SeonJoo Park

Complete Plastome Sequence of Thalictrum Coreanum (Ranunculaceae) and Transfer of the rpl32 Gene to the Nucleus in the Ancestor of the Subfamily Thalictroideae

BackgroundPlastids originated from cyanobacteria and the majority of the ancestral genes were lost or functionally transferred to the nucleus after endosymbiosis. Comparative genomic investigations have shown that gene transfer from plastids to the nucleus is an ongoing evolutionary process but molecular evidence for recent functional gene transfers among seed plants have only been documented for the four genes accD, infA, rpl22, and rpl32.ResultsThe complete plastid genome of Thalictrum coreanum, the first from the subfamily Thalictroideae (Ranunculaceae), was sequenced and revealed the losses of two genes, infA and rpl32. The functional transfer of these two genes to the nucleus in Thalictrum was verified by examination of nuclear transcriptomes. A survey of the phylogenetic distribution of the rpl32 loss was performed using 17 species of Thalictrum and representatives of related genera in the subfamily Thalictroideae. The plastid-encoded rpl32 gene is likely nonfunctional in members of the subfamily Thalictroideae (Aquilegia, Enemion, Isopyrum, Leptopyrum, Paraquilegia, and Semiaquilegia) including 17 Thalictrum species due to the presence of indels that disrupt the reading frame. A nuclear-encoded rpl32 with high sequence identity was identified in both Thalictrum and Aquilegia. The phylogenetic distribution of this gene loss/transfer and the high level of sequence similarity in transit peptides suggest a single transfer of the plastid-encoded rpl32 to the nucleus in the ancestor of the subfamily Thalictroideae approximately 20–32 Mya.ConclusionsThe genome sequence of Thalictrum coreanum provides valuable information for improving the understanding of the evolution of plastid genomes within Ranunculaceae and across angiosperms. Thalictrum is unusual among the three sequenced Ranunculaceae plastid genomes in the loss of two genes infA and rpl32, which have been functionally transferred to the nucleus. In the case of rpl32 this represents the third documented independent transfer from the plastid to the nucleus with the other two transfers occurring in the unrelated angiosperm families Rhizophoraceae and Salicaceae. Furthermore, the transfer of rpl32 provides additional molecular evidence for the monophyly of the subfamily Thalictroideae.

Analysis of the Complete Chloroplast Genome of a Medicinal Plant, Dianthus superbus var. longicalyncinus, from a Comparative Genomics Perspective

Dianthus superbus var. longicalycinus is an economically important traditional Chinese medicinal plant that is also used for ornamental purposes. In this study, D. superbus was compared to its closely related family of Caryophyllaceae chloroplast (cp) genomes such as Lychnis chalcedonica and Spinacia oleracea. D. superbus had the longest large single copy (LSC) region (82,805 bp), with some variations in the inverted repeat region A (IRA)/LSC regions. The IRs underwent both expansion and constriction during evolution of the Caryophyllaceae family; however, intense variations were not identified. The pseudogene ribosomal protein subunit S19 (rps19) was identified at the IRA/LSC junction, but was not present in the cp genome of other Caryophyllaceae family members. The translation initiation factor IF-1 (infA) and ribosomal protein subunit L23 (rpl23) genes were absent from the Dianthus cp genome. When the cp genome of Dianthus was compared with 31 other angiosperm lineages, the infA gene was found to have been lost in most members of rosids, solanales of asterids and Lychnis of Caryophyllales, whereas rpl23 gene loss or pseudogization had occurred exclusively in Caryophyllales. Nevertheless, the cp genome of Dianthus and Spinacia has two introns in the proteolytic subunit of ATP-dependent protease (clpP) gene, but Lychnis has lost introns from the clpP gene. Furthermore, phylogenetic analysis of individual protein-coding genes infA and rpl23 revealed that gene loss or pseudogenization occurred independently in the cp genome of Dianthus. Molecular phylogenetic analysis also demonstrated a sister relationship between Dianthus and Lychnis based on 78 protein-coding sequences. The results presented herein will contribute to studies of the evolution, molecular biology and genetic engineering of the medicinal and ornamental plant, D. superbus var. longicalycinus.

The Complete Chloroplast Genome Sequences of Three Veroniceae Species (Plantaginaceae): Comparative Analysis and Highly Divergent Regions

Previous studies of Veronica and related genera were weakly supported by molecular and paraphyletic taxa. Here, we report the complete chloroplast genome sequence of Veronica nakaiana and the related species Veronica persica and Veronicastrum sibiricum. The chloroplast genome length of V. nakaiana, V. persica, and V. sibiricum ranged from 150,198 bp to 152,930 bp. A total of 112 genes comprising 79 protein coding genes, 29 tRNA genes, and 4 rRNA genes were observed in three chloroplast genomes. The total number of SSRs was 48, 51, and 53 in V. nakaiana, V. persica, and V. sibiricum, respectively. Two SSRs (10 bp of AT and 12 bp of AATA) were observed in the same regions (rpoC2 and ndhD) in three chloroplast genomes. A comparison of coding genes and non-coding regions between V. nakaiana and V. persica revealed divergent sites, with the greatest variation occurring petD-rpoA region. The complete chloroplast genome sequence information regarding the three Veroniceae will be helpful for elucidating Veroniceae phylogenetic relationships.

