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.
2012
Authors
Jens Rohloff Eivind Uleberg Laura Jaakola Kajetan Trost Olavi Junttila Hely Häggman Inger MartinussenAbstract
Individual bilberry plants from two Northern and two Southern clones were studied for climatic effects on production and quality in a controlled phytotrone experiment at 12 °C and 18 °C in a 2-year trial. At each temperature the following light conditions were tested: 1) 12 h natural light (short day); 2) 24 h natural light (long day) and 3) 24 h natural light (long day) plus red light. In order to ensure sufficient and comparable fruit set between treatments, flower pollination was executed outdoors. Berry yield, quality parameters such as total anthocyanins, total phenols and antioxidant capacity, and chemical composition (GC/MS-based metabolite profiling) were recorded in both years, while HPLC-based anthocyanin analysis was only carried out in the second year. All analyzed compounds showed significant year-to-year variation with the exception of antioxidant activity. The experiment was conducted under natural light conditions, and therefore light intensity and quality varied between the two growing seasons. The first experimental year there was no difference in yield between temperatures, however, the second experimental year the berry yield was significantly higher at 18 °C. Temperature treatments led to faster berry ripening in the Northern than in the Southern clones at 12 °C. Metabolite profiling also revealed higher levels of flavanols, hydroxycinnamic acids, quinic acid and carbohydrates at 12 °C. Clonal effects showed that the content of all anthocyanin derivatives, as well as levels of antioxidants, total phenolics, malic acid and sucrose were highest in the Northern clones, while Southern clones had higher levels of hydroxycinamic acids, epicatechin, quinic acid and myo-inositol. Northern clones were also more responsive to additional red light with highest levels of anthocyanins under long-day treatment.
Authors
Inger Martinussen Jens Rohloff Laura Jaakola Kajetan Trost Olavi Junttila Hely Häggman Eivind UlebergAbstract
The effects of climate on production and the quality of bilberries have been studied in a controlled phytotrone experiment using clonal material originating from Northern and Southern parts of Finland. In the experiment individual plants from two Northern clones and two Southern clones have been grown at 12° and 18°C. At each temperature 3 different light treatments have been tested; 1) 24 h natural light (long day), 2) 12 h natural light (short day) and 3) 24 h natural light with an addition of extra red light. All berries produced by each plant have been harvested at maturity and have been analyzed for several important quality parameters. The metabolic profiling results show that levels of flavonols (epicatechin and catechin), hydroxyl acids (chlorogenic acid, hydroxyl cinnamic acid), quinic acid and all analyzed carbohydrates (myo-inositol, fructose, glucose and sucrose) are highest at 12°C. On the contrary, total anthocyanins levels were highest at 18°C and this was also reflected in the results on analysis of several anthocyanins derivates with the exception of Del 3‑Ara that was significantly higher at 12°C than 18°C. Northern clones had significantly higher levels of total anthocyanins, all measured anthocyanin derivates, total phenols, malic acid and sucrose than Southern clones.
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Authors
Gage Koehler Jens Rohloff Robert Wilson Per Winge Anita Sønsteby Muath Alsheikh Stephen K, RandallAbstract
There is limited research about variations between cultivars for freezing tolerance in fruit crops and indeed much less is known about the distinctive in ground structure of the crown that herbaceous perennials depend on for regeneration in spring. Because strawberry is a representative species for the Rosaceae crops knowledge gained is expected to be transferrable to benefit improvement of many of these related crops. To gain insight into the molecular basis that may contribute to overwintering hardiness, a comparative proteomic analysis was carried out for four Fragaria x ananassa (octoploid strawberry) cultivars that differ in freezing tolerance. Protein expression was investigated in the overwintering relevant crown structure of strawberry from plants exposed to 0, 2, and 42 day cold treatments and were examined by two-dimensional gel electrophoresis (2D). Some proteins, such as molecular chaperones, antioxidants / detoxifying enzymes, metabolic enzymes, and pathogenesis related proteins were revealed to be at significantly higher levels before cold exposure in the most freezing tolerant cultivars, (‘Jonsok’ and ‘Senga Sengana’) compared to the least tolerant cultivars (‘Frida’ and ‘Elsanta’). Freezing tolerance was evaluated for the cultivars before and after cold exposure, with findings that support that the most freezing tolerant cultivars are poised for rapid adaptation to cold exposure, suggesting potential differences in capacity or rate for cold acclimation. Thus, the molecular basis for enhanced overwintering survival may be related to the elevated basal level of a number of proteins, many of which are known to confer stress tolerances. These findings are presented and overlaid with a LFQP shotgun analysis and microarray analysis. This study presents the largest quantitative proteomic data-set for strawberry crown tissue during cold exposure to date. Through the comparison of these cultivars that differ in freezing tolerance, proteins that may contribute to cold tolerance but lack significant cold induction were revealed.
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Authors
Gage Koehler Robert Wilson John V. Goodpaster Anita Sønsteby Xianyin Lai Frank A. Witzmann Jin-Sam You Jens Rohloff Stephen K, Randall Muath Alsheikh-YousefAbstract
To gain insight into the molecular basis contributing to overwintering hardiness, a comprehensive proteomic analysis comparing crowns of Fragaria × ananassa (octoploid strawberry) cultivars that differ in freezing tolerance was conducted. Four cultivars were examined for freeze tolerance and the most cold-tolerant cultivar (‘Jonsok’) and least tolerant cultivar (‘Frida’) were compared with a goal to reveal how freezing tolerance is achieved in this distinctive overwintering structure and to identify potential cold-tolerance associated biomarkers. Supported by univariate and multivariate analysis, a total of 63 spots from 2DE analysis and 135 proteins from label-free quantitative proteomics (LFQP) were identified as significantly differentially expressed in crown tissue from the two strawberry cultivars exposed to 0, 2, and 42 day cold treatment. Proteins identified as cold tolerance associated included molecular chaperones, antioxidants/detoxifying enzymes, metabolic enzymes, pathogenesis related proteins and flavonoid pathway proteins. A number of proteins were newly identified as associated with cold tolerance. Distinctive mechanisms for cold tolerance were characterized for two cultivars. In particular, the ‘Frida’ cold response emphasized proteins specific to flavonoid biosynthesis, while the more freezing tolerant ‘Jonsok’ had a more comprehensive suite of known stress responsive proteins including those involved in antioxidation, detoxification, and disease resistance. The molecular basis for ‘Jonsok’ enhanced cold tolerance can be explained by the constitutive level of a number of proteins that provide a physiological stress-tolerant “poise”.