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Ginseng, the roots of Panax species, is an important medicinal herb used as a tonic. As ginsenosides are key bioactive components of ginseng, holistic chemical profiling of them has provided many insights into understanding ginseng. Mass spectrometry has been a major methodology for profiling, which has been applied to realize numerous goals in ginseng research, such as the discrimination of different species, geographical origins, and ages, and the monitoring of processing and biotransformation. This review summarizes the various applications of ginsenoside profiling in ginseng research over the last three decades that have contributed to expanding our understanding of ginseng. However, we also note that most of the studies overlooked a crucial factor that influences the levels of ginsenosides: genetic variation. To highlight the effects of genetic variation on the chemical contents, we present our results of untargeted and targeted ginsenoside profiling of different genotypes cultivated under identical conditions, in addition to data regarding genome-level genetic diversity. Additionally, we analyze the other limitations of previous studies, such as imperfect variable control, deficient metadata, and lack of additional effort to validate causation. We conclude that the values of ginsenoside profiling studies can be enhanced by overcoming such limitations, as well as by integrating with other -omics techniques.

Abstract 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.

Rising health concerns regarding chronic diseases call for exploring natural sources of antioxidants and factors that influence their activity. This study evaluated the diversity of 112 sesame germplasms from Africa and Asia based on ten agronomic traits (seven quantitative and three qualitative), two antioxidant activities (ABTS and DPPH radical scavenging activities), and the content of one metabolite (TPC). TPC, DPPH, and ABTS were in the ranges of 4.98–87.88 µg GAE/mg DE, 3.97–46.23 µg AAE/mg DE, and 3.42–176.01 µg TE/mg DE, respectively. Statistical analyses revealed significant variations in agronomic traits, TPC, and antioxidant activities among the sesame germplasms (p < 0.05). Furthermore, the individual and interaction effects of seed color and the continent of origin on the levels of the quantitative traits, TPC, ABTS, and DPPH were analyzed, and the correlation among the traits was further evaluated. Diversity in TPC, ABTS, and DPPH was significantly associated with seed color and most of the quantitative agronomic traits (p < 0.05) but not with continent of origin. Principal component analysis revealed TPC, ABTS, DPPH, and five quantitative traits as the most discriminant traits. In general, six sesame accessions with high TPC and antioxidant activities (IT194356, IT170094, IT29971, IT185998, IT104246, and IT169623) as well as important agronomic traits were identified and, hence, could be used for developing improved sesame varieties.

Sesame is an important oilseed crop grown for human consumption in many countries, with a high commercial value due to its high oleic/linoleic acid ratio (O/L ratio). However, its properties may vary among different accessions. In the current study, 282 sesame accessions were evaluated to determine the effects of agronomic traits and genotypes on the O/L ratio. The O/L ratio was positively correlated with the oleic acid (C18:1), stearic acid (C18:0), and myristic acid (C14:0) concentrations, as well as the capsule zone length (CZL), capsule width (CW), and capsule length (CL), and negatively correlated with the linoleic acid (C18:2) and linolenic acid (C18:3) concentrations, the days to maturity (DTM), days to flowering (DTF), and the height of the first capsule-bearing node (HFC) (p < 0.05). In addition, the O/L ratio was affected by the FAD2 haplotype, as the Hap2 and Hap3 sesame accessions had lower O/L ratios. Therefore, we suggest that the increase and decrease in the contents of C18:1 and C18:2 are associated with the FAD2 haplotype. A total of 25 agronomic traits and fatty acid compositions were compared via statistical analysis, and accessions with a high O/L ratio were selected. The results of this study can be used as a basis for further research on the development of new sesame varieties through enhancing nutritional functionality.

Abstract Ginsenosides are the most valuable and pharmacologically active triterpenoid saponins found in Panax ginseng. Although light quality affects ginsenoside content, little is known about the underlying genetic and regulatory mechanisms. Additionally, the correlation between the adaptability of ginseng to shade and ginsenoside biosynthesis remains poorly understood. In the present study, transcriptome analysis of ginseng seedlings using RNA sequencing revealed that the expression of ginsenoside biosynthesis genes, including PgHMGR, PgFPS, PgSS, and PgUGT, was enhanced in shade conditions but downregulated by red light, indicating that far-red light might play an essential role in ginsenoside production. Further, gene expression analysis in adventitious roots and 2-year-old plants using qRT-PCR showed that the light quality-mediated expression patterns of ginsenoside genes varied with tissue and age. However, unlike the transcriptome, there was no difference in the total ginsenoside content in seedlings among various light conditions. Nevertheless, the amount of major protopanaxadiol-type ginsenosides increased under shade and red light conditions. Unlike seedlings and adventitious roots, there was a decrease in the expression of PgHMGR, PgFPS, PgSS, and PgDDS in 2-year-old plants, along with an increase in the ginsenoside content, under far-red light. Taken together, our findings suggest that far-red light is an important environmental factor for ginsenoside biosynthesis and diversification and provide information that can improve the quality of ginseng produced for medicinal purposes.

The tribe Hydrangeeae displays a unique, distinctive disjunct distribution encompassing East Asia, North America and Hawaii. Despite its complex trait variations and polyphyletic nature, comprehensive phylogenomic and biogeographical studies on this tribe have been lacking. To address this gap, we sequenced and characterized 28 plastomes of Hydrangeeae. Our study highlights the highly conserved nature of Hydrangeaceae chloroplast (cp) genomes in terms of gene content and arrangement. Notably, synapomorphic characteristics of tandem repeats in the conserved domain of accD were observed in the Macrophyllae, Chinenses, and Dichroa sections within the Hydrangeeae tribe. Additionally, we found lower expression of accD in these sections using structure prediction and quantitative real-time PCR analysis. Phylogenomic analyses revealed the subdivision of the Hydrangeeae tribe into two clades with robust support values. Consistent with polyphyletic relationships, sect. Broussaisia was identified as the basal group in the tribe Hydrangeeae. Our study also provides insights into the phylogenetic relationships of Hydrangea petiolaris in the Jeju and Ulleung Island populations, suggesting the need for further studies with more samples and molecular data. Divergence time estimation and biogeographical analyses suggested that the common ancestors of the tribe Hydrangeeae likely originated from North America and East Asia during the Paleocene period via the Bering Land Bridge, potentially facilitating migration within the tribe between these regions. In conclusion, this study enhances our understanding of the evolutionary history and biogeography of the tribe Hydrangeeae, shedding light on the dispersal patterns and origins of this intriguing plant group with its unique disjunct distribution.

