Hyun Oh Lee

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.

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.

Exceptional reduction of the plastid genome of saguaro cactus (Carnegiea gigantea): Loss of the ndh gene suite and inverted repeat

UNLABELLED • PREMISE OF THE STUDY Land-plant plastid genomes have only rarely undergone significant changes in gene content and order. Thus, discovery of additional examples adds power to tests for causes of such genome-scale structural changes.• METHODS Using next-generation sequence data, we assembled the plastid genome of saguaro cactus and probed the nuclear genome for transferred plastid genes and functionally related nuclear genes. We combined these results with available data across Cactaceae and seed plants more broadly to infer the history of gene loss and to assess the strength of phylogenetic association between gene loss and loss of the inverted repeat (IR).• KEY RESULTS The saguaro plastid genome is the smallest known for an obligately photosynthetic angiosperm (∼113 kb), having lost the IR and plastid ndh genes. This loss supports a statistically strong association across seed plants between the loss of ndh genes and the loss of the IR. Many nonplastid copies of plastid ndh genes were found in the nuclear genome, but none had intact reading frames; nor did three related nuclear-encoded subunits. However, nuclear pgr5, which functions in a partially redundant pathway, was intact.• CONCLUSIONS The existence of an alternative pathway redundant with the function of the plastid NADH dehydrogenase-like complex (NDH) complex may permit loss of the plastid ndh gene suite in photoautotrophs like saguaro. Loss of these genes may be a recurring mechanism for overall plastid genome size reduction, especially in combination with loss of the IR.

Comprehensive analysis of Panax ginseng root transcriptomes

BackgroundKorean 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.ResultsHere, 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.ConclusionOur analysis provides new insights into the role of the root transcriptome in development and secondary metabolite biosynthesis in P. ginseng.

Association of molecular markers derived from the BrCRISTO1 gene with prolycopene‑enriched orange‑colored leaves in Brassica rapa

AbstractKey messageSequence polymorphism inBrCRTISO1, encodingcarotenoid isomerase, is identified in orange-coloredB. rapa, and three resulting gene-based markers will be useful for marker-assisted breeding of OC cultivars.Abstract Carotenoids are color pigments that are important for protection against excess light in plants and essential sources of retinols and vitamin A for animals. We identified a single recessive gene that might cause orange-colored (OC) inner leaves in Brassica rapa. The inner leaves of the OC cultivar were enriched in lycopene-like compounds, specifically prolycopene and its isomers, which can be a useful functional trait for Kimchi cabbage. We used a candidate gene approach based on the 21 genes in the carotenoid pathway to identify a candidate gene responsible for the orange color. Among them, we focused on two carotenoid isomerase (CRTISO) genes, BrCRTISO1 and BrCRTISO2. The expression of BrCRTISO1 was higher than that of BrCRTISO2 in a normal yellow-colored (YE) cultivar, but full-length BrCRTISO1 transcripts were not detected in the OC cultivar. Genomic sequence analysis revealed that BrCRTISO1 of the OC cultivar had many sequence variations, including single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels), compared to that of the YE cultivar. We developed molecular makers for the identification of OC phenotype based on the polymorphic regions within BrCRTISO1 in B. rapa breeding. The BrCRTISO1 gene and its markers identified in this study are novel genetic resources and will be useful for studying the carotenoid biosynthesis pathway as well as developing new cultivars with unique carotenoid contents in Brassica species.

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

Abstract 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.

Analysis of expressed sequence tags from a normalized cDNA library of perilla (Perilla frutescens)

Perilla (Perilla frutescens), an herbal plant belonging to the Lamiaceae family, has long been cultivated in Asia. Perilla is notable as an aroma-rich leaf vegetable and as the oilseed crop richest in omega-3 fatty acids. However, molecular analysis of this herbal plant is lacking due to insufficient genetic resources. Here, we constructed a normalized cDNA library from whole young perilla plants and analyzed expressed sequence tags (ESTs). A total of 4,582 uniESTs were generated from analysis of 5,435 ESTs. Among these, 307 uniESTs (6.7%) were identified as unique in perilla and 3,625 uniESTs were assigned at least one GO term through similarity searches in public databases. The most frequent GO terms were related to abiotic and biotic stress responses. In addition, we identified 141 uniESTs involved in lipid metabolism, of which four genes encoded fatty acid desaturases. We found one new candidate omega-3 fatty acid desaturase gene, in addition to the four that were previously reported. This analysis of uniESTs from perilla provides a valuable genetic resource to elucidate the molecular underpinnings of lipid metabolism and for molecular breeding of perilla species.

The complete chloroplast genome sequence of the Taraxacum officinale F.H.Wigg (Asteraceae)

Abstract Taraxacum officinale is a distributed weedy plant used as a traditional medicinal herb belonging to the family Asteraceae. The complete chloroplast genome of T. officinale was generated by de novo assembly with whole genome sequence data. The chloroplast genome was 151 324 bp in length, which consisted of a large single copy region of 83 895 bp and a short single copy region of 18 549 bp separated by a pair of inverted repeat regions of 24 440 bp. The chloroplast genome contained 79 protein-coding genes, 29 tRNA genes and four rRNA genes. Phylogenetic analysis revealed that T. officinale was closely related to Lactuca sativa.

Complete chloroplast genome sequence of Artemisia fukudo Makino (Asteraceae)

Abstract In this study, a complete chloroplast genome sequence of Artemisia fukudo (Asteraceae family) was characterized by de novo assembly using whole genome sequence data. The chloroplast genome was 151,011 bp in length, comprising a large single-copy region of 82,751 bp, a small single copy region of 18,348 bp and a pair of inverted repeats of 24,956 bp. The genome contained 80 protein-coding genes, 4 rRNA genes and 30 tRNA genes. Phylogenetic tree revealed that A. fukudo was closely located in other Artemisia species, Artemisia montana and Artemisia frigida.

The complete chloroplast genome of Eclipta prostrata L. (Asteraceae)

Abstract Eclipta prostrata is an herbal medicinal plant belonging to the Asteraceae family. In this study, complete chloroplast genome sequence of the E. prostrata was characterized by de novo assembly using whole genome sequence data. The genome of E. prostrata was 151,757 bp in length, which was composed of large single copy region of 83,285 bp, small single copy region of 18,346 bp and a pair of inverted repeat regions of 25,063 bp. The genome harboured 80 protein coding sequences, 30 tRNA genes and 4 rRNA genes. We confirmed close taxonomic relationship between E. prostrata and Helianthus annuus through phylogenetic analysis with chloroplast protein-coding genes.