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
Abstract
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Authors
Fride Høistad ScheiAbstract
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Abstract
The winter hardiness of strawberry cultivars used in perennial production systems varies greatly, although a strong linkage exists between transcriptional and metabolic changes during cold acclimation. Still, little information is available on how plant metabolism adapts to cold and freezing temperatures under natural temperature and light conditions. In order to examine the hardening process of overwintering meristematic tissue in Fragaria x ananassa, crown samples of field-grown cvs. ‘Polka’ and ‘Honeoye’ were consecutively collected over a period of 15 weeks, i.e. from the end of the season (week 35/ end August) until midwinter (week 50/ December). Samples were subjected to qGC MS metabolite profiling to assess the reconfiguration of central metabolism, and characterize the regulation of selected compatible solutes (amino acids, Krebs metabolites, sugars, polyols). Besides changes in amino acid patterns (glutamic acid, aspartic acid, and asparagine), monosaccharide levels (fructose) were strongly enhanced until the end of the acclimation period in cv. ‘Honeoye’ (180-fold compared to start control). In contrast, ‘Polka’ showed a concentration peak (36-fold) in week 47 and a decline towards week 50. Also sucrose levels were steadily enhanced throughout the cold hardening period with averagely 6-fold higher levels in ‘Honeoye’ compared to ‘Polka’, thus underscoring cultivar differences. However, both cultivars showed a clear decline in sucrose levels after week 47. Particularly, the raffinose pathway was affected leading to strongly and transiently increased levels of the precursor galactinol (week 42/ mid October) and the trisaccharide raffinose (weeks 43 to 47/ end October to mid November). While galactinol biosynthesis was obviously earlier induced in cv. ‘Polka’ (week 38) compared to ‘Honeoye’ (week 39), subsequent raffinose production and concentration peaks were clearly delayed in ‘Polka’ (week 47) in contrast to ‘Honeoye’ (week 45). Major metabolic changes in both cultivars coincided with a decrease in daylength below 14 h after week 37 (mid September), and a consistent drop below 10°C average day temperature in week 39 (end September). The effect of temperature and light conditions on metabolic cold acclimation in field-grown strawberry is discussed. Keywords: Winter hardiness, metabolite profiling, quadrupole gas chromatography-mass spectrometry (qGC-MS), temperature, light
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.
Authors
Jens Rohloff Joachim Kopka Alexander Erban Per Winge Robert Charles Wilson Atle M. Bones Jahn Davik Stephen K, Randall Muath AlsheikhAbstract
Winter freezing damage is a crucial factor in overwintering crops such as the octoploid strawberry (Fragaria × ananassa Duch.) when grown in a perennial cultivation system. Our study aimed at assessing metabolic processes and regulatory mechanisms in the close-related diploid model woodland strawberry (Fragaria vesca L.) during a 10-days cold acclimation experiment. Based on gas chromatography/ time-of-flight-mass spectrometry (GC/TOF-MS) metabolite profiling of three F. vesca genotypes, clear distinctions could be made between leaves and non-photosynthesizing roots, underscoring the evolvement of organ-dependent cold acclimation strategies. Carbohydrate and amino acid metabolism, photosynthetic acclimation, and antioxidant and detoxification systems (ascorbate pathway) were strongly affected. Metabolic changes in F. vesca included the strong modulation of central metabolism, and induction of osmotically-active sugars (fructose, glucose), amino acids (aspartatic acid), and amines (putrescine). In contrast, a distinct impact on the amino acid proline, known to be cold-induced in other plant systems, was conspicuously absent. Levels of galactinol and raffinose, key metabolites of the cold-inducible raffinose pathway, were drastically enhanced in both leaves and roots throughout the cold acclimation period of 10 days. Furthermore, initial freezing tests and multifaceted GC/TOF-MS data processing (Venn diagrams, Independent Component Analysis, Hierarchical Clustering) showed that changes in metabolite pools of cold-acclimated F. vesca were clearly influenced by genotype.
Abstract
No abstract has been registered
Authors
Paal KrokeneAbstract
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Authors
Erik J. JonerAbstract
No abstract has been registered
Authors
Igor A. Yakovlev YeonKyeong Lee Adam Vivian-Smith Jorunn Elisabeth Olsen Carl Gunnar FossdalAbstract
In Norway spruce there is an enigmatic epigenetic memory of the temperature conditions during embryogenesis affecting vital phenological traits (Yakovlev et al. 2012). Adaptive phenological traits such as bud burst and bud set, observed as clinal variation in nature, are the ones affected.The epigenetic memory is establishment exclusively during embryogenesis in response to environmental impact. The epitype fixated by the time the embryo is fully developed without any change in the primary DNA sequence and is mitotically propogated. The epigenetic mechanism influence the phenotype through altered regulation of gene expression and is propagated throughout every growth cycle for the entire lifespan of this long lived species.The epigenetic memory may be realized through several molecular mechanisms including DNA methylation, and histone modifications affecting chromatin, as well as by small non-coding RNAs, and may also be related to the mechanisms silencing transposable or repetitive elements in the genome. MicroRNAs (miRNAs), endogenous small regulatory RNAs, are shown to be differentially expressed in genetically identically but epigenetically different progenies, in regards to the timing of bud burst and bud set (Yakovlev et al. 2010).We have started large scale studies using next regeneration sequencing approaches to identify and characterize the genes and regulatory elements involved in the initiation, maintenance, and heritability of the epigenetic memory. Epigenetic related changes in miRNA regulation during the establishment of the epigenetic memory are now studied in in vitro derived somatic embryos developing under cold (18C) and warm (30C) environmental conditions (that induce epitypes).We have constructed and sequenced 10 small RNA libraries during proliferation, maturation stage 1, 2 3 and the mature stage of embryo formation in the contrasted temperatures, in two control libraries during proliferation at 22C, as well as their mRNA transcriptomes using the Ion Torrent PGMTM (Life technologies) platform.We are expecting to determine at what stage(s) during embryogenesis the epigenetic memory marks are being laid down by identifying when the transcriptomic differences, of small RNA and mRNAs, between the epitypes are the most prominent during embryogenesis. The identification of novel miRNA candidates and the confirmation of conserved and novel miRNAs will be presented.
Abstract
Fungal degradation alters the microstructure of wood and its physical and chemical properties are also changed. While these changes are well investigated as a function of mass