Overexpression of R2R3-MYB IbMYB1a induces anthocyanin pigmentation in soybean cotyledon.

KEY MESSAGE: This is the first report showing anthocyanin accumulation in the soybean cotyledon via genetic transformation of a single gene. Soybean [Glycine max (L.) Merrill] contains valuable components, including anthocyanins. To enhance anthocyanin production in Korean soybean Kwangankong, we utilized the R2R3-type MYB gene (IbMYB1a), known for inducing anthocyanin pigmentation in Arabidopsis. This gene was incorporated into constructs using two promoters: the CaMV 35S promoter (P35S) and the ß-conglycinin promoter (Pß-con). Kwangankong was transformed using Agrobacterium, and the presence of IbMYB1a and Bar transgenes in T0 plants was confirmed through polymerase chain reaction (PCR), followed by gene expression validation. Visual inspection revealed that one P35S:IbMYB1a and three Pß-con:IbMYB1a lines displayed seed color change. Pß-con:IbMYB1a T1 seeds accumulated anthocyanins in cotyledon outer layers, whereas P35S:IbMYB1a and non-transgenic black soybean (Cheongja 5 and Seum) accumulated anthocyanins in the seed coat. During the germination and growth phase, T1 seedlings from Pß-con:IbMYB1a lines exhibited anthocyanin pigmentation in cotyledons for up to 1 month without growth aberrations. High-performance liquid chromatography confirmed cyanidin-3-O-glucoside as the major anthocyanin in the Pß-con:IbMYB1a line (#3). We analyzed the expression patterns of anthocyanin biosynthesis genes, chalcone synthase 7,8, chalcone isomerase 1A, flavanone 3-hydroxylase, flavanone 3'-hydroxylase, dihydroflavanol reductase 1, dihydroflavanol reductase 2, anthocyanidin synthase 2, anthocyanidin synthase 3, and UDP glucose flavonoid 3-O-glucosyltransferase in transgenic and control Kwangankong and black soybean (Cheongja 5 and Seum) seeds using quantitative real-time PCR. We conclude that the induction of gene expression in transgenic plants in comparison with Kwangankong was attributable to IbMYB1a transformation. Notably, flavanone 3-hydroxylase, flavanone 3'-hydroxylase, and dihydroflavanol reductase 1 were abundantly expressed in black soybean seed coat, distinguishing them from transgenic cotyledons.

Flavobacterium endoglycinae sp. nov., an endophytic bacterium isolated from soybean (Glycine max L. cv. Gwangan) stems.

A Gram-stain-negative, facultatively anaerobic, motile by gliding, rod-shaped, oxidase- and catalase-positive bacterial strain, designated BB8T, was isolated from the stems of a Korean soybean cultivar (Glycine max L. cv. Gwangan). The strain produced a yellow pigment on tryptic soy agar. Growth of strain BB8T occurred at pH 5.0-8.0 (optimum, pH 7.0), at 10-35 °C (optimum, 25-30 °C) and in the presence of 0-1 % (w/v) NaCl (optimum, 0.5%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BB8T formed a lineage within the genus Flavobacterium and was most closely related to Flavobacterium artemisiae SYP-B1015T (96.9 % 16S rRNA gene sequence similarity) and Flavobacterium ustbae T13T (96.8%). The complete genome sequence of strain BB8T was 5 513 159 bp long with a G+C content of 34.1 mol%. The major fatty acids (>10 %) of strain BB8T were iso-C15 : 0 (21 %), summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c, 20.3%) and iso-C16 : 0 3-OH (13.7%). The predominant polar lipids were phosphatidylethanolamine and unidentified aminolipids, and the major respiratory quinone was menaquinone-6. Based on these phenotypic, genotypic and chemotaxonomic characteristics, strain BB8T is considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacterium endoglycinae sp. nov. is proposed. The type strain is BB8T (=KCTC 82167T=CCTCC AB 2020070T).

Highly Efficient Bioconversion of trans-Resveratrol to δ-Viniferin Using Conditioned Medium of Grapevine Callus Suspension Cultures.

