Genetic diversity and structure of Saussurea polylepis (Asteraceae) on continental islands of Korea: Implications for conservation strategies and management.

Saussurea polylepis Nakai is an herbaceous perennial endemic to Korea and is highly restricted to several continental islands in the southwestern part of the Korean Peninsula. Given its very narrow geographical distribution, it is more vulnerable to anthropogenic activities and global climate changes than more widely distributed species. Despite the need for comprehensive genetic information for conservation and management, no such population genetic studies of S. polylepis have been conducted. In this study, genetic diversity and population structure were evaluated for 97 individuals from 5 populations (Gwanmaedo, Gageodo, Hongdo, Heusando, and Uido) using 19 polymorphic microsatellites. The populations were separated by a distance of 20-90 km. We found moderate levels of genetic diversity in S. polylepis (Ho = 0.42, He = 0.43). This may be due to long lifespans, outcrossing, and gene flow, despite its narrow range. High levels of gene flow (Nm = 1.76, mean Fst = 0.09), especially from wind-dispersed seeds, would contribute to low levels of genetic differentiation among populations. However, the small population size and reduced number of individuals in the reproductive phase of S. polylepis can be a major threat leading to inbreeding depression and genetic diversity loss. Bayesian cluster analysis revealed three significant structures at K = 3, consistent with DAPC and UPGMA. It is thought that sea level rise after the last glacial maximum may have acted as a geographical barrier, limiting the gene flow that would lead to distinct population structures. We proposed the Heuksando population, which is the largest island inhabited by S. polylepis, as a source population because of its large population size and high genetic diversity. Four management units (Gwanmaedo, Gageodo, Hongdo-Heuksando, and Uido) were suggested for conservation considering population size, genetic diversity, population structure, unique alleles, and geographical location (e.g., proximity).

Genetic diversity and population structure of the endangered orchid Pelatantheria scolopendrifolia (Orchidaceae) in Korea.

Due to substantial population decline, the Korean orchid P. scolopendrifolia is considered endangered and highly threatened. Like many endangered species, it is vulnerable to biological and anthropogenic threats that can lead to the loss of genetic diversity and, ultimately, extinction. Therefore, the assessment of genetic diversity and population genetic structure is imperative for conservation. In this study, we newly developed 15 polymorphic microsatellite markers. Analyses of genetic diversity and population genetic structure that included 182 samples from 11 populations were conducted using microsatellite markers and four noncoding regions of chloroplast DNA. Our study revealed a relatively low level of genetic diversity (Ho = 0.529, He = 0.356), albeit harboring with private alleles based on microsatellite genotyping data, and high haplotype diversities based on chloroplast DNA sequences data. The results of STRUCTURE and PCoA based on microsatellite genotyping data showed population differentiations. An AMOVA based on chloroplast DNA sequence data further corroborated these conclusions, indicating about 70% of variations found among populations. Low genetic diversity and divergence among the population might have been caused by factors, such as asexual reproduction, demographic events (bottleneck and population expansion), geographic isolation, and low gene flow. The development and implication of conservation strategies and management of P. scolopendrifolia are proposed based on these results.

Microsatellite markers for Saussurea polylepis (Asteraceae), a vulnerable continental island species endemic to Korea.

PREMISE: Nuclear microsatellite markers were developed for Saussurea polylepis (Asteraceae), a vulnerable species with very limited distribution in a few southwestern continental islands of the Korean peninsula, in order to facilitate future population genetic studies. METHODS AND RESULTS: Based on the Illumina sequence data, a total of 21 microsatellite primer pairs were designed and tested for their suitability. Nineteen of these primers, with two to 11 alleles per locus, were polymorphic in three natural populations of S. polylepis. The levels of expected and observed heterozygosity ranged from 0.000 to 0.842 and 0.000 to 0.933, respectively. Sixteen of these simple sequence repeat (SSR) markers were successfully cross-amplified in five congeneric species, namely S. gracilis, S. grandifolia, and S. tanakae for all 21 loci, and S. maximowiczii and S. pulchella for 18 loci. CONCLUSIONS: The SSR markers developed here will be useful for future population genetic studies on S. polylepis and related species.

Two complete chloroplast genomes of an endangered orchid species, Pelatantheria scolopendrifolia (Orchidaceae), in Korea.

We determined the complete chloroplast genome sequence of two individuals of Pelatantheria scolopendrifolia, an endangered orchid species in Korea. The total chloroplast genome size of Mokpo (MG752972) and Naju (MG752973) population was 146,971 bp and 146,848 bp, respectively. The chloroplast genome contained 106 genes, including 72 protein-coding genes, 30 tRNA genes, and four rRNA genes. Variation in gene contents and structures was not found between two individuals. We found truncated or deleted ndh genes in P. scolopendrifolia. Phylogenetic analysis, based on the whole chloroplast genome sequences of 25 species of Orchidaceae, showed that P. scolopendrifolia was most closely related to Gastrochilus fuscopunctatus.

The complete chloroplast genome sequence of Saussurea polylepis (Asteraceae), a vulnerable endemic species of Korea.

The complete chloroplast genome sequence of Saussurea polylepis, one of vulnerable and endemic species of Korea, was determined. The genome size was 152,488 bp in length with 37.7% GC content. It included a pair of inverted repeats (IRa and IRb) of 25,191 bp, which were separated by small single copy (SSC: 18,689 bp) and large single copy (LSC: 83,417 bp) regions. The cp genome contained 113 genes, including 80 protein-coding genes, 29 tRNA genes, and four rRNA genes. Phylogenetic analysis of the combined 80 protein coding genes and four rRNA genes showed that S. polylepis was closely related to S. chabyoungsanica.