Ju-Sun Shim

Isolation of Sesquiterpene Synthase Homolog from Panax ginseng C.A. Meyer

Sesquiterpenes are found naturally in plants and insects as defensive agents or pheromones. They are produced in the cytosolic acetate/mevalonate pathway for isoprenoid biosynthesis. The inducible sesquiterpene synthases (STS), which are responsible for the transformation of the precursor farnesyl diphosphate, appear to generate very few olefinic products that are converted to biologically active metabolites. In this study, we isolated the STS gene from Panax ginseng C.A. Meyer, designated PgSTS, and investigated the correlation between its expression and various abiotic stresses using real-time PCR. PgSTS cDNA was observed to be 1,883 nucleotides long with an open reading frame of 1,707 bp, encoding a protein of 568 amino acids. The molecular mass of the mature protein was determined to be 65.5 kDa, with a predicted isoelectric point of 5.98. A GenBank BlastX search revealed the deduced amino acid sequence of PgSTS to be homologous to STS from other plants, with the highest similarity to an STS from Lycopersicon hirsutum (55% identity, 51% similarity). Real-time PCR analysis showed that different abiotic stresses triggered significant induction of PgSTS expression at different time points.

Isolation of S-adenosyl-L-methionine synthetase gene from Panax ginseng C.A. meyer and analysis of its response to abiotic stresses.

A cDNA clone containing a S-adenosyl-L-methionine synthetase (SAMS) gene, named as PgSAM, was isolated from a commercial medicinal plant Panax ginseng. PgSAM is predicted to encode a precursor protein of 307 amino acid residues, and its sequence shares high homology with a number of other plant SAMS. PgSAM is expressed at different levels in various organs of ginseng. The expression of PgSAM in adventitious roots and hairy roots of P. ginseng were analyzed using reverse transcriptase (RT)-PCR and real-time PCR under various abiotic stresses. Salt, salicylic acid, abscisic acid and chilling stresses induced PgSAM significantly at different time points within 2–72 h post-treatment. This study revealed that PgSAM may help to protect the plants against various abiotic stresses.

Isolation and Characterization of Pathogenesis-Related Protein 5 (PgPR5) Gene from Panax ginseng

A pathogenesis-related protein (PgPR5) gene that isolated from the leaf of Panax ginseng was characterized. The ORF is 756 bp with a deduced amino acid sequence of 251 residues. The calculated molecular mass of the matured protein is approximately 27.5 kDa with a predicated isoelectric point of 7.80. A GenBank BlastX search revealed that the deduced amino acid of PgPR5 shares highest sequence similarity to PR5 of Actinidia deliciosa (80% identity, 87% similarity). PgPR5 has a C-terminal and N-terminal signal peptide, suggesting that it is a vacuolar secreted protein. The expression of PgPR5 under various environmental stresses was analyzed at different time points using real-time PCR. Our results reveal that PgPR5 is induced by salt stress, chilling stress, heavy metal, UV, and pathogen infection. These results suggest that the PgPR5 could play a role in the molecular defence response of ginseng to abiotic and pathogen attack. This is the first report of the isolation of PR5 gene from the P. ginseng.

Somatic embryogenesis of two new Panax ginseng cultivars, Yun-Poong and Chun-Poong

Somatic embryogenesis from single cells is important for normal plant regeneration of ginseng. Cotyledon explants from zygotic embryos of two new ginseng cultivars, Chun-Poong and Yun-Poong, produced somatic embryos on Murashige and Skoog (MS) basal medium and MS medium containing growth regulators. The highest frequency of single somatic embryo formation was obtained when cotyledon explants were excised from premature (cultured for 1 day) zygotic embryos (about 6 mm in length) of both cvs. Chun-Poong and Yun-Poong and then cultured on MS medium supplemented with 7% sucrose. The frequency of single somatic embryo formation was strongly enhanced when Chun-Poong cotyledons were subjected to plasmolysis with 0.1–0.5 M sucrose for 24 h and Yun-Poong cotyledons to plasmolysis with 1.0 M sucrose for 24 h and then cultured on MS medium with 2,4-D.

Isolation and Characterization of Cinnamoyl-CoA Reductase Gene from Panax ginseng C. A. Meyer

Cinnamoyl-CoA reductase (CCR, EC 1.2.1.44) catalyses the reduction of cinnamic acid CoA esters into their corresponding aldehydes, the first step of the phenylpropanoid pathway specially dedicated to monolignol biosynthesis. A cDNA clones encoding CCR have been isolated from Panax ginseng C.A. Meyer and its expression was investigated in response to abiotic stresses. The cDNA, designated PgCCR which is 865 nucleotides long and has an open reading frame of 590 bp with a deduced amino acid sequence of 176 residues. The PgCCR encoded protein possesses substantial homology with CCRs isolated and cloned from other sources; the highest identity (51.8%) was observed with CCR from Tomato (Lycopersicon esculentum). Under various stress conditions, expression patterns of the PgCCR were highly induced in adventitious and hairy roots by several abiotic stresses. These results indicated that PgCCR plays protective role against diverse environmental stresses.

