[Identification and functional characterization of candidate genes involved in biosynthesis of ginsenoside Rg_1].

Panax ginseng is a perennial herb with the main active compounds of ginsenosides. Among the reported ginsenosides, ginsenoside Rg_1 not only has a wide range of medicinal functions and abundant content but also is one of the major ginsenoside for the quality evaluation of this herb in the Chinese Pharmacopoeia. The main biosynthesis pathway of ginsenoside Rg_1 in P. ginseng has been clarified, which lays a foundation for the comprehensive and in-depth analysis of the biosynthesis and regulatory mechanism of ginseno-side Rg_1. However, the biosynthesis of ginsenoside Rg_1 is associated with other complex processes involving a variety of regulatory genes and catalyzing enzyme genes, which remain to be studied comprehensively. With the transcriptome data of 344 root samples from 4-year-old P. ginseng plants and their corresponding ginsenoside Rg_1 content obtained in the previous study, this study screened out 217 differentially expressed genes(DEGs) with Rg_1 content changes by DEseq2 analysis in R language. Furthermore, the weighted gene co-expression network analysis(WGCNA) revealed 40 hub genes among the DEGs.Pearsoncorrelation analysis was further perforned to yield 20 candidate genes significantly correlated with ginsenoside Rg_1 content, and these genes were annotated to multiple metabolic processes including primary metabolism and secondary metabolism. Finally, the treatment of P. ginseng adventitious roots with methyl jasmonate indicated that 16 of these genes promoted the biosynthesis of ginsenoside Rg_1 in response to methyl jasmonate induction. Finally, one of the 16 genes was randomly selected to verify the function of the gene by genetic transformation and qRT-PCR and to confirm the rationality of the methodology of this study. The above results lay a foundation for studying the mechanism for regulation on the synthesis of ginsenoside Rg_1 and provide genetic resources for the industrial production of ginsenoside Rg_1.

Functional Validation of the Cytochrome P450 Family PgCYP309 Gene in Panax ginseng.

Ginseng (Panax ginseng C. A. Meyer) is an ancient and valuable Chinese herbal medicine, and ginsenoside, as the main active ingredient of ginseng, has received wide attention because of its various pharmacological active effects. Cytochrome P450 is the largest family of enzymes in plant metabolism and is involved in the biosynthesis of terpenoids, alkaloids, lipids, and other primary and secondary plant metabolites. It is significant to explore more PgCYP450 genes with unknown functions and reveal their roles in ginsenoside synthesis. In this study, based on the five PgCYP450 genes screened in the pre-laboratory, through the correlation analysis with the content of ginsenosides and the analysis of the interactions network of the key enzyme genes for ginsenoside synthesis, we screened out those highly correlated with ginsenosides, PgCYP309, as the target gene from among the five PgCYP450 genes. Methyl jasmonate-induced treatment of ginseng adventitious roots showed that the PgCYP309 gene responded to methyl jasmonate induction and was involved in the synthesis of ginsenosides. The PgCYP309 gene was cloned and the overexpression vector pBI121-PgCYP309 and the interference vector pART27-PgCYP309 were constructed. Transformation of ginseng adventitious roots by the Agrobacterium fermentum-mediated method and successful induction of transgenic ginseng hairy roots were achieved. The transformation rate of ginseng hairy roots with overexpression of the PgCYP309 gene was 22.7%, and the transformation rate of ginseng hairy roots with interference of the PgCYP309 gene was 40%. Analysis of ginseng saponin content and relative gene expression levels in positive ginseng hairy root asexual lines revealed a significant increase in PPD, PPT, and PPT-type monomeric saponins Re and Rg2. The relative expression levels of PgCYP309 and PgCYP716A53v2 genes were also significantly increased. PgCYP309 gene promotes the synthesis of ginsenosides, and it was preliminarily verified that PgCYP309 gene can promote the synthesis of dammarane-type ginsenosides.

Genome-wide identification and integrated analysis of the FAR1/FHY3 gene family and genes expression analysis under methyl jasmonate treatment in Panax ginseng C. A. Mey.