δ-Viniferin is a resveratrol dimer that possesses potent antioxidant properties and has attracted attention as an ingredient for cosmetic and nutraceutical products. Enzymatic bioconversion and plant callus and cell suspension cultures can be used to produce stilbenes such as resveratrol and viniferin. Here, δ-viniferin was produced by bioconversion from trans-resveratrol using conditioned medium (CM) of grapevine (Vitis labruscana) callus suspension cultures. The CM converted trans-resveratrol to δ-viniferin immediately after addition of hydrogen peroxide (H2O2). Peroxidase activity and bioconversion efficiency in CM increased with increasing culture time. Optimized δ-viniferin production conditions were determined regarding H2O2 concentration, incubation time, temperature, and pH. Maximum bioconversion efficiency reached 64% under the optimized conditions (pH 6.0, 60 °C, 30 min incubation time, 6.8 mM H2O2). In addition, in vitro bioconversion of trans-resveratrol was investigated using CM of different callus suspension cultures, showing that addition of trans-resveratrol and H2O2 to the CM led to production of δ-viniferin via extracellular peroxidase-mediated oxidative coupling of two molecules of trans-resveratrol. We thus propose a simple and low-cost method of δ-viniferin production from trans-resveratrol using CM of plant callus suspension cultures, which may constitute an alternative approach for in vitro bioconversion of valuable molecules.

Mutation of GmIPK1 Gene Using CRISPR/Cas9 Reduced Phytic Acid Content in Soybean Seeds.

Phytic acid (PA) acts as an antinutrient substance in cereal grains, disturbing the bioavailability of micronutrients, such as iron and zinc, in humans, causing malnutrition. GmIPK1 encodes the inositol 1,3,4,5,6-pentakisphosphate 2-kinase enzyme, which converts myo-inopsitol-1,3,4,5,6-pentakisphosphate (IP5) to myo-inositol-1,2,3,4,5,6-hexakisphosphate (IP6) in soybean (Glycine max L.). In this study, for developing soybean with low PA levels, we attempted to edit the GmIPK1 gene using the CRISPR/Cas9 system to introduce mutations into the GmIPK1 gene with guide RNAs in soybean (cv. Kwangankong). The GmIPK1 gene was disrupted using the CRISPR/Cas9 system, with sgRNA-1 and sgRNA-4 targeting the second and third exon, respectively. Several soybean Gmipk1 gene-edited lines were obtained in the T0 generation at editing frequencies of 0.1-84.3%. Sequencing analysis revealed various indel patterns with the deletion of 1-9 nucleotides and insertions of 1 nucleotide in several soybean lines (T0). Finally, we confirmed two sgRNA-4 Gmipk1 gene-edited homozygote soybean T1 plants (line #21-2: 5 bp deletion; line #21-3: 1 bp insertion) by PPT leaf coating assay and PCR analysis. Analysis of soybean Gmipk1 gene-edited lines indicated a reduction in PA content in soybean T2 seeds but did not show any defects in plant growth and seed development.

Pedobacter endophyticus sp. nov., an endophytic bacterium isolated from Carex pumila.

An aerobic, Gram-stain-negative, weak-motile, short-rod-shaped bacterial strain, designated JBR3-12T, was isolated from halophyte Carex pumila plants, and its taxonomic position was investigated by using a polyphasic taxonomic approach. The strain produced a pink pigment on tryptic soy agar and grew optimally at 25 °C, pH 8 and in the presence of 3 % (w/v) NaCl. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain JBR3-12T formed a lineage within the genus Pedobacter and was most closely related to Pedobacter sandarakinus DS-27T (98.0 %) and Pedobacter agri PB92T (97.6 %). The DNA G+C content of the genome was 41.3 mol%; the whole genome length was 5 426 070 bp. The major fatty acids of JBR3-12T were iso-C15 : 0, summed feature 3 (comprising C16 : 1 ω6c and/or C16 : 1 ω7c) and iso-C17 : 0 3-OH. The predominant polar lipid was phosphatidylethanolamine. The predominant quinone was menaquinone-7. Based on its phenotypic, phylogenetic and genotypic features, strain JBR3-12T is proposed to represent a novel species of the genus Pedobacter, for which the name is Pedobacter endophyticus sp. nov. The type strain is JBR3-12T (=KCTC 82363T=NBRC 114901T).