The complete chloroplast genome sequence of Aster spathulifolius (Asteraceae); genomic features and relationship with Asteraceae.

Aster spathulifolius, a member of the Asteraceae family, is distributed along the coast of Japan and Korea. This plant is used for medicinal and ornamental purposes. The complete chloroplast (cp) genome of A. sphathulifolius consists of 149,473 bp that include a pair of inverted repeats of 24,751 bp separated by a large single copy region of 81,998 bp and a small single copy region of 17,973 bp. The chloroplast genome contains 78 coding genes, four rRNA genes and 29 tRNA genes. When compared to other cpDNA sequences of Asteraceae, A. spathulifolius showed the closest relationship with Jacobaea vulgaris, and its atpB gene was found to be a pseudogene, unlike J. vulgaris. Furthermore, evaluation of the gene compositions of J. vulgaris, Helianthus annuus, Guizotia abyssinica and A. spathulifolius revealed that 13.6-kb showed inversion from ndhF to rps15, unlike Lactuca of Asteraceae. Comparison of the synonymous (Ks) and nonsynonymous (Ka) substitution rates with J. vulgaris revealed that synonymous genes related to a small subunit of the ribosome showed the highest value (0.1558), while nonsynonymous rates of genes related to ATP synthase genes were highest (0.0118). These findings revealed that substitution has occurred at similar rates in most genes, and the substitution rates suggested that most genes is a purified selection.

The Complete Chloroplast Genome Sequence of Ampelopsis: Gene Organization, Comparative Analysis, and Phylogenetic Relationships to Other Angiosperms

Ampelopsis brevipedunculata is an economically important plant that belongs to the Vitaceae family of angiosperms. The phylogenetic placement of Vitaceae is still unresolved. Recent phylogenetic studies suggested that it should be placed in various alternative families including Caryophyllaceae, asteraceae, Saxifragaceae, Dilleniaceae, or with the rest of the rosid families. However, these analyses provided weak supportive results because they were based on only one of several genes. Accordingly, complete chloroplast genome sequences are required to resolve the phylogenetic relationships among angiosperms. Recent phylogenetic analyses based on the complete chloroplast genome sequence suggested strong support for the position of Vitaceae as the earliest diverging lineage of rosids and placed it as a sister to the remaining rosids. These studies also revealed relationships among several major lineages of angiosperms; however, they highlighted the significance of taxon sampling for obtaining accurate phylogenies. In the present study, we sequenced the complete chloroplast genome of A. brevipedunculata and used these data to assess the relationships among 32 angiosperms, including 18 taxa of rosids. The Ampelopsis chloroplast genome is 161,090 bp in length, and includes a pair of inverted repeats of 26,394 bp that are separated by small and large single copy regions of 19,036 bp and 89,266 bp, respectively. The gene content and order of Ampelopsis is identical to many other unrearranged angiosperm chloroplast genomes, including Vitis and tobacco. A phylogenetic tree constructed based on 70 protein-coding genes of 33 angiosperms showed that both Saxifragales and Vitaceae diverged from the rosid clade and formed two clades with 100% bootstrap value. The position of the Vitaceae is sister to Saxifragales, and both are the basal and earliest diverging lineages. Moreover, Saxifragales forms a sister clade to Vitaceae of rosids. Overall, the results of this study will contribute to better support of the evolution, molecular biology and genetic improvement of the plant Ampelopsis.

The Chloroplast Genome of Elaeagnus macrophylla and trnH Duplication Event in Elaeagnaceae.

Elaeagnaceae, which harbor nitrogen-fixing actinomycetes, is a plant family of the Rosales and sister to Rhamnaceae, Barbeyaceae and Dirachmaceae. The results of previous molecular studies have not strongly supported the families of Elaeagnaceae, Rhamnaceae, Barbeyaceae and Dirachmaceae. However, chloroplast genome studies provide valuable phylogenetic information; therefore, we determined the chloroplast genome of Elaeaganus macrophylla and compared it to that of Rosales such as IR junction and infA gene. The chloroplast genome of Elaeagnus macrophylla is 152,224 bp in length and the infA gene of E. macrophylla was psuedogenation. Phylogenetic analyses based on 79 genes in 30 species revealed that Elaeagnus was closely related to Morus. Comparison of the IR junction in six other rosids revealed that the trnH gene contained the LSC region, whereas E. macrophylla contained a trnH gene duplication in the IR region. Comparison of the LSC/IRb (JLB) and the IRa/LSC (JLA) regions of Elaeagnaceae (Elaeagnus and Shephedia) and Rhamnaceae (Rhamnus) showed that trnH gene duplication only occurred in the Elaeagnaceae. The complete chloroplast genome of Elaeagnus macrophylla provides unique characteristics in rosids. The infA gene has been lost or transferred to the nucleus in rosids, while E. macrophylla lost the infA gene. Evaluation of the chloroplast genome of Elaeagnus revealed trnH gene duplication for the first time in rosids. The availability of Elaeagnus cp genomes provides valuable information describing the relationship of Elaeagnaceae, Barbeyaceae and Dirachmaceae, IR junction that will be valuable to future systematics studies.

