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  • Schwarz, Dietmar  (9)
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  • 1
    Language: English
    In: Food Chemistry, 2010, Vol.122(3), pp.566-571
    Description: Flavonoids have gained much attention because of their proposed positive effects for human health. Onions are a rich source of flavonoids, consisting mainly of the major flavonols quercetin-3,4′- -diglucoside (QDG) and quercetin-4′- -monoglucoside (QMG) in the bulb and the aglycone quercetin in the outer scales. In this study, distribution of these three flavonoids was determined in 16 onion cultivars ( ) using HPLC–DAD. Three different parts of the onion bulb, the inner layers, the middle layers and the outer scales were analysed. The analysis showed varietal differences in the selected onion cultivars. The cultivars with the highest total flavonoid content were the red skinned ‘Red Baron’ and the yellow skinned cultivars ‘Ailsa Craig’ and ‘Prilep’. The distribution of the total flavonoid content in the different parts of the onion bulb showed the following order: middle layers 〉 outer scales 〉 inner layers. In the inner layers QDG was the major flavonoid, while in the middle layers QDG and QMG were in equal amounts. In the outer scales quercetin was the major flavonoid prior to QMG.
    Keywords: Onions ; Allium Cepa ; Flavonoids ; Quercetin Glucosides ; Cultivars ; Profiling ; Chemistry ; Diet & Clinical Nutrition ; Economics
    ISSN: 0308-8146
    E-ISSN: 1873-7072
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  • 2
    Language: English
    In: Journal of the Science of Food and Agriculture, September 2011, Vol.91(12), pp.2234-2240
    Description: Food allergies are increasing in the European population. At present the onset of symptoms can be avoided only by elimination of a particular fruit or vegetable from the diet. A new approach is to develop hypoallergenic food products. This study characterises the allergenic potential of tomatoes, considering cultivation conditions, developmental stages and genotypes, in order to identify hypoallergenic fruits. Patients with a history of tomato allergy were recruited for skin allergy tests. Tomatoes carrying distinct genotypes were grown under various cultivation conditions and harvested at different maturation stages. Cultivation conditions (nitrogen fertilisation, light exposure and plant nutrition) did not affect the skin reactivity in tomato‐allergic patients. However, skin reactivity was significantly lower when using green‐unripe compared with red‐ripe tomatoes and when using landrace cultivars compared with cultivars bred for use in organic horticulture. Depending on their genetic background and maturity level, some tomato cultivars elicit positive reactions in tomato‐allergic patients in the skin allergy test. This novel finding should pave the way for the development of tomatoes with reduced allergenicity to relieve sufferers of tomato allergy. Copyright © 2011 Society of Chemical Industry
    Keywords: Food Allergy ; Tomato ; Cultivars ; Environmental Cultivation Conditions
    ISSN: 0022-5142
    E-ISSN: 1097-0010
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  • 3
    Language: English
    In: Scientia Horticulturae, 2011, Vol.130(3), pp.485-490
    Description: ► Three S levels, two NH :NO ratios, and AM fungi were tested on Chinese chive. ► Intermediate S was sufficient for optimal growth of . ► Increasing S concentration in the substrate increased organosulfur compounds. ► AM fungi decreased organosulfur compounds. ► Highest yield of organosulfur compounds was produced at NH :NO ratio of 50:50. Tissue concentrations of phytochemicals formed by species may be influenced by plant nutrient supply or rhizosphere microorganism activity. To test these relations, three plant nutritional factors were varied in two experiments with Chinese chive [ ]: (a) increasing sulfur concentrations in the substrate, (b) two ratios of ammonium to nitrate in supply, and (c) inoculation with arbuscular mycorrhizal (AM) fungi. Shoot dry weight, nutrient composition (nitrate, N, P, S), and organosulfur compounds (measured indirectly as pyruvic acid) were determined. In the first experiment, the supply of intermediate sulfur compared to low sulfur supply resulted in increased shoot dry weight and pyruvic acid concentrations. A further increase in sulfur supply increased plant pyruvic acid production in the absence of effects on dry weight. In the second experiment, AM fungi hardly increased shoot dry weight, nutrient, or pyruvic acid concentrations significantly. Pyruvic acid concentration was increased at an ammonium:nitrate ratio of 50:50 compared to a ratio of 5:95, whereas shoot dry weight was not significantly different. We conclude that both, supply of surplus sulfur or supply of equal amounts of ammonium and nitrate, can contribute to the production of high amounts of health related organosulfur compounds in Chinese chive.