Background: The genus Panax in the Araliaceae family has been used as traditional medicinal plants worldwide and is known to biosynthesize ginsenosides and phytosterols. However, genetic variation between Panax species has influenced their biosynthetic pathways is not fully understood. Methods: Simultaneous analysis of transcriptomes and metabolomes obtained from adventitious roots of two tetraploid species (Panax ginseng and P. quinquefolius) and two diploid species (P. notoginseng and P. vietnamensis) revealed the diversity of their metabolites and related gene expression profiles. Results: The transcriptome analysis showed that 2,3-OXIDOSQUALENE CYCLASEs (OSCs) involved in phytosterol biosynthesis are upregulated in the diploid species, while the expression of OSCs contributing to ginsenoside biosynthesis is higher in the tetraploid species. In agreement with these results, the contents of dammarenediol-type ginsenosides were higher in the tetraploid species relative to the diploid species. Conclusion: These results suggest that a whole-genome duplication event has influenced the triterpene biosynthesis pathway in tetraploid Panax species during their evolution or ecological adaptation. This study provides a basis for further efforts to explore the genetic variation of the Panax genus.

The climbing plant Cynanchum rostellatum (Turcz.) Liede & Khanum is widely distributed throughout Korea and Northeast Asia as a member of the Apocynaceae family. Although this plant has a high value in medicinal and industrial purposes, genetic research on this plant is insufficient. This study announces the complete plastid genome (plastome) sequence of C. rostellatum with 663× mean coverage, which was assembled using 763 Mbp short-read data generated by the Illumina HiSeq X platform. The C. rostellatum plastome was 158,018 bp in length and displayed the typical quadripartite structure composed of the large single-copy (LSC) region (89,058 bp), the small single-copy (SSC) region (18,718 bp), and a pair of inverted repeat (IR) regions (25,116 bp). A total of 129 genes have been annotated, including 84 protein-coding genes, 37 transfer RNA genes, and eight ribosomal RNA genes. Phylogenetic analysis indicated the genus Cynanchum including 12 Cynanchum plastome sequences, was monophyletic and was located within the sub-family Asclepiadoideae. Two C. rostellatum plastomes, including the plastome assembled in this study, formed a subclade and were sister to the C. thesioides plastome, whereas the other C. rostellatum, which was previously reported one, was located within the clade of C. wilfordii and C. bungei.

Abstract Long terminal repeat retrotransposons (LTR-RTs) make up a considerable portion of plant genomes. New insertions of these active LTR-RTs modify gene structures and functions and play an important role in genome evolution. Therefore, identifying active forms of LTR-RTs could uncover the effects of these elements in plants. Extrachromosomal linear DNA (eclDNA) forms during LTR-RT replication; therefore, amplification LTRs of eclDNAs followed by sequencing (ALE-seq) uncover the current transpositional potential of the LTR-RTs. The ALE-seq protocol was validated by identification of Tos17 in callus of Nipponbare cultivar. Here, we identified two active LTR-RTs belonging to the Oryco family on chromosomes 6 and 9 in rice cultivar Dongjin callus based on the ALE-seq technology. Each Oryco family member has paired LTRs with identical sequences and internal domain regions. Comparison of the two LTR-RTs revealed 97% sequence identity in their internal domains and 65% sequence identity in their LTRs. These two putatively active Oryco LTR-RT family members could be used to expand our knowledge of retrotransposition mechanisms and the effects of LTR-RTs on the rice genome.

Abstract Interspecific somatic hybridization has been performed in potato breeding experiments to increase plant resistance against biotic and abiotic stress conditions. We analyzed the mitochondrial and plastid genomes and 45S nuclear ribosomal DNA (45S rDNA) for the cultivated potato (S. tuberosum, St), wild potato (S. commersonii, Sc), and their somatic hybrid (StSc). Complex genome components and structure, such as the hybrid form of 45S rDNA in StSc, unique plastome in Sc, and recombinant mitogenome were identified. However, the mitogenome exhibited dynamic multipartite structures in both species as well as in the somatic hybrid. In St, the mitogenome is 756,058 bp and is composed of five subgenomes ranging from 297,014 to 49,171 bp. In Sc, it is 552,103 bp long and is composed of two sub-genomes of 338,427 and 213,676 bp length. StSc has 447,645 bp long mitogenome with two subgenomes of length 398,439 and 49,206 bp. The mitogenome structure exhibited dynamic recombination mediated by tandem repeats; however, it contained highly conserved genes in the three species. Among the 35 protein-coding genes of the StSc mitogenome, 21 were identical for all the three species, and 12 and 2 were unique in Sc and St, respectively. The recombinant mitogenome might be derived from homologous recombination between both species during somatic hybrid development.

Abstract Background Cynanchum wilfordii (Cw) and Cynanchum auriculatum (Ca) have long been used in traditional medicine and as functional food in Korea and China, respectively. They have diverse medicinal functions, and many studies have been conducted, including pharmaceutical efficiency and metabolites. Especially, Cw is regarded as the most famous medicinal herb in Korea due to its menopausal symptoms relieving effect. Despite the high demand for Cw in the market, both species are cultivated using wild resources with rare genomic information. Results We collected 160 Cw germplasm from local areas of Korea and analyzed their morphological diversity. Five Cw and one Ca of them, which were morphologically diverse, were sequenced, and nuclear ribosomal DNA (nrDNA) and complete plastid genome (plastome) sequences were assembled and annotated. We investigated the genomic characteristics of Cw as well as the genetic diversity of plastomes and nrDNA of Cw and Ca. The Cw haploid nuclear genome was approximately 178 Mbp. Karyotyping revealed the juxtaposition of 45S and 5S nrDNA on one of 11 chromosomes. Plastome sequences revealed 1226 interspecies polymorphisms and 11 Cw intraspecies polymorphisms. The 160 Cw accessions were grouped into 21 haplotypes based on seven plastome markers and into 108 haplotypes based on seven nuclear markers. Nuclear genotypes did not coincide with plastome haplotypes that reflect the frequent natural outcrossing events. Conclusions Cw germplasm had a huge morphological diversity, and their wide range of genetic diversity was revealed through the investigation with 14 molecular markers. The morphological and genomic diversity, chromosome structure, and genome size provide fundamental genomic information for breeding of undomesticated Cw plants.