Inhibition of melanogenesis by Aster yomena callus pellet extract in melanoma cells and patients with skin pigmentation.

Plant tissue culture holds immense potential for the production of secondary metabolites with various physiological functions. We recently established a plant tissue culture system capable of producing secondary metabolites from Aster yomena. This study aimed to uncover the mechanisms underlying the potential therapeutic effects of Aster yomena callus pellet extract (AYC-P-E) on photoaging-induced skin pigmentation. Excessive melanogenesis was induced in B16F10 melanoma cells using α-melanocyte stimulating hormone (α-MSH). The effects of AYC-P-E treatment on melanin biosynthesis inducers and melanin synthesis inhibition were assessed. Based on the results, a clinical study was conducted in subjects with skin pigmentation. AYC-P-E inhibited melanogenesis in α-MSH-treated B16F10 cells, accompanied by decreased mRNA and protein expression of melanin biosynthesis inducers, including cyclic AMP response element-binding protein (CREB), tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase related protein-1 (TRP-1), and TRP-2. This anti-melanogenic effect was mediated by mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) and protein kinase B (AKT) phosphorylation. Treatment of subjects with skin pigmentation with AYC-P-E-containing cream formulations resulted in 3.33%, 7.06%, and 8.68% improvement in the melanin levels at 2, 4, and 8 weeks, respectively. Our findings suggest that AYC-P-E inhibits excessive melanogenesis by activating MEK/ERK and AKT signaling, potentiating its cosmetic applications in hyperpigmentation treatment.

TSA Promotes CRISPR/Cas9 Editing Efficiency and Expression of Cell Division-Related Genes from Plant Protoplasts.

Trichostatin A (TSA) is a representative histone deacetylase (HDAC) inhibitor that modulates epigenetic gene expression by regulation of chromatin remodeling in cells. To investigate whether the regulation of chromatin de-condensation by TSA can affect the increase in the efficiency of Cas9 protein-gRNA ribonucleoprotein (RNP) indel formation from plant cells, genome editing efficiency using lettuce and tobacco protoplasts was examined after several concentrations of TSA treatments (0, 0.1, 1 and 10 µM). RNP delivery from protoplasts was conducted by conventional polyethylene glycol (PEG) transfection protocols. Interestingly, the indel frequency of the SOC1 gene from TSA treatments was about 3.3 to 3.8 times higher than DMSO treatment in lettuce protoplasts. The TSA-mediated increase of indel frequency of the SOC1 gene in lettuce protoplasts occurred in a concentration-dependent manner, although there was not much difference. Similar to lettuce, TSA also increased the indel frequency by 1.5 to 1.8 times in a concentration-dependent manner during PDS genome editing using tobacco protoplasts. The MNase test clearly showed that chromatin accessibility with TSA treatments was higher than that of DMSO treatment. Additionally, TSA treatment significantly increased the level of histone H3 and H4 acetylation from lettuce protoplasts. The qRT-PCR analysis showed that expression of cell division-related genes (LsCYCD1-1, LsCYCD3-2, LsCYCD6-1, and LsCYCU4-1) was increased by TSA treatment. These findings could contribute to increasing the efficiency of CRISPR/Cas9-mediated genome editing. Furthermore, this could be applied for the development of useful genome-edited crops using the CRISPR/Cas9 system with plant protoplasts.

Synergistic Effect of Methyl Jasmonate and Abscisic Acid Co-Treatment on Avenanthramide Production in Germinating Oats.

The oat (Avena sativa L.) is a grain of the Poaceae grass family and contains many powerful anti-oxidants, including avenanthramides as phenolic alkaloids with anti-inflammatory, anti-oxidant, anti-itch, anti-irritant, and anti-atherogenic activities. Here, the treatment of germinating oats with methyl jasmonate (MeJA) or abscisic acid (ABA) resulted in 2.5-fold (582.9 mg/kg FW) and 2.8-fold (642.9 mg/kg FW) increase in avenanthramide content, respectively, relative to untreated controls (232.6 mg/kg FW). Moreover, MeJA and ABA co-treatment synergistically increased avenanthramide production in germinating oats to 1505 mg/kg FW. Individual or combined MeJA and ABA treatment increased the expression of genes encoding key catalytic enzymes in the avenanthramide-biosynthesis pathway, including hydroxycinnamoyl-CoA:hydrocyanthranilate N-hydroxycinnamoyl transferase (HHT). Further analyses showed that six AsHHT genes were effectively upregulated by MeJA or ABA treatment, especially AsHHT4 for MeJA and AsHHT5 for ABA, thereby enhancing the production of all three avenanthramides in germinating oats. Specifically, AsHHT5 exhibited the highest expression following MeJA and ABA co-treatment, indicating that AsHHT5 played a more crucial role in avenanthramide biosynthesis in response to MeJA and ABA co-treatment of germinating oats. These findings suggest that elicitor-mediated metabolite farming using MeJA and ABA could be a valuable method for avenanthramide production in germinating oats.

