, which are biosynthesized by glycosylation at C3-OH and/or C20-OH of protopanaxadiol (PPD), C6-OH and/or C20-OH of protopanaxatriol (PPT). The C12-glycosylated ginsenosides have scarcely been identified from Panax species. The C12-glycosylated ginsenosides produced from PPD by chemical semi-synthesis have been reported to exhibit higher cytotoxicity than the natural ginsenosides. However, the chemical semi-synthesis approach is not practical due to its complexity and high cost. In our study, a new UDP-glycosyltransferase UGT109A1 was identified from Bacillus subtilis. This enzyme transferred a glucose moiety to C3-OH and C20-OH of dammarenediol-II (DM), C3-OH and C12-OH of PPD and PPT respectively to produce the unnatural ginsenosides 3ß-O-Glc-DM, 3ß,20S-Di-O-Glc-DM, 3ß,12ß-Di-O-Glc-PPD and 3ß,12ß-Di-O-Glc-PPT. Among these unnatural ginsenosides, 3ß,12ß-Di-O-Glc-PPT is a new compound which has never been reported before. The anti-cancer activities of these unnatural ginsenosides were evaluated in vitro and in vivo. 3ß,12ß-Di-O-Glc-PPD exhibited higher anti-lung cancer activity than Rg3, which is the most active natural ginsenoside against lung cancer. Finally, we constructed metabolically engineered yeasts to produce 3ß,12ß-Di-O-Glc-PPD by introducing the genes encoding B. subtilis UGT109A1, Panax ginseng dammarenediol-II synthase (DS), P. ginseng cytochrome P450-type protopanaxadiol synthase (PPDS) together with Arabidopsis thaliana NADPH-cytochrome P450 reductase (ATR1) into Saccharomyces cerevisiae INVSc1. The yield of 3ß,12ß-Di-O-Glc-PPD was increased from 6.17mg/L to 9.05mg/L by overexpressing tHMG1. Thus, this study has established an alternative route to produce the unnatural ginsenoside 3ß,12ß-Di-O-Glc-PPD by synthetic biology strategies, which provides a promising candidate for anti-cancer drug discovery.

[Research of genes expression related to ginsenosides biosynthesis by methyl jasmonic acid in ginseng hair roots].

In order to obtain the expression of ginsenoside biosynthetic pathway related enzyme gene in ginseng hairy root under the control of elicitors, methyl jasmonate (MeJA) was added exogenously as elicitors. Ginseng hairy root clones induced by 4-year-old ginseng root was used as material, total saponin content in ginseng hairy root before and after MeJA treatment was determined by vanillin-sulfuric acid colorimetry, Meanwhile, relative expression of squalene synthase genes, squalene epoxidase genes, oxidized squalene cyclase genes, dammarenediol synthase genes, ß-amyrin synthase genes, cycloartenol synthase genes before and after MeJA treatment were determined by Real-time PCR. The optimum conditions of MeJA which added to ginseng hairy root were obtained, the optimum additional concentration was 6×10⁻4 µmol•L⁻¹, the optimum additional time was 22 d, and the optimum action time was 5 d. The addition of MeJA could improve the enzymatic activity of peroxidase (PPD), catalase (CAT) and peroxidase (PPD) in ginseng hairy root. The expression of SQS，SQE，OSC，DS and ß-AS genes of ginsenoside biosynthetic pathway increased significantly after MeJA treatment, while the change of CAS gene expression were not significant. The expression of key enzyme SQS，SQE，OSC，DS and ß-AS genes in ginsenoside biosynthetic pathway was consistent with the changes of PPD，CAT，PPO enzymatic activity.

Enhancement of ginsenoside biosynthesis and secretion by Tween 80 in Panax ginseng hairy roots.

