Efficient Somatic Embryogenesis, Regeneration and Acclimatization of Panax ginseng Meyer: True-to-Type Conformity of Plantlets as Confirmed by ISSR Analysis.

Panax ginseng Meyer grows in east Russia and Asia. There is a high demand for this crop due to its medicinal properties. However, its low reproductive efficiency has been a hindrance to the crop's widespread use. This study aims to establish an efficient regeneration and acclimatization system for the crop. The type of basal media and strength were evaluated for their effects on somatic embryogenesis, germination, and regeneration. The highest rate of somatic embryogenesis was achieved for the basal media MS, N6, and GD, with the optimal nitrogen content (≥35 mM) and NH4+/NO3- ratio (1:2 or 1:4). The full-strength MS medium was the best one for somatic embryo induction. However, the diluted MS medium had a more positive effect on embryo maturation. Additionally, the basal media affected shooting, rooting, and plantlet formation. The germination medium containing 1/2 MS facilitated good shoot development; however, the medium with 1/2 SH yielded outstanding root development. In vitro-grown roots were successfully transferred to soil, and they exhibited a high survival rate (86.3%). Finally, the ISSR marker analysis demonstrated that the regenerated plants were not different from the control. The obtained results provide valuable information for a more efficient micropropagation of various P. ginseng cultivars.

Volatile Compositions of Panax ginseng and Panax quinquifolium Grown for Different Cultivation Years.

The present study examined the volatile profiles of Panax ginseng (Korean ginseng) and Panax quinquefolium (American ginseng) grown for different cultivation years by using HS-SPME/GC-MS and determined the key discriminant volatile compounds by chemometric analysis including principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least squares-discrimination analysis (PLS-DA). Fifty-six compounds, including forty terpenes, eight alcohols, one alkane, one ketone, and one furan, were identified in the ginseng roots. The chemometric results identified two major clusters of American ginseng and Korean ginseng cultivars with distinct volatile compositions. The volatile compounds in fresh white ginseng roots were affected by the species, but the influence of different cultivation ages was ambiguous. The major volatile components of ginseng roots are terpenes, including monoterpenes and sesquiterpenes. In particular, panaginsene, ginsinsene, α-isocomene, and caryophyllene were predominant in Korean ginseng cultivars, whereas ß-farnesene levels were higher in American ginseng. The difference in volatile patterns between Panax ginseng and Panax quinquefolium could be attributed to the composition of sesquiterpenes such as ß-panaginsene, ginsinsene, caryophyllene, and ß-farnesene.

The complete mitochondrial genome of Panax ginseng (Apiales, Araliaceae): an important medicinal plant.

Ginseng (Panax ginseng C. A. Meyer) is a multifunctional medicinal herb used worldwide and is an economically important high-value crop in Korea. Here, we presented the mitochondrial genome of P. ginseng landrace 'Jakyung', which is one of the most common cultivars cultivated in Korean farms. The complete mitochondrial genome sequence was 464,661 bp in length and had a single circular form. The ginseng mitochondrial genome encoded 72 unique genes, including 45 protein-coding genes, 24 tRNA genes, and three rRNA genes. Nucleotide composition analysis revealed a GC content of 45.1%, with a slightly higher A + T bias (A, 27.1%; T, 27.8%; G, 22.5%; C, 22.6%). Phylogenetic analysis showed that P. ginseng was closely related to Daucus carota in the Apiales. This complete mitochondrial genome sequence of P. ginseng provides valuable genetic information for further studies of this important medicinal plant.

Development of genomic simple sequence repeat markers for Glycyrrhiza lepidota and cross-amplification of other Glycyrrhiza species.

BACKGROUND: Licorice (Glycyrrhiza spp. L.) is used as a natural sweetener and medicinal herb in European and Asian countries. Molecular studies have been conducted to find differences between wild and cultivated species because most wild species are highly resistant to abiotic and biotic stresses compared with their cultivated species. However, few molecular markers have been developed for studying the genetic diversity and population structure of licorice species and to identify differences between cultivars. Thus, the present study aimed to develop a set of genomic simple sequence repeat (SSR) markers for molecular studies of these species. METHODS: In the present study, we developed polymorphic SSR markers based on whole-genomesequence data of Glycyrrhiza lepidota. Then, based on the sequence information, the polymorphic SSR markers were developed. The SSR markers were applied to 23 Glycyrrhiza individual plants. We also evaluated the phylogenetic relationships and interspecies transferability among samples. RESULTS: The genetic diversity analysis using these markers identified 2-23 alleles, and the major allele frequency, observed heterozygosity, genetic diversity, and polymorphism information content were 0.11-0.91, 0-0.90, 0.17-0.94, and 0.15-0.93, respectively. Interspecies transferability values were 93.5%, 91.6%, and 91.1% for G. echinata, G. glabra, and G. uralensis, respectively. Phylogenetic analysis clustered cultivated (group 1) and wild (group 2) species into three and two subgroups, respectively. The reported markers represent a valuable resource for the genetic characteri z ation of Glycyrrhiza spp. for theanalysis of its genetic variability, and as a tool for licorice transferability. This is the first intraspecific study in a collection of Glycyrrhiza spp. germplasm using SSR markers.

