Dong-Hyuk Lee

Phylogeography and genetic diversity of East Asian Neolitsea sericea (Lauraceae) based on variations in chloroplast DNA sequences

Neolitseasericea is an evergreen broad leaved tree in the warm-temperate regions of East Asia. This area is a hotspot for plant species richness and endemism caused by dynamic changes in land configuration during the Quaternary. However, the historical migration of such evergreen tree species is still poorly understood. In an attempt to reconstruct the phylogeographic history of N. sericea during the Quaternary, we identified the chloroplast DNA haplotypes of 287 individuals from 33 populations covering almost all of its geographic range. Analyses were based on sequence data from the trnL–F, psbC–trnS, and rps16 regions. Nine haplotypes were identified. The majority included ancestral types in the southwestern part of the main islands of Japan, with other region-specific haplotypes being found in populations on the Korean Peninsula, Taiwan (Isl. Lanyu), and elsewhere in Japan. A statistical parsimony network revealed two lineages derived from Japanese main islands. One was represented on the Korean Peninsula, the other on Isl. Lanyu. The current distribution of N. sericea has been shaped by colonization via land bridges. During the glacial periods, two primary, but separate migration routes were followed—from the southwestern part of the Japanese main islands to either the Korean Peninsula or Taiwan. In addition, we believe the Zhoushan populations were shaped by post-glacial processes through an ECS land bridge (East China Sea basin) from northern refugia that existed during the late Pleistocene.

Genetic diversity and historical migration patterns of an endemic evergreen oak, Quercus acuta , across Korea and Japan, inferred from nuclear microsatellites

Forests dominated by broad-leaved evergreen trees cover a narrow zone of the southern coast of Korea as well as warm-temperate and subtropical regions of Japan. However, little is known about their establishment history, especially in Korea. Endemic Quercus acuta grows in Korea and Japan. We evaluated its genetic diversity, population structure, and degree of lineage admixture in terms of its distribution history. Analyses utilized seven nuclear microsatellites that were genotyped from 330 individuals of 16 populations. Genetic diversity was highest for the Japanese Kyushu populations. The allelic diversity of populations was similar between Jeju Island and Kyushu, implying that they are putative refugia. Although the mean FST value was very low, patterns for isolation-by-distance were strong and significant. Results from Bayesian clustering and Monmonier’s algorithm indicated that populations are roughly partitioned from west (Korea and Kyushu) to east (Japanese Honshu). Therefore, the two divisions within this species are demographically independent and may have arisen due to past fragmentation. In considering the mixed genetic structure between Korea and Kyushu populations, and the higher levels of genetic diversity in mainland Korea relative to Honshu, we hypothesized that this species has been able to survive within Jeju Island and Kyushu. Consequently, mainland Korea populations might have been shaped by range expansion that kept them well mixed from a continuous and large genetic resource.

Complete Plastome Sequencing Reveals an Extremely Diminished SSC Region in Hemiparasitic Pedicularis ishidoyana (Orobanchaceae)

The species within Orobanchaceae cover all forms of parasitism from full autotrophy to holoparasitism. Although parasitic species have gone through dramatic genome changes, the plastomes of land plants generally contain highly conserved structures. We investigated the complete plastome sequence of hemiparasitic Pedicularis ishidoyana, belonging to the largest genus in Orobanchaceae, and compared it with the highly rearranged genomes of other taxa in that family. This plastome comprises a total of 152 571 bp, with two inverted repeats (IRs) of 35 281 bp, a large single-copy region (LSC) of 81 982 bp, and an extremely reduced small single-copy (SSC) region of 27 bp. Although IR expansion and SSC contraction have been reported in the plastomes of other hemiparasitic species in Orobanchaceae, the IR region of P. ishidoyana is extremely expanded, resulting in a very small SSC region. This genome contains 101 genes that encode 67 proteins, four rRNAs, 30 tRNAs, and 22 duplicated genes in the IR region. In contrast to other hemi- or holoparasitic members of Orobanchaceae, genes in the ndh family in P. ishidoyana (except ndhE) have lost their function through pseudogenization (six genes) or deletion (four genes). Therefore, it seems that the degradation of this gene family in P. ishidoyana has occurred independently. Phylogenetic analysis, including all parasitic types, strongly supports the conclusion that P. ishidoyana diverged early from autotrophs and is sister to holoparasitic taxa. Our results suggest that these hemiparasitic Pedicularis plants might represent an early stage of parasitism that has developed stepwise in this family from non-parasites to holoparasites.

