Sun-Lim Kim

Phenolic Compound Concentration and Antioxidant Activities of Edible and Medicinal Mushrooms from Korea

A study was conducted to determine the content of phenolic compounds and the antioxidative activity of five edible and five medicinal mushrooms commonly cultivated in Korea. Phenolic compounds were analyzed using high performance liquid chromatography, and antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase activity. A total of 28 phenolic compounds were detected in the mushrooms studied. The average total concentration of phenolic compounds was 326 microg/g, the average being of 174 microg/g in edible mushrooms and 477 microg/g in medicinal mushrooms. The average total flavonoids concentration was 49 microg/g, with averages of 22 and 76 microg/g in edible and medicinal mushrooms, respectively. The DPPH radical scavenging activities ranged between 15 (Pleurotus eryngii) and 70% (Ganoderma lucidum) when reaction time was for 1 min. When reaction time was 30 min, the values ranged between 5 (Pleurotus eryngii) and 78% (Agaricus bisporus). The SOD activity averaged 28% among the 10 mushroom species, averages for edible and medicinal mushrooms being comparable. DPPH activities was significantly correlated (p < 0.01) with total content of phenolic compounds in edible mushrooms, while in medicinal mushrooms there was a significant correlation (p < 0.01) between SOD activity and total concentration of phenolic compounds. Numerous significant positive correlations were observed between phenolic compounds detected and antioxidative potential.

Analysis of Isoflavone, Phenolic, Soyasapogenol, and Tocopherol Compounds in Soybean [Glycine max (L.) Merrill] Germplasms of Different Seed Weights and Origins

This study investigated the functional compounds, including isoflavones, phenolics, soyasapogenols, and tocopherols, that were detected in 204 soybean [ Glycine max (L.) Merrill] germplasms. The soybean samples were divided into three groups according to origin: America, China, and Korea. The soybean samples were also classified into three groups on the basis of 100-seed weight: small (<13 g), medium (13-24 g), and large (>24 g). Among the soybean germplasms, CSRV121 (Bosukkong) had the highest level of isoflavone content (4778.1 μg g(-1)), whereas CS01316 had the lowest isoflavone content (682.4 μg g(-1)). Of the soybeans from the three different countries of origin, those from Korea showed the highest average concentration of total isoflavones (2252.6 μg g(-1)). The small seeds had the highest average total isoflavone concentration (2520.0 μg g(-1)) of the three different seed sizes. Among the 204 soybean germplasms, CS01405 had the highest content of total phenolics (5219.6 μg g(-1)), and CSRV017 (Hwangkeumkong) had the lowest phenolic content (654.6 μg g(-1)). The mean concentrations of total phenolic compounds were 2729.1 μg g(-1) in American soybean seeds, 1680.4 μg g(-1) in Chinese soybean seeds, and 1977.6 μg g(-1) in Korean soybean seeds. Of the soybean seeds from the three different countries of origin, American soybean seeds had the highest average concentration of total phenolic compounds, and Korean varieties showed the second highest value. Small soybean seeds had the highest average content of total phenolic compounds (2241.7 μg g(-1)), whereas medium-sized (1926.8 μg g(-1)) and large (1949.9 μg g(-1)) soybeans had lower concentrations of phenolic compounds. In whole soybean germplasms, the level of total soyasapogenols was higher in CS01173 (1802.3 μg g(-1)) and CS01346 (1736.8 μg g(-1)) than in the other types of soybeans. The mean concentrations of total soyasapogenol were 1234.0 μg g(-1) in American, 1294.5 μg g(-1) in Chinese, and 1241.5 μg g(-1) in Korean soybean varieties. Chinese soybean varieties showed the highest mean concentration of total soyasapogenol, and Korean soybean seeds showed the second highest level. The medium-seed group had the highest soyasapogenol content (1269.3 μg g(-1)) of the seeds that were grouped by size. A larger amount of soyasapogenol B than soyasapogenol A was detected. In whole soybeans, CS01202 showed the highest level of total tocopherols (330.5 μg g(-1)), whereas CSRV056 (Pungsannamulkong) had the lowest content (153.3 μg g(-1)). Chinese soybeans had the highest average concentration of total tocopherols (255.1 μg g(-1)). By comparison, the medium-sized Chinese soybean group had the highest (256.1 μg g(-1)) average total tocopherol content.