Metagenomic analysis of bacterial endophyte community structure and functions in Panax ginseng at different ages.

This study investigated the root-associated bacterial endophytes of Panax ginseng at different ages by shotgun metagenomic analysis. After mapping metagenome data to the complete ginseng genome to identify unmapped sequences, we predicted the structure and functions of ginseng bacterial endophytes by metagenomic rapid annotation using subsystems technology analysis. While Proteobacteria and Actinobacteria were the predominant phyla in all samples (2-6-year-old roots), class Alphaproteobacteria was most abundant in 3-, 4-, and 5-year-old plants. We found that 3-year-old P. ginseng had a 0.66% unmapped rate against the whole ginseng genome and showed the greatest diversity of endophytic bacteria (α diversity = 299). Prediction of endophytic bacterial functions at different ages by SEED subsystem analysis revealed that siderophore and auxin-related traits-which are known to promote plant growth-were most highly represented in 3-year-old plants. This was supported by a gene frequency analysis of plant growth-promoting genes, including those responsible for solubilization of phosphate and nitrogen metabolism, using BLASTn. These results suggest that endophytic bacteria of the P. ginseng root affect plant growth. Furthermore, the isolation and purification of plant growth-promoting endophytes identified in this study could promote sustainable cultivation of ginseng in the future.

Complete Genome Sequence of the Endophytic Bacterium Chryseobacterium indologenes PgBE177, Isolated from Panax quinquefolius.

Chryseobacterium indologenes PgBE177, isolated from the root tissue of a 4-year-old Panax quinquefolius plant, showed antagonistic activity against Pseudomonas syringae pv. tomato DC3000, a bacterial pathogen. Here, we report the whole-genome sequence of C. indologenes PgBE177. The bacterium contains bacteriocin gene clusters and has the potential to stimulate plant growth.

Complete Genome Sequence of the Endophytic Bacterium Bacillus cereus PgBE311, Isolated from Panax ginseng.

Bacillus cereus PgBE311, isolated from the root tissue of a 5-year-old Panax ginseng plant, showed activities against the fungal pathogens Cylindrocarpon destructans and Botrytis cinerea. Here, we report the genome sequence of B. cereus PgBE311. The bacterium contains antibiotic-related gene clusters and has the potential to stimulate plant growth.

Development of cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers from the chloroplast genome of Glycyrrhiza species.

Licorice (Glycyrrhiza glabra) is an important medicinal crop often used as health foods or medicine worldwide. The molecular genetics of licorice is under scarce owing to lack of molecular markers. Here, we have developed cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers based on single nucleotide polymorphisms (SNP) by comparing the chloroplast genomes of two Glycyrrhiza species (G. glabra and G. lepidota). The CAPS and HRM markers were tested for diversity analysis with 24 Glycyrrhiza accessions. The restriction profiles generated with CAPS markers classified the accessions (2-4 genotypes) and melting curves (2-3) were obtained from the HRM markers. The number of alleles and major allele frequency were 2-6 and 0.31-0.92, respectively. The genetic distance and polymorphism information content values were 0.16-0.76 and 0.15-0.72, respectively. The phylogenetic relationships among the 24 accessions were estimated using a dendrogram, which classified them into four clades. Except clade III, the remaining three clades included the same species, confirming interspecies genetic correlation. These 18 CAPS and HRM markers might be helpful for genetic diversity assessment and rapid identification of licorice species.

Applications of molecular markers in the discrimination of Panax species and Korean ginseng cultivars (Panax ginseng).