The Effect of Sodium Butyrate on Adventitious Shoot Formation Varies among the Plant Species and the Explant Types.

Histone acetylation plays an important role in plant growth and development. Here, we investigated the effect of sodium butyrate (NaB), a histone deacetylase inhibitor, on adventitious shoot formation from protoplast-derived calli and cotyledon explants of tobacco (Nicotiana benthamiana) and tomato (Solanum lycopersicum). The frequency of adventitious shoot formation from protoplast-derived calli was higher in shoot induction medium (SIM) containing NaB than in the control. However, the frequency of adventitious shoot formation from cotyledon explants of tobacco under the 0.1 mM NaB treatment was similar to that in the control, but it decreased with increasing NaB concentration. Unlike in tobacco, NaB decreased adventitious shoot formation in tomato explants in a concentration-dependent manner, but it did not have any effect on adventitious shoot formation in calli. NaB inhibited or delayed the expression of D-type cyclin (CYCD3-1) and shoot-regeneration regulatory gene WUSCHEL (WUS) in cotyledon explants of tobacco and tomato. However, compared to that in control SIM, the expression of WUS was promoted more rapidly in tobacco calli cultured in NaB-containing SIM, but the expression of CYCD3-1 was inhibited. In conclusion, the effect of NaB on adventitious shoot formation and expression of CYCD3-1 and WUS genes depended on the plant species and whether the effects were tested on explants or protoplast-derived calli.

Temporal and Spatial Expression Analysis of Shoot-Regeneration Regulatory Genes during the Adventitious Shoot Formation in Hypocotyl and Cotyledon Explants of Tomato (CV. Micro-Tom).

Enhancing the competence for plant regeneration in tissue culture studies is an important issue not only for efficient genetic transformation of commercial crops but also for the reproducibility of scientific reports. In this study, we investigated optimization of several tissue culture conditions including plant growth regulators, types and ages of explants, culture densities, and plant position in order to improve the competence of adventitious shoot formation of the tomato (Solanum lycopersicum cv. Micro-Tom). In addition, we examined the differential expression of D-type cyclin (CYCD3-1) and several shoot regeneration regulatory genes from hypocotyl and cotyledon explants of tomato during shoot organogenesis. A treatment of 1 mg L-1 Zeatin and 0.1 mg L-1 Indole-3-acetic acid (IAA) in Murashige and Skoog (MS) medium containing 3% sucrose was optimal for adventitious shoot formation from hypocotyl and cotyledon explants. The younger explants exhibited more shoot formation regardless of explant types. Additionally, those closest to the shoot apical meristem produced more shoots compared to the other regions in the hypocotyl and the cotyledon explants. Gene expression of CYCD3-1, SHOOT MERISTEMLESS (STM), and cytokinin dependent WUSCHEL (WUS) was significantly higher in younger explants than in older ones. Furthermore, an increase in CYCD3-1, STM, and WUS expression was evident at the distal part of hypocotyls and the proximal part of cotyledons compared to other regions. These differential gene expression profiles exhibited good agreement with the results of shoot formation obtained from diverse explants of tomato. These results suggest that temporal and spatial gene expression of shoot regeneration regulatory genes plays an important role in enhancing the competence and the reproducibility of adventitious shoot formation from tomato explants.

The Synergistic Effect of Co-Treatment of Methyl Jasmonate and Cyclodextrins on Pterocarpan Production in Sophora flavescens Cell Cultures.