Introduction and nutritional evaluation of germinated soy germ

Germinated soy germ (GSG) were developed and evaluated for their nutritional value. Separated soy germ was germinated at room temperature for 24h under running water. As germination progressed, the protein and fibre content of GSG increased slightly, while the lipid and carbon to nitrogen (C/N) ratio decreased; free amino acids including GABA increased considerably while free sugars decreased. Linoleic and linolenic acid were the most abundant unsaturated fatty acids in soy germ, and slight changes were observed in GSG. The tocopherol and isoflavone contents showed a rapid increase of 32.4% and 27.9%, respectively, during germination. The abundance of GABA, isoflavones and tocopherols demonstrates the high nutritional value of GSG and suggests that GSG can be utilised as a reasonable and effective source of healthy foods.

Comparison of Isoflavones and Anthocyanins in Soybean [Glycine max (L.) Merrill] Seeds of Different Planting Dates

The concentrations of isoflavones and anthocyanins in five soybean seed cultivars of three different planting dates were determined in this study. Among the seeds of three different planting dates, the highest concentration of average total isoflavones (4098 μg g(-1)) was measured in those from early July, whereas the lowest concentration of average total isoflavones (3238 μg g(-1)) was measured in those from late May. Anthocyanin compounds were detected only in the Cheongjakong 3 cultivar. Among the three different planting dates, late-planted Cheongjakong 3 accumulated the highest concentration of total anthocyanins (10103 μg g(-1)), whereas the variety at an earlier planting date exhibited the lowest concentration of average total anthocyanins (7115 μg g(-1)). On the basis of these results, it was concluded that environmental factors such as temperature and precipitation may change the isoflavone and anthocyanin contents of soybean, altering the nutritional values of soy products.

Metabolic Differentiation of Diamondback Moth (Plutella xylostella (L.)) Resistance in Cabbage (Brassica oleracea L. ssp. capitata)

The diamondback moth, Plutella xylostella (L.), is a major pest responsible for destroying cabbage and other Brassica vegetable crops. A diamondback moth-resistant cabbage line was studied by comparing its metabolite profiles with those of a susceptible cabbage. Fourier transform infrared spectroscopy analysis revealed that carbohydrates, aromatic compounds, and amides were the major factors that distinguished the resistant and susceptible genotypes. Gas chromatography-time-of-flight mass spectrometry profiled 46 metabolites, including 19 amino acids, 15 organic acids, 8 sugars, 3 sugar alcohols, and 1 amine in two genotypes and F1 hybrid cabbages. The levels of glycolic acid, quinic acid, inositol, fumaric acid, glyceric acid, trehalose, shikimic acid, and aspartic acid were found to be very significantly different between the resistant and susceptible genotypes with a P value of <0.0001. These results will provide a foundation for further studies on diamondback moth resistance in cabbage breeding and for the development of other herbivore-resistant crops.

Inheritance and Quantitative Trait Loci Analysis of Resistance Genes to Bruchid and Bean Bug in Mungbean ( Vigna radiata L. Wilczek)

Bruchid (Callosobruchus chinenesis L.) and pod sucking bug (Riptortus clavatus Thunberg) are serious insect pests during the reproduction stage and seed storage period of legume crops worldwide. However, few sources of resistance to each of these insects have been identified and characterized, and no genetic studies have been carried out with simultaneous tests of these two insects. In this study, the inheritance of seed resistance to Callosobruchus chinenesis L. and Riptortus clavatus Thunberg was examined in a mungbean cultivar, Jangan mungbean, which was developed by backcrossing with the V2709 resistant donor. The F1, F2, and F3 seed generations were developed from the cross between susceptible and resistant parents, and evaluated for resistance to the two insects. It was found that resistance to bruchid and bean bug was controlled by a single dominant gene in the F1 and F2 seeds. However, the segregation pattern of reciprocal reaction to each insect in F2 seeds showed seeds were susceptible to each insect. These results suggest that the resistance genes in Jangan mungbean to bug and weevil are either different or closely linked with each other. A genetic linkage map 13.7 cM in length with 6 markers was successfully constructed. Two QTLs were identified for bruchid resistance, and a QTL for bean bug resistance was detected. One of the QTLs for resistance to bruchid was shared with the QTL for bean bug. These newly developed closely linked markers will be used for cloning of the resistance genes to bruchid and bean bug in the future.