Allium ulleungense (AU) and A. microdictyon (AM) are valuable medicinal and edible vegetables, referred to as mountain garlic in Korea. The identification of AU, AM and a neighboring species A. ochotense (AO) is difficult because of their morphological similarities. We collected samples from three species and 46 cultivated collections to understand the genetic diversity of these valuable Allium species. Among them, we sequenced six collections, including three species and three cultivating collections to obtain data from the plastid genome (plastome) and nuclear 45S ribosomal DNA (nrDNA) for super-barcoding. The AM and AO showed around 60 single nucleotide polymorphisms (SNPs) and 39 Insertion/Deletion (InDels) in the plastome but no variations in the nrDNA sequences. Conversely, the AU and AM showed more than 170 SNPs and 80 InDels in the plastomes, and 20 SNPs and 1 InDel were found in the 45S nrDNA sequences. Among the three cultivating collections, one TB collection was determined to be the AU type in both plastome and nrDNA sequences. However, the other two collections, JB and SA, showed the AM type plastome but were heterozygous in the 45S nrDNA sequences, indicating both AU and AM types (putative AM x AU hybrid). Ten molecular markers were developed based on sequence variations to identify these three species and assess their genetic diversity. A total of 49 collections were genotyped using the ten developed markers and classified into five groups: 14 AU, 22 AM, 1 AO, 3 putative AM x AU hybrids, and 9 putative AU x AM hybrid collections. Super-barcoding with plastomes and nrDNAs revealed the genetic diversity of the three Allium species and putative hybrids between species. The newly developed markers will facilitate species and hybrid identification, thereby benefiting marker-assisted molecular breeding of Allium species.

[This corrects the article DOI: 10.1371/journal.pone.0264576.].

Whole-genome shogun sequence (WGS) data generated by next-generation sequencing (NGS) platforms are a valuable resource for crop improvement. We produced 5–6 × WGS coverage of 44 Brassica oleracea breeding lines representing seven subspecies/morphotypes: cabbage, broccoli, cauliflower, kailan, kale, Brussels sprout, and kohlrabi to systematically evaluate the nuclear and chloroplast (Cp) diversity in the 44 B. oleracea breeding lines. We then exploited the impact of low-coverage NGS by evaluating nuclear genome diversity and assembly, annotation of complete chloroplast (Cp) genomes and 45S nuclear ribosomal DNA (45S nrDNA) sequences, and copy number variation for major repeats. Nuclear genome diversity analysis has revealed a total of 496 463 SNPs and 37 493 indels in the nuclear genome across the 44 accessions. Interestingly, some SNPs showed subspecies enrichment at certain chromosomal regions. The assembly of complete Cp genomes contained 153 361–153 372 bp with 37 variants including SNPs and indels. The 45S nrDNA transcription unit was 5 802 bp long with a total of 31 SNPs from the 44 lines. The phylogenetic tree inferred from the nuclear and Cp genomes coincided and clustered broccoli, cauliflower, and kailan in one group and cabbage, Brussels sprout, kale, and kohlrabi in another group. The morphotypes diverged during the last 0.17 million years. The Cp genome diversity reflected the unique cytoplasm of each subspecies, and revealed that the cytoplasm of many breeding lines was replaced and intermingled via inter-subspecies crosses during the breeding process instead. The polymorphic Cp markers provide a classification system for the cytoplasm types in B. oleracea. Furthermore, copy numbers of major transposable elements (TEs) showed high diversity among the 44 accessions, indicating that many TEs have become active recently. Overall, we demonstrated a comprehensive utilization of low-coverage NGS data and might shed light on the genetic diversity and evolution of diverse B. oleracea morphotypes.

Peucedanum hakuunense Nakai is one of the rare species in the Korean Peninsula. This study characterized the complete plastid genome (plastome) sequence of P. hakuunense by de novo assembly with next-generation sequencing data. The complete plastome of P. hakuunense is 147,426 bp in length with a typical quadripartite structure comprising a large single-copy region of 91,915 bp, a small single-copy region of 17,425 bp, and two inverted repeat regions of 19,043 bp in length. The plastome of P. hakuunense is composed of 85 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. The phylogenetic analysis revealed that two Peucedanum species formed an independent subclade, sister to the subclade of Angelica species within the tribe Selineae.

Complete plastid genome (plastome) and ribosomal DNA (rDNA) sequences of three Rubus accessions (two Rubus longisepalus and one R. hirsutus) were newly assembled using Illumina whole-genome sequences. Rubus longisepalus Nakai and R. longisepalus var. tozawai, described as different varieties, have identical plastomes and rDNA sequences. The plastomes are 155,957 bp and 156,005 bp and the 45S rDNA transcription unit sizes are 5809 bp and 5811 bp in R. longisepalus and R. hirsutus, respectively. The 5S rDNA transcription unit is an identical 121 bp in three Rubus accessions. We developed three DNA markers to authenticate R. longisepalus and R. hirsutus based on plastome diversity. Phylogenomic analysis revealed that the Rubus species classified as two clades and R. longisepalus, R. hirsutus, and R. chingii are the most closely related species in clade 1.

Abstract Ilex is a monogeneric plant group (containing approximately 600 species) in the Aquifoliaceae family and one of the most commonly used medicinal herbs. However, its taxonomy and phylogenetic relationships at the species level are debatable. Herein, we obtained the complete chloroplast genomes of all 19 Ilex types that are native to Hong Kong. The genomes are conserved in structure, gene content and arrangement. The chloroplast genomes range in size from 157,119 bp in Ilex graciliflora to 158,020 bp in Ilex kwangtungensis. All these genomes contain 125 genes, of which 88 are protein-coding and 37 are tRNA genes. Four highly varied sequences (rps16-trnQ, rpl32-trnL, ndhD-psaC and ycf1) were found. The number of repeats in the Ilex genomes is mostly conserved, but the number of repeating motifs varies. The phylogenetic relationship among the 19 Ilex genomes, together with eight other available genomes in other studies, was investigated. Most of the species could be correctly assigned to the section or even series level, consistent with previous taxonomy, except Ilex rotunda var. microcarpa, Ilex asprella var. tapuensis and Ilex chapaensis. These species were reclassified; I. rotunda was placed in the section Micrococca, while the other two were grouped with the section Pseudoaquifolium. These studies provide a better understanding of Ilex phylogeny and refine its classification.

Abstract Both genomes in chloroplasts and mitochondria of plant cell are usually inherited from maternal parent, with rare exceptions. To characterize the inheritance patterns of the organelle genomes in cucumber (Cucumis sativus var. sativus), two inbred lines and their reciprocal F1 hybrids were analyzed using an next generation whole genome sequencing data. Their complete chloroplast genome sequences were de novo assembled, and a single SNP was identified between the parental lines. Two reciprocal F1 hybrids have the same chloroplast genomes with their maternal parents. Meanwhile, 292 polymorphic sites were identified between mitochondrial genomes of the two parental lines, which showed the same genotypes with their paternal parents in the two reciprocal F1 hybrids, without any recombination. The inheritance patterns of the chloroplast and mitochondria genomes were also confirmed in four additional cucumber accessions and their six reciprocal F1 hybrids using molecular markers derived from the identified polymorphic sites. Taken together, our results indicate that the cucumber chloroplast genome is maternally inherited, as is typically observed in other plant species, whereas the large cucumber mitochondrial genome is paternally inherited. The combination of DNA markers derived from the chloroplast and mitochondrial genomes will provide a convenient system for purity test of F1 hybrid seeds in cucumber breeding.

