Gynura Bicolor DC Research Articles

Combined application of sucrose and 1-MCP alleviated the senescence of Gynura bicolor DC through regulating hexose accumulation

As a leaf vegetable, Gynura bicolor DC (G. bicolor) experiences a rapid deterioration after harvest including insufficient supply of sugar and destruction of cell membranes. In this research, four treatments were experimented on G. bicolor including the control (CK), 12% (g/g) sucrose (ST), 10 μL L−1 1-MCP (MT), and the combination of sucrose and 1-MCP (SMT). The results showed that three treated groups reduced respiratory rate, inhibited hexose consumption and promoted the decrease of starch and sucrose, which was converted into hexose including glucose and fructose to maintain cell membrane integrity. Meanwhile, the activities of AI, NI, SS-C, amylase, and corresponding gene expression levels were significantly up-regulated in three treated groups at 1 d, among which AI played a crucial role in regulating the accumulation of hexose. Furthermore, ST exerted a pronounced effect on hexose accumulation at the beginning while MT reduced hexose consumption through lowered respiratory metabolism during storage. Notably, SMT exhibited an optimum preservation effect on inhibited respiratory metabolism, maintaining cell membrane integrity, enhancing the retention of hexose, indicating that a synergistic effect of ST and MT were developed during storage.

High-resolution Tandem Mass Spectrometry for Studying Chemical Constituents of Gynura bicolor DC.

The separation and analysis of the desired chemical components are important subjects for the fundamental research of traditional Chinese medicine (TCM). Ultra-high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) has gradually become a leading technology for the identification of TCM ingredients. Gynura bicolor DC. (BFH), a perennial stemless herb used for medicine and food in China has medicinal effects such as clearing heat, moistening the lung, relieving cough, dispersing stasis, and relieving swelling. Polyphenols and flavonoids contain numerous isomers, which hinder the identification of the complex compounds in BFH. This paper presents a systematic protocol for studying chemical constituents of BFH based on solvent extraction and integrated data via UPLC-Q-TOF-MS. The method described here includes systematic protocols for sample pretreatment, MS calibration, MS acquisition, data processing, and analysis of results. Sample pretreatment includes collection, cleaning, drying, crushing, and extraction. MS calibration consists of multipoint and single-point correction. Data processing includes data importing, method establishment, analysis processing, and result presentation. Representative results of the typical fragmentation pattern of phenolic acids, esters, and glycosides in Gynura bicolor DC. (BFH) are presented in this paper. In addition, organic solvent selection, extraction, data integration, collision energy selection, and method improvement are discussed in detail. This universal protocol can be widely used to identify complex compounds in TCM.

In silico characterization of GbPAL, GbCHS, GbDFR and GbANS structural genes involved in the biosynthesis of flavonoids in Gynura bicolor DC

Gynura bicolor is a member of the Asteraceae family, possessing important pharmaceutical compounds such as flavonoids, anthocyanins, and terpenoids. Genetic and molecular studies focusing on the biosynthesis of flavonoids are indispensable to determining their regulation. GbPAL, GbCHS, GbDFR, and GbANS are genes encoding Phenylalanine ammonia lyase, Chalcone synthase, Dihydroflavonol reductase, and Anthocyanidin synthase enzymes, resepectively and are involved in the biosynthesis of flavonoids in G. bicolor, resepectively. There are still a few studies concerning the characterization of these genes. In this study, the structural enzyme sequences were selected to be characterized in silico using bioinformatics software. The phylogenetic analysis demonstrated that the genes in question were closely related to several species of the Asteraceae family. Our data revealed that the G. bicolor PAL, CHS, DFR and ANS genes are closely related to the sequence of genes found in Chrysanthemum morifolium. Furthermore, the CHS, DFR and ANS of G. bicolor also tightly correlated with sequence from Callistephus chinensis. Further analysis also demonstrated that all conserved motifs contain active functional and catalytic domain supporting the flavonoid-related enzyme functions. All physicochemical parameters used in this study also meet the prediction criteria. The investigation of secondary structure prediction using two instruments (PSIPRED and SOPMA) revealed that all enzymes tested possess similar α-helix (H), β-sheet (E), and coil (C) composition. GbPAL showed a secondary structure dominated by helix (mainly alpha), GbCHS and GbDFR (Alpha-beta), and GbANS (mainly beta). Each enzyme was modeled, with RMSD values superimposed on the template: 0.125 Å (GbPAL), 0.061 Å (GbCHS), 0.065 Å (GbDFR), and 0.089 Å (GbANS). The 3D model evaluation was checked using four parameters, including PROCHECK, Verify3D, ERRAT, and QMEAN-Z score. All the parameters verified that the model showed a high quality (more than 90 % of the favored region), high ressemblence of the 3D and 1D amino acid sequence, the 3D modeles were acceptable since they possesed high resolution of the protein structure (2.5 – 3 Å), and the enzyme models have Z-Score values in the permissible range. The accuracy and reliability of the generated models met Ramachandran value in comparison to experimentally resolved protein templates. The molecular docking analysis showed that each substrate compound docked at the real binding site in every tested enzyme. Furthermore, they also showed similar results compared to other experimentally observed proteins. The overall findings provide an insight into the molecular characteristics of flavonoid-related genes, which might enrich our understanding for further genomic application of the Gynura bicolor.