We evaluated the effect of Tween 80 permeabilization on ginsenoside secretion in Panax ginseng hairy roots. Tween 80 (1.2%, w/v) had no significant effect on hairy root vitality. After a 25-day treatment with Tween 80, approximately 76% of the total ginsenosides was released into the surrounding medium. In the case of control, the ginsenosides secreted into the medium were negligible. Furthermore, when compared with control, the level of total ginsenosides was enhanced by approximately threefold under Tween treatment. Additionally, secretion of the typical ginsenoside monomers including Rb1 , Rg1 , and Re was analyzed, indicating that the most of them were released into the medium. Moreover, it was observed that dammarenediol synthase, a key enzyme involved in ginsenoside biosynthesis, was upregulated at both gene expression and enzyme activity levels. The expression of genes CYP716A47 and CYP716A53v2 encoding Cyt P450 enzymes catalyzing the formation of protopanaxadiol from dammarenediol and protopanaxatriol from protopanaxadiol, respectively, was slightly upregulated. These results clearly demonstrated that Tween 80 could act not only as an efficient permeabilizer to enhance ginsenoside secretion from the hairy roots, but also as an elicitor to promote the biosynthesis of ginsenoside.

Two ginseng UDP-glycosyltransferases synthesize ginsenoside Rg3 and Rd.

Ginseng is a medicinal herb that requires cultivation under shade conditions, typically for 4-6 years, before harvesting. The principal components of ginseng are ginsenosides, glycosylated tetracyclic terpenes. Dammarene-type ginsenosides are classified into two groups, protopanaxadiol (PPD) and protopanaxatriol (PPT), based on their hydroxylation patterns, and further diverge to diverse ginsenosides through differential glycosylation. Three early enzymes, dammarenediol-II synthase (DS) and two P450 enzymes, protopanaxadiol synthase (PPDS) and protopanaxatriol synthase (PPTS), have been reported, but glycosyltransferases that are necessary to synthesize specific ginsenosides have not yet been fully identified. To discover glycosyltransferases responsible for ginsenoside biosynthesis, we sequenced and assembled the ginseng transcriptome de novo and characterized two UDP-glycosyltransferases (PgUGTs): PgUGT74AE2 and PgUGT94Q2. PgUGT74AE2 transfers a glucose moiety from UDP-glucose (UDP-Glc) to the C3 hydroxyl groups of PPD and compound K to form Rh2 and F2, respectively, whereas PgUGT94Q2 transfers a glucose moiety from UDP-Glc to Rh2 and F2 to form Rg3 and Rd, respectively. Introduction of the two UGT genes into yeast together with PgDS and PgPPDS resulted in the de novo production of Rg3. Our results indicate that these two UGTs are key enzymes for the synthesis of ginsenosides and provide a method for producing specific ginsenosides through yeast fermentation.

Weighted gene co-expression network analysis and identification of ginsenoside biosynthesis candidate genes for ginseng adventitious roots under MeJA treatment.

BACKGROUND: Ginseng (Panax ginseng) is an herb with a long history and a wide range of applications. Ginsenoside is one of the most representative and active ginseng compounds, with various pharmacological effects. Therefore, the development of bioreactors using methyl jasmonate (MeJA) as an inducer for targeted ginsenoside production is of great commercial value. Combined with transcriptomic research tools, screenings to obtain candidate genes involved in ginsenoside biosynthesis are crucial for future discoveries about the molecular mechanism of MeJA-regulated ginsenoside biosynthesis. OBJECTIVE AND METHODS: In our study, the ginsenoside content of ginseng adventitious roots treated with MeJA at different times was analyzed. Transcriptome analysis was performed to investigate the effects of MeJA on changes in ginsenoside content in ginseng adventitious roots. RESULTS: The MeJA could significantly increase changes in the content of pro-ginsenodiol ginsenosides as well as pro-triol ginsenosides Rg3, Re, and Rf in ginseng adventitious roots. Differential gene expression analysis showed that a total of 14,009 differentially expressed genes were obtained from the screening of the present study. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that differentially expressed genes were mainly enriched under GO terms in response to stimuli, metabolic processes, and the regulation of biological processes, with significant annotation to the metabolic terms of terpenoids and polyketides. Two expression modules of genes highly related to ginsenoside biosynthesis were obtained via WGCNA. CONCLUSIONS: Our study provides a reference system for the targeted ginsenoside production using MeJA as an inducer, and also provides genetic and gene resources for subsequently validating genes related to the regulation of ginsenoside biosynthesis using weighted gene co-expression network analysis (WGCNA).