The development of molecular markers is one of the most useful methods for molecular breeding and marker-based molecular associated selections. Even though there is less information on the reference genome, molecular markers are indispensable tools for determination of genetic variation and identification of species with high levels of accuracy and reproducibility. The demand for molecular approaches for marker-based breeding and genetic discriminations in Panax species has greatly increased in recent times and has been successfully applied for various purposes. However, owing to the existence of diverse molecular techniques and differences in their principles and applications, there should be careful consideration while selecting appropriate marker types. In this review, we outline the recent status of different molecular marker applications in ginseng research and industrial fields. In addition, we discuss the basic principles, requirements, and advantages and disadvantages of the most widely used molecular markers, including restriction fragment length polymorphism, random amplified polymorphic DNA, sequence tag sites, simple sequence repeats, and single nucleotide polymorphisms.

Isoform Sequencing Provides a More Comprehensive View of the Panax ginseng Transcriptome.

Korean ginseng (Panax ginseng C.A. Meyer) has been widely used for medicinal purposes and contains potent plant secondary metabolites, including ginsenosides. To obtain transcriptomic data that offers a more comprehensive view of functional genomics in P. ginseng, we generated genome-wide transcriptome data from four different P. ginseng tissues using PacBio isoform sequencing (Iso-Seq) technology. A total of 135,317 assembled transcripts were generated with an average length of 3.2 kb and high assembly completeness. Of those unigenes, 67.5% were predicted to be complete full-length (FL) open reading frames (ORFs) and exhibited a high gene annotation rate. Furthermore, we successfully identified unique full-length genes involved in triterpenoid saponin synthesis and plant hormonal signaling pathways, including auxin and cytokinin. Studies on the functional genomics of P. ginseng seedlings have confirmed the rapid upregulation of negative feed-back loops by auxin and cytokinin signaling cues. The conserved evolutionary mechanisms in the auxin and cytokinin canonical signaling pathways of P. ginseng are more complex than those in Arabidopsis thaliana. Our analysis also revealed a more detailed view of transcriptome-wide alternative isoforms for 88 genes. Finally, transposable elements (TEs) were also identified, suggesting transcriptional activity of TEs in P. ginseng. In conclusion, our results suggest that long-read, full-length or partial-unigene data with high-quality assemblies are invaluable resources as transcriptomic references in P. ginseng and can be used for comparative analyses in closely related medicinal plants.

De novo transcriptome assembly and the identification of gene-associated single-nucleotide polymorphism markers in Asian and American ginseng roots.

We performed de novo transcriptome sequencing for Panax ginseng and Panax quinquefolius accessions using the 454 GS FLX Titanium System and discovered annotation-based genome-wide single-nucleotide polymorphism (SNPs) using next-generation ginseng transcriptome data without reference genome sequence. The comprehensive transcriptome characterization with the mature roots of four ginseng accessions generated 297,170 reads for 'Cheonryang' cultivar, 305,673 reads for 'Yunpoong' cultivar, 311,861 reads for the G03080 breeding line, and 308,313 reads for P. quinquefolius. In transcriptome assembly, the lengths of the sample read were 156.42 Mb for 'Cheonryang', 161.95 Mb for 'Yunpoong', 165.07 Mb for G03080 breeding line, and 166.48 Mb for P. quinquefolius. A total of 97 primer pairs were designed with the homozygous SNP presented in all four accessions. SNP genotyping using high-resolution melting (HRM) analysis was performed to validate the putative SNP markers of 97 primer pairs. Out of the 73 primer pairs, 73 primer pairs amplified the target sequence and 34 primer pairs showed polymorphic melting curves in samples from 11 P. ginseng cultivars and one P. quinquefolius accession. Among the 34 polymorphic HRM-SNP primers, four primers were useful to distinguish ginseng cultivars. In the present study, we demonstrated that de novo transcriptome assembly and mapping analyses are useful in providing four HRM-SNP primer pairs that reliably show a high degree of polymorphism among ginseng cultivars.

Practical application of DNA markers for high-throughput authentication of Panax ginseng and Panax quinquefolius from commercial ginseng products.

Korean ginseng (Panax ginseng) and American ginseng (Panax quinquefolius) are widely used medicinal plants with similar morphology but different medicinal efficacy. Roots, flowers, and processed products of Korean and American ginseng can be difficult to differentiate from each other, leading to illegal trade in which one species is sold as the other. This study was carried out to develop convenient and reliable chloroplast genome-derived DNA markers for authentication of Korean and American ginseng in commercial processed products. One codominant marker could reproducibly identify both species and intentional mixtures of the two species. We further developed a set of species-unique dominant DNA markers. Each species-specific dominant marker could detect 1% cross contamination with other species by low resolution agarose gel electrophoresis or quantitative polymerase chain reaction. Both markers were successfully applied to evaluate the original species from various processed ginseng products purchased from markets in Korea and China. We believe that high-throughput application of this marker system will eradicate illegal trade and promote confident marketing for both species to increase the value of Korean as well as American ginseng in Korea and worldwide.