Characterization of anthocyanins in Gynura bicolor DC using HPLC-Q-Orbitrap MS and its stability during microwave vacuum drying

Gynura bicolor DC (G. bicolor) is largely consumed as a vegetable in many parts of the world, and due to its content in anthocyanin can be considered as a health-promoting food. This study aimed to characterize the anthocyanin composition of G. bicolor and compare the effect of microwave vacuum drying (MVD) on the anthocyanin content with that of hot air drying (HAD). Anthocyanins were characterized using high-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (HPLC-Q-Orbitrap MS), which accurately identified five anthocyanin compounds. Delphinidin 3-O-neohesperidoside is the main anthocyanin compound found in G. bicolor. MVD decreased the drying time by 89% compared to HAD. MVD retained 87% of the total anthocyanins in G. bicolor, compared to 18% retained by HAD. This study revealed that MVD produced high-quality dried G. bicolor products, while exhibiting reduced processing times compared to those achieved using HAD.

Effect of postharvest 1-methylcyclopropene application on reactive oxygen species scavenging and sucrose metabolism in Gynura bicolor DC

After harvest, the metabolism of Gynura bicolor DC (G. bicolor) is vigorous, resulting in sugar scarcity and reactive oxygen species (ROS) accumulation, thus aggravating the quality deterioration. 1-Methylcyclopropene (1-MCP) shows crucial effect in alleviating the postharvest metabolism of vegetables and fruits. This research aimed to evaluate the effect of 1-MCP on ROS scavenging and sucrose metabolism in G. bicolor. In this research, G. bicolor was treated with 10 μL L−1 1-MCP for 12 h, followed by storage at 20 ± 2 °C and 90 ± 5% relative humidity in darkness for 7 days. During storage, the increases in the respiration rate, electrolytic leakage, weight loss rate, ROS levels, and membrane lipid oxidation were effectively inhibited by 1-MCP. Moreover, starch and hexose degradation was decreased in the 1-MCP group, as were sucrose synthesis and catabolism. Correlation analysis indicated that sugar starvation was associated with respiration, activities regulation of CAT, SOD, and enzymes involved in sucrose metabolism were associated with the levels of hydrogen peroxide at the early storage. In conclusion, 1-MCP delayed postharvest quality deterioration of G. bicolor by alleviating respiration, inducing oxidative stress to enhance ROS scavenging, and inhibiting sucrose metabolism.

Postharvest application of 1-methylcyclopropene delays chloroplast degradation in Gynura bicolor DC under sugar scarcity conditions