Genetic and molecular dissection of ginseng (Panax ginseng Mey.) germplasm using high-density genic SNP markers, secondary metabolites, and gene expressions.

Genetic and molecular knowledge of a species is crucial to its gene discovery and enhanced breeding. Here, we report the genetic and molecular dissection of ginseng, an important herb for healthy food and medicine. A mini-core collection consisting of 344 cultivars and landraces was developed for ginseng that represents the genetic variation of ginseng existing in its origin and diversity center. We sequenced the transcriptomes of all 344 cultivars and landraces; identified over 1.5 million genic SNPs, thereby revealing the genic diversity of ginseng; and analyzed them with 26,600 high-quality genic SNPs or a selection of them. Ginseng had a wide molecular diversity and was clustered into three subpopulations. Analysis of 16 ginsenosides, the major bioactive components for healthy food and medicine, showed that ginseng had a wide variation in the contents of all 16 ginsenosides and an extensive correlation of their contents, suggesting that they are synthesized through a single or multiple correlated pathways. Furthermore, we pair-wisely examined the relationships between the cultivars and landraces, revealing their relationships in gene expression, gene variation, and ginsenoside biosynthesis. These results provide new knowledge and new genetic and genic resources for advanced research and breeding of ginseng and related species.

Comparative transcriptome analysis on wild-simulated ginseng of different age revealed possible mechanism of ginsenoside accumulation.

Panax ginseng is one of the most famous pharmaceutical plants in Asia. Ginseng plants grown in mountain have longer longevity which ensures higher accumulation of ginsenoside components than those grown in farms. However, wild-simulated ginseng over certain age cannot be easily distinguished in morphology. To identify transcriptomic mechanism of ginsenoside accumulation in older wild-simulated ginseng without large phenotype change, we performed comparative transcriptome analysis for leaf, shoot, and root tissues of 7-yr-old and 13yr-old wild-simulated ginseng. Of 559 differentially expressed genes (DEGs) in comparison between 7-yr-old and 13yr-old wild-simulated ginseng, 280 leaf-, 103 shoot-, and 164 root-mainly expressing genes were found to be changed in transcript level according to age. Functional analysis revealed that pentose-phosphate shunt and abscisic acid responsive genes were up-regulated in leaf tissues of 7-yr-old ginseng while defense responsive genes were up-regulated in root tissues of 13-yr-old ginseng. Quantitative real-time PCR revealed that jasmonic acid responsive genes, ERDL6, and some UGTs were up-regulated in 13-yr-old ginseng in higher order lateral root tissues. These data suggest that bacterial stimulation in mountain region can enhance the expression of several genes which might support minor ginsenoside biosynthesis.

Transcriptome-Wide Integrated Analysis of the PgGT25-04 Gene in Controlling Ginsenoside Biosynthesis in Panax ginseng.

Panax ginseng is a valuable medicinal herb of the Araliaceae family with various pharmacological activities. The Trihelix transcription factors family is involved in growth and secondary metabolic processes in plants, but no studies have been reported on the involvement of Trihelix genes in secondary metabolic processes in ginseng. In this study, weighted co-expression network analysis, correlation analysis between PgGTs and ginsenosides and key enzyme genes, and interaction network analysis between PgGTs and key enzyme genes were used to screen out the PgGT25-04 gene, which was negatively correlated with ginsenoside synthesis. Using ABA treatment of ginseng hair roots, PgGT genes were found to respond to ABA signals. Analysis of the sequence characteristics and expression pattern of the PgGT25-04 gene in ginseng revealed that its expression is spatiotemporally specific. The interfering vector pBI121-PgGT25-04 containing the PgGT25-04 gene was constructed, and the ginseng adventitious roots were transformed using the Agrobacterium-mediated method to obtain the pBI121-PgGT25-04 positive hairy root monocot line. The saponin contents of positive ginseng hair roots were measured by HPLC, and the changes in PgGT25-04 and key enzyme genes in positive ginseng hair roots were detected via fluorescence quantitative RT-PCR. These results preliminarily identified the role of the PgGT25-04 gene in the secondary metabolism of ginseng in Jilin to provide a theoretical basis for the study of Trihelix transcription factors in Panax ginseng.