Liriope platyphylla F.T. Wang & Tang and Ophiopogon japonicus (Thunb.) Ker Gawl are morphologically similar perennial herbaceous plants belonging to the Asparagaceae family used as evergreen ornamental plants as well as for medicinal purposes. Complete plastid genomes (plastomes) and 45S nuclear ribosomal DNA (45S rDNA) sequences were obtained from two L. platyphylla accessions and one O. japonicus accessions using low-coverage, whole-genome data. Phylogenomic analysis using plastomes or 45S rDNA of the three accessions showed identical topology. Comparative analysis of the three accessions and representatives of 28 other Asparagaceae species revealed that L. platyphylla and O. japonicus are the most closely related species in the family Asparagaceae. The plastomes were 156,754–157,071 bp and the 45S rDNA transcriptional unit was 5906–5789 bp, providing super-barcoding information. Plastome sequences contained 817 single-nucleotide polymorphisms (SNPs) and 173 insertions or deletions (InDels) at the interspecific level and 88 SNPs and 56 InDels at the intraspecific level. 45S rDNA sequences contained 70 SNPs and 3 InDels at the interspecific level and 12 SNPs and 1 InDel at the intraspecific level. We developed four dominant and two codominant DNA markers based on the plastome diversity for authentication of L. platyphylla and O. japonicus and successfully applied these to ingredients distributed in the herbal medicine market.

Background: Ginseng (Panax ginseng Meyer) is one of the world's most valuable medicinal plants with numerous pharmacological effects. Ginseng has been cultivated from wild mountain ginseng collections for a few hundred years. However, the genetic diversity of cultivated and wild ginseng populations is not fully understood. Methods: We developed 92 polymorphic microsatellite markers based on whole-genome sequence data. We selected five markers that represent clear allele diversity for each of their corresponding loci to elucidate genetic diversity. These markers were applied to 147 individual plants, including cultivars, breeding lines, and wild populations in Korea and neighboring countries. Results: Most of the 92 markers displayed multiple-band patterns, resulting from genome duplication, which causes confusion in interpretation of their target locus. The five high-resolution markers revealed 3 to 8 alleles from each single locus. The proportion of heterozygosity (He) ranged from 0.027 to 0.190, with an average of 0.132, which is notably lower than that of previous studies. Polymorphism information content of the markers ranged from 0.199 to 0.701, with an average of 0.454. There was no statistically significant difference in genetic diversity between cultivated and wild ginseng groups, and they showed intermingled positioning in the phylogenetic relationship. Conclusion: Ginseng has a relatively high level of genetic diversity, and cultivated and wild groups have similar levels of genetic diversity. Collectively, our data demonstrate that current breeding populations have abundant genetic diversity for breeding of elite ginseng cultivars.

Background: Panax species are important herbal medicinal plants in the Araliaceae family. Recently, we reported the complete chloroplast genomes and 45S nuclear ribosomal DNA sequences from seven Panax species, two (P. quinquefolius and P. trifolius) from North America and five (P. ginseng, P. notoginseng, P. japonicus, P. vietnamensis, and P. stipuleanatus) from Asia. Methods: We conducted phylogenetic analysis of these chloroplast sequences with 12 other Araliaceae species and comprehensive comparative analysis among the seven Panax whole chloroplast genomes. Results: We identified 1,128 single nucleotide polymorphisms (SNP) in coding gene sequences, distributed among 72 of the 79 protein-coding genes in the chloroplast genomes of the seven Panax species. The other seven genes (including psaJ, psbN, rpl23, psbF, psbL, rps18, and rps7) were identical among the Panax species. We also discovered that 12 large chloroplast genome fragments were transferred into the mitochondrial genome based on sharing of more than 90% sequence similarity. The total size of transferred fragments was 60,331 bp, corresponding to approximately 38.6% of chloroplast genome. We developed 18 SNP markers from the chloroplast genic coding sequence regions that were not similar to regions in the mitochondrial genome. These markers included two or three species-specific markers for each species and can be used to authenticate all the seven Panax species from the others. Conclusion: The comparative analysis of chloroplast genomes from seven Panax species elucidated their genetic diversity and evolutionary relationships, and 18 species-specific markers were able to discriminate among these species, thereby furthering efforts to protect the ginseng industry from economically motivated adulteration. Keywords: Araliaceae evolution, Chloroplast genome, dCAPS markers, Ginseng authentication, Panax species

Euonymus hamiltonianus and its relatives (Celastraceae family) are used for ornamental and medicinal purposes. However, species identification in Euonymus is difficult due to their morphological diversity. Using plastid genome (plastome) data, we attempt to reveal phylogenetic relationship among Euonymus species and develop useful markers for molecular identification. We assembled the plastome and nuclear ribosomal DNA (nrDNA) sequences from five Euonymus lines collected from South Korea: three Euonymus hamiltonianus accessions, E. europaeus, and E. japonicus. We conducted an in-depth comparative analysis using ten plastomes, including other publicly available plastome data for this genus. The genome structures, gene contents, and gene orders were similar in all Euonymus plastomes in this study. Analysis of nucleotide diversity revealed six divergence hotspots in their plastomes. We identified 339 single nucleotide polymorphisms and 293 insertion or deletions among the four E. hamiltonianus plastomes, pointing to abundant diversity even within the same species. Among 77 commonly shared genes, 9 and 33 were identified as conserved genes in the genus Euonymus and E. hamiltonianus, respectively. Phylogenetic analysis based on plastome and nrDNA sequences revealed the overall consensus and relationships between plastomes and nrDNAs. Finally, we developed six barcoding markers and successfully applied them to 31 E. hamiltonianus lines collected from South Korea. Our findings provide the molecular basis for the classification and molecular taxonomic criteria for the genus Euonymus (at least in Korea), which should aid in more objective classification within this genus. Moreover, the newly developed markers will be useful for understanding the species delimitation of E. hamiltonianus and closely related species.

The genus Artemisia is an important source of medicines in both traditional and modern pharmaceutics, particularly in East Asia. Despite the great benefits of herbal medicine, quality assessment methods for these medicinal herbs are lacking. The young leaves from Artemisia species are generally used, and most of the species have similar morphology, which often leads to adulteration and misuse. This study assembled five complete chloroplast genomes of three Artemisia species, two accessions of A. gmelinii and A. capillaris, and one A. fukudo. Through comparative analysis, we revealed genomic variations and phylogenetic relationships between these species and developed seven InDel-based barcode markers which discriminated the tested species from each other. Additionally, we analyzed specialized metabolites from the species using LC-MS and suggested chemical markers for the identification and authentication of these herbs. We expect that this integrated and complementary authentication method would aid in reducing the misuse of Artemisia species.