• 1-MCP fumigation effectively delayed sugar scarcity. • 1-MCP fumigation delayed RuBisCo and chlorophyll degradation. • 1-MCP fumigation blocked the expression of GbATGs and GbSAG101 . • Sugar scarcity induced ROS burst in chloroplasts. • RuBisCo was preferentially degraded over chlorophyll. During postharvest transport and storage stage , Gynura bicolor DC ( G. bicolor ) is commonly handled in the darkness. However, long-term storage in the dark exacerbates postharvest sugar scarcity. 1-methylcyclopropene (1-MCP) was showing effective in inhibiting postharvest physiological metabolism of fruits and vegetables. The aim of this research was to uncover the mechanism underlying the effects of 1-MCP on the chloroplasts of G. bicolor under postharvest sugar scarcity conditions. The status of carbon sources, the enzymes and genes involved in chloroplast degradation were investigated. Furthermore, reactive oxygen species (ROS), chloroplast function, and chloroplast structure were also investigated to examine the physiological changes that occur in chloroplasts during storage. Degradations of starch, soluble sugar, and soluble protein were effectively retarded by 1-MCP. The increase of free amino acid content and decay rate were markedly inhibited by 1-MCP. 1-MCP not only inhibited the ROS burst, structural disintegration, and function (maximum photochemical efficiency Fv/Fm, effective quantum yield of PSII photochemistry QY, and relative electron transfer rate ETR) decreased in chloroplast, but also delayed the increased activities of chlorophyll degraded-related enzymes (chlorophyllase CHL, pheophytin pheophorbide hydrolase PPH and Mg-dechelatase), and proteinases (cysteine proteinase CP, serine proteinase SP and total proteinases TP), which retarding the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo), and chlorophyll degradation. The upregulated expressions of GbCHL, GbPPH, Gb-proteinases, GbATGs , and GbSAG101 were markedly blocked by 1-MCP. Correlation analysis showed that ROS burst was associated with sugar scarcity, the upregulated expressions of GbATGs , and GbSAG101 were associated with sugar scarcity and ROS burst, chlorophyll degradation was associated with the RuBisCo level. In conclusion, 1-MCP effectively delayed chloroplast degradation in G. bicolor by retarding sugar scarcity, inhibiting ROS burst in chloroplast, blocking the upregulated expressions of genes involved chloroplast degradation, and delaying the activities increase in proteases and chlorophyll degraded-related enzymes.

Screening of suitable reference genes for gene expression using quantitative real-time PCR in Gynura bicolor DC.

Screening of suitable reference genes for gene expression using quantitative real-time PCR in Gynura bicolor DC.

Effects of 1-methylcyclopropene treatment on phenolic metabolism in postharvest Gynura bicolor DC

We examined the effects of 10 μ L−1 1-methylcyclopropene (1-MCP) treatment on phenolic metabolism in postharvest Gynura bicolor DC stored at 20 ± 2 °C. The results indicated that 1-MCP treatment stimulated the biosynthesis of flavonoids and anthocyanins but inhibited that of lignin by regulating gene expression and enzyme activity. Specifically, 1-MCP treatment increased the contents of cinnamic acid, kaempferol, rutin, and chlorogenic acid by upregulating the expression of GbPAL, GbCHS, GbDFR, GbANS and GbUFGT, and decreased the ferulic acid content by downregulating the expression of GbC4H, GbCOMT, GbF5H and GbCCoAOMT. A correlation heatmap suggested close relations between individual phenolics and gene expression. The resulting accumulation of phenolics enhanced 2,2-diphenyl-1-picrylhydrazyl hydrate radical (DPPH·) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS·+) scavenging ability and ferric ion-reducing antioxidant power (FRAP). Furthermore, 1-MCP treatment decreased electrolyte leakage and inhibited the activity of peroxidase and polyphenol oxidase, alleviating the risks of phenolics degradation and the increase in superoxide anion (O2·−) and H2O2 levels. In summary, 1-MCP treatment increased the contents of total phenolics, flavonoids, and anthocyanins by stimulating gene expression, and retarded the risk of phenolic degradation, thus delaying senescence of G. bicolor leaves.

The basic helix-loop-helix transcription factor TabHLH1 increases chlorogenic acid and luteolin biosynthesis in Taraxacum antungense Kitag

Polyphenols are the main active components of the anti-inflammatory compounds in dandelion, and chlorogenic acid (CGA) is one of the primary polyphenols. However, the molecular mechanism underlying the transcriptional regulation of CGA biosynthesis remains unclear. Hydroxycinnamoyl-CoA:quinate hydroxycinnamoyl transferase (HQT2) is the last rate-limiting enzyme in chlorogenic acid biosynthesis in Taraxacum antungense. Therefore, using the TaHQT2 gene promoter as a probe, a yeast one-hybrid library was performed, and a basic helix-loop-helix (bHLH) transcription factor, TabHLH1, was identified that shared substantial homology with Gynura bicolor DC bHLH1. The TabHLH1 transcript was highly induced by salt stress, and the TabHLH1 protein was localized in the nucleus. CGA and luteolin concentrations in TabHLH1-overexpression transgenic lines were significantly higher than those in the wild type, while CGA and luteolin concentrations in TabHLH1-RNA interference (RNAi) transgenic lines were significantly lower. Quantitative real-time polymerase chain reaction demonstrated that overexpression and RNAi of TabHLH1 in T. antungense significantly affected CGA and luteolin concentrations by upregulating or downregulating CGA and luteolin biosynthesis pathway genes, especially TaHQT2, 4-coumarate-CoA ligase (Ta4CL), chalcone isomerase (TaCHI), and flavonoid-3′-hydroxylase (TaF3′H). Dual-luciferase, yeast one-hybrid, and electrophoretic mobility shift assays indicated that TabHLH1 directly bound to the bHLH-binding motifs of proTaHQT2 and proTa4CL. This study suggests that TabHLH1 participates in the regulatory network of CGA and luteolin biosynthesis in T. antungense and might be useful for metabolic engineering to promote plant polyphenol biosynthesis.