Ginseng (Panax ginseng C. A. Mey.) is an important and valuable medicinal plant species used in traditional Chinese medicine, and its metabolite ginsenoside is the primary active ingredient. The FAR1/FHY3 gene family members play critical roles in plant growth and development as well as participate in a variety of physiological processes, including plant development and signaling of hormones. Studies have indicated that methyl jasmonate treatment of ginseng adventitious roots resulted in a significant increase in the content of protopanaxadiol ginsenosides. Therefore, it is highly significant to screen the FAR1/FHY3 gene family members in ginseng and preliminarily investigate their expression patterns in response to methyl jasmonic acid signaling. In this study, we screened and identified the FAR1/FHY3 family genes in the ginseng transcriptome databases. And then, we analyzed their gene structure and phylogeny, chromosomal localization and expression patterns, and promoter cis-acting elements, and made GO functional annotations on the members of this family. After that, we treated the ginseng adventitious roots with 200 mM methyl jasmonate and investigated the trend of the expression of four genes containing the largest number of methyl jasmonate cis-acting elements at different treatment times. All four genes were able to respond to methyl jasmonate, the most significant change was in the PgFAR40 gene. This study provides data support for subsequent studies of this family member in ginseng and provides experimental reference for subsequent validation of the function of this family member under methyl jasmonic acid signaling.

Genome-wide identification of the LEA gene family in Panax ginseng: Evidence for the role of PgLEA2-50 in plant abiotic stress response.

Ginseng frequently encounters environmental stress during its growth and development. Late Embryogenesis Abundant (LEA) proteins play a crucial role in combating adversity stress, particularly against abiotic challenges In this study, 107 LEA genes from ginseng, spanning eight subfamilies, were identified, demonstrating significant evolutionary conservation, with the LEA2 subfamily being most prominent. Gene duplication events, primarily segmental duplications, have played a major role in the expansion of the LEA gene family, which has undergone strong purifying selection. PgLEAs were unevenly distributed across 22 chromosomes, with each subfamily featuring unique structural domains and conserved motifs. PgLEAs were expressed in various tissues, exhibiting distinct variations in abundance and tissue specificity. Numerous regulatory cis-elements, related to abiotic stress and hormones, were identified in the promoter region. Additionally, PgLEAs were regulated by a diverse array of abiotic stress-related transcription factors. A total of 35 PgLEAs were differentially expressed following treatments with ABA, GA, and IAA. Twenty-three PgLEAs showed significant but varied responses to drought, extreme temperatures, and salinity stress. The transformation of tobacco with the key gene PgLEA2-50 enhanced osmoregulation and antioxidant levels in transgenic lines, improving their resistance to abiotic stress. This study offers insights into functional gene analysis, focusing on LEA proteins, and establishes a foundational framework for research on ginseng's resilience to abiotic stress.

Analysis Transcriptome and Phytohormone Changes Associated with the Allelopathic Effects of Ginseng Hairy Roots Induced by Different-Polarity Ginsenoside Components.

The allelopathic autotoxicity of ginsenosides is an important cause of continuous cropping obstacles in ginseng planting. There is no report on the potential molecular mechanism of the correlation between polarity of ginsenoside components and their allelopathic autotoxicity. This study applied a combination of metabolomics and transcriptomics analysis techniques, combined with apparent morphology, physiological indexes, and cell vitality detection of the ginseng hairy roots, through which the molecular mechanism of correlation between polarity and allelopathic autotoxicity of ginsenosides were comprehensively studied. The hairy roots of ginseng presented more severe cell apoptosis under the stress of low-polarity ginsenoside components (ZG70). ZG70 exerted allelopathic autotoxicity by regulating the key enzyme genes of cis-zeatin (cZ) synthesis pathway, indole-3-acetic acid (IAA) synthesis pathway, and jasmonates (JAs) signaling transduction pathway. The common pathway for high-polarity ginsenoside components (ZG50) and ZG70 to induce the development of allelopathic autotoxicity was through the expression of key enzymes in the gibberellin (GA) signal transduction pathway, thereby inhibiting the growth of ginseng hairy roots. cZ, indole-3-acetamid (IAM), gibberellin A1 (GA1), and jasmonoyl-L-isoleucine (JA-ILE) were the key response factors in this process. It could be concluded that the polarity of ginsenoside components were negatively correlated with their allelopathic autotoxicity.

Genome-Wide Identification and Analysis of the Aux/IAA Gene Family in Panax ginseng: Evidence for the Role of PgIAA02 in Lateral Root Development.