Integrative SMRT sequencing and ginsenoside profiling analysis provide insights into the biosynthesis of ginsenoside in Panax quinquefolium.

Panax quinquefolium is one of the most common medicinal plants worldwide. Ginsenosides are the major pharmaceutical components in P. quinquefolium. The biosynthesis of ginsenosides in different tissues of P. quinquefolium remained largely unknown. In the current study, an integrative method of transcriptome and metabolome analysis was used to elucidate the ginsenosides biosynthesis pathways in different tissues of P. quinquefolium. Herein, 22 ginsenosides in roots, leaves, and flower buds showed uneven distribution patterns. A comprehensive P. quinquefolium transcriptome was generated through single molecular real-time (SMRT) and second-generation sequencing (NGS) technologies, which revealed the ginsenoside pathway genes and UDP-glycosyltransferases (UGT) family genes explicitly expressed in roots, leaves, and flower buds. The weighted gene co-expression network analysis (WGCNA) of ginsenoside biosynthesis genes, UGT genes and ginsenoside contents indicated that three UGT genes were positively correlated to pseudoginsenoside F11, notoginsenoside R1, notoginsenoside R2 and pseudoginsenoside RT5. These results provide insights into ginsenoside biosynthesis in different tissues ofP. quinquefolium.

Biogenic Synthesis and Spatial Distribution of Endogenous Phytohormones and Ginsenosides Provide Insights on Their Intrinsic Relevance in Panax ginseng.

Ginseng, the root and rhizome of Panax ginseng C. A. Mey., is a well-known and valuable traditional Chinese medicine. The pharmacological activities of ginseng are mainly attributed to the presence of ginsenosides, which are considered to be critical biomarkers for evaluating ginseng quality. The biosynthesis of triterpenes, which serve defensive functions in plants, is regulated by endogenous phytohormones that play key roles in growth and defense of plant populations. However, the role of major hormones that are closely related to secondary metabolism pathways in P. ginseng is poorly understood. To gain insight into their potential correlation, we performed a spatial synthesis analysis and studied the distribution of endogenous phytohormones and ginsenosides in different tissue regions of the entire P. ginseng plant. Gibberellins are growth hormones that accumulate in the fiber root. In contrast, abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA), which are considered stress hormones, were predominantly found in the leaf and leaf peduncle. We observed a tissue-specific distribution of phytohormones consistent with the expression of genes involved in hormone biosynthesis that influenced ginsenoside synthesis and distribution. The aim of this study was to investigate the role of different endogenous phytohormones on triterpene metabolites in ginseng innate immunity.

Expression analysis of transcription factor ERF gene family of Panax ginseng / 中国中药杂志

Ethylene responsive factor(ERF), one of the largest families of transcriptional factors in plants, plays a key role in se-condary metabolism of herbal plants. To analyze the expression of ERF family genes, the heat map clustering method was used by analyzing the ginseng transcriptomes of different parts and different growth years. The contents of ginsenosides Rg_1, Re and Rb_1 in various concentrations of MeJA-treated ginseng adventitious roots were determined by UPLC-MS/MS method. The expression of key genes of ginsenoside biosynthesis(DDS, CYP716A47, CYP716A53v2) and ERF family genes in MeJA-treated ginseng adventitious roots were determined by using real-time quantitative PCR. Pearson correlation was adopted to analyze the gene expression pattern of DDS, CYP716A47, CYP716A53v2 gene and ERF family. The results showed that the content of ginseng diol ginsenoside Rb_1 in ginseng adventitious roots treated with different concentrations of MeJA increased, and the content of ginseng triol ginsenoside Rg_1 and Re decreased. It is consistent with the increase of DDS and CYP716A47 expression and the decrease of CYP716A53v2 gene expression. The expression of ERF003, ERF118 and ERF012 genes was significantly positively correlated with CYP716A53v2, but negatively correlated with DDS. While the expression of ERF1B was significantly negatively correlated with CYP716A47.It is proved that ERF003, ERF118 and ERF012 were likely to inhibit the expression of DDS and promote the expression of CYP716A53v2, and ERF1B was likely to inhibit CYP716A47. This work could provide theoretical basis of ERF functional verification of regulating the biosynthesis of ginsenosides.