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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 β-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.

Panax ginseng C.A. Meyer is one of the most highly valued medicinal plants in the world. To analyze the transcriptome of P. ginseng and discover the genes involved in ginsenoside biosynthesis, cDNAs derived from the total RNA of 11-year-old, wood-grown P. ginseng roots were analyzed by 454 sequencing. A total of 217,529 high quality reads (expressed sequence tags, ESTs), with an average length of 409 bases, were generated from a one-quarter run to yield 31,741 unique sequences. The majority (20,198; 63.6%) of the unique sequences were annotated using BLAST similarity searches. A total of 16,810 and 16,577 unique sequences were assigned to functional classifications and biochemical pathways based on Gene Ontology analysis and the Kyoto Encyclopedia of Genes and Genomes assignment, respectively. Nine genes involved in the biosynthesis of ginsenoside skeletons and many candidate genes putatively responsible for modification of the skeletons, including 133 cytochrome P450s and 235 glycosyltransferases, were identified. From these candidates, six transcripts encoding UDP-glycosyltransferases that were most likely to be involved in ginsenoside biosynthesis were selected. These results open a new avenue by which to explore and exploit biosynthetic and biochemical properties that may lead to drug improvement. These 454 ESTs will provide the foundation for further functional genomic research into the traditional herb P. ginseng or its closely related species.

KEY MESSAGE : When one of them was inhibited, the two pathways could compensate with each other to guarantee normal growth. Moreover, the sterol biosynthesis inhibitor miconazole could enhance ginsenoside level. Ginsenosides, a kind of triterpenoid saponins derived from isopentenyl pyrophosphate (IPP), represent the main pharmacologically active constituents of ginseng. In plants, two pathways contribute to IPP biosynthesis, namely, the mevalonate pathway in cytosol and the non-mevalonate pathway in plastids. This motivates biologists to clarify the roles of the two pathways in biosynthesis of IPP-derived compounds. Here, we demonstrated that both pathways are involved in ginsenoside biosynthesis, based on the analysis of the effects from suppressing either or both of the pathways on ginsenoside accumulation in Panax ginseng hairy roots with mevinolin and fosmidomycin as specific inhibitors for the mevalonate and the non-mevalonate pathways, respectively. Furthermore, the sterol biosynthesis inhibitor miconazole could enhance ginsenoside levels in the hairy roots. These results shed some light on the way toward better understanding of ginsenoside biosynthesis.

Background Panax notoginseng (PN) is a medicinal plant containing essential ginsenosides. Given the therapeutic significance of ginsenosides, we delved into the mechanisms of ginsenoside Rb3 biosynthesis in PN flowers. We examined this process from the pre-differentiation stage to the end of flowering, aiming to uncover the biochemical pathways underlying ginsenoside production in PN. Results Budding stage (T2) was found critical for enhanced Rb3 production. Transcriptomic analysis revealed a marked shift in gene expression beginning at T2, with upregulation in pathways associated with secondary metabolite production. Gene set enrichment analysis (GSEA) illuminated the upregulation of genes involved in terpenoid backbone biosynthesis, amino acid degradation, and terpenoid modifications, specifically at T2. We correlated the fluctuating hormone levels with the activity of the transcription factor MYC2 to underscore hormonal influence on ginsenoside biosynthesis. Biosynthesis pathway reconstruction revealed the dominance of the mevalonate pathway. Critical enzymes such as ACAT, PPDS, DDS, and LUP4 were vital in precursor biosynthesis and modification. Notably, key genes such as HMGCS , FDPS , and DDS , as well as transcription factors MYC2, MYB124, and MYB61.1, showed a concerted surge in activity at T2. Conclusions These findings provide insights into the complex gene networks and molecular pathways that regulate ginsenoside biosynthesis, thereby promoting the medicinal properties of PN.

The Panax ginseng C.A. Meyer belonging to the Araliaceae has long been used as an herbal medicine. Although public databases are presently available for this family, no methyl jasmonate (MeJA) elicited transcriptomic information was previously reported on this species, with the exception of a few expressed sequence tags (ESTs) using the traditional Sanger method. Here, approximately 53 million clean reads of adventitious root transcriptome were separately filtered via Illumina HiSeq™2000 from two samples treated with MeJA (Pg-MeJA) and equal volumes of solvent, ethanol (Pg-Con). Jointly, a total of 71,095 all-unigenes from both samples were assembled and annotated, and based on sequence similarity search with known proteins, a total of 56,668 unigenes was obtained. Out of these annotated unigenes, 54,920 were assigned to the NCBI non-redundant protein (Nr) database, 35,448 to the Swiss-prot database, 43,051 to gene ontology (GO), and 19,986 to clusters of orthologous groups (COG). Searching in the Kyoto encyclopedia of genes and genomes (KEGG) pathway database indicated that 32,200 unigenes were mapped to 128 KEGG pathways. Moreover, we obtained several genes showing a wide range of expression levels. We also identified a total of 749 ginsenoside biosynthetic enzyme genes and 12 promising pleiotropic drug resistance (PDR) genes related to ginsenoside transport.