Growing period classification of Gynura bicolor DC using GL-CNN

Determining the optimal growth stage of leafy vegetables suitable for harvesting is of great importance. Despite the availability of many intelligent programs designed for plant classification, identifying the growth stage of a vegetable from its leaf features remains a major challenge. Gynura bicolor DC (G. bicolor) is an important vegetable, and its leaves are harvested for culinary use at a specific growth stage. The produce quality of leaves is compromised when they are harvested at improper stage. A classification model named GL-CNN was proposed based on convolutional neural networks to address this issue. The proposed model merges the features using a network fusion strategy to expand the feature representation on the basis of the intact leaf and leaf patch image sets. The networks were validated using a new dataset of G. bicolor planted and collected by ourselves. “Early fusion” and “late fusion” networks were designed and compared with GL-CNN to verify the rationality of network fusion location. The test accuracy of GL-CNN reaches 95.63%, which is the best in the classification task.

Molecular Cloning and Expression Analysis of Cu/Zn SOD Gene from Gynura bicolor DC.

Superoxide dismutase is an important antioxidant enzyme extensively existing in eukaryote, which scavenges reactive oxygen species (ROS) and plays an essential role in stress tolerance of higher plants. A full-length cDNA encoding Cu/Zn SOD was cloned from leaves of Gynura bicolor DC. by rapid amplification of cDNA ends (RACE). The full-length cDNA of Cu/Zn SOD is 924 bp and has a 681 bp open reading frame encoding 227 amino acids. Bioinformatics analysis revealed that belonged to the plant SOD super family. Cu/Zn SODs of the Helianthus annuus, Mikania micrantha, and Solidago canadensis var. scabra all have 86% similarity to the G. bicolor Cu/Zn SOD. Analysis of the expression of Cu/Zn SOD under different treatments revealed that Cu/Zn SOD was a stress-responsive gene, especially to 1-MCP. It indicates that the Cu/Zn SOD gene would be an important gene in the resistance to stresses and will be helpful in providing evidence for future research on underlying molecular mechanism and choosing proper postharvest treatments for G. bicolor.

Chemical composition, aroma evaluation, and inhibitory activity towards acetylcholinesterase of essential oils from Gynura bicolor DC.

The compositions of the essential oils obtained from leaves and stems of Gynura bicolor DC. were analyzed by GC-MS. One hundred eight components of these oils were identified. (E)-β-caryophyllene (31.42 %), α-pinene (17.11 %), and bicyclogermacrene (8.09 %) were found to be the main components of the leaf oil, while α-pinene (61.42 %), β-pinene (14.39 %), and myrcene (5.10 %) were the major constituents of the stem oil. We found 73 previously unidentified components in these oils from G. bicolor. The oils were also subjected to odor evaluation. Eleven and 12 aroma-active compounds were detected in the leaf and stem oils, respectively. The abilities of these oils to inhibit acetylcholinesterase (AChE) activity were determined. The sesquiterpenoids in the oils were found to inhibit AChE activity more strongly than the monoterpenoids in the oils did. It was suggested that the three main components in each essential oil act synergistically against AChE activity. These results show that the essential oils obtained from G. bicolor are a good dietary source of AChE activity inhibition.

