• Journal of Plant Biotechnology
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• v.46 no.4
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• pp.297-302
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• 2019

Hibiscus syriacus L., the national flower of Korea, is a commonly grown ornamental species found in parks, gardens and along roadsides in Korea. This study sought to establish a plant regeneration system of H. syriacus 'Nanpa' using mature leaves as an explant. Sterilized mature leaf explants were cultured on modified MS medium with combinations of NAA and BAP at various concentrations for 6 weeks. Among the various media evaluated, modified MS media containing 0.46 mg/L NAA and 0.5 mg/L BAP (CI-1) or 0.92 mg/L NAA and 1 mg/L BAP (CI-4) were the most effective for callus formation. Whitish-yellow calluses were observed on CI-1 medium, while green calluses formed on CI-4 medium. The whitish-yellow callus derived from CI-1 medium showed a higher frequency of shoot induction than the green callus derived from CI-4 on modified MS medium containing 0.5 mg/L BAP. Among the various media evaluated in this study, modified MS medium containing 0.46 mg/L NAA and 0.5 mg/L BAP was the most optimal for shoot-forming callus production. Our findings show that mature leaves of H. syriacus 'Nanpa' can be used for in vitro plant regeneration, and the regeneration system described here may be a powerful tool for molecular breeding of H. syriacus 'Nanpa' in the future.

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.174-178
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• 2009

Presently, we report a simple, reproducible and high frequency plant regeneration in Hibiscus syriacus L. using axillary buds. H. syriacus was regenerated from axillary buds directly or through a callus phase. Regenerated shoots were directly induced from young and fresh axillary buds cultured on Murashige and Skoog medium (MS) supplemented with 0.01 mg/L of the growth regulator thidiazuron (TDZ) after 2 weeks of culture. Directly induced shoots were transferred to hormone-free MS medium and root development was observed after 6 weeks. On the other hand, old and stale axillary buds were regenerated to shoots via callus induction on MS medium containing 0.01–2 mg/L TDZ after 4 weeks. A TDZ concentration of 0.01 mg/L was most effective in callus formation. Green callus was transferred to MS medium containing 0.01 mg/L α-naphthalene acetic acid (NAA) and 0.5 mg/L benzylaminopurine (BA). After 4 weeks, callus had developed into multiple shoots. Plantlets were formed from 10 week cultures of single shoots on hormone-free MS medium. Regenerated plantlets were cultured on MS medium for one month and then transferred to pots containing garden soil. Potted plants were acclimatized for one month and grown to maturity under greenhouse conditions. The present study has shown that various concentrations of plant growth regulator can be effective for in vitro plant regeneration of H. syriacus. The direct and indirect regeneration protocol presented here will be useful for understanding the manipulation and propagation of H. syriacus.

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.179-183
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• 2009

To understand the effect of reactive oxygen species (ROS) on floral senescence in Hibiscus syriacus L., we have investigated change in relative water potential, malondialdehyde (MDA) content, H_2O_2 content and the activity of antioxidative enzymes in the petals during flower opening and senescence. Hibiscus flowers were achieved full bloom at early morning and started to in-rolling and showed petal in-rolling over than 50% at 24 h and 36 h after full bloom, respectively. The flower was a decrease in fresh weight by 30% and showed water loss with floral senescence. MDA content and activity of antioxidative enzymes such as APX, GR and CAT were showed no significant change until 36 h after full bloom. In the flower 48 h after full bloom that showed complete petal in-rolling and wilting, however, activity of antioxidative enzymes and H_2O_2 content was greatly increased as compared with 0 h after full bloom. These results suggest that reactive oxygen species are related to accelerating the later senescence more than inducing the early senescence during Hibiscus flower senescence.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2004.10a
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• pp.103-105
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• 2004

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.91-91
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• 2019

Hibiscus syriacus L. is widely distributed throughout Eastern and Southern Asia and its root bark has been used as a traditional remedy. Recently, the extracts of H. syriacus L. exerts anti-cancerous, anti-microbial, and anti-inflammatory activities. However, the effect of anthocyanin-rich fraction of H. syriacus L. petals (PS) has not been studied under excessive oxidative stress. In this study, we evaluated the cellular protective effect of PS in HaCaT human skin keratinocytes under hydrogen peroxide ($H_2O_2$)-induced oxidative stress conditions. PS at below $400{\mu}g/ml$ did not show any cell death; however, over $800{\mu}g/ml$ of PS gradually increased cell death. PS at below $400{\mu}g/ml$ significantly inhibited $H_2O_2$-induced apoptosis in HaCaT cells concomitant with downregulation of Bax and upregulation of pro-PARP and p-Bcl-2. Additionally, PS remarkably reversed $H_2O_2$-induced excessive reactive oxygen species (ROS) production and apoptosis, and also significantly inhibited mitochondrial ROS production concomitant with suppression of $H_2O_2$-induced mitochondrial depolarization. $H_2O_2$-mediated ratio of Bax to Bcl-2, and caspase-3 activation were markedly abolished in the presence of PS. Moreover, the inhibition of HO-1 function using zinc protoporphyrin, an HO-1 inhibitor, significantly attenuated the cellular protective effects of PS against $H_2O_2$, indicating the significance of HO-1 in PS mediated cytoprotective effect, which was mediated by activating nuclear factor erythroid 2-related factor-2 (Nrf2). Taken together, our results suggest that cytoprotective effect of PS in HaCaT keratinocytes against oxidative stress-induced apoptosis is mediated by inhibiting cellular and mitochondrial ROS production, which is downregulated by activating Nrf2/HO-1 axis.