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).

Methyl jasmonate (MeJA) treatment increases the levels of plant secondary metabolites, including ginsenosides, which are considered to be the main active compounds in ginseng (Panax ginseng C.A. Meyer). To create a ginseng gene resource that contains the genes involved in the biosynthesis of secondary metabolites, including ginsenosides, we generated 3,134 expression sequence tags (ESTs) from MeJA-treated ginseng hairy roots. These ESTs assembled into 370 clusters and 1,680 singletons. Genes yielding highly abundant transcripts were those encoding proteins involved in fatty acid desaturation, the defense response, and the biosynthesis of secondary metabolites. Analysis of the latter group revealed a number of genes that may be involved in the biosynthesis of ginsenosides, namely, oxidosqualene cyclase (OSC), cytochrome P450, and glycosyltransferase. A novel OSC gene was also identified by this analysis. RNA gel blot analysis confirmed that transcription of this OSC gene, along with squalene synthase (SS) and squalene epoxidase (SE) gene transcription, is increased by MeJA treatment. This ginseng EST data set will also provide important information on the genes that are involved in the biosynthesis of other secondary metabolites and the genes that are responsive to MeJA treatment.

Plant in vitro cultures represent an attractive and cost-effective alternative to classical approaches to plant secondary metabolite (PSM) production (the “Plant Cell Factory” concept). Among other advantages, they constitute the only sustainable and eco-friendly system to obtain complex chemical structures biosynthesized by rare or endangered plant species that resist domestication. For successful results, the biotechnological production of PSM requires an optimized system, for which elicitation has proved one of the most effective strategies. In plant cell cultures, an elicitor can be defined as a compound introduced in small concentrations to a living system to promote the biosynthesis of the target metabolite. Traditionally, elicitors have been classified in two types, abiotic or biotic, according to their chemical nature and exogenous or endogenous origin, and notably include yeast extract, methyl jasmonate, salicylic acid, vanadyl sulphate and chitosan. In this review, we summarize the enhancing effects of elicitors on the production of high-added value plant compounds such as taxanes, ginsenosides, aryltetralin lignans and other types of polyphenols, focusing particularly on the use of a new generation of elicitors such as coronatine and cyclodextrins.

Panax ginseng C. A. Meyer is an important traditional herb in eastern Asia. It contains ginsenosides, which are primary bioac- tive compounds with medicinal properties. Although ginseng has been cultivated since at least the Ming dynasty to increase production, cultivated ginseng has lower quantities of ginsenosides and lower disease resistance than ginseng grown under natural conditions. We extracted root RNA from six varieties of fifth-year P. ginseng cultivars representing four different growth conditions, and performed Illumina paired-end sequencing. In total, 163,165,706 raw reads were obtained and used to generate a de novo transcriptome that consisted of 151,763 contigs （76,336 unigenes）, of which 100,648 contigs （66.3%） were successfully annotated. Differential expression analysis revealed that most differentially expressed genes （DEGs） were upreg- ulated （246 out of 258, 95.3%） in ginseng grown under natural conditions compared with that grown under artificial conditions These DEGs were enriched in gene ontology （GO） terms including response to stimuli and localization. In particular, some key ginsenoside biosynthesis-related genes, including HMG-CoA synthase （HMGS）, mevalonate kinase （MVK）, and squalene epoxidase （SE）, were upregulated in wild-grown ginseng. Moreover, a high proportion of disease resistance-related genes were upregulated in wild-grown ginseng. This study is the first transcriptome analysis to compare wild-grown and cultivated gin- seng, and identifies genes that may produce higher ginsenoside content and better disease resistance in the wild; these genes may have the potential to improve cultivated ginseng grown in artificial environments.

Dear Editor, Ginseng has been traditionally used as herbal medicine in Asia for thousands of years to enhance physical performance and to increase resistance to stress and aging, and has been developed into various kinds of dietary supplement with increasing market demand. Its active constituents are ginsenosides, a group of triterpene saponins （ca. 2% in Panax ginseng dried roots） . However,