Pterocarpans are derivatives of isoflavonoids, found in many species of the family Fabaceae. Sophora flavescens Aiton is a promising traditional Asian medicinal plant. Plant cell suspension cultures represent an excellent source for the production of valuable secondary metabolites. Herein, we found that methyl jasmonate (MJ) elicited the activation of pterocarpan biosynthetic genes in cell suspension cultures of S. flavescens and enhanced the accumulation of pterocarpans, producing mainly trifolirhizin, trifolirhizin malonate, and maackiain. MJ application stimulated the expression of structural genes (PAL, C4H, 4CL, CHS, CHR, CHI, IFS, I3'H, and IFR) of the pterocarpan biosynthetic pathway. In addition, the co-treatment of MJ and methyl-ß-cyclodextrin (MeßCD) as a solubilizer exhibited a synergistic effect on the activation of the pterocarpan biosynthetic genes. The maximum level of total pterocarpan production (37.2 mg/g dry weight (DW)) was obtained on day 17 after the application of 50 µM MJ on cells. We also found that the combined treatment of cells for seven days with MJ and MeßCD synergistically induced the pterocarpan production (trifolirhizin, trifolirhizin malonate, and maackiain) in the cells (58 mg/g DW) and culture medium (222.7 mg/L). Noteworthy, the co-treatment only stimulated the elevated extracellular production of maackiain in the culture medium, indicating its extracellular secretion; however, its glycosides (trifolirhizin and trifolirhizin malonate) were not detected in any significant amounts in the culture medium. This work provides new strategies for the pterocarpan production in plant cell suspension cultures, and shows MeßCD to be an effective solubilizer for the extracellular production of maackiain in the cell cultures of S. flavescens.

Hepatitis C virus genotype 3 was associated with the development of hepatocellular carcinoma in Korea.

Although hepatitis C virus (HCV) genotype 3 infection is thought to be an important risk factor for hepatocellular carcinoma (HCC), current evidence is limited because only a few Western studies have evaluated the occurrence of HCC in patients with HCV genotype 3 infection. We evaluated the impact of genotype 3 and non-3 on HCC incidence and on disease progression in chronic HCV patients; this is the first study reporting such findings in an Asian population. We performed a retrospective cohort study using the data of 1448 consecutive chronic HCV patients evaluated at three centres in Korea between January 2005 and December 2016. Of these, 604, 675 and 169 had genotype 1, genotype 2 and genotype 3 HCV infections, respectively. Over a mean follow-up period of 53.2 months, 75 and 143 patients of all the patients developed HCC and experienced disease progression, respectively. The incidences of HCC were 1.10, 0.92 and 2.50 per 100 person-years, and those of disease progression were 1.95, 1.62 and 6.72 per 100 person-years for HCV genotypes 1, 2 and 3, respectively. In multivariate Cox regression analysis, genotype 3 was associated with an increased risk of HCC (hazard ratio [HR] = 4.26, 95% confidence interval [CI] = 2.02-8.97) and an increased risk of disease progression (HR = 4.88, 95%; CI = 2.94-8.08). Our study proposes that HCV genotype 3 is an independent risk factor for HCC and disease progression in chronic HCV patients.

Neobacillus endophyticus sp. nov., an endophytic bacterium isolated from Selaginella involvens roots.

A Gram-stain-positive, facultatively anaerobic, rod-shaped, endospore-forming, oxidase-positive, and catalase-negative strain designated as BRMEA1T was isolated from the surface-sterilized Selaginella involvens roots. Growth of strain BRMEA1T was found to occur at pH 6.0-8.0 (optimum, pH 7.0), 15-50 °C (optimum, 25-30 °C) and in the absence of NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BRMEA1T formed a lineage within the genus Neobacillus (family Bacillaceae) and showed the highest sequence similarity to Neobacillus drentensis DSM 15600T (98.3 %) and Neobacillus fumarioli KCTC 13885T (98.2 %), and less than 98.2 % 16S rRNA gene sequence similarity to the other members of the genus Neobacillus. Whole-genome analysis of strain BRMEA1T comprised a circular chromosome (5 632 809 bp in size) with 38.5 mol% G+C content. Digital DNA-DNA hybridization analyses revealed that strain BRMEA1T showed 20.5 and 22.0% genomic DNA relatedness with the closest species, N. drentensis DSM 15600T and N. fumarioli KCTC 13885T, respectively. The whole-genome sequence of strain BRMEA1T showed the presence of 11 specific conserved signature indels for the genus Neobacillus. The major cellular fatty acids (>10 %) of strain BRMEA1T were found to be iso-C15 : 0 and anteiso-C15 : 0, while the major polar lipids were found to be diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Polyphasic analysis results revealed that BRMEA1T represents a novel species of the genus Neobacillus, with the proposed name Neobacillus endophyticus sp. nov. The type strain is BRMEA1T (=KCTC 43208T=CCTCC AB 2020071T).

