• Korean Journal of Plant Taxonomy
• /
• v.38 no.3
• /
• pp.233-250
• /
• 2008

Morphological and molecular data from the nuclear ribosomal ITS regions were examined to reevaluate the taxonomic position of the Korean endemic species, Stewartia koreana Nakai ex Rehder (Theaceae). Comparing to its morphologically closely related S. pseudocamellia Maxim, S. koreana has diagnostic characters including a larger leaf blade (10 cm length and 5.5 cm wide) and a longer pedicel (2.5 cm length). In addition, S. koreana formed a different clade from S. pseudocamellia in the ITS trees. The morphological and ITS sequence data supported S. koreana as a Korean endemic species distinct from the closely related species, S. pseudocamellia.

• Horticultural Science & Technology
• /
• v.29 no.2
• /
• pp.116-122
• /
• 2011

In this study, we report the generation and analysis of 1,392 expressed sequence tags (ESTs) from Korean Stewartia (Stewartia koreana Nakai). A cDNA library was generated from the young leaf tissue and a total of 1,392 cDNA were partially sequenced. EST and unigene sequence quality were determined by computational filtering, manual review, and BLAST analyses. Finally, 1,301 ESTs were acquired after the removal of the vector sequence and filtering over a minimum length 100 nucleotides. A total of 893 unigene, consisting of 150 contigs and 743 singletons, was identified after assembling. Also, we identified 95 new microsatellite-containing sequences from the unigenes and classified the structure according to their repeat unit. According to homology search with BLASTX against the NCBI database, 65% of ESTs were homologous with known function and 11.6% of ESTs were matched with putative or unknown function. The remaining 23.2% of ESTs showed no significant similarity to any protein sequences found in the public database. Annotation based searches against multiple databases including wine grape and populus sequences helped to identify putative functions of ESTs and unigenes. Gene ontology (GO) classification showed that the most abundant GO terms were transport, nucleotide binding, plastid, in terms biological process, molecular function and cellular component, respectively. The sequence data will be used to characterize potential roles of new genes in Stewartia and provided for the useful tools as a genetic resource.

• Korean Journal of Plant Resources
• /
• v.17 no.3
• /
• pp.272-277
• /
• 2004

Zygotic embryos of Stewartia korean Nakai were cultured to determine the effects both of BA and NAA on adventitious shoot induction. Multiple shoots (about 11 per explant) were formed when the embryos were treated with 1.0 mg/L BA alone. On the other hand, NAA appeared to inhibit shoot induction when treated with BA. Adventitious shoots looked differ in form and color by the combinations of BA and NAA treated. When both BA and NAA were present, the shoots became short and developed dark color. The highest rooting was observed at 0.5mg/L NAA. The results could be useful for the establishment of in vitro regeneration system for Stewartia koreana Nakai.

• Korean Journal of Plant Resources
• /
• v.19 no.1
• /
• pp.189-195
• /
• 2006

We investigated the genetic variation in Stewartia koreana Nakai by examining 61 I-SSR amplicons in 120 individuals distributed among six natural populations in Korea. The overall percentage of polymorphic I-SSR amplicons was 81.9% and mean number of amplicons per I-SSR primer was 12.2. Levels of genetic diversity within 6 populations were similar each other[Shannon's Index $0.358{\sim}0.467$(mean: 0.407)]. The Mt. Obong population had the highest level of genetic diversity and was most distinctive from the other populations. Most variation existed among individuals within population(88.2%). Genetic differentiation among populations(${\phi}_{ST}$) was 0.118. The UPGMA dendrogram based on the genetic distance failed in showing decisive geographic relationships.

• Korean Journal of Plant Tissue Culture
• /
• v.22 no.2
• /
• pp.77-81
• /
• 1995

When cultured on MS medium supplemented with 0.5 mg/L NAA alone or 1.0 mg/L 2,4-D and 0.5 mg/L BA, immature zygotic embryos of Stewartia koreana formed embryogenic calli and somatic embryos. In investigate effect of sucrose concentration on somatic embryo development, embryogenic calli were transferred to MS basal medium containing 1.5,3, 6 or 9% sucrose. The greatest frequency of somatic embryos was obtained on medium containing 6% sucrose. However addition of 1.5 or 9% sucrose to medium inhibited somatic embryo germination and development into normal plantlet After 5 weeks of hardening culture on medium containing 6% sucrose, somatic embryos were transferred to half strangth MS medium supplemented with 0.1% charcol, wherein these embryo developed into the normal plantlets.