Suppression of Akt-HIF-1α signaling axis by diacetyl atractylodiol inhibits hypoxia-induced angiogenesis.

Hypoxia-inducible factor (HIF)-1α is a key regulator associated with tumorigenesis, angiogenesis, and metastasis. HIF-1α regulation under hypoxia has been highlighted as a promising therapeutic target in angiogenesis-related diseases. Here, we demonstrate that diacetyl atractylodiol (DAA) from Atractylodes japonica (A. japonica) is a potent HIF-1α inhibitor that inhibits the Akt signaling pathway. DAA dose-dependently inhibited hypoxia-induced HIF-1α and downregulated Akt signaling without affecting the stability of HIF-1α protein. Furthermore, DAA prevented hypoxia-mediated angiogenesis based on in vitro tube formation and in vivo chorioallantoic membrane (CAM) assays. Therefore, DAA might be useful for treatment of hypoxia-related tumorigenesis, including angiogenesis. [BMB Reports 2016; 49(9): 508-513]

Genistein production in rice seed via transformation with soybean IFS genes

To produce genistein in rice, the isoflavone synthase (IFS) genes, SpdIFS1 and SpdIFS2 were cloned from the Korean soybean cultivar, Sinpaldalkong II as it has a higher genistein content than other soybean varieties. SpdIFS1 and SpdIFS2 show a 99.6% and 98.2% identity at the nucleotide level and 99.4% and 97.9% identity at the amino acid level, respectively, with IFS1 and IFS2 from soybean (GenBank accession Nos. AF195798 and AF195819). Plant expression vectors were constructed harboring SpdIFS1 or SpdIFS2 under the control of a rice globulin promoter that directs seed specific expression, and used to transform two rice varieties, Heugnam, a black rice, and Nakdong, a normal rice cultivar without anthocyanin pigment. Because naringenin, the substrate of SpdIFS1 and SpdIFS2, is on the anthocyanin biosynthesis pathway, the relative production rate of genistein was compared between SpdIFS-expressing transgenic Heugnam and Nakdong. Southern blot analysis of eight of the resulting transgenic rice plants revealed that the T0 plants had one to three copies of the SpdIFS1 or SpdIFS2 gene. The highest level of genistein content found in rice seeds was 103 μg/g. These levels were about 30-fold higher in our transgenic rice lines than the genistein aglycon content of a non-leguminous IFS-expressing transgenic tobacco petal, equaling about 12% of total genistein content of Sinpaldalkong II. There were no significant differences found between the genistein content in Heugnam and Nakdong transgenic rice plants.

Comparison of mid-Winter cold-hardiness and soluble sugars contents in the shoots of 21 highbush blueberry (Vaccinium corymbosum) cultivars