• 한국약용작물학회:학술대회논문집
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• 2008.05a
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• pp.246-247
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• 2008

• Journal of Plant Biology
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• v.38 no.1
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• pp.95-105
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• 1995

Complete microsporogenesis of Hibiscus syriacus L. were carried out employing LM, TEM, and SEM to investigate the pollen ontogeny that undergoes considerable structural differentiation. The process first began with several cell diYisions in the anther primordium that produces 3 different tissues of epidennal, archesporial, and connective tissues. Only archesporial tissue involved further differentiation into the tapetum and formation of reproductive cells, pollen mother cells (PMC). The tapetum and PMC were closely associated with each other structurally and metabolically by exhibiting numerous plasmodesmata, mitochondria, and many small vacuoles in their dense cytoplasm. A callosic wall began to surround the PMC while meiosis took place in the PMC to produce 4 microspores. When thick callose encircled each microspore as a frame, the sporodenn development initiated from the plasma membrane of a pollen grain in a tetrad. The first fonned sporoderm layer was bacules and tectum of sexine that originated from the plasma membrane. After the dissolution of a callose, further development Qf sporoderm continued in the order of nexine 1, nexine 2, and intine layer. The nexine layer was thicker (ca. $2-3.5\;\mu\textrm{m}$) than the intine layer whose thickness was about $0.9-1.5\;\mu\textrm{m}$. Upon completion of the sporoderm development, that is after intine formation, spines and apertures of pollen surface ornamentation initiated from the tectum. Spines were dimorphic, about $4-9\;\mu\textrm{m}\;an;15-20\;\mu\textrm{m}$ in length, and no basal cushion was detected. The mature pollen grains ranged $100-200\;\mu\textrm{m}$ in diameter, but their average was about $170\;\mu\textrm{m}$. About 120 spines were observed over the spheroidal pollen surface. Apertures were simple punctures of $2-3\;\mu\textrm{m}$ in diameter and about 50 apertures were arranged somewhat helically over the surface. Comparing such features of form and size of the pollen, sporodenn sculpture and structure, and aperture and spine conditions with known evolutionary trends in the genus Hibiscus, Hibiscus syriacus seemed to possess many advanced features in the sporodenn differentiation.iation.

• Korean Journal of Medicinal Crop Science
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• v.23 no.3
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• pp.190-197
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• 2015

In this study, we tried to offer the possibility of White Hibiscus syriacus L. (WHS) flower extracts as a preventive and improving agent of osteoporosis that bone mass reduction is induced by an decrease of osteoblast involved in bone formation and increase of bone resorption by osteoclast activity. As a results, it was found to have antioxidant activity and contain a flavonoid contents ($47.74 mg/g) of the WHS flower. There was cytotoxicity at more than $250{\mu}g/m{\ell}$ concentration of WHS flower extract of RANKL-induced osteoclast in RAW264.7. There were no significant inhibited TRAP activity in the WHS leaf and stem. However, it was confirmed that it is significantly inhibited the differentiation activity of osteoclasts in 50 and $100{\mu}g/m{\ell}$ concentration of cells of stability levels of only WHS flower extracts (p < 0.01). The WHS flower prominently inhibited RANKL-induced osteoclast differentiation activity by decreased calcitonin receptor and TRAP mRNA (p < 0.01). These results indicate that of osteoclasts differentiation activity is inhibited by protection of oxidative stress due to the antioxidant activity of the WHS flower. Therefore, suggesting the WHS flower may be a presents the possibility as a preventive and therapeutic agents for osteoporosis.

• Korean Journal of Plant Resources
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• v.19 no.1
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• pp.144-149
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• 2006

This is a study on relationship between soil pH and flower color and growth of Hibiscus siriacus L, looking for the pH range to result the most ideal flower color. I anticipate this study result will lay a foundation of improved breeding plan of Hibiscus siriacus L. According to the result of investigation and analysis on bleeding peculiarities by each soil pH, the numbers of leaves in Honghwarang and Younggwang reached the highest at pH 7: 188.73 and 135.87 respectively. Increased pH resulted the increased number of leaves. According to the result of investigation and analysis on color changes of four kinds of Hibiscus siriacus L. at various pH level, Honghwarang's L value gradually decreased from 17.05 to 12.26 at pH increase while a value increased from 16.37 to 20.91.

• Horticultural Science & Technology
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• v.16 no.4
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• pp.525-527
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• 1998

This study was conducted to determine the optimum cultural condition and method for in vitro mass production of Hibiscus syriacus L. 'Honghwarang'. When callus induced in MS solid medium supplemented with 0.01 mg/L TDZ was cultured in liquid medium containing 0.01mg/L TDZ, callus growth and shoot primordia formation was most effective. Formed shoot primordia were regenerated into shoot in MS or 1/2 MS medium of growth regulator-free condition. Effects of mesh size, shaking speed on callus and shoot primordia formation were examined after 5 weeks. Callus and shoot primordia formation was formed most effectively at 10 mesh and 80 rpm shaking speed in liquid medium.