The diversity of secondary metabolites of individual plants results from multiple enzymatic processes in planta and various environmental factors, such as temperature, moisture, and soil conditions. Chemical composition analysis of plants can lead to a new method to understand relationship among comparable plants along with biological classification such as genetic and anatomical method. In this study, the chemical diversity of nine different Lauraceae species was investigated, and the plant samples were chemically analyzed and classified. Multivariate analysis methods, such as PLS-DA, were used to select important metabolites distinguishing the nine Lauraceae species. The selected metabolites were identified through preparative LC-MS or MS/MS fragment pattern analysis. In addition, the chemical dendrogram for the nine Lauraceae species was interpreted through molecular network analysis and compared with the genetic dendrogram. This approach enabled us to compare the complete chemical compositions of multiple plant samples to identify relationships among plants.

Epimedium pubescens Maxim. is a well-known traditional Chinese medicine herb. In this study, the complete chloroplast genome of E. pubescens was sequenced. The genome was 158 956 bp in length, with a large single-copy region of 86,345 bp, a small single-copy region of 17,075 bp, and 2 inverted repeat regions of 27,768 bp. The genome consisted of 113 genes, including 79 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. The GC contents were 38.82%. Phylogenetic analysis showed that E. pubescens of series Brachyrcerae was firstly clustered with E. acumiantum Franch. of ser. Dolichocerae, but not with E. brevicornu Maxim. from the same series.

Background: Panax ginseng has been used in traditional medicine to strengthen the body and mental well-being of humans for thousands of years. Many elite ginseng cultivars have been developed, and ginseng cultivation has become well established during the last century. However, heat stress poses an important threat to the growth and sustainable production of ginseng. Efforts have been made to study the effects of high temperature on ginseng physiology, but knowledge of the molecular responses to heat stress is still limited. Methods: We sequenced the transcriptomes (RNA-Seq) of two ginseng cultivars, Chunpoong (CP) and Yunpoong (YP), which are sensitive and resistant to heat stress, respectively, after 1- and 3-week heat treatments. Differential gene expression and gene ontology enrichment along with profiled chlorophyll contents were performed. Results: CP is more sensitive to heat stress than YP and exhibited a lower chlorophyll content than YP. Moreover, heat stress reduced the chlorophyll content more rapidly in CP than in YP. A total of 329 heat-responsive genes were identified. Intriguingly, genes encoding chlorophyll a/b–binding proteins, WRKY transcription factors, and fatty acid desaturase were predominantly responsive during heat stress and appeared to regulate photosynthesis. In addition, a genome-wide scan of photosynthetic and sugar metabolic genes revealed reduced transcription levels for ribulose 1,5-bisphosphate carboxylase/oxygenase under heat stress, especially in CP, possibly attributable to elevated levels of soluble sugars. Conclusion: Our comprehensive genomic analysis reveals candidate loci/gene targets for breeding and functional studies related to developing high temperature–tolerant ginseng varieties. Keywords: Chunpoong, Heat stress, Panax ginseng, RNA-Seq, Yunpoong

Miniature inverted-repeat transposable elements (MITEs) are non-autonomous class II transposons which have been shown to influence genome evolution. Brassica nigra L. (B-genome) is one of three Brassica diploids cultivated primarily as an oil crop, which harbors novel alleles important for breeding. Two new high copy hAT MITE families (BniHAT-1 and BniHAT-2) from the B-genome were characterized and their prevalence assessed in the genomes of the related diploids, rapa L. (A) and Brassica oleracea L. (C). Both novel MITE families were present at high copy numbers in the B-genome with 434 and 331 copies of BniHAT-1 and BniHAT-2, respectively. Yet less than 20 elements were identified in the genome assemblies of the A, and C -genomes, supporting B-genome specific proliferation of these MITE families. Although apparently randomly distributed across the genome, 68 and 70% of the B-genome MITEs were present within 2 kb flanking regions of annotated genes suggesting they might influence gene expression and/or function. In addition, MITE derived microRNAs and transcription factor binding sites suggested a putative role in gene regulation. Age of insertion analysis revealed that the major proliferation of these elements occurred during 2–3 million years ago. Additionally, site-specific polymorphism analyses showed that 44% MITEs were undergoing active amplification into the B-genome. Overall, this study provides a comprehensive analysis of two high copy MITE families, which were specifically amplified in the B-genome, suggesting a potential role in shaping the Brassica B-genome.

Abstract The concept of U’s triangle, which revealed the importance of polyploidization in plant genome evolution, described natural allopolyploidization events in Brassica using three diploids [B. rapa (A genome), B. nigra (B), and B. oleracea (C)] and derived allotetraploids [B. juncea (AB genome), B. napus (AC), and B. carinata (BC)]. However, comprehensive understanding of Brassica genome evolution has not been fully achieved. Here, we performed low-coverage (2–6×) whole-genome sequencing of 28 accessions of Brassica as well as of Raphanus sativus [R genome] to explore the evolution of six Brassica species based on chloroplast genome and ribosomal DNA variations. Our phylogenomic analyses led to two main conclusions. (1) Intra-species-level chloroplast genome variations are low in the three allotetraploids (2~7 SNPs), but rich and variable in each diploid species (7~193 SNPs). (2) Three allotetraploids maintain two 45SnrDNA types derived from both ancestral species with maternal dominance. Furthermore, this study sheds light on the maternal origin of the AC chloroplast genome. Overall, this study clarifies the genetic relationships of U’s triangle species based on a comprehensive genomics approach and provides important genomic resources for correlative and evolutionary studies.

Abstract Background The ginseng (Panax ginseng C.A. Meyer) is a perennial herbaceous plant that has been used in traditional oriental medicine for thousands of years. Ginsenosides, which have significant pharmacological effects on human health, are the foremost bioactive constituents in this plant. Having realized the importance of this plant to humans, an integrated omics resource becomes indispensable to facilitate genomic research, molecular breeding and pharmacological study of this herb. Description The first draft genome sequences of P. ginseng cultivar “Chunpoong” were reported recently. Here, using the draft genome, transcriptome, and functional annotation datasets of P. ginseng, we have constructed the Ginseng Genome Database http://ginsengdb.snu.ac.kr/, the first open-access platform to provide comprehensive genomic resources of P. ginseng. The current version of this database provides the most up-to-date draft genome sequence (of approximately 3000 Mbp of scaffold sequences) along with the structural and functional annotations for 59,352 genes and digital expression of genes based on transcriptome data from different tissues, growth stages and treatments. In addition, tools for visualization and the genomic data from various analyses are provided. All data in the database were manually curated and integrated within a user-friendly query page. Conclusion This database provides valuable resources for a range of research fields related to P. ginseng and other species belonging to the Apiales order as well as for plant research communities in general. Ginseng genome database can be accessed at http://ginsengdb.snu.ac.kr/.