Phylogenetic Relationships of the Fern Cyrtomium falcatum (Dryopteridaceae) from Dokdo Island Based on Chloroplast Genome Sequencing

Cyrtomium falcatum is a popular ornamental fern cultivated worldwide. Native to the Korean Peninsula, Japan, and Dokdo Island in the Sea of Japan, it is the only fern present on Dokdo Island. We isolated and characterized the chloroplast (cp) genome of C. falcatum, and compared it with those of closely related species. The genes trnV-GAC and trnV-GAU were found to be present within the cp genome of C. falcatum, whereas trnP-GGG and rpl21 were lacking. Moreover, cp genomes of Cyrtomium devexiscapulae and Adiantum capillus-veneris lack trnP-GGG and rpl21, suggesting these are not conserved among angiosperm cp genomes. The deletion of trnR-UCG, trnR-CCG, and trnSeC in the cp genomes of C. falcatum and other eupolypod ferns indicates these genes are restricted to tree ferns, non-core leptosporangiates, and basal ferns. The C. falcatum cp genome also encoded ndhF and rps7, with GUG start codons that were only conserved in polypod ferns, and it shares two significant inversions with other ferns, including a minor inversion of the trnD-GUC region and an approximate 3 kb inversion of the trnG-trnT region. Phylogenetic analyses showed that Equisetum was found to be a sister clade to Psilotales-Ophioglossales with a 100% bootstrap (BS) value. The sister relationship between Pteridaceae and eupolypods was also strongly supported by a 100% BS, but Bayesian molecular clock analyses suggested that C. falcatum diversified in the mid-Paleogene period (45.15 ± 4.93 million years ago) and might have moved from Eurasia to Dokdo Island.

Genetic Diversity and Differentiation of a Narrowly Distributed and Endemic Species, Aster spathulifolius Maxim (Asteraceae), Revealed with Inter Simple Sequence Repeat Markers

Aster spathulifolius Maxim is a narrowly distributed and endemic species occurring in coastal regions of Korea and Japan. The genetic diversity and differentiation of fifteen populations of the species were analyzed in eight-two loci using six Inter Simple Sequence Repeat primers. Total genetic diversity at species level was extremely high (P=98.78%, Hsp=0.333±0.144, I=0.501±0.180), whereas the genetic diversity at population level was relatively low (P=43.74%, Hpop=0.150±0.189, I=0.227±0.274). High genetic differentiation among populations was detected based on genetic differentiation coefficient (Gst=0.549) and analysis of molecular variance (AP=54.06%). These findings together with low gene flow estimates (Nm=0.205) suggest that genetic drift by isolation is the most critical factor for establishing the current genetic structure of the species. The decrease in abundance of A. spathulifolius along with low levels of genetic diversity indicates that conservation strategies are necessary.

The Vascular Plants in Mt. Bohyeon, Gyeongbuk, Korea

This study was carried out to investigate the vascular plants of Mt. Bohyeon (Gyeongbuk). The vascular plants were collected 22 times and summarized as 589 taxa, including 105 families, 327 genera, 522 species, 11 subspecies, 48 varieties and 8 forms respectively. Among them, 13 Korean endemics, 10 red list of vascular plants, 2 endangered plants and 83 specially designated plants by the Ministry of Environment were included respectively. The naturalized plants were 37 taxa and the naturalized ratio was 6.41 of 589 taxa. Usage of 589 taxa were consists of 240 taxa (40.1%) of edible plants, 205 taxa (34.2%) of medicinal plants, 62 taxa (10.3%) of ornamental plants, 213 taxa (35.6%) of pasture plants, 15 taxa (2.5%) of timber plants, 8 taxa (1.3%) of fiberplants, and 3 taxa (0.5%) of industrial plants.

Complete chloroplast genome of Clematis fusca var. coreana (Ranunculaceae)

Abstract The complete chloroplast (cp) genome sequence of Clematis fusca var. coreana, an endemic plant in Korea, was determined. The genome size is 159,609 bp in length, with 38% GC content. A pair of inverted repeats (IRs) of 31,039 bp is separated by a large single copy (LSC) and a small single copy (SSC) of 79,478 bp and 18,053 bp, respectively. The complete cp genome contains 112 unique genes, including 79 coding genes, 4 rRNA genes, and 29 tRNA genes.