Panax ginseng C. A. Meyer (Ginseng) is one of the most used traditional Chinese herbal medicines, with its roots being used as the main common medicinal parts; its therapeutic potential has garnered significant attention. AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) is a family of early auxin-responsive genes capable of regulating root development in plants through the auxin signaling pathway. In the present study, 84 Aux/IAA genes were identified from the ginseng genome and their complexity and diversity were determined through their protein domains, phylogenetic relationships, gene structures, and cis-acting element predictions. Phylogenetic analyses classified PgIAA into six subgroups, with members in the same group showing greater sequence similarity. Analyses of interspecific collinearity suggest that segmental duplications likely drove the evolution of PgIAA genes, followed by purifying selection. An analysis of cis-regulatory elements suggested that PgIAA family genes may be involved in the regulation of plant hormones. RNA-seq data show that the expression pattern of Aux/IAA genes in Ginseng is tissue-specific, and PgIAA02 and PgIAA36 are specifically highly expressed in lateral, fibrous, and arm roots, suggesting their potential function in root development. The PgIAA02 overexpression lines exhibited an inhibition of lateral root growth in Ginseng. In addition, yeast two-hybrid and subcellular localization experiments showed that PgIAA02 interacted with PgARF22/PgARF36 (ARF: auxin response factor) in the nucleus and participated in the biological process of root development. The above results lay the foundation for an in-depth study of Aux/IAA and provide preliminary information for further research on the role of the Aux/IAA gene family in the root development of Ginseng.

The AP2/ERF Transcription Factor PgERF120 Regulates Ginsenoside Biosynthesis in Ginseng.

Ginseng (Panax ginseng C.A. Meyer) is a perennial herb belonging to the family Araliaceae and has been used for thousands of years in East Asia as an essential traditional medicine with a wide range of pharmacological activities of its main active ingredient, ginsenosides. The AP2/ERF gene family, widely present in plants, is a class of transcription factors capable of responding to ethylene regulation that has an influential role in regulating the synthesis of major active ingredients in medicinal plants and in response to biotic and abiotic stresses, which have not been reported in Panax ginseng. In this study, the AP2/ERF gene was localized on the ginseng chromosome, and an AP2/ERF gene duplication event was also discovered in Panax ginseng. The expression of seven ERF genes and three key enzyme genes related to saponin synthesis was measured by fluorescence quantitative PCR using ethylene treatment of ginseng hairy roots, and it was observed that ethylene promoted the expression of genes related to the synthesis of ginsenosides, among which the PgERF120 gene was the most sensitive to ethylene. We analyzed the sequence features and expression patterns of the PgERF120 gene and found that the expression of the PgERF120 gene was specific in time and space. The PgERF120 gene was subsequently cloned, and plant overexpression and RNA interference vectors were constructed. Ginseng adventitious roots were transformed using the Agrobacterium tumefaciens-mediated method to obtain transgenic ginseng hairy roots, and the gene expression, ginsenoside content and malondialdehyde content in overexpression-positive hairy roots were also analyzed. This study preliminarily verified that the PgERF120 gene can be involved in the regulation of ginsenoside synthesis, which provides a theoretical basis for the study of functional genes in ginseng and a genetic resource for the subsequent use of synthetic biology methods to improve the yield of ginsenosides.

Beyond genome: Advanced omics progress of Panax ginseng.

Ginseng is a perennial herb of the genus Panax in the family Araliaceae as one of the most important traditional medicine. Genomic studies of ginseng assist in the systematic discovery of genes related to bioactive ginsenosides biosynthesis and resistance to stress, which are of great significance in the conservation of genetic resources and variety improvement. The transcriptome reflects the difference and consistency of gene expression, and transcriptomics studies of ginseng assist in screening ginseng differentially expressed genes to further explore the powerful gene source of ginseng. Protein is the ultimate bearer of ginseng life activities, and proteomic studies of ginseng assist in exploring the biosynthesis and regulation of secondary metabolites like ginsenosides and the molecular mechanism of ginseng adversity adaptation at the overall level. In this review, we summarize the current status of ginseng research in genomics, transcriptomics and proteomics, respectively. We also discuss and look forward to the development of ginseng genome allele mapping, ginseng spatiotemporal, single-cell transcriptome, as well as ginseng post-translational modification proteome. We hope that this review will contribute to the in-depth study of ginseng and provide a reference for future analysis of ginseng from a systems biology perspective.