Mahonia eurybracteata subsp. ganpinensis (H.Lév.) T.S.Ying & Boufford. is an evergreen shrub of Berberidaceae and has the potentials for horticultural and medicinal development. In the present paper, the complete chloroplast genome of Mahonia eurybracteata subsp. ganpinensis (H.Lév.) T.S.Ying & Boufford. was sequenced. The complete chloroplast genome was 165,562 bp in length, containing a large single copy region (73,394 bp), a small single copy region (18,698 bp) and two inverted repeat regions (36,735 bp). The genome consisted of 113 genes, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Phylogenetic analysis showed that M. eurybracteata subsp. ganpinensis and M. bealei were firstly clustered into a branch and the two Mahonia species were most closely related to the genus Berberis of Berberidaceae.

Abstract Background Transposable elements are major evolutionary forces which can cause new genome structure and species diversification. The role of transposable elements in the expansion of nucleotide-binding and leucine-rich-repeat proteins (NLRs), the major disease-resistance gene families, has been unexplored in plants. Results We report two high-quality de novo genomes (Capsicum baccatum and C. chinense) and an improved reference genome (C. annuum) for peppers. Dynamic genome rearrangements involving translocations among chromosomes 3, 5, and 9 were detected in comparison between C. baccatum and the two other peppers. The amplification of athila LTR-retrotransposons, members of the gypsy superfamily, led to genome expansion in C. baccatum. In-depth genome-wide comparison of genes and repeats unveiled that the copy numbers of NLRs were greatly increased by LTR-retrotransposon-mediated retroduplication. Moreover, retroduplicated NLRs are abundant across the angiosperms and, in most cases, are lineage-specific. Conclusions Our study reveals that retroduplication has played key roles for the massive emergence of NLR genes including functional disease-resistance genes in pepper plants.

Background: Panax ginseng Meyer (Asian ginseng) has a large nuclear genome size of > 3.5 Gbp in haploid genome equivalent of 24 chromosomes. Tandem repeats (TRs) occupy significant portions of the genome in many plants and are often found in specific genomic loci, making them a valuable molecular cytogenetic tool in discriminating chromosomes. In an effort to understand the P. ginseng genome structure, we characterized an ultrahigh copy 167-bp TR (Pg167TR) and explored its chromosomal distribution as well as its utility for chromosome identification. Methods: Polymerase chain reaction amplicons of Pg167TR were labeled, along with 5S and 45S rDNA amplicons, using a direct nick-translation method. Direct fluorescence in situ hybridization (FISH) was used to analyze the chromosomal distribution of Pg167TR. Results: Recently, we reported a method of karyotyping the 24 chromosome pairs of P. ginseng using rDNA and DAPI (4′,6-diamidino-2-phenylindole) bands. Here, a unique distribution of Pg167TR in all 24 P. ginseng chromosomes was observed, allowing easy identification of individual homologous chromosomes. Additionally, direct labeling of 5S and 45S rDNA probes allowed the identification of two additional 5S rDNA loci not previously reported, enabling the refinement of the P. ginseng karyotype. Conclusion: Identification of individual P. ginseng chromosomes was achieved using Pg167TR-FISH. Chromosome identification is important in understanding the P. ginseng genome structure, and our method will be useful for future integration of genetic linkage maps and genome scaffold anchoring. Additionally, it is a good tool for comparative studies with related species in efforts to understand the evolution of P. ginseng.

Abstract Genome duplication and repeat multiplication contribute to genome evolution in plants. Our previous work identified a recent allotetraploidization event and five high-copy LTR retrotransposon (LTR-RT) families PgDel, PgTat, PgAthila, PgTork, and PgOryco in Panax ginseng. Here, using whole-genome sequences, we quantified major repeats in five Panax species and investigated their role in genome evolution. The diploids P. japonicus, P. vietnamensis, and P. notoginseng and the tetraploids P. ginseng and P. quinquefolius were analyzed alongside their relative Aralia elata. These species possess 0.8–4.9 Gb haploid genomes. The PgDel, PgTat, PgAthila, and PgTork LTR-RT superfamilies accounted for 39–52% of the Panax species genomes and 17% of the A. elata genome. PgDel included six subfamily members, each with a distinct genome distribution. In particular, the PgDel1 subfamily occupied 23–35% of the Panax genomes and accounted for much of their genome size variation. PgDel1 occupied 22.6% (0.8 Gb of 3.6 Gb) and 34.5% (1.7 Gb of 4.9 Gb) of the P. ginseng and P. quinquefolius genomes, respectively. Our findings indicate that the P. quinquefolius genome may have expanded due to rapid PgDel1 amplification over the last million years as a result of environmental adaptation following migration from Asia to North America.

Abstract We produced complete sequences and conducted comparative analysis of the maternally inherited chloroplast (cp) genomes and bi-parentally inherited 45S nuclear ribosomal RNA genes (nrDNA) from ten Araliaceae species to elucidate the genetic diversity and evolution in that family. The cp genomes ranged from 155,993 bp to 156,730 bp with 97.1–99.6% similarity. Complete 45S nrDNA units were about 11 kb including a 5.8-kb 45S cistron. Among 79 cp protein-coding genes, 74 showed nucleotide variations among ten species, of which infA, rpl22, rps19 and ndhE genes showed the highest Ks values and atpF, atpE, ycf2 and rps15 genes showed the highest Ka/Ks values. Four genes, petN, psaJ, psbF, and psbN, related to photosynthesis and one gene, rpl23, related to the ribosomal large subunit remain conserved in all 10 Araliaceae species. Phylogenetic analysis revealed that the ten species could be resolved into two monophyletic lineages, the Panax-Aralia and the Eleutherococcus-Dendropanax groups, which diverged approximately 8.81–10.59 million years ago (MYA). The Panax genus divided into two groups, with diploid species including P. notoginseng, P. vietnamensis, and P. japonicus surviving in Southern Asia and a tetraploid group including P. ginseng and P. quinquefolius Northern Asia and North America 2.89–3.20 MYA.

Background: Prenyltransferases catalyze the sequential addition of isopentenyl diphosphate units to allylic prenyl diphosphate acceptors and are classified as either trans-prenyltransferases (TPTs) or cis-prenyltransferases (CPTs). The functions of CPTs have been well characterized in bacteria, yeast, and mammals compared to plants. The characterization of CPTs also has been less studied than TPTs. In the present study, molecular cloning and functional characterization of a CPT from a medicinal plant, Panax ginseng Mayer were addressed. Methods: Gene expression patterns of PgCPT1 were analyzed by quantitative reverse transcription polymerase chain reaction. In planta transformation was generated by floral dipping using Agrobacterium tumefaciens. Yeast transformation was performed by lithium acetate and heat-shock for rer2Δ complementation and yeast-two-hybrid assay. Results: The ginseng genome contains at least one family of three putative CPT genes. PgCPT1 is expressed in all organs, but more predominantly in the leaves. Overexpression of PgCPT1 did not show any plant growth defect, and its protein can complement yeast mutant rer2Δ via possible protein–protein interaction with PgCPTL2. Conclusion: Partial complementation of the yeast dolichol biosynthesis mutant rer2Δ suggested that PgCPT1 is involved in dolichol biosynthesis. Direct protein interaction between PgCPT1 and a human Nogo-B receptor homolog suggests that PgCPT1 requires an accessory component for proper function.