Relationships between Cd concentrations in different vegetables and those in arable soils, and food safety evaluation of vegetables in Taiwan

The cadmium (Cd) accumulation capacity of various vegetables and the relationship between Cd concentrations in edible parts of vegetables and those in soils were assessed by conducting field experiments at Cd-contaminated sites in northern and central Taiwan. In addition, to thoroughly assess Cd concentrations in vegetables and to understand the food safety of vegetables in Taiwan, 2257 paired vegetable and surface soil samples were collected from major vegetable production areas for Cd concentration analysis. According to the bioconcentration factors calculated, the Cd accumulation capacity varied considerably among the vegetable species tested, and the order of the five vegetables with the highest capacities is peanut (Arachis hypogaea L.) > amaranth (Amaranthus tricolor L.) > spinach (Spinacia oleraceae L.) > gynura (Gynura bicolor DC.) > okra (Hibiscus esculentus L.), whereas the order of the five vegetables with the lowest capacities is bitter gourd (Momordica charantia L.) < cucumber (Cucumis sativus L.) < asparagus bean (Vigna unguiculata (L.) Walp. ssp. sesquipedalis (L.) Verdc.) < snap bean (Phaseolus vulgaris L.) < sponge gourd (Luffa cylindrica Roem.). We derived 29 soil–plant transfer models of Cd for individual vegetable species based on available pools of the Cd, manganese (Mn), zinc (Zn), copper (Cu) and iron (Fe) concentrations; soil pH; and cation exchange capacity (CEC). According to the derived models, the available Cd, Mn and Zn concentrations, and pH, served as the main factors affecting Cd concentrations in the edible parts of vegetables, whereas the CEC and available Cu and Fe concentrations are less important factors. The data of previous studies and those of this study from major vegetable production areas, including 30 vegetable crops, were used to evaluate the safety of vegetables in Taiwan. The results indicated that the percentage of vegetables with Cd concentrations exceeding the regulatory concentration was 0.54%; therefore, the food safety concern is low. However, 9.8, 1.0, 0.9 and 0.6% of amaranth, cabbage (Brassica oleracea L. Capitata Group), Chinese cabbage (Brassica pekinensis Skeels.) and carrot (Daucus carota L.), respectively, had Cd concentrations in the edible parts exceeding the regulatory concentration. Particular attention should be paid when planning production areas for these vegetables. We recommend cultivating peanuts in fields with a soil Cd concentration < 0.33 mg kg−1. The bioconcentration factors and soil–plant transfer models derived in this study might serve as assessment tools for planning farming areas for these vegetables.

Growth, morphological and photosynthetic characteristics, antioxidant capacity, biomass yield and water use efficiency of Gynura bicolor DC exposed to super-elevated CO2

As a consequence of the increasing importance of leaf vegetables in Bioregenerative life support system (BLSS), there is an interest in enhancing both the productivity and quality of Gynura bicolor DC (G. bicolor). The effects of super-elevated carbon dioxide concentration (3000ppm) on G. bicolor in different periods were investigated to reveal plausible underlying mechanisms for the growth, photosynthetic characteristics, antioxidant capacity and biomass yield. Experimental results showed that not only the photosynthetic rate but also the antioxidant capacity were increased in short-term super-elevated CO2 concentration. However, under long-term super-elevated CO2 concentrations, photosynthetic rate and pigment contents of G. bicolor significantly decreased due to photo inhibition. Elevated CO2 can be able to dwarf the G. bicolor plants. The leaves in high CO2 concentration were curled, which may affect the photosynthetic efficiency. At 3000ppm level, leaf senescence accelerated but biomass yield had no significant difference. Furthermore, elevated CO2 controlled transpiration rate and then enhanced water use efficiency. Superoxide dismutase (SOD) activity, peroxide activity (POD) and total antioxidant capacity (T-AOC) in 3000ppm condition were significantly lower than that in 400ppm condition. On the contrary, catalase (CAT) activity, glutathione (GSH) content and hydrogen peroxide (H2O2) were significantly enhanced under high CO2 concentration.

Nutritional status and ion uptake response of Gynura bicolor DC. between Porous-tube and traditional hydroponic growth systems