Plant synthetic GP4 and GP5 proteins from porcine reproductive and respiratory syndrome virus elicit immune responses in pigs.

MAIN CONCLUSION: We demonstrated successful overexpression of porcine reproductive and respiratory syndrome virus (PRRSV)-derived GP4D and GP5D antigenic proteins in Arabidopsis. Pigs immunized with transgenic plants expressing GP4D and GP5D proteins generated both humoral and cellular immune responses to PRRSV. Porcine reproductive and respiratory syndrome virus (PRRSV) causes PRRS, the most economically significant disease affecting the swine industry worldwide. However, current commercial PRRSV vaccines (killed virus or modified live vaccines) show poor efficacy and safety due to concerns such as reversion of virus to wild type and lack of cross protection. To overcome these problems, plants are considered a promising alternative to conventional platforms and as a vehicle for large-scale production of recombinant proteins. Here, we demonstrate successful production of recombinant protein vaccine by expressing codon-optimized and transmembrane-deleted recombinant glycoproteins (GP4D and GP5D) from PRRSV in planta. We generated transgenic Arabidopsis plants expressing GP4D and GP5D proteins as candidate antigens. To examine immunogenicity, pigs were fed transgenic Arabidopsis leaves expressing the GP4D and GP5D antigens (three times at 2-week intervals) and then challenged with PRRSV at 6-week post-initial treatment. Immunized pigs showed significantly lower lung lesion scores and reduced viremia and viral loads in the lung than pigs fed Arabidopsis leaves expressing mYFP (control). Immunized pigs also had higher titers of PRRSV-specific antibodies and significantly higher levels of pro-inflammatory cytokines (TNF-α and IL-12). Furthermore, the numbers of IFN-γ+-producing cells were higher, and those of regulatory T cells were lower, in GP4D and GP5D immunized pigs than in control pigs. Thus, plant-derived GP4D and GP5D proteins provide an alternative platform for producing an effective subunit vaccine against PRRSV.

Profiling of the Major Phenolic Compounds and Their Biosynthesis Genes in Sophora flavescens Aiton.

Sophorae Radix (Sophora flavescens Aiton) has long been used in traditional medicine in East Asia due to the various biological activities of its secondary metabolites. Endogenous contents of phenolic compounds (phenolic acid, flavonol, and isoflavone) and the main bioactive compounds of Sophorae Radix were analyzed based on the qualitative HPLC analysis and evaluated in different organs and at different developmental stages. In total, 11 compounds were detected, and the composition of the roots and aerial parts (leaves, stems, and flowers) was significantly different. trans-Cinnamic acid and p-coumaric acid were observed only in the aerial parts. Large amounts of rutin and maackiain were detected in the roots. Four phenolic acid compounds (benzoic acid, caffeic acid, ferulic acid, and chlorogenic acid) and four flavonol compounds (kaempferol, catechin hydrate, epicatechin, and rutin) were higher in aerial parts than in roots. To identify putative genes involved in phenolic compounds biosynthesis, a total of 41 transcripts were investigated. Expression patterns of these selected genes, as well as the multiple isoforms for the genes, varied by organ and developmental stage, implying that they are involved in the biosynthesis of various phenolic compounds both spatially and temporally.

Effect of Sunlight Radiation on the Growth and Chemical Constituents of Salvia plebeia R.Br.