Background: Various Panax ginseng cultivars exhibit a range of diversity for morphological and physiological traits. However, there are few studies on diversity of metabolic profiles and genetic background to understand the complex metabolic pathway in ginseng. Methods: To understand the complex metabolic pathway and related genes in ginseng, we tried to conduct integrated analysis of primary metabolite profiles and related gene expression using five ginseng cultivars showing different morphology. We investigated primary metabolite profiles via gas chromatography–mass spectrometry (GC-MS) and analyzed transcriptomes by Illumina sequencing using adventitious roots grown under the same conditions to elucidate the differences in metabolism underlying such genetic diversity. Results: GC-MS analysis revealed that primary metabolite profiling allowed us to classify the five cultivars into three independent groups and the grouping was also explained by eight major primary metabolites as biomarkers. We selected three cultivars (Chunpoong, Cheongsun, and Sunhyang) to represent each group and analyzed their transcriptomes. We inspected 100 unigenes involved in seven primary metabolite biosynthesis pathways and found that 21 unigenes encoding 15 enzymes were differentially expressed among the three cultivars. Integrated analysis of transcriptomes and metabolomes revealed that the ginseng cultivars differ in primary metabolites as well as in the putative genes involved in the complex process of primary metabolic pathways. Conclusion: Our data derived from this integrated analysis provide insights into the underlying complexity of genes and metabolites that co-regulate flux through these pathways in ginseng.

Liriope platyphylla is herbaceous perennial plant belonging to the Asparagaceae family and widely used both as ornamental plant and herbal medicine. The complete chloroplast genome of L. platyphylla was 156,754 bp in length, which was composed of four distinct parts; a large single copy (LSC) of 85,118 bp, a small single copy (SSC) of 18,680 bp, and a pair of inverted repeat regions (IRa and IRb) of 26,478 bp. A total of 130 genes including 83 protein-coding genes, 39 tRNA genes and 8 rRNA genes were identified. The phylogenetic tree showed that L. platyphylla has a close relationship with other Nolinoideae plants, especially with Maianthemum dilatatum and Nolina atopocarpa.

Plagiorhegma dubia Maxim. is a traditional Chinese medicinal herb from Plagiorhegma, Berberidaceae, which is distributed in the northeast of China, Korea, Russia. The complete chloroplast genome is 152,468 bp in length, with large single copy (LSC 82,257 bp) and small single copy (SSC 16,599 bp) regions separated by a pair of inverted repeats (IR 26 805 bp). The genome has a total of 113 genes including 79 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Phylogenetic analysis shows that P. dubia is closely related with Sinopodophyllum hexandrum and Epimedium species. The results are of great implication for the development and utilization of P. dubia and the phylogenetic researches on Berberidaceae.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Plant mitochondrial genomes (mtDNAs) vary in sequence structure. We assembled the Brassica oleracea var. capitata mtDNA using a mean coverage depth of 25X whole genome sequencing (WGS) and confirmed the presence of eight contigs/fragments by BLASTZ using the previously reported KJ820683 and AP012988 mtDNA as reference. Assembly of the mtDNA sequence reads resulted in a circular structure of 219,975 bp. Our assembled mtDNA, NCBI acc. no. KU831325, contained 34 protein-coding genes, 3 rRNA genes, and 19 tRNA genes with similarity to the KJ820683 and AP012988 reference mtDNA. No large repeats were found in the KU831325 assembly. However, KU831325 showed differences in the arrangement of bases at different regions compared to the previously reported mtDNAs. In the reference mtDNAs KJ820683 and AP012988, contig/fragment number 4 is partitioned into two contigs/fragments, 4a and 4b. However, contig/fragment number 4 was a single contig/fragment with 29,661 bp in KU831325. PCR and qRT-PCR using flanking markers from separate parts of contig/fragment number 4 confirmed it to be a single contig/fragment. In addition, genome re-alignment of the plastid genome and mtDNAs supported the presence of heteroplasmy and reverse arrangement of the heteroplasmic blocks within the other mtDNAs compared to KU831325 that might be one of the causal factors for its diversity. Our results thus confirm the existence of different mtDNAs in diverse B. oleracea subspecies.

Lonicera maackii is native to Northeastern Asia and considered as an invasive plant in North America. In this study, the complete chloroplast genome of L. maackii was obtained by high-throughput next-generation sequencing technology. The chloroplast genome was 155,318 bp in length and had typical quadripartite structures comprising a large single copy, a small single copy, and a pair of inverted repeat regions of 89,202, 18,680, and 23,718 bp long, respectively. The genome contained 80 protein-coding genes, four rRNA genes and 30 tRNA genes. Phylogenetic tree revealed that L. maackii was grouped with other Caprifoliaceae species, L. japonica, Patrinia saniculifolia, and Kolkwitzia amabilis.

Wolfiporia cocos have been used as diuretic, sedative, and tonic medicine. Although its medicinal effects were reported, its genomic information is rare. In this paper, we report the complete mitochondrial genome of Wolfiporia cocos which is a 136,067 bp circular structure with 5 protein-coding genes, 25 tRNA genes, and 2 rRNA genes. Additional six protein-coding genes (cob, cox1, cox2, cox3, nad2, nad6) were truncated or pseudogenized by internal stop codons. Phylogenetic analysis of the mitochondrial genome of W. cocos showed the distinct relationship with other five mitochondrial genomes of Polyporales.

Rehmannia glutinosa is a plant used as traditional medicine for its various tonic effects in Korea and China. In this study, chloroplast genomes of two R. glutinosa were completed by de novo assembly using whole-genome Illumina sequence data. The length of chloroplast genomes of R. glutinosa collected from China and Korea was 153,680 bp and 153,499 bp, respectively. A total of 114 coding regions were predicted in both R. glutinosa including 80 protein-coding genes, 4 rRNA genes, and 30 tRNA genes. We identified abundant intra-species diversity of 87 InDels and 147 SNPs, among three R. glutinosa chloroplast genome sequences including one from GenBank. The phylogenetic analysis showed that these R. glutinosa were closely clustered with related Rehmannia species, separated from other Orobanchaceae and Scrophulariaceae species.

