Comparison of genetic diversity in the two arctic–alpine plants Diapensia lapponica var. obovata (Diapensiaceae) and Empetrum nigrum var. japonicum (Empetraceae) between Sakhalin in Russian Far East and Jeju Island in Korea, the southernmost edge of their distribution range

Optimized ultrasound-assisted extraction of total polyphenols from Empetrum nigrum and its bioactivities

Optimization of ultrasound-assisted extraction (UAE) of total polyphenols (TPP) from Empetrum nigrum aerial parts was carried out by response surface methodology (RSM). The optimum UAE conditions of extraction time, extraction temperature, ethanol concentration, and solvent-to-material ratio were 21.38 min, 42.32 °C, 61.93% and 53.29:1 mL/g, respectively. Under the optimum conditions, the extraction yield of TPP was 32.17 ± 0.46 mg/g, which was 1.29-1.44 folds to those by the conventional extraction methods. In addition, the bioactivities of the extracts were investigated. Antioxidant activity test by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay revealed that the TPP extracts had a high potential for free radical scavenging activity. The TPP extracts showed remarkable antibacterial activity against both Gram-positive and Gram-negative strains, especially against Gram-positive strains. The evaluation of antitumor activity by the MTT assay and flow cytometric analysis indicated that the TPP extracts significantly inhibited B 16F 10 melanoma cell proliferation and effectively induced apoptosis of melanoma cells. These results demonstrate that E. nigrum aerial parts are rich in TPP and show great application potential in the pharmaceutical industry.

Was Jeju Island a glacial refugium for East Asian warm-temperate plants? Insights from the homosporous fern Selliguea hastata (Polypodiaceae)

PREMISE OF THE STUDY

We posed two hypotheses for broad scenarios of postglacial recolonization of Korea by the warm-temperate vegetation: (1) that extant Korean populations are derived from a single refugium, or (2) that they are derived from multiple refugia. We chose a homosporous fern typical of East Asian warm-temperate vegetation, Selliguea hastata, to test which of the two scenarios is more likely and to check whether Japan contained putative glacial refugia.

METHODS

Using 16 allozyme loci, we obtained genotypes of 756 individuals from 20 populations, representative of the whole distribution area in Korea (including Jeju Island), Japan, and Taiwan. We assessed genetic variability within and among populations, Wright's F-statistics, and conducted analysis of molecular variance, model-based Bayesian clustering, and bottleneck tests.

KEY RESULTS

We found no allozyme variation within populations of S. hastata in mainland Korea, whereas genetic polymorphism was detected for populations from Jeju Island, Japan (in particular a population from southeastern Shikoku), and Taiwan. The levels of inbreeding within populations were high, consistent with the potential of S. hastata for intragametophytic selfing.

CONCLUSIONS

Data on allelic richness together with Bayesian clustering methods suggest a pattern of postglacial recolonization of mainland Korea from a single refugium, probably located either on Jeju Island or in Japan. Jeju Island should merit the highest priority for conservation biogeography, as it played a role as a Quaternary refugium for arctic-alpine, boreal, temperate as well as warm-temperate plants, as suggested here.