This study investigated the chemical composition changes of Salvia plebeia R.Br. cultivated under different light sources, including florescent light and sunlight. The plants were exposed to fluorescent light for four months and sunlight and then examined for the next 5-7 months. Plants were harvested monthly during the seven months, and we examined whether the difference in light source affected the phenolic and flavonoid contents and antioxidant activity. A simple and reliable HPLC method using a PAH C18 column was applied for the quantitative analysis of two triterpenoids from the S. plebeia groups. Oleanolic acid (OA) and ursolic acid (UA) showed good linearity (R² > 0.9999) within the test ranges (0.005-0.05 mg/mL), and the average percentage recoveries of the OA and UA were 95.1-104.8% and 97.2-107.1%, respectively. The intra- and inter-day relative standard deviations (RSDs) were less than 2.0%. After exposure to sunlight, the phenolic contents, including rosmarinic acid, showed a reduced tendency, whereas the flavonoid contents, including homoplantaginin and luteolin 7-glucoside, were increased. The content of the triterpenoids also showed an increased tendency under sunlight irradiation, but the variance was not larger than those of the phenolic and flavonoid contents. Among experimental groups, the group harvested at six months, having been exposed to sunlight for two months, showed the most potent antioxidant activity. Therefore, these results showed that the chemical composition and antioxidant activities of S. plebeia R.Br. was affected from environmental culture conditions, such as light source. Our studies will be useful for the development of functional materials using S. plebeia R.Br.

Enhanced production of resveratrol derivatives in tobacco plants by improving the metabolic flux of intermediates in the phenylpropanoid pathway.

The biosynthesis of flavonoids such as anthocyanin and stilbenes has attracted increasing attention because of their potential health benefits. Anthocyanins and stilbenes share common phenylpropanoid precursor pathways. We previously reported that the overexpression of sweetpotato IbMYB1a induced anthocyanin pigmentation in transgenic tobacco (Nicotiana tabacum) plants. In the present study, transgenic tobacco (Nicotiana tabacum SR1) plants (STS-OX and ROST-OX) expressing the RpSTS gene encoding stilbene synthase from rhubarb (Rheum palmatum L. cv. Jangyeop) and the RpSTS and VrROMT genes encoding resveratrol O-methyltransferase from frost grape (Vitis riparia) were generated under the control of 35S promoter. Phenotypic alterations in floral organs, such as a reduction in floral pigments and male sterility, were observed in STS-OX transgenic tobacco plants. However, we failed to obtain STS-OX and ROST-OX plants with high levels of resveratrol compounds. Therefore, to improve the production of resveratrol derivatives in plants, we cross-pollinated flowers of STS-OX or ROST-OX and IbMYB1a-OX transgenic lines (SM and RSM). Phenotypic changes in vegetative and reproductive development of SM and RSM plants were observed. Furthermore, by HPLC and LC-MS analyses, we found enhanced production of resveratrol derivatives such as piceid, piceid methyl ether, resveratrol methyl ether O-hexoside, and 5-methyl resveratrol-3,4'-O-ß-D-diglucopyranoside in SM and RSM cross-pollinated lines. Here, total contents of trans- and cis-piceids ranged from approximately 104-240 µg/g fresh weight in SM (F2). Collectively, we suggest that coexpression of RpSTS and IbMYB1a via cross-pollination can induce enhanced production of resveratrol compounds in plants by increasing metabolic flux into stilbenoid biosynthesis.

Chalcones isolated from Angelica keiskei inhibit cysteine proteases of SARS-CoV.

Two viral proteases of severe acute respiratory syndrome coronavirus (SARS-CoV), a chymotrypsin-like protease (3CL(pro)) and a papain-like protease (PL(pro)) are attractive targets for the development of anti-SARS drugs. In this study, nine alkylated chalcones (1-9) and four coumarins (10-13) were isolated from Angelica keiskei, and the inhibitory activities of these constituents against SARS-CoV proteases (3CL(pro) and PL(pro)) were determined (cell-free/based). Of the isolated alkylated chalcones, chalcone 6, containing the perhydroxyl group, exhibited the most potent 3CL(pro) and PL(pro) inhibitory activity with IC50 values of 11.4 and 1.2 µM. Our detailed protein-inhibitor mechanistic analysis of these species indicated that the chalcones exhibited competitive inhibition characteristics to the SARS-CoV 3CL(pro), whereas noncompetitive inhibition was observed with the SARS-CoV PL(pro).

