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Intraspecific genetic variation provides the information on the distributional pattern of plant species by inducing local adaptation, range shifts, and range reduction. Here, genetic variation of amplified fragment length polymorphism (AFLP) and three chloroplast DNA (cpDNA) regions (atpI-atpH, trnD-psbM, and trnT-L) is investigated in 37 populations of Camellia japonica to assess the genetic diversity and population structure. We also infer the phylogeographical history of C. japonica distributed in South Korea, Japan (Kyushu and Okinawa), and Taiwan of East Asia. The AFLP results reveal high levels of genetic diversity in C. japonica across East Asia. At the regional level, the Kyushu populations display the highest level of genetic variation, whereas the mainland populations of South Korea exhibit the lowest level of variation. Our results show trends of loss of genetic diversity along with latitude. On the basis of 154 polymorphic sites of the combined three cpDNA regions, 11 haplotypes (A-K) were identified across the East Asian C. japonica populations. Haplotypes A-C are dominant and widespread in South Korea and Japan, while Haplotypes G, I, and J in Taiwan. In addition, five haplotypes (A, B, D-F) are exclusively occur in South Korea/Japan and five (G-K) are in Taiwan. Our molecular dating analysis estimates the age of initial diversification of C. japonica haplotypes in the late Tertiary. The phylogeographic patterns of C. japonica coupled with molecular dating suggest vicariance as key mechanism for initial diversification between South Korea/Japan and Taiwan. In contrast, the haplotypes of Japan are shared with those of South Korea indicating that they had insufficient time to form population structures at the regional level.

Recent advances in phylogenetics indicate that reticulate evolution has played an important role in the emergence of Isoetes species in the North Pacific region. However, the biogeographical origin of the North Pacific Isoetes species remains contentious. We present a fossilcalibrated phylogeny of species from the North Pacific region based on molecular data. Within this framework, we discuss their ancestral areas and biogeographical history. North Pacific Isoetes are divided into two clades: clade I, consisting of East Asian, Papua New Guinean, and Australian species, and clade II, consisting of West Beringian and western North American species. Within clade I, Australian Isoetes species were an early divergent group, and Papua New Guinea’s species form a sister clade to the East Asian species. Biogeographical reconstructions suggest an Australasian origin for the East Asian species that arose through long-distance dispersal during the late Oligocene. Within clade II, I. asiatica from West Beringia forms a clade with I. echinospora and I. muricata from Alaska. Western North America was the area of origin for the dispersal of Isoetes species to West Beringia via the Bering land bridge during the late Miocene. Our study identifies the biogeographic origin of the North Pacific Isoetes and suggests long-distance dispersal as the most likely explanation for their intercontinental distribution.

Genetic variation of nuclear ribosomal ITS (nrITS) and chloroplast DNA (cpDNA) regions was investigated in Brasenia schreberi (Cabombaceae) to assess the population structure and to infer the evolutionary relationship among 12 populations distributed in South Korea. The combined sequence of the two regions was aligned to 2,069 bp, of which 28 sites were variable. In total, 20 genotypes were identified from 240 individuals of B. schreberi. Genotype diversity (Gd) and nucleotide diversity (Pi) on Jeju Island (Gd = 0.2511, Pi = 0.00012) were higher than those of the mainland of South Korea (Gd = 0.1358, Pi = 0.00005). The relatively low level of genetic variation of the mainland populations is associated with its higher genetic differentiation (G ST = 0.095 on mainland and 0.039 on Jeju Island) and human activities. Minimum spanning network analysis demonstrated that the investigated populations of B. schreberi were subdivided into two geographical groups: the mainland of South Korea and Jeju Island. In addition, analysis of molecular variation showed that a large proportion (73.55%) of genetic differentiation existed between the two regions. These results strongly suggest the presence of significant barriers to gene flow between regions. Thus, the management unit for B. schreberi should be carefully designed to avoid the potential risk that can results from the admixture of individuals from the mainland and Jeju Island regions.