Hydroponic culture has traditionally been used for Bioregenerative Life Support Systems (BLSS) because the optimal environment for roots supports high growth rates. Recent developments in Porous-tube Nutrient Delivery System (PTNDS) also offer high control of the root environment which is designed to provide a means for accurate environmental control and to allow for two-phase flow separation in microgravity. This study compared the effects of PTNDS and traditional hydroponic cultures on biomass yield, nutritional composition and antioxidant defense system (T-AOC, GSH, H2O2 and MDA) of G. bicolor, and ionic concentration (NH4+, K+, Mg2+, Ca2+, NO3−, H2PO4−, SO42−) of nutrient solution during planting period in controlled environment chambers. The results indicated that the biomass production and yield of G. bicolor grown in PTNDS were higher than in hydroponic culture, although Relative water content (RWC), leaf length and shoot height were not significantly different. PTNDS cultivation enhanced calories from 139.5 to 182.3kJ/100g dry matter, and carbohydrate from 4.8 to 7.3g/100g dry matter and reduced the amount of protein from 7.3 to 4.8g/100g dry matter and ash from 1.4 to1.0g/100g dry matter, compared with hydroponic culture. PTNDS cultivation accumulated the nutrition elements of Ca, Cu, Fe and Zn, and reduced Na concentration. T-AOC and GSH contents were significantly lower in PTNDS than in hydroponic culture in the first harvest. After the first harvest, the contents of MDA and H2O2 were significantly higher in PTNDS than in hydroponic culture. However, the activity of T-AOC and GSH and H2O2 and MDA contents had no significant differences under both cultures after the second and third harvest. Higher concentrations of K+, Mg2+ and Ca2+ were found in nutrient solution of plants grown in hydroponics culture compared to PTNDS, wherein lower concentrations of NO3−, H2PO4− and SO42− occurred. Our results demonstrate that PTNDS culture has more potential to maintain nutritional quality and the optimal root zone environment for G. bicolor compared with hydroponic culture. And further refinements in PTNDS culture would make it a viable alternative for achieving high productivity in a BLSS.

Changes of the antioxidant capacity in Gynura bicolor DC under different light sources

In this work, the effects of different light sources, including high pressure sodium lamp (HPS), T5 fluorescent lamps (T5) and Red–Blue light-emitting diodes (R–B LEDs), on the antioxidant capacity of Gynura bicolor DC were studied through the analysis on the changes of the antioxidant indicators (phenolic compounds, flavonoids, glutathione) and antioxidant activity (DPPH and FRAP) in G. bicolor. The results showed that the highest contents of phenolic compounds and flavonoids were found in G. bicolor under T5, and the antioxidant potential in G. bicolor evaluated by either DPPH or FRAP assay also increased under T5 than others, while the antioxidant activity in G. bicolor under R–B LEDs with narrower spectrum was the lowest under the equal light intensity.

Effect of Shading on Anthocyanin and Non-flavonoid Polyphenol Biosynthesis of Gynura bicolor Leaves in Midsummer

The effect of shading in midsummer on anthocyanin and non-flavonoid polyphenol biosynthesis of Gynura bicolor DC leaves was examined using a control (full solar radiation) and a shade treatment (50% shading of full solar radiation). Leaf temperature in the shade plot remained ≈40 °C in the daytime, ≈6 °C lower than in the control. Plants in the shade plot grew better than the control. The content of chlorogenic acid (CGA) in leaves decreased with leaf maturation for both treatments, and a larger amount of CGA was detected in leaves from the control than the shade treatment. The profiles of reactive oxygen species (ROS) scavenging activity exhibited an identical pattern to the content of CGA. Although there was an abrupt increase in the content of anthocyanin in the early stage of leaf expansion, the content decreased rapidly as the leaves matured. The increase in anthocyanin early during leaf expansion was much more limited in control leaves than shaded leaves. There were no correlation between the profiles of anthocyanin and gene expression such as GbPAL, GbC4H, Gb4CL, GbCHS, GbCHI, GbF3H, and GbUFGT. However, the profiles of expression of genes such as GbMYB2, GbF3′H, GbDFR, and GbANS were similar to the anthocyanin profiles. These results suggest that artificial shading in midsummer is an effective method to promote anthocyanin accumulation but reduces ROS scavenging capacity as a result of lowered CGA production.

Changes in volatile constituents and phenols from Gynura bicolor DC grown in elevated CO2 and LED lighting

Volatile constituents and phenols of Gynura bicolor DC grown under three different CO2 levels of ambient (450μmolmol−1) and elevated (1200, 2000μmolmol−1) and three LED light conditions of WL (white light), RB20 (red/blue=8/2) and RB40 (red/blue=6/4) were investigated to improve efficient production of bioactive compounds in this vegetables under controlled environment. Results showed that increased CO2 caused a significant decrease in volatile terpenoids from G. bicolor DC leaves as compared with ambient CO2 at any light treatments. Plants grown under ambient CO2 with RB20 LED lighting had the highest yield of volatile terpenoids. In addition, CO2 elevation from 450 to 1200 improved the production of phenols (including anthocyanins, flavonoids and phenolics), while increasing CO2 from 1200 to 2000 appeared to negate such promotion. Furthermore, phenols contents were promoted by RB20 as compared with WL light treatment, whereas those were not further improved when increasing blue lights up to 40% (RB40). Our results indicated that the better choices for G. bicolor DC to produce more volatile terpenoids and phenols under controlled environment were at ambient and elevated CO2 levels with RB20 LED lighting condition, respectively.