Overexpression of the IbMYB1 gene in an orange-fleshed sweet potato cultivar produces a dual-pigmented transgenic sweet potato with improved antioxidant activity.

The R2R3-type protein IbMYB1 is a key regulator of anthocyanin biosynthesis in the storage roots of sweet potato [Ipomoea batatas (L.) Lam]. Previously, we demonstrated that IbMYB1 expression stimulated anthocyanin pigmentation in tobacco leaves and Arabidopsis. Here, we generated dual-pigmented transgenic sweet potato plants that accumulated high levels of both anthocyanins and carotenoids in a single sweet potato storage root. An orange-fleshed cultivar with high carotenoid levels was transformed with the IbMYB1 gene under the control of either the storage root-specific sporamin 1 (SPO1) promoter or the oxidative stress-inducible peroxidase anionic 2 (SWPA2) promoter. The SPO1-MYB transgenic lines exhibited higher anthocyanin levels in storage roots than empty vector control (EV) or SWPA2-MYB plants, but carotenoid content was unchanged. SWPA2-MYB transgenic lines exhibited higher levels of both anthocyanin and carotenoids than EV plants. Analysis of hydrolyzed anthocyanin extracts indicated that cyanidin and peonidin predominated in both overexpression lines. Quantitative reverse transcription-polymerase chain reaction analysis demonstrated that IbMYB1 expression in both IbMYB1 transgenic lines strongly induced the upregulation of several genes in the anthocyanin biosynthetic pathway, whereas the expression of carotenoid biosynthetic pathway genes varied between transgenic lines. Increased anthocyanin levels in transgenic plants also promoted the elevation of proanthocyanidin and total phenolic levels in fresh storage roots. Consequently, all IbMYB1 transgenic plants displayed much higher antioxidant activities than EV plants. In field cultivations, storage root yields varied between the transgenic lines. Taken together, our results indicate that overexpression of IbMYB1 is a highly promising strategy for the generation of transgenic plants with enhanced antioxidant capacity.

Biosynthesis of methylated resveratrol analogs through the construction of an artificial biosynthetic pathway in E. coli.

BACKGROUND: Methylated resveratrol analogs show similar biological activities that are comparable with those of the resveratrol. However, the methylated resveratrol analogs exhibit better bioavailability as they are more easily transported into the cell and more resistant to degradation. Although these compounds are widely used in human health care and in industrial materials, at present they are mainly obtained by extraction from raw plant sources. Accordingly their production can suffer from a variety of economic problems, including low levels of productivity and/or heterogeneous quality. On this backdrop, large-scale production of plant metabolites via microbial approaches is a promising alternative to chemical synthesis and extraction from plant sources. RESULTS: An Escherichia coli system containing an artificial biosynthetic pathway that produces methylated resveratrol analogues, such as pinostilbene (3,4'-dihydroxy-5-methoxystilbene), 3,5-dihydroxy-4'-methoxystilbene, 3,4'-dimethoxy-5-hydroxystilbene, and 3,5,4'-trimethoxystilbene, from simple carbon sources is developed. These artificial biosynthetic pathways contain a series of codon-optimized O-methyltransferase genes from sorghum in addition to the resveratrol biosynthetic genes. The E. coli cells that harbor pET-opTLO1S or pET-opTLO3S produce the one-methyl resveratrol analogues of 3,5-dihydroxy-4'-methoxystilbene and pinostilbene, respectively. Furthermore, the E. coli cells that harbor pET-opTLO13S produce 3,5-dihydroxy-4'-methoxystilbene, bis-methyl resveratrol (3,4'-dimethoxy-5-hydroxystilbene), and tri-methyl resveratrol (3,5,4'-trimethoxystilbene). CONCLUSIONS: Our strategy demonstrates the first harness microorganisms for de novo synthesis of methylated resveratrol analogs used a single vector system joined with resveratrol biosynthetic genes and sorghum two resveratrol O-methyltransferase genes. Thus, this is also the first report on the production of the methylated resveratrol compounds bis-methyl and tri-methyl resveratrol (3,4'-dimethoxy-5-hydroxystilbene and 3,5,4'-trimethoxystilbene) in the E. coli culture. Thus, the production of the methylated resveratrol compounds was performed on the simple E. coli medium without precursor feeding in the culture.