On the basis of amplified fragment length polymorphism (AFLP) and nucleotide sequence data from nuclear ribosomal internal transcribed spacer (nrITS) and three chloroplast DNA regions (rbcL, cpITS, and trnS-psbC spacer), we investigated the species delimitation and the evolutionary lineage of Isoetes asiatica from Hokkaido, Japan. The neighbor-joining (NJ) dendrogram based on AFLP markers revealed the well-defined clusters (bootstrap value = 100%) of I. asiatica. Results from the principal component analysis are largely congruent with those obtained in the NJ dendrogram. The maximum parsimony analysis, based on data from nrITS and three chloroplast DNA sequences, supported a monophyly of three species, I. asiatica, Isoetes echinospora, and Isoetes maritima from Hokkaido, Kamchatka, and Alaska regions. The distinct species status of I. asiatica was also well supported in the combined chloroplast DNA phylogeny. Therefore, I. asiatica appear to represent example of gradual speciation due to spatial isolation of ancestral populations followed by genetic divergence. Our results also suggest that I. asiatica is probably not the ancestral diploid of the polyploids occurring in East Asia.

We name and describe two new species,Isoetes jejuensis and I.hallasanensis, from Jeju Island, South Korea. These taxa are compared with related species in East Asia, including I.coreana andI. sinensis. The rugulate megaspore ornamentation ofI. jejuensis differs from those otherIsoetes species. Furthermore,I. hallasanensis varies fromI. asiatica in its microspore ornamentation and chromosome number, although both species have an echinate megaspore ornamentation. These new species are tetraploid (2n = 44), whereasI. coreana is hexaploid (2n = 66).

A previously unrecordedTypha species has been found in Korea. Its morphology is characterized by short plant height (1.0 ± 0.2 m), narrow leaves (3.2 ± 0.9 mm), short pistillate inflorescences (4.7 ±1.4 cm), and a high ratio of staminate inflorescence length to pistillate inflorescence length (2.2 ± 0.4). Because these characters are identical to the original description ofTypha laxmanni Lepechin, we can now report its distribution in Korea.

The taxonomic status ofLigusticum tenuissimum (Nakai) Kitagawa andLibanotis coreana (Wolff) Kitagawa has been controversial in Korea. We examined their phylogenetic relationships by comparing the internal transcribed spacer (=ITS) sequences of the nuclear ribosomal RNA gene (=rDNA) with another seven species in the Korean Umbelliferae. Our results support the legitimacy of the nomenclatural combination withL. tenuissimum Kitagawa rather than withAngelica tenuissima Nakai. We also suggest usingL coreana (Wolff) Kitagawa instead ofSeseli coreanum Wolff becauseL. coreana has been completely separated from most taxa of the genusSeseli. In addition, we have confirmed at least three phylogenetic lines in the genusLigusticum. One is the core group ofLigusticum that comprisesL tenuissimum and four other species. This clade includes theLigusticum hultenii line andLigusticum scothicum, known as an anomaly ofLigusticum. The second clade is composed ofLigusticum physospermifolium withSeseli monatum, which indicates the polyphyly ofLigusticum. The third line isLigusticum acutilobum, clustered as a sister grade ofDystaenia.

For the cloning of nuclear ribosomal DNA (rDNA) fromBupleurum euphorbioides (Apiaceae), ten clones were screened by DNA-DNA hybridization method. Among them, two clones were strongly hybridized with a heterologous probe of rice rDNA and with an autologous probe of an internally-transcribed region ofB. euphorbioides amplified by PCR. We sequenced both ends of the two genomic clones aligned with a known sequence of rDNA. ITS2 sequences of the two clones showed 98% and 83% homology with the ITS2 sequence ofB. euphorbioides. Our clones showed 1 bp and 3 bp nucleotide substitutions in the 25S and intergenic spacer regions, respectively, and the ITS1 and 18S regions were both missing. Restriction enzyme sites and the orientation of both clones were analyzed for physical mapping purposes. Apart from the length difference between the two clones, we found restriction site variations in the 25S and intergenic spacer regions.