Carvacrol as a Stimulant of the Expression of Key Genes of the Ginsenoside Biosynthesis Pathway and Its Effect on the Production of Ginseng Saponins in Panax quinquefolium Hairy Root Cultures.

The accumulation of ginsenosides (triterpenic saponins) was determined in Panax quinquefolium hairy root cultures subjected to an elicitation process using carvacrol at 5, 10, 25, 50, 100, 250, and 500 µM concentrations during 24 and 72 h exposure. This study was the first one in which carvacrol was applied as an elicitor. The content of eight ginsenosides, Rb1, Rb2, Rb3, Rc, Rd, Rg1, Rg2, and Re, was determined using HPLC analysis. Moreover, the quantitative RT-PCR method was applied to assess the relative expression level of farnesyl diphosphate synthase, squalene synthase, and dammarenediol synthase genes in the studied cultures. The addition of carvacrol (100 µM) was an effective approach to increase the production of ginsenosides. The highest content and productivity of all detected saponins were, respectively, 20.01 mg∙g-1 d.w. and 5.74 mg∙L-1∙day-1 after 72 h elicitation. The production profile of individual metabolites in P. quinquefolium cultures changed under the influence of carvacrol. The biosynthesis of most examined protopanaxadiol derivatives was reduced under carvacrol treatment. In contrast, the levels of ginsenosides belonging to the Rg group increased. The strongest effect of carvacrol was noticed for Re metabolites, achieving a 7.72-fold increase in comparison to the control. Saponin Rg2, not detected in untreated samples, was accumulated after carvacrol stimulation, reaching its maximum concentration after 72 h exposure to 10 µM elicitor.

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.

Expression, purification, characterization and crystallization of Panax quinquefolius ginsenoside glycosyltransferase Pq3-O-UGT2.

Pq3-O-UGT2, derived from Panax quinquefolius, functions as a ginsenoside glucosyltransferase, utilizing UDP-glucose (UDPG) as the sugar donor to catalyze the glycosylation of Rh2 and F2. An essential step in comprehending its catalytic mechanism involves structural analysis. In preparation for structural analysis, we expressed Pq3-O-UGT2 in the Escherichia coli (E. coli) strain Rosetta (DE3). The recombinant Pq3-O-UGT2 was purified through Ni-NTA affinity purification, a two-step ion exchange chromatography, and subsequently size-exclusion chromatography (SEC). Notably, the purified Pq3-O-UGT2 showed substantial activity toward Rh2 and F2, catalyzing the formation of Rg3 and Rd, respectively. This activity was discernible within a pH range of 4.0-9.0 and temperature range of 30-55 °C, with optimal conditions observed at pH 7.0-8.0 and 37 °C. The catalytic efficiency of Pq3-O-UGT2 toward Rh2 and F2 was 31.43 s-1 mΜ-1 and 169.31 s-1 mΜ-1, respectively. We further crystalized Pq3-O-UGT2 in both its apo form and co-crystalized forms with UDPG, Rh2 and F2, respectively. High-quality crystals were obtained and X-ray diffraction data was collected for all co-crystalized samples. Analysis of the diffraction data revealed that the crystal of Pq3-O-UGT2 co-crystalized with UDP-Glc belonged to space group P1, while the other two crystals belonged to space group P212121. Together, this study has laid a robust foundation for subsequent structural analysis of Pq3-O-UGT2.

Genetic diversity of Panax ginseng cultivated in Japan and its relation with some plant characteristics.

In East Asia, Panax ginseng is one of the most important medicinal plants and has been used in traditional medicines from ancient times. Today, P. ginseng is cultivated in Korea, China, and Japan. Although the genetic diversity of P. ginseng in Korea and China has been reported previously, that of P. ginseng cultivated in Japan is largely unknown. In the present study, genetic diversity of P. ginseng cultivated in Japan was analyzed using eight simple sequence repeat markers that have been used in other studies, and the results were compared with previous results for Korea and China. The correlation between genetic diversity and plant characteristics, such as ginsenoside contents, were also examined. The genetic diversity of P. ginseng in Japan was substantially different from that in Korea and China, probably due to Japan's history of cultivation and the ginseng reproduction system of agamospermy. The genetic analysis indicated that P. ginseng cultivated in Japan could be classified into two clusters. The classification was related to the contents of ginsenosides Re and Ro in the main root but not to the cultivation region of the samples. These results may be useful for the cultivation and quality control of P. ginseng in Japan.

