The complete chloroplast genome sequence and phylogenetic analysis of Asplenium antiquum Makino 1929, an Endangered species in Korea.

Asplenium antiquum Makino 1929 is one of the Endangered endemic species on the Korean Peninsula. The complete chloroplast of A. antiquum is 150,690 bp in length with typical quadripartite structure comprised of large single-copy region of (83,166 bp), a small single copy region (21,932 bp), and two inverted repeat regions, each 22,796 bp in length. 114 genes were detected in the chloroplast genome of A. antiquum, comprising 84 protein-encoding genes, 26 tRNA genes, and 4 rRNA genes. The phylogenetic analysis revealed a monophyletic relationship, placing A. antiquum as a sister to voth A. Prolongatum and A. nidus, forming a subclade of Asplenium species within the Aspleniaceae family. The genomic data obtained from this study will serve as valuable information for the species' genetic classification of Asplenium.

The complete plastid genome sequence of Peucedanum hakuunense Nakai (Apiaceae), an endemic and rare species in Korea.

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.

Inheritance of chloroplast and mitochondrial genomes in cucumber revealed by four reciprocal F1 hybrid combinations.

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.

Dynamic Chloroplast Genome Rearrangement and DNA Barcoding for Three Apiaceae Species Known as the Medicinal Herb "Bang-Poong".

Three Apiaceae species Ledebouriella seseloides, Peucedanum japonicum, and Glehnia littoralis are used as Asian herbal medicines, with the confusingly similar common name "Bang-poong". We characterized the complete chloroplast (cp) genomes and 45S nuclear ribosomal DNA (45S nrDNA) sequences of two accessions for each species. The complete cp genomes of G. littoralis, L. seseloides, and P. japonicum were 147,467, 147,830, and 164,633 bp, respectively. Compared to the other species, the P. japonicum cp genome had a huge inverted repeat expansion and a segmental inversion. The 45S nrDNA cistron sequences of the three species were almost identical in size and structure. Despite the structural variation in the P. japonicum cp genome, phylogenetic analysis revealed that G. littoralis diverged 5-6 million years ago (Mya), while P. japonicum diverged from L. seseloides only 2-3 Mya. Abundant copy number variations including tandem repeats, insertion/deletions, and single nucleotide polymorphisms, were found at the interspecies level. Intraspecies-level polymorphism was also found for L. seseloides and G. littoralis. We developed nine PCR barcode markers to authenticate all three species. This study characterizes the genomic differences between L. seseloides, P. japonicum, and G. littoralis; provides a method of species identification; and sheds light on the evolutionary history of these three species.

Genome and evolution of the shade-requiring medicinal herb Panax ginseng.

Panax ginseng C. A. Meyer, reputed as the king of medicinal herbs, has slow growth, long generation time, low seed production and complicated genome structure that hamper its study. Here, we unveil the genomic architecture of tetraploid P. ginseng by de novo genome assembly, representing 2.98 Gbp with 59 352 annotated genes. Resequencing data indicated that diploid Panax species diverged in association with global warming in Southern Asia, and two North American species evolved via two intercontinental migrations. Two whole genome duplications (WGD) occurred in the family Araliaceae (including Panax) after divergence with the Apiaceae, the more recent one contributing to the ability of P. ginseng to overwinter, enabling it to spread broadly through the Northern Hemisphere. Functional and evolutionary analyses suggest that production of pharmacologically important dammarane-type ginsenosides originated in Panax and are produced largely in shoot tissues and transported to roots; that newly evolved P. ginseng fatty acid desaturases increase freezing tolerance; and that unprecedented retention of chlorophyll a/b binding protein genes enables efficient photosynthesis under low light. A genome-scale metabolic network provides a holistic view of Panax ginsenoside biosynthesis. This study provides valuable resources for improving medicinal values of ginseng either through genomics-assisted breeding or metabolic engineering.

The complete chloroplast genome sequence with a novel 24-bp deletion of a Korean solid green-type cucumber variety (Cucumis sativus var. sativus).