    Keywords: Allium Tuberosum ; Am Fungi ; Ammonium ; Nitrate ; Organosulfur Compounds ; Sulfur ; Agriculture
    ISSN: 0304-4238
    E-ISSN: 1879-1018
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  • 4
    Language: English
    In: Mycorrhiza, 2011, Vol.21(5), pp.341-349
    Description: Arbuscular mycorrhizal (AM) fungi influence the expression of defence-related genes in roots and can cause systemic resistance in plants probably due to the induced expression of specific defence proteins. Among the different groups of defence proteins, plant food allergens were identified. We hypothesized that tomato-allergic patients differently react to tomatoes derived from plants inoculated or not by mycorrhizal fungi. To test this, two tomato genotypes, wild-type 76R and a nearly isogenic mycorrhizal mutant RMC, were inoculated with the AM fungus Glomus mosseae or not under conditions similar to horticultural practice. Under such conditions, the AM fungus showed only a very low colonisation rate, but still was able to increase shoot growth of the wild-type 76R. Nearly no colonisation was observed in the mutant RMC, and shoot development was also not affected. Root fresh weights were diminished in AM-inoculated plants of both genotypes compared to the corresponding controls. No mycorrhizal effects were observed on the biomass and the concentration of phosphate and nitrogen in fruits. Real-time quantitative polymerase chain reaction analysis revealed that six among eight genes encoding for putative allergens showed a significant induced RNA accumulation in fruits of AM-colonised plants. However, human skin reactivity tests using mixed samples of tomato fruits from the AM-inoculated and control plants showed no differences. Our data indicate that AM colonisation under conditions close to horticultural practice can induce the expression of allergen-encoding genes in fruits, but this does not lead necessarily to a higher allergenic potential.
    Keywords: Allergy ; Defence proteins ; Glomus mosseae ; RNA accumulation ; Skin prick test
    ISSN: 0940-6360
    E-ISSN: 1432-1890
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  • 5
    Language: English
    In: Journal of agricultural and food chemistry, 28 May 2008, Vol.56(10), pp.3538-45
    Description: The aim of the present study was to test whether variations in the root environment affect the content of health-related organosulfur compounds, total phenolic compounds, and flavonol glycoside concentrations in onions. For this purpose, greenhouse-grown onions ( Allium cepa L.) were either inoculated with a commercial arbuscular mycorrhizal inoculum or a sterile inoculum and were provided with two NH(4)(+):NO(3)(-) ratios as a nitrogen source. Onion growth, arbuscular mycorrhizal colonization rate, sugars, and nutrient element concentrations were also quantified. The plant antioxidant activity and quercetin monoglucoside and organosulfur compound concentrations increased with dominant nitrate supply. Furthermore, mycorrhizal colonization increased the antioxidant activity and also concentrations of the major quercetin glucosides. The present study provides clear evidence that antioxidant activity, quercetin glycosides, and organosulfur compounds can be increased in sufficiently supplied onion plants by dominant nitrate supply or application of arbuscular mycorrhizal fungi. This was probably due to increased precursor production and induced defense mechanisms.
    Keywords: Mycorrhizae -- Growth & Development ; Nitrates -- Administration & Dosage ; Onions -- Chemistry ; Phenols -- Analysis ; Sulfur Compounds -- Analysis
    ISSN: 0021-8561
    E-ISSN: 15205118
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  • 6
    Language: English
    In: Mycorrhiza, 2007, Vol.17(5), pp.469-474
    Description: Two challenges frequently encountered in the production of ornamental plants in organic horticulture are: (1) the rate of mineralization of phosphorus (P) and nitrogen (N) from organic fertilizers can be too slow to meet the high nutrient demand of young plants, and (2) the exclusive use of peat as a substrate for pot-based plant culture is discouraged in organic production systems. In this situation, the use of beneficial soil microorganisms in combination with high quality compost substrates can contribute to adequate plant growth and flower development. In this study, we examined possible alternatives to highly soluble fertilizers and pure peat substrates using pelargonium ( Pelargonium peltatum L’Her.) as a test plant. Plants were grown on a peat-based substrate with two rates of compost addition and with and without arbuscular mycorrhizal (AM) fungi. Inoculation with three different commercial AM inocula resulted in colonization rates of up to 36% of the total root length, whereas non-inoculated plants remained free of root colonization. Increasing the rate of compost addition increased shoot dry weight and shoot nutrient concentrations, but the supply of compost did not always completely meet plant nutrient demand. Mycorrhizal colonization increased the number of buds and flowers, as well as shoot P and potassium (K) concentrations, but did not significantly affect shoot dry matter or shoot N concentration. We conclude that addition of compost in combination with mycorrhizal inoculation can improve nutrient status and flower development of plants grown on peat-based substrates.