Summary Cold-hardiness and the soluble sugars contents of the shoots of 21 highbush blueberry (Vaccinium corymbosum) cultivars (‘Berkeley’, ‘Bluecrop’, ‘Bluegold’, ‘Bluehaven’, ‘Bluejay’, ‘Burlington’, ‘Chippewa’, ‘Collins’, ‘Dixi’, ‘Duke’, ‘Herbert’, ‘Jersey’, ‘Nelson’, ‘Northblue’, ‘Northland’, ‘Polaris’, ‘Rancocas’, ‘Sharpblue’, ‘Sierra’, ‘Spartan’, and ‘Sunrise’) were compared in mid-Winter. The level of cold-hardiness was determined by measuring electrolyte leakage at various freezing temperatures and was expressed as LT50, the temperature at which the incidence of injury reached 50%, and as Tmax, the temperature at which the rate of injury was maximal. The LT50 and Tmax values for the shoots of all 21 highbush blueberry cultivars ranged from –31.8º ± 0.09ºC to –41.1º ± 0.12ºC, and from –29.7º ± 0.06ºC to –36.9º ± 0.13ºC, respectively. Tmax values were significantly positively correlated with LT50 values (r = 0.98**, P ≤ 0.01). Based on their levels of cold-hardiness in terms of LT50 values, the 21 highbush blueberry cultivars were ranked in order as follows: ‘Jersey’ > ‘Northland’ > ‘Northblue’ > ‘Dixi’ > ‘Berkeley’ = ‘Sierra’ > ‘Chippewa’ > ‘Bluegold’ > ‘Burlington’ > ‘Bluejay’ > ‘Spartan’ > ‘Bluecrop’ = ‘Polaris’ > ‘Sunrise’ > ‘Duke’ > ‘Rancocas’ > ‘Herbert’ > ‘Sharpblue’ > ‘Collins’ > ‘Bluehaven’ > ‘Nelson’. Cold-hardiness, as estimated by LT50 and Tmax, was highly negatively correlated with total soluble sugars content (r = –0.78**, P ≤ 0.01 and r = –0.69**, P ≤ 0.01 for LT50 and Tmax, respectively). Among the soluble sugars detected, fructose and glucose concentrations, in particular, were significantly positively correlated with the levels of cold-hardiness in the shoots of all 21 highbush blueberry cultivars, but sucrose and raffinose concentrations were not correlated with cold-hardiness. Knowledge of intra-species differences in mid-Winter cold-hardiness in relation to soluble sugars contents will be useful during the breeding and cultivation of highbush blueberries.

Photosynthetic characteristics of highbush blueberry (Vaccinium corymbosum cv. Bluecrop) leaves in response to water stress and subsequent re-irrigation

SUMMARY Gas exchange and photosystem II (PSII) activities in the leaves of 2-year-old ‘Bluecrop’ highbush blueberry (Vaccinium corymbosum) were monitored during water stress and subsequent re-irrigation to investigate the effects of the intensity of water stress on changes in photosynthetic characteristics. The blueberry shrubs were not irrigated for 3 to 5 weeks, then re-irrigated daily up to 8 weeks. The decrease in soil water potential during water stress caused a progressive decrease in leaf water potential. Soil water potentials decreased to -0.26 MPa and -0.34 MPa at 3 and 5 weeks, respectively, following water stress, but recovered following subsequent re-irrigation, while the soil water potential in daily-irrigated shrubs was maintained at over -0.13 MPa throughout the experiment. Chlorophyll concentrations decreased with an increasing duration of water stress. Chlorophyll concentrations in leaves on shrubs subjected to water stress for 5 weeks did not recover following re-irrigation, unlike those subjected to water stress for 3 weeks. The leaves on shrubs subjected to water stress for 5 weeks maintained lower levels of chlorophyll during reirrigation. The net rate of CO2 assimilation (An) decreased significantly with an increasing duration of water stress. Reirrigation reversed the decrease in An in leaves on shrubs subjected to water stress for 3 weeks. Stomatal conductance (gs) exhibited a similar pattern to An. The actual quantum yield of photosystem II (ΦPSII) and the electron transport rate (ETR) also decreased significantly with an increasing duration of water stress, although the Fv/Fm ratio was not affected. ΦPPSII and ETR values in the leaves on shrubs subjected to water stress for 5 weeks did not recover after reirrigation, unlike those subjected to water stress for 3 weeks. Non-photochemical quenching increased with an increasing duration of water stress, but subsequent re-irrigation did not reverse the increase. These results indicate that the timing of re-irrigation of water-stressed ‘Bluecrop’ highbush blueberry is critical in order to maintain their photosynthetic capacity. Among the photosynthetic characteristics measured, ΦPSII and ETR could be used as sensitive indicators to assess the physiological status of leaves of ‘Bluecrop’ highbush blueberry growing under water stress conditions.