Cucumber (Cucumis sativus var. sativus) is one of the economically important vegetable crops. In this study, we characterized the complete chloroplast genome sequence of inbred line ID YHB bred from Korean solid green-type cucumber variety, through de novo assembly using next-generation sequencing. The chloroplast genome is 155,501 bp long and has typical quadripartite structures and gene contents as found in reported cucumber chloroplast genomes. Interestingly, sequence comparison revealed a novel 24-bp deletion present only in the chloroplast genome of the inbred line. Phylogenetic analysis confirmed that the inbred line was closely grouped with cucumber cultivars.

Genotyping-by-sequencing map permits identification of clubroot resistance QTLs and revision of the reference genome assembly in cabbage (Brassica oleracea L.).

Clubroot is a devastating disease caused by Plasmodiophora brassicae and results in severe losses of yield and quality in Brassica crops. Many clubroot resistance genes and markers are available in Brassica rapa but less is known in Brassica oleracea. Here, we applied the genotyping-by-sequencing (GBS) technique to construct a high-resolution genetic map and identify clubroot resistance (CR) genes. A total of 43,821 SNPs were identified using GBS data for two parental lines, one resistant and one susceptible lines to clubroot, and 18,187 of them showed >5× coverage in the GBS data. Among those, 4,103 were credibly genotyped for all 78 F2 individual plants. These markers were clustered into nine linkage groups spanning 879.9 cM with an average interval of 1.15 cM. Quantitative trait loci (QTLs) survey based on three rounds of clubroot resistance tests using F2 : 3 progenies revealed two and single major QTLs for Race 2 and Race 9 of P. brassicae, respectively. The QTLs show similar locations to the previously reported CR loci for Race 4 in B. oleracea but are in different positions from any of the CR loci found in B. rapa. We utilized two reference genome sequences in this study. The high-resolution genetic map developed herein allowed us to reposition 37 and 2 misanchored scaffolds in the 02-12 and TO1000DH genome sequences, respectively. Our data also support additional positioning of two unanchored 3.3 Mb scaffolds into the 02-12 genome sequence.

The complete chloroplast genome sequence of a Korean indigenous ornamental plant Hydrangea serrata for. fertilis Nakai (Hydrangeaceae).

De novo assembly with whole genome sequencing data of Hydrangea serrata for. fertilis, a great ornamental landscape plant species worldwide, facilitated to generate the complete chloroplast genome sequence in this study. The complete sequence was a circular DNA molecule of 157 730 bp in length, containing the large single-copy (LSC) region of 86 789 bp, small single-copy (SSC) region of 18 711 bp and two inverted repeats (IRs) regions of 26 115 bp. The genome encoded 114 genes consisting of 80 protein-coding genes, 30 tRNA genes and four rRNA genes. Phylogenetic analysis with matK gene-coding sequences of 19 species in family Hydrangeaceae showed a close relationship of H. serrata for. fertilis Nakai with H. macrophylla.

The complete chloroplast genome sequence of Rhus chinensis Mill (Anacardiaceae).

In this study, complete chloroplast genome sequences of Rhus chinensis was characterized by de novo assembly using whole genome sequence data. The chloroplast genome of R. chinensis were 149,011bp long, which was comprised of a large single copy region of 96,882 bp, a small single copy region of 18,647bp, and a pair of inverted repeats of 16,741 bp. The genome contained 77 protein-coding genes, four rRNA genes and 30 tRNA genes. Phylogenetic tree revealed that R. chinensis was closely grouped with Spondias species, S. tuberosa and S. bahiensis, belonging to the Anacardiaceae family.

Complete chloroplast and ribosomal sequences for 30 accessions elucidate evolution of Oryza AA genome species.

Cytoplasmic chloroplast (cp) genomes and nuclear ribosomal DNA (nR) are the primary sequences used to understand plant diversity and evolution. We introduce a high-throughput method to simultaneously obtain complete cp and nR sequences using Illumina platform whole-genome sequence. We applied the method to 30 rice specimens belonging to nine Oryza species. Concurrent phylogenomic analysis using cp and nR of several of specimens of the same Oryza AA genome species provides insight into the evolution and domestication of cultivated rice, clarifying three ambiguous but important issues in the evolution of wild Oryza species. First, cp-based trees clearly classify each lineage but can be biased by inter-subspecies cross-hybridization events during speciation. Second, O. glumaepatula, a South American wild rice, includes two cytoplasm types, one of which is derived from a recent interspecies hybridization with O. longistminata. Third, the Australian O. rufipogan-type rice is a perennial form of O. meridionalis.