Research on the dentification of Panax ginseng and Panax quinquefolium using catalysed hairpin assembly technology.

INTRODUCTION: Panax ginseng and Panax quinquefolium are traditional Chinese herb medicines and similar in morphology and some chemical components but differ in drug properties, so they cannot be mixed. However, the processed products of them are often sold in the form of slices, powder, and capsules, which are difficult to identify by traditional morphological methods. Furthermore, an accurate evaluation of P. ginseng, P. quinquefolium and the processed products have not been conducted. OBJECTIVE: This study aimed to establish a catalysed hairpin assembly (CHA) identification method for authenticating products made from P. ginseng and P. quinquefolium based on single nucleotide polymorphism (SNP) differences. METHOD: By analysing the differences of SNP in internal transcribed spacer 2 (ITS2) in P. ginseng and P. quinquefolium to design CHA-specific hairpins. Establish a sensitive and efficient CHA method that can identify P. ginseng and P. quinquefolium, use the sequencing technology to verify the accuracy of this method in identifying Panax products, and compare this method with high-resolution melting (HRM). RESULTS: The reaction conditions of CHA were as follows: the ratio of forward and reverse primers, 20:1; hairpin concentration, 5 ng/µL. Compared with capillary electrophoresis, this method had good specificity and the limit of detection was 0.5 ng/µL. The result of Panax product identification with CHA method were coincidence with that of the sequencing method; the positive rate of CHA reaction was 100%. CONCLUSION: This research presents an effective identification method for authenticating P. ginseng and P. quinquefolium products, which is helpful to improve the quality of Panax products.

Evolution of the Araliaceae family involved rapid diversification of the Asian Palmate group and Hydrocotyle specific mutational pressure.

The Araliaceae contain many valuable species in medicinal and industrial aspects. We performed intensive phylogenomics using the plastid genome (plastome) and 45S nuclear ribosomal DNA sequences. A total of 66 plastome sequences were used, 13 of which were newly assembled in this study, 12 from new sequences, and one from existing data. While Araliaceae plastomes showed conserved genome structure, phylogenetic reconstructions based on four different plastome datasets revealed phylogenetic discordance within the Asian Palmate group. The divergence time estimation revealed that splits in two Araliaceae subfamilies and the clades exhibiting phylogenetic discordances in the Asian Palmate group occurred at two climatic optima, suggesting that global warming events triggered species divergence, particularly the rapid diversification of the Asian Palmate group during the Middle Miocene. Nucleotide substitution analyses indicated that the Hydrocotyloideae plastomes have undergone accelerated AT-biased mutations (C-to-T transitions) compared with the Aralioideae plastomes, and the acceleration may occur in their mitochondrial and nuclear genomes as well. This implies that members of the genus Hydrocotyle, the only aquatic plants in the Araliaceae, have experienced a distinct evolutionary history from the other species. We also discussed the intercontinental disjunction in the genus Panax and proposed a hypothesis to complement the previously proposed hypothesis. Our results provide the evolutionary trajectory of Araliaceae and advance our current understanding of the evolution of Araliaceae species.

Application of a modified tetra-primer ARMS-PCR assay for rapid Panax species identity authentication in ginseng products.

Panax ginseng products can be adulterated with materials from other Panax species. The purpose of this study is to provide a rapid P. ginseng authentication method for simultaneous identification of P. ginseng and detection of adulteration in ginseng products at different processing stages. First, a tetra-primer ARMS-PCR assay was designed based on a single-nucleotide polymorphism (SNP) within the trnL-trnF region and was tested at 28 PCR cycles with DNA extracted from Botanical Reference Materials (BRMs). Next, 5' end random nucleotide and 3' terminus phosphorothioates linkage modifications were incorporated into the inner primers to improve sensitivity and specificity at 40 PCR cycles. Finally, the modified assay was validated using characterized market ginseng materials and the detection limit was determined. The modified tetra-primer ARMS-PCR assay can achieve the desired sensitivity and specificity using one set of reaction conditions in ginseng materials at different stages. In validation, it was able to correctly identify target species P. ginseng and differentiate it from closely related species. This study suggests that the modified tetra-primer ARMS-PCR assay can be used for the rapid, species identity authentication of P. ginseng material in ginseng products. This assay can be used to complement chemical analytical methods in quality control, so both species identity and processing attributes of ginseng products can be efficiently addressed.