Glucosinolates are anti-carcinogenic, anti-oxidative biochemical compounds that defend plants from insect and microbial attack. Glucosinolates are abundant in all cruciferous crops, including all vegetable and oilseed Brassica species. Here, we studied the expression of glucosinolate biosynthesis genes and determined glucosinolate contents in the edible organs of a total of 12 genotypes of Brassica oleracea: three genotypes each from cabbage, kale, kohlrabi and cauliflower subspecies. Among the 81 genes analyzed by RT-PCR, 19 are transcription factor-related, two different sets of 25 genes are involved in aliphatic and indolic biosynthesis pathways and the rest are breakdown-related. The expression of glucosinolate-related genes in the stems of kohlrabi was remarkably different compared to leaves of cabbage and kale and florets of cauliflower as only eight genes out of 81 were expressed in the stem tissues of kohlrabi. In the stem tissue of kohlrabi, only one aliphatic transcription factor-related gene, Bol036286 (MYB28) and one indolic transcription factor-related gene, Bol030761 (MYB51), were expressed. The results indicated the expression of all genes is not essential for glucosinolate biosynthesis. Using HPLC analysis, a total of 16 different types of glucosinolates were identified in four subspecies, nine of them were aliphatic, four of them were indolic and one was aromatic. Cauliflower florets measured the highest number of 14 glucosinolates. Among the aliphatic glucosinolates, only gluconapin was found in the florets of cauliflower. Glucoiberverin and glucobrassicanapin contents were the highest in the stems of kohlrabi. The indolic methoxyglucobrassicin and aromatic gluconasturtiin accounted for the highest content in the florets of cauliflower. A further detailed investigation and analyses is required to discern the precise roles of each of the genes for aliphatic and indolic glucosinolate biosynthesis in the edible organs.

Panax ginseng C.A. Meyer is a traditional medicinal herb that produces bioactive compounds such as ginsenosides. Here, we investigated the diversity of ginsenosides and related genes among five genetically fixed inbred ginseng cultivars (Chunpoong [CP], Cheongsun [CS], Gopoong [GO], Sunhyang [SH], and Sunun [SU]). To focus on the genetic diversity related to ginsenoside biosynthesis, we utilized in vitro cultured adventitious roots from the five cultivars grown under controlled environmental conditions. PCA loading plots based on secondary metabolite composition classified the five cultivars into three groups. We selected three cultivars (CS, SH, and SU) to represent the three groups and conducted further transcriptome and gas chromatography-mass spectrometry analyses to identify genes and intermediates corresponding to the variation in ginsenosides among cultivars. We quantified ginsenoside contents from the three cultivars. SH had more than 12 times the total ginsenoside content of CS, with especially large differences in the levels of panaxadiol-type ginsenosides. The expression levels of genes encoding squalene epoxidase (SQE) and dammarenediol synthase (DDS) were also significantly lower in CS than SH and SU, which is consistent with the low levels of ginsenoside produced in this cultivar. Methyl jasmonate (MeJA) treatment increased the levels of panaxadiol-type ginsenosides up to 4-, 13-, and 31-fold in SH, SU, and CS, respectively. MeJA treatment also greatly increased the quantity of major intermediates and the expression of the underlying genes in the ginsenoside biosynthesis pathway; these intermediates included squalene, 2,3-oxidosqualene, and dammarenediol II, especially in CS, which had the lowest ginsenoside content under normal culture conditions. We conclude that SQE and DDS are the most important genetic factors for ginsenoside biosynthesis with diversity among ginseng cultivars.

Background: Panax ginseng Meyer is a traditional medicinal plant famous for its strong therapeutic effects and serves as an important herbal medicine. To understand and manipulate genes involved in secondary metabolic pathways including ginsenosides, transcriptome profiling of P. ginseng is essential. Methods: RNA-seq analysis of adventitious roots of two P. ginseng cultivars, Chunpoong (CP) and Cheongsun (CS), was performed using the Illumina HiSeq platform. After transcripts were assembled, expression profiling was performed. Results: Assemblies were generated from ∼85 million and ∼77 million high-quality reads from CP and CS cultivars, respectively. A total of 35,527 and 27,716 transcripts were obtained from the CP and CS assemblies, respectively. Annotation of the transcriptomes showed that approximately 90% of the transcripts had significant matches in public databases. We identified several candidate genes involved in ginsenoside biosynthesis. In addition, a large number of transcripts (17%) with different gene ontology designations were uniquely detected in adventitious roots compared to normal ginseng roots. Conclusion: This study will provide a comprehensive insight into the transcriptome of ginseng adventitious roots, and a way for successful transcriptome analysis and profiling of resource plants with less genomic information. The transcriptome profiling data generated in this study are available in our newly created adventitious root transcriptome database (http://im-crop.snu.ac.kr/transdb/index.php) for public use.

Background: Panax ginseng, the most famous medicinal herb, has a highly duplicated genome structure. However, the genome duplication of P. ginseng has not been characterized at the sequence level. Multiple band patterns have been consistently observed during the development of DNA markers using unique sequences in P. ginseng. Methods: We compared the sequences of multiple bands derived from unique expressed sequence tag-simple sequence repeat (EST-SSR) markers to investigate the sequence level genome duplication. Results: Reamplification and sequencing of the individual bands revealed that, for each marker, two bands around the expected size were genuine amplicons derived from two paralogous loci. In each case, one of the two bands was polymorphic, showing different allelic forms among nine ginseng cultivars, whereas the other band was usually monomorphic. Sequences derived from the two loci showed a high similarity, including the same primer-binding site, but each locus could be distinguished based on SSR number variations and additional single nucleotide polymorphisms (SNPs) or InDels. A locus-specific marker designed from the SNP site between the paralogous loci produced a single band that also showed clear polymorphism among ginseng cultivars. Conclusion: Our data imply that the recent genome duplication has resulted in two highly similar paralogous regions in the ginseng genome. The two paralogous sequences could be differentiated by large SSR number variations and one or two additional SNPs or InDels in every 100 bp of genic region, which can serve as a reliable identifier for each locus.

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.

Lonicera japonica is a traditional medicinal plant well known for its anti-inflammatory effect. The complete chloroplast genome sequence of L. japonica collected from Korea was obtained by de novo assembly using whole genome sequence data. The chloroplast genome is 155,060 bp in length, containing 88,853 bp in a large single copy (LSC), 18,653 bp in a small single copy (SSC) and 23,777 bp in a pair of inverted repeats (IRs). A total of 112 genes including 78 protein-coding genes and 34 structural RNA genes were identified. The sequence comparison of two L. japonica collected from Korea and China revealed 48 single nucleotide polymorphisms (SNPs) and 45 insertions/deletions (InDels). In addition, phylogenetic analysis represented intraspecific diversity within L. japonica species collected in Korea and China.