Comprehensive Survey of Genetic Diversity in Chloroplast Genomes and 45S nrDNAs within Panax ginseng Species.

We report complete sequences of chloroplast (cp) genome and 45S nuclear ribosomal DNA (45S nrDNA) for 11 Panax ginseng cultivars. We have obtained complete sequences of cp and 45S nrDNA, the representative barcoding target sequences for cytoplasm and nuclear genome, respectively, based on low coverage NGS sequence of each cultivar. The cp genomes sizes ranged from 156,241 to 156,425 bp and the major size variation was derived from differences in copy number of tandem repeats in the ycf1 gene and in the intergenic regions of rps16-trnUUG and rpl32-trnUAG. The complete 45S nrDNA unit sequences were 11,091 bp, representing a consensus single transcriptional unit with an intergenic spacer region. Comparative analysis of these sequences as well as those previously reported for three Chinese accessions identified very rare but unique polymorphism in the cp genome within P. ginseng cultivars. There were 12 intra-species polymorphisms (six SNPs and six InDels) among 14 cultivars. We also identified five SNPs from 45S nrDNA of 11 Korean ginseng cultivars. From the 17 unique informative polymorphic sites, we developed six reliable markers for analysis of ginseng diversity and cultivar authentication.

Comprehensive analysis of Panax ginseng root transcriptomes.

BACKGROUND: Korean ginseng (Panax ginseng C.A. Meyer) is a highly effective medicinal plant containing ginsenosides with various pharmacological activities, whose roots are produced commercially for crude drugs. RESULTS: Here, we used the Illumina platform to generate over 232 million RNA sequencing reads from four root samples, including whole roots from one-year-old plants and three types of root tissue from six-year-old plants (i.e., main root bodies, rhizomes, and lateral roots). Through de novo assembly and reference-assisted selection, we obtained a non-redundant unigene set consisting of 55,949 transcripts with an average length of 1,250 bp. Among transcripts in the unigene set, 94 % were functionally annotated via similarity searches against protein databases. Approximately 28.6 % of the transcripts represent novel gene sequences that have not previously been reported for P. ginseng. Digital expression profiling revealed 364 genes showing differential expression patterns among the four root samples. Additionally, 32 were uniquely expressed in one-year-old roots, while seven were uniquely expressed in six-year-old root tissues. We identified 38 transcripts encoding enzymes involved in ginsenoside biosynthesis pathways and 189 encoding UDP-glycosyltransferases. CONCLUSION: Our analysis provides new insights into the role of the root transcriptome in development and secondary metabolite biosynthesis in P. ginseng.

Genome-wide SNP identification and QTL mapping for black rot resistance in cabbage.

BACKGROUND: Black rot is a destructive bacterial disease causing large yield and quality losses in Brassica oleracea. To detect quantitative trait loci (QTL) for black rot resistance, we performed whole-genome resequencing of two cabbage parental lines and genome-wide SNP identification using the recently published B. oleracea genome sequences as reference. RESULTS: Approximately 11.5 Gb of sequencing data was produced from each parental line. Reference genome-guided mapping and SNP calling revealed 674,521 SNPs between the two cabbage lines, with an average of one SNP per 662.5 bp. Among 167 dCAPS markers derived from candidate SNPs, 117 (70.1%) were validated as bona fide SNPs showing polymorphism between the parental lines. We then improved the resolution of a previous genetic map by adding 103 markers including 87 SNP-based dCAPS markers. The new map composed of 368 markers and covers 1467.3 cM with an average interval of 3.88 cM between adjacent markers. We evaluated black rot resistance in the mapping population in three independent inoculation tests using F2:3 progenies and identified one major QTL and three minor QTLs. CONCLUSION: We report successful utilization of whole-genome resequencing for large-scale SNP identification and development of molecular markers for genetic map construction. In addition, we identified novel QTLs for black rot resistance. The high-density genetic map will promote QTL analysis for other important agricultural traits and marker-assisted breeding of B. oleracea.