Evolutionary roles of polyploidization-derived structural variations in the phenotypic diversification of Panax species.

Genomic structural variations (SVs) are widespread in plant and animal genomes and play important roles in phenotypic novelty and species adaptation. Frequent whole genome duplications followed by (re)diploidizations have resulted in high diversity of genome architecture among extant species. In this study, we identified abundant genomic SVs in the Panax genus that are hypothesized to have occurred through during the repeated polyploidizations/(re)diploidizations. Our genome-wide comparisons demonstrated that although these polyploidization-derived SVs have evolved at distinct evolutionary stages, a large number of SV-intersecting genes showed enrichment in functionally important pathways related to secondary metabolites, photosynthesis and basic cellular activities. In line with these observations, our metabolic analyses of these Panax species revealed high diversity of primary and secondary metabolites both at the tissue and interspecific levels. In particular, genomic SVs identified at ginsenoside biosynthesis genes, including copy number variation and large fragment deletion, appear to have played important roles in the evolution and diversification of ginsenosides. A further herbivore deterrence experiment demonstrated that, as major triterpenoidal saponins found exclusively in Panax, ginsenosides provide protection against insect herbivores. Our study provides new insights on how polyploidization-derived SVs have contributed to phenotypic novelty and plant adaptation.

Regulation of transcriptome networks that mediate ginsenoside biosynthesis by essential ecological factors.

Ginseng, a valuable Chinese medicinal herb, is renowned worldwide for its effectiveness in alleviating certain conditions and promoting overall health. In this study, we performed weighted gene co-expression network analysis (WGCNA) on the accumulation of essential saponins under the influence of 13 essential environmental factors (including air temperature, air bottom temperature, surface mean temperature, soil temperature, surface shortwave radiation, soil moisture, soil water content, rainfall, total precipitation, elevation, soil type, soil pH, and soil water potential). We identified a total of 40 transcript modules associated with typical environmental factors and the accumulation of essential saponins. Among these, 18 modules were closely related to the influence of typical environmental factors, whereas 22 modules were closely related to the accumulation of essential saponins. These results were verified by examining the transcriptome, saponin contents, environmental factor information and the published data and revealed the regulatory basis of saponin accumulation at the transcriptome level under the influence of essential environmental factors. We proposed a working model of saponin accumulation mediated by the transcriptional regulatory network that is affected by typical environmental factors. An isomorphic white-box neural network was constructed based on this model and the predicted results of the white-box neural network correlated with saponin accumulation. The effectiveness of our correlation-directed graph in predicting saponin contents was verified by bioinformatics analysis based on results obtained in this study and transcripts known to affect the biosynthesis of saponin Rb1. The directed graph represents a useful tool for manipulating saponin biosynthesis while considering the influence of essential environmental factors in ginseng and other medicinal plants.

Promoting Photosynthetic Production of Dammarenediol-II in Chlamydomonas reinhardtii via Gene Loading and Culture Optimization.

Ginsenosides are major bioactive compounds found in Panax ginseng that exhibit various pharmaceutical properties. Dammarenediol-II, the nucleus of dammarane-type ginsenosides, is a promising candidate for pharmacologically active triterpenes. Dammarenediol-II synthase (DDS) cyclizes 2,3-oxidosqualene to produce dammarenediol-II. Based on the native terpenoids synthetic pathway, a dammarane-type ginsenosides synthetic pathway was established in Chlamydomonas reinhardtii by introducing P. ginseng PgDDS, CYP450 enzyme (PgCYP716A47), or/and Arabidopsis thaliana NADPH-cytochrome P450 reductase gene (AtCPR), which is responsible for producing dammarane-type ginsenosides. To enhance productivity, strategies such as "gene loading" and "culture optimizing" were employed. Multiple copies of transgene expression cassettes were introduced into the genome to increase the expression of the key rate-limiting enzyme gene, PgDDS, significantly improving the titer of dammarenediol-II to approximately 0.2 mg/L. Following the culture optimization in an opt2 medium supplemented with 1.5 mM methyl jasmonate under a light:dark regimen, the titer of dammarenediol-II increased more than 13-fold to approximately 2.6 mg/L. The C. reinhardtii strains engineered in this study constitute a good platform for the further production of ginsenosides in microalgae.

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.