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2003.04a
• /
• pp.120-120
• /
• 2003

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2003.10a
• /
• pp.163-163
• /
• 2003

• Journal of Life Science
• /
• v.32 no.1
• /
• pp.56-62
• /
• 2022

This study was investigated to evaluate the potential of Stewartia koreana Nakai as an oral healthcare material. The inhibitory effects of extracts on the biofilm formation and fimbriae genes expression of Porphyromonas gingivalis were determined by minimal inhibitory concentrations (MIC), biofilm biomass staining, SEM, and qRT-PCR analysis. The S. koreana Nakai branch was extracted into 70% ethanol, and bacteriostatic MIC of extracts against P. gingivalis were 0.6 mg/ml. In P. gingivalis cultures treated with 0.2-2.0 mg/ml of extract, biofilm production rate was significantly decreased in a concentration-dependent manner. The morphology of treated and untreated samples was observed by SEM, and cell aggregation and biofilm were only observed in those treated with extract. Subsequently, qRT-PCR analysis showed that the mRNA expression on fimbriae genes fimA and fimB was suppressed in a concentration-dependent manner. Based on these results, it can be suggested that S. koreana branch extract has the potential to be used as naturally derived oral healthcare material because of its bacteriostatic action and inhibition of P. gingivalis biofilm formation.

• Journal of Life Science
• /
• v.31 no.2
• /
• pp.229-236
• /
• 2021

This study was carried out to evaluate the antioxidant properties of the dried leaves and branches of Stewartia koreana Nakai. The dried leaf and branch of S. koreana were extracted with 70% ethanol at 80℃. The antioxidant activities of ethanol extracts of S. koreana leaf (EESL) and S. koreana branch (EESB) were analyzed. The total polyphenol contents in EESL and EESB were 162.57±0.9 mg of GAEs/extract g and 59.1±0.9 mg of GAEs/extract g, respectively. The flavonoid contents in EESL and EESB were 59.1±0.9 mg of QEs/extract g and 4.7±0.1 mg of QEs/extract g, respectively. EESL showed a better scavenging ability with DPPH and ABTS than EESB, at 0.4 mg/ml. Moreover, EESL were more effective according to ORAC values than EESL. The toxicity of EESL was investigated using a WST-1 assay on the human skin fibroblast cell line CCD-986sk. Therefore, EESL can be used as a potential source of functional, naturally-sourced material in cosmetics as well as food.

• Journal of Life Science
• /
• v.28 no.5
• /
• pp.509-516
• /
• 2018

Five phenolic compounds were isolated from the ethyl acetate fraction of leaves from Stewartia koreana, and their nitric-oxide (NO) inhibitory activities were measured to identify the major active constituents responsible for the efficacy of the extract against inflammatory reactions. These five compounds were quercetin (1), quercitrin (2), hyperin (3), quercetin-3-O-(6"-O-galloyl)-${\beta}$-D-galactopyranoside (4), and kaempferol 3-O-[2",6"-di-O-(trans-p-coumaroyl)]-${\beta}$-D-glucopyranoside (5). Among the separated compounds in the EtOAc fraction, compounds 4 and 5 were isolated for the first time, and no study has yet reported their anti-inflammatory effects. The compounds were identified by spectroscopic analysis, and the isolated compounds showed significant NO inhibitory effects in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Compound 5 showed the most potent inhibitory effect (63.35% inhibition) against LPS-induced NO production compared to that of compound 1 (17.17%), compound 2 (5.0%), compound 3 (3.92%), and compound 4 (6.32%) at $10{\mu}g/ml$ concentration. NO production was inhibited by suppressing the protein expression of inducible nitric-oxide synthase in LPS-stimulated RAW 264.7 macrophages. These results indicate that kaempferol 3-O-[2",6"-di-O-(trans-p-coumaroyl)]-${\beta}$-D-glucopyranoside might be the major active compound responsible for the anti-inflammatory effects of S. koreana.