    Keywords: Arbuscular mycorrhiza ; Compost ; Organic horticulture ; Pelargonium
    ISSN: 0940-6360
    E-ISSN: 1432-1890
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  • 7
    In: HortScience, 06/2006, Vol.41(3), pp.628-632
    Description: Organic horticultural production systems often are characterized by the use of beneficial soil microorganisms because the application of soluble inorganic P or N fertilizers is not endorsed. Due to the limited supply of soluble nutrients in organic production systems, nutrient deficiency may limit plant growth and yield. The sole use of peat for pot-based cultures is also discouraged in organic production systems. Therefore, we have studied viable alternatives for highly soluble fertilizers and pure peat substrates using leek [Allium ampeloprasum L. var. Porrum] as a test plant. Plants were grown on peat-based substrates with different rates of compost additions, and with and without inoculation with arbuscular mycorrhizal (AM) fungi. Inoculation with a commercial AM fungus inoculum resulted in colonization rates of up to 70% of total root length, whereas not inoculated plants remained free of root colonization. Mycorrhizal fungus colonization increased shoot Zn and K concentrations, but did not significantly affect shoot dry matter or shoot N and P concentrations. In contrast, compost addition increased plant growth, and also increased P and K concentrations in plants. We conclude that plants with high rates of mycorrhizal colonization can be obtained on peat-based substrates, but that under these conditions plants may not consistently benefit in growth from the mycorrhizal symbiosis. In contrast, additions of compost are a possible means to improve the substrate quality in organic horticultural production. ; Includes references ; p. 628-632.
    Keywords: Zinc ; Mycorrhizal Fungi ; Allium Ampeloprasum ; Phosphorus ; Microbial Colonization ; Organic Production ; Allium Porrum ; Growing Media ; Inoculation Methods ; Nitrogen ; Vesicular Arbuscular Mycorrhizae ; Peat ; Dry Matter Accumulation ; Nutrient Uptake ; Plant Growth ; Potassium ; Composts ; Plant Nutrition ; Leeks;
    ISSN: 0018-5345
    E-ISSN: 2327-9834
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  • 8
    Language: English
    In: Journal of Plant Nutrition and Soil Science, December 2007, Vol.170(6), pp.762-768
    Description: In recent years, interest has grown in cultivating species with enhanced health benefits and/or distinct flavor. Concentrations of phytochemicals determining these desired characteristics may be influenced by nitrogen forms (ammonium or nitrate) and arbuscular mycorrhizal (AM) fungi. We examined these relations with the test plant bunching onion ( L.). Three different ammonium‐to‐nitrate (NH : NO) ratios were supplied in combination with or without inoculation with an AM fungus (). The plants were evaluated for dry weight, leaf number, and content of nutrients (N, NO, P, S), sugars (glucose, fructose, and sucrose), and organosulfur compounds (measured as pyruvic acid). The experiment was carried out under controlled conditions in a greenhouse. Plants were grown on perlite amended twice a day with nutrient solution. In nonmycorrhizal plants, the application of nutrient solution with predominant NO or NHNO as N source supported adequate growth of while predominant NH supply resulted in decreased growth and occurrence of wilting symptoms. Mycorrhizal inoculation significantly increased dry weight and leaf number of predominantly NH‐fed or NHNO‐fed plants. While shoot P concentration increased with higher NH supply, shoot N concentration increased in predominantly NH‐fed plants only. Nitrogen form and AM colonization had little effect on shoot S or sugar concentrations. The total content in organosulfur compounds was significantly affected by both, N form and AM colonization. The optimal growth condition for a high formation of organosulfur compounds in this experiment was a nutrient solution with predominant NO supply, but when supported by AM fungi, produced similar amounts of pyruvic acid in NHNO‐fed plants.
    Keywords: Am Fungi ; Ammonium ; Nitrate ; Organosulfur Compounds ; Pyruvic Acid
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 9
    Language: English
    In: Journal of proteome research, March 2009, Vol.8(3), pp.1111-22
    Description: Tomato fruit and seed allergens were detected by IgE-immunoblotting using sera from 18 adult tomato-sensitized patients selected based on a positive history skin prick test (SPT) and specific Immunglobulin (Ig) E-levels. Isolated tomato seed total protein showed high SPT activity comparable or even higher than tomato fruit protein. For the molecular characterization of tomato seed allergens, a multidimensional protein fractionation strategy and LC-MS/MS was used. Two legumin- and vicilin-proteins were purified and showed strong IgE-reactivity in immunoblots. Individual patient sera exhibited varying IgE-sensitivity against the purified proteins. In silico structural modeling indicates high homology between epitopes of known walnut allergens and the detected IgE-crossreactive tomato proteins.
    Keywords: Allergens -- Immunology ; Immunoglobulin E -- Immunology ; Lycopersicon Esculentum -- Immunology ; Plant Proteins -- Immunology ; Seed Storage Proteins -- Immunology ; Seeds -- Immunology
    ISSN: 1535-3893
    E-ISSN: 15353907
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