Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2010
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Ingunn ØvsthusAbstract
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Tomato plants (Solanum lycopersicum, cv. Suzanne) were subjected to complete nutrient solution or a solution without nitrogen (N), and placed at different temperatures and light conditions to test the effects of environment on flavonoids and caffeoyl derivatives and related gene expression. N depletion during 4-8 days resulted in enhanced levels of flavonoids and caffeoyl derivatives. Anthocyanins showed pronounced increased levels when lowering the growth temperature from 24 degrees C to 18 degrees C or 12 degrees C. Flavonol levels increased when the light intensity was increased from 100 mu mol m(-2) s(-1) to 200 mu mol m(-2) s(-1) PAR. Synergistic effects of the various environmental factors were observed. The increase in content of quercetin derivatives in response to low temperatures was only found under conditions of N depletion, and especially at the higher light intensity. Expression of structural genes in the phenylpropanoid and flavonoid pathways, PAL (phenylalanine ammonia lyase), CHS (chalcone synthase), F3H (flavanone 3-hydroxylase), and FLS (flavonol synthase) increased in response to N depletion, in agreement with a corresponding increase in flavonoid and caffeoyl content. Expression of these structural genes generally also increased in response to lower temperatures. As indicated through expression studies and correlation analysis, effects of N depletion were apparently mediated through the overall regulators of the pathway the MYB transcription factor ANT1 (ANTHOCYANIN 1) and SlJAF13 (a bHLH transcription factor orthologue of petunia JAF13 and maize RED genes). A PAL gene (PAL6) was identified, and correlation analysis was compatible with PAL6 being an actively expressed gene with function in flavonoid synthesis. (C) 2009 Elsevier Ltd. All rights reserved.
Authors
Jens Rohloff Inger Martinussen Eivind Uleberg Olavi Junttila Anja Hohtola Laura Jaakola Hely HäggmanAbstract
The fruit quality of European blueberry (EB) is mainly determined by taste compounds (sugars, acids, flavour) and health-beneficial structures generally denoted as antioxidants (vitamin C, phenolic acids, flavonols, anthocyanins, proanthocyanidins). Content and compound composition is strongly affected by the growth environment regarding light, temperature, water and edaphic factors. In order to assess genotypic relationships (northern and southern clones of EB) and environmental impact (temperature, day length) on berry quality parameters, a high-throughput system for blueberry metabolite profiling of nutritional compounds was established based on gas chromatography coupled with mass spectrometry (GC/MS). Dried methanol/H2O extracts from fresh-frozen berry tissue were derivatized, and subjected to GC/MS in order to detect polar compounds such as organic acids from Krebs-cycle, amino acids, sugars, polyols, and partly secondary metabolites (phenols, flavonoids). In addition, general quality parameters such as total phenols, total anthocyanins and antioxidant capacity (FRAP) were measured. Fructose (5 g), glucose (5 g), and sucrose (0.5 g/ 100 g f.w. at average) were the most abundant carbohydrates, together with high levels of organic acids such as citric acid (1.3 g), quinic acid (1.6 g), and malic acid (0.3 g/ 100 g f.w. at average). More than 50 metabolites per sample (identified compounds and not-annotated mass spectral tags) could be detected, and established the basis for multivariate statistics using principal component analysis, hierarchical clustering, and metabolite network analysis. Genotypic differences, modulation of metabolite pools and biosynthetic relationships are being discussed in-depth.
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Two female and two male cultivars have previously been released as a result of clone evaluation at Bioforsk Nord Holt. Selection criteria have been number of pistils or stamens per flower, number of flowers and number of shoots per m2. Currently a new group of clones are evaluated with the aim of finding new cultivars for release. The clones are collected from different parts of Norway, as well as from England and Spitsbergen. Preliminary results from harvesting 2005, 2006, 2007 and 2008 indicate good production potential for a couple of the tested clones. In addition to prior selection criteria based on berry yield, the levels of total anthocyanins and total phenols have been analyzed. This includes studies on the role of female clone, male pollinator and temperature on berry quality.
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In this study we investigated the interaction between temperature and genotype on fruit development and levels of total phenols and anthocyanins in cloudberry. The experiment was done in a phytotron using one female (‘Fjellgull") and one hermaphroditic (‘Nyby") cultivar. Plants were grown at 9, 12, 15 and 18°C in 24-h photoperiod. The female cultivars were pollinated with pollen from a male (‘Apollen") clone and from the hermaphrodite clone. Parthenocarpic fruit development was induced by gibberellic acid (GA3). Ripe berries were frozen individually at -80°C and stored until analyses. There was a linear, double logarithmic relationship between temperature and number of days from pollination/GA3-treatment to ripening. ‘Fjellgull" had significantly larger berries than ‘Nyby", and the largest berries were obtained at 12 and 9°C. Pollen clone did not have a significant effect on berry size. GA3 induced parthenogenesis in ‘Fjellgull" and partial parthenogenesis in ‘Nyby". In ‘Fjellgull", the parthenocarpic berries were comparable to pollinated ones at low temperatures, but at 18°C their development was restricted. The level of total anthocyanins was significantly higher in ‘Fjellgull" than in ‘Nyby", and these levels were significantly enhanced at 9 and 12°C compared to higher temperatures. Levels of total phenolic compounds were not significantly affected. In conclusion, the present results indicate that low temperature is favourable both for size and quality of cloudberries.
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