In vitro Induction of Tetraploid Roots by Various Pretreatments from Anther of Panax ginseng C. A. Meyer

This experiment was done to determine the optimum conditions for the induction of tetraploidy in Panax ginseng C. A. Meyer using bud length, temperature and plant growth regulator pretreatments. Highest callus formation was obtained when the medium was inoculated with flower bud in the size of 2-3 ㎜ in length. The optimum temperature for the callus formation was high when treated at 4℃ for 4-5 days. Among the treatments of growth regulators and different concentration, highest callus formation was observed in combination of 5 ㎎/L 2,4-D and 1 ㎎/L kinetin for P. ginseng. As a result of flow cytometer analysis, all 7 adventitious roots were confirmed as tetraploidys. Cytological analysis revealed that the chromosome number of tetraploid roots was 96, while that of diploid roots was 48. Tetraploid ginseng roots were inoculated to flower bud size of 2-3 ㎜ in length. The callus formation was optimum when treated with l ㎎/L 2,4-D at 4℃ for 5 days. Compared with control roots, tetraploid roots were thicker and longer and had few lateral branches. Fresh weight of tetraploid roots was relatively higher than the control roots.

Inhibitory effects of the transgenic Panax ginsengs on phorbol ester plus A23187-induced IL-6 production and cyclooxygenase-2 via suppression of NF-κB and MAPKs in HMC-1

Our previous studies have that demonstrated the overexpression of the squalene synthase gene enhances the biosynthesis of triterpene and phytosterol in Panax ginseng. The total ginsenoside contents in adventitious roots of transgenic P. ginseng were about 1.6–3-fold higher than those in the wild-type. In the present work, we have evaluated the anti-inflammatory effects of two types of transgenic P. ginseng (BS and SS) and the wild-type P. ginseng (GS) in a stimulated human mast cell line 1 (HMC-1). GS, BS, and SS inhibited not only the production of interleukin 6 (IL-6), but also the expression of cyclooxygenase-2 in phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187 (PMACI)-stimulated HMC-1. Additionally, GS, BS, and SS suppressed the expression of the nuclear transcription factor κB and mitogen-activated protein kinases induced by PMACI. The anti-inflammatory effects of BS and SS were higher than that of GS. These results provide new insights into the pharmacological actions of transgenic P. ginseng as a potential molecule for use in therapy in mast cell-mediated inflammatory diseases.

Isolation and Characterization of Terpene Synthase Gene from Panax ginseng

Terpene synthase plays a key role in biosynthesis of triterpene saponins (ginsenosides) and is intermediate in the biosynthesis of a number of secondary metabolites. A terpene synthase (PgTPS) cDNA was isolated and characterized from the root of Panax ginseng C.A. Meyer. The deduced amino acid sequence of PgTPS showed a similarity with A. deliciosa (AAX16121) 61%, V. vinifera (AAS66357) 61%, L hirsutum (AAG41891) 55%, M truncatula (AAV36464) 52%. And the segment of a terpene synthase gene was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). We studied expression of terpene synthase under stressful conditions like chilling, salt, UV, and heavy metal stress treatment. Expression of PgTPS was increased gradually after exposure to stresses such as chilling, salt, and UV illumination. But its transcription seems to be reduced by cadmium and copper treatment.

The Effect of Haliotidis Concha on the Growth and Ginsenoside Biosynthesis of Korean Ginseng Hairy Root

In order to investigate the effects of elicitors on the growth and ginsenoside biosynthesis of ginseng hairy roots, we treated Panax ginseng hairy root with various concentrations of Haliotidis concha according to different time course. Haliotidis concha supplement increased the biomass and ginsenoside accumulation at 10 ㎎/L concentration. The growth rate of hairy root under a lighter concentration was greater than hairy root treated with a denser concentration. The highest content and productivity of ginsenosides appeared at 2 weeks after the treatment of 10 ㎎/L Haliotidis concha. The gene expression of squalene synthase, squalene epoxidase, dammarenediol synthase, cycloartenol synthase, β-amyrin synthase in hairy roots of ginseng were examined by RT-PCR. The Haliotidis concha treatment resulted in the obvious accumulation of the mRNA of triterpene biosynthesis in Panax ginseng hairy root as compared with the control. In this study, Haliotidis concha acts as a kind of elicitor for the production of ginsenosides.