Nontargeted metabolomics approach for age differentiation and structure interpretation of age-dependent key constituents in hairy roots of Panax ginseng.

The age of the ginseng plant has been considered as an important criterion to determine the quality of this species. For age differentiation and structure interpretation of age-dependent key constituents of Panax ginseng, hairy root (fine root) extracts aged from four to six years were analyzed using a nontargeted approach with ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS). Various classification methods were used to determine an optimal method to best describe ginseng age by selecting influential metabolites of different ages. Through the metabolite selection process, several age-dependent key constituents having the potential to be biomarkers were determined, and their structures were identified according to tandem mass spectrometry and accurate mass spectrometry by comparing them with an in-house ginsenoside library and with literature data. This proposed method applied to the hairy roots of P. ginseng showed an improved efficiency of age differentiation when compared to previous results on the main roots and increases the possibility of the identification of key metabolites that can be used as biomarker candidates for quality assurance in ginseng.

CAPS markers using mitochondrial consensus primers for molecular identification of Panax species and Korean ginseng cultivars (Panax ginseng C. A. Meyer).

Cleaved amplified polymorphic sequence (CAPS) marker system using mitochondrial consensus primers was applied for molecular identification of Korean ginseng cultivars (Panax ginseng). Initially, a total of 34 primers were tested to six Korean ginseng cultivars and two foreign Panax species, P. quinquefolius and P. notoginseng. In the polymerase chain reaction (PCR) amplification results, four primers (mt7, mt11, mt13, and mt18) generated co-dominant polymorphic banding patterns discriminating the Korean ginseng cultivars from P. quinquefolius and P. notoginseng. In the CAPS analysis results, the majority of the cleaved PCR products also yielded additional latent polymorphisms between the Korean ginseng cultivars and two foreign Panax species. Specific latent CAPS polymorphisms for cultivar Gopoong and Chunpoong were detected from internal region amplified with mt9 primer by treating HinfI and Tsp509I endonucleases, respectively. Sequencing analysis revealed that the length of amplified region of Korean ginseng cultivars was 2,179 bp, and those of P. quinquefolius and P. notoginseng were 2,178 and 2,185 bp, respectively. Blast search revealed that the amplified region was a mitochondrial cytochrome oxidase subunit 2 (cox2) gene intron II region. Nineteen single nucleotide polymorphisms (SNP) including each specific SNP for Gopoong and Chunpoong, and three insertion and deletion (InDel) polymorphisms were detected by sequence alignment. The CAPS markers developed in this study, which are specific to Gopoong and Chunpoong, and between the Korean ginseng cultivars and two foreign Panax species, will serve as a practical and reliable tool for their identification, purity maintenance, and selection of candidate lines and cultivars.

NMR-based metabolic profiling and differentiation of ginseng roots according to cultivation ages.

Ginseng is an important herbal resource worldwide, and the adulteration or falsification of cultivation age has been a serious problem in the commercial market. In this study, ginseng (Panax ginseng) roots, which were cultivated for 2-6 years under GAP standard guidelines, were analyzed by NMR-based metabolomic techniques using two solvents. At first, ginseng root samples were extracted with 50% methanol, and analyzed by NMR with D(2)O as the NMR dissolution solvent. The 2-, 3-, 4-, and 5/6-year-old ginseng root samples were separated in PLS-DA-derived score plots. However, 5- and 6-year-old ginseng roots were not separated by the solvent system. Therefore, various solvents were tested to differentiate the 5- and 6-year-old ginseng root samples, and 100% methanol-d(4) was chosen as the direct extraction and NMR dissolution solvent. In the PLS model using data from the 100% methanol-d(4) solvent, 5- and 6-year-old ginseng roots were clearly separated, and the model was validated using internal and external data sets. The obtained RMSEE and RMSEP values suggested that the PLS model has strong predictability for discriminating the age of 5- and 6-years-old ginseng roots. The present study suggests that the age of ginseng could be successfully predicted using two solvents, and the developed method in this study can be used as a standard protocol for discriminating and predicting the ages of ginseng root samples.

Metabolomic approach for age discrimination of Panax ginseng using UPLC-Q-Tof MS.

An ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-Tof MS)-based metabolomic technique was applied for metabolite profiling of 60 Panax ginseng samples aged from 1 to 6 years. Multivariate statistical methods such as principal component analysis and hierarchical clustering analysis were used to compare the derived patterns among the samples. The data set was subsequently applied to various metabolite selection methods for sophisticated classification with the optimal number of metabolites. The results showed variations in accuracy among the classification methods for the samples of different ages, especially for those aged 4, 5, and 6 years. This proposed analytical method coupled with multivariate analysis is fast, accurate, and reliable for discriminating the cultivation ages of P. ginseng samples and is a potential tool to standardize quality control in the P. ginseng industry.

Rapid Identification of Ginseng Cultivars (Panax ginseng Meyer) Using Novel SNP-Based Probes.

In order to develop a novel system for the discrimination of five ginseng cultivars (Panax ginseng Meyer), single nucleotide polymorphism (SNP) genotyping assays with real-time polymerase chain reaction were conducted. Nucleotide substitution in gDNA library clones of P. ginseng cv. Yunpoong was targeted for the SNP genotyping assay. From these SNP sites, a set of modified SNP specific fluorescence probes (PGP74, PGP110, and PGP130) and novel primer sets have been developed to distinguish among five ginseng cultivars. The combination of the SNP type of the five cultivars, Chungpoong, Yunpoong, Gopoong, Kumpoong, and Sunpoong, was identified as 'ATA', 'GCC', 'GTA', 'GCA', and 'ACC', respectively. This study represents the first report of the identification of ginseng cultivars by fluorescence probes. An SNP genotyping assay using fluorescence probes could prove useful for the identification of ginseng cultivars and ginseng seed management systems and guarantee the purity of ginseng seed.

Molecular genetic diversity and population structure in Lycium accessions using SSR markers.

This study was conducted to assess the genetic diversity and population structure of 139 Lycium chinense accessions using 18 simple sequence repeat (SSR) markers. In total, 108 alleles were detected. The number of alleles per marker locus ranged from two to 17, with an average of six. The gene diversity and polymorphism information content value averaged 0.3792 and 0.3296, with ranges of 0.0793 to 0.8023 and 0.0775 to 0.7734, respectively. The average heterozygosity was 0.4394. The model-based structure analysis revealed the presence of three subpopulations, which was consistent with clustering based on genetic distance. An AMOVA analysis showed that the between-population component of genetic variance was less than 15.3%, in contrast to 84.7% for the within-population component. The overall F(ST) value was 0.1178, indicating a moderate differentiation among groups. The results could be used for future L. chinense allele mining, association mapping, gene cloning, germplasm conservation, and designing effective breeding programs.

Construction of genomic DNA library of Korean ginseng (Panax ginseng C. A. MEYER) and development of sequence-tagged sites.

This study describes an efficient approach for developing sequence tagged sites (STS) for Panax ginseng C.A. MEYER, and their applications for line discrimination. By using the methylation filtering (MF) technique, a genomic library was constructed, in which clone inserts were derived from the hypomethylated regions of ginseng genome. A methylation unfiltered genomic library was also constructed and the clone inserts were compared to those from the MF library in terms of sequence characteristics. Sequence analysis revealed that MF efficiently enriched the protein coding region of P. ginseng, for which the repetitive DNA appeared to be as little as 2.5 fold lower than clones in the unfiltered library, and also indicated that the P. ginseng genome may contain a large fraction of methylated repetitive DNA elements. A total of 99 and 100 highly stringent STS primer sets were designed from the filtered and unfiltered library, respectively. Amplification products were tested for latent polymorphism across six cultivars of P. ginseng and other 2 Panax species using six endonucleases recognizing four-bases. STS primer sets described here will be useful for marker-assisted selection, genome mapping and line discrimination of P. ginseng or its cultivars from other Panax species.

Molecular authentication of 21 Korean artemisia species (Compositae) by polymerase chain reaction-restriction fragment length polymorphism based on trnL-F region of chloroplast DNA.

The present study describes the molecular authentication of 21 Korean Artemisia species using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) technique based on the trnL-F sequences in chloroplast DNA. Five different banding patterns were generated from 21 Artemisia species using HinfI restriction enzyme. A. apiacea, A. keiskeana and A. sieversiana have specific banding patterns. The remaining 18 species had shared two banding patterns. Phylogenetic analysis based on trnL-F sequence variations showed results similar to PCR-RFLP banding patterns. It suggested that the trnL-F region does not have sufficient variations to identify the 21 Artemisia species. However, the specific banding patterns for A. apiacea, A. keiskeana and A. sieversiana can be utilized as a DNA marker for discriminating them from other Artemisia species. These markers will be also useful for developing A. apiacea, A. keiskeana and A. sieversiana into new medicine and food based on their efficacy.