Isolation and Characterization of 13 Microsatellite Loci from a Korean Endemic Species, Sophora koreensis (Fabaceae)

To evaluate the population genetics structure as a means of devising conservation strategies, we developed microsatellite primers for Sophora koreensis, a narrowly endemic and endangered species in Korea. Thirteen polymorphic microsatellite markers were developed in Korean populations of S. koreensis. Genetic diversity was analyzed in 40 individuals from two populations. The number of alleles per locus ranged from 4 to 14, with observed and expected heterozygosities ranging from 0.200 to 1.000 and from 0.189 to 0.864, respectively. The microsatellite markers described here are valuable tools for the population genetics research of S. koreensis. They can be used to obtain information for creating suitable management strategies to conserve this endemic and endangered species.

The complete chloroplast genome of hemi-parasitic Pedicularis hallaisanensis (Orobanchaceae)

Abstract We determined the complete chloroplast genome of Pedicularis hallaisanensis (Orobanchaceae), a hemi-parasitic perennial herb. This genome is 143,469 bp long and features a large single-copy region (81,664 bp) and a small single-copy region (12,203 bp), separated by two inverted-repeat regions (24,801 bp each). It contains 115 genes – 70 for coding, eight for rRNA, and 37 for tRNA. However, 11 ndh genes have been pseudogenized, truncated, or deleted. Our phylogenetic tree showed that these hemi-parasitic plants are sister to holo-parasitic genera within Orobanchaceae.

The complete plastid genome of Suaeda malacosperma (Amaranthaceae/Chenopodiaceae), a vulnerable halophyte in coastal regions of Korea and Japan

Abstract Suaeda malacosperma has limited distribution in the coastal regions of Korea and Japan and is named as a vulnerable halophyte in the Red List of Japan. The complete plastid genome of S. malacosperma is 151,989 bp long, and is composed of large single-copy (83,492 bp) and small single-copy (18,121 bp) regions plus two inverted repeats (25,188 bp each). The plastid genome encodes 130 genes, including 8 rRNAs, 37 tRNAs, and 83 protein-coding genes. rpl23 is pseudogenized. Phylogenetic analysis showed a sister relationship between Suaeda and Bienertia. This complete plastid genome is the first reported in genus Suaeda.

The establishment history of alpine Leontopodium japonicum (Asteraceae) resembles that of warm-temperate plants on the Korean Peninsula

Historical migration patterns of boreal and alpine plants have had a narrow focus on the Korean Peninsula, generally being characterized as southern relics from northern-sourced populations. Here, we present another hypothesis for the pattern associated with Korean alpine species. A genetic analysis was conducted with Leontopodium japonicum Miq., which grows in high mountain ranges with a disjunct distribution across Korea, China, and Japan. We inferred its phylogeography using sequences of nuclear (ITS) and chloroplast DNA (trnL–F, rps16, and rpl16) for 11 populations from Korea and adjacent regions. Our molecular data (SAMOVA and network analyses) revealed a distinct genetic isolation of Korean populations with the highest genetic differentiation (Korea vs. China and Japan). By comparison, a nonsignificant level of differentiation, but a high degree of genetic diversity, was detected between Chinese and Japanese populations, resembling that of warm-temperate species. These findings demonstrate that, rather than migrating southward from more northern latitudes, current populations in Korea are distributed due to colonization via East China Sea land bridges, similar to movement by warm-temperate species. Furthermore, geographical isolation because of an oceanic barrier has led to allopatric speciation for Korean populations. This specific scenario for L. japonicum is a meaningful example that will enhance our understanding of the history of plants growing in alpine (or subalpine) zones of Korea.