First Report of Corynespora Leaf Spot Caused by Corynespora cassiicola on Gynura in China.

Gynura (Gynura bicolor DC.) is a perennial herbaceous plant in the family Compositae. It is an important Chinese vegetable, and is commonly used as a Chinese herbal medicine. In 2010, a severe leaf spot disease was observed on gynura grown in the main production areas in Tong Nan County, Chongqing City, China. Some farms experienced 60% disease incidence. Symptoms usually began on the lower leaves, as circular to elliptical or irregular spots with concentric rings. Individual spots were dark brown with grayish centers, sometimes coalescing and leading to extensive necrosis. The fungus associated with lesions was characterized as follows: Conidiophores were single or in clusters, straight or flexuous, unbranched, percurrent, cylindrical, pale to dark brown, 87.5 to 375.0 μm long and 5.0 to 10.5 μm wide. Conidia were solitary or catenate, straight to slightly curved, obclavate to cylindrical, 3 to 14 pseudoseptate, 82.8 to 237.5 μm long and 7.0 to 7.8 μm wide, and pale brown. The morphological characteristics of the conidia and conidiophores agreed with the descriptions for Corynespora cassiicola (1). To isolate the causal pathogen, surface-sterilized tissue at the margin of lesions was immersed in 75% ethanol for 30 s, rinsed in sterile water, dried in a laminar flow bench, transferred to PDA, and incubated at 28°C. Four single-spore cultures of the isolates were obtained and named from ZBTK10110637 to ZBTK10110640. All strains were identified as C. cassiicola. The isolate ZBTK10110637 was selected as representative for molecular identification. Genomic DNA was extracted by CTAB (2). The internal transcribed spacer (ITS) region of the rDNA was amplified using primers with ITS1 (5'-TCCGATGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3'). Amplicons were 433 bp (GenBank Accession No. JX867272) and shared 100% similarity with that of C. cassiicola (NRC2-1 No. AB539285.1). To confirm pathogenicity, four isolates were used to inoculate 12 gynura plants (6 weeks old) by mist spray-inoculation with 108 spores/ml suspension in sterile distilled water on the leaves. Control plants were misted with sterile distilled water. After inoculation, all plants were incubated in a greenhouse maintained at 20 to 28°C with relative humidity of 80 to 85%. Five days after inoculation, dark brown spots with a grayish center typical of field symptoms were observed on all inoculated plants. No symptoms were seen on water-treated control plants. The fungus was re-isolated from inoculated plants. The morphological characteristics of isolates were identical with the pathogen recovered originally. This is the first report of C. cassiicola on gynura.

Effects of different carbon dioxide and LED lighting levels on the anti-oxidative capabilities of Gynura bicolor DC

Gynura bicolor DC is not only an edible plant but also a kind of traditional Chinese herbal medicine. G. bicolor DC grown in controlled environmental chambers under 3 CO2 concentrations [450 (ambient), 1500 (elevated), 8000 (super-elevated) μmolmol−1] and 3 LED lighting conditions [white (WL), 85% red+15% blue (RB15), 70% red+30% blue (RB30) ] were investigated to reveal plausible antioxidant anabolic responses to CO2 enrichment and LED light quality. Under ambient and elevated CO2 levels, blue light increasing from 15% to 30% was conducive to the accumulation of anthocyanins and total flavonoids, and the antioxidant activity of extract was also increased, but plant biomass was decreased. These results demonstrated that the reinforcement of blue light could induce more antioxidant of secondary metabolites, but depress the effective growth of G. bicolor DC under ambient and elevated CO2 levels. In addition, compared with the ambient and elevated CO2 levels, the increased anthocyanins, total flavonoids contents and antioxidant enzyme activities of G. bicolor DC under super-elevated CO2 level could serve as important components of antioxidative defense mechanism against CO2 stress. Hence, G. bicolor DC might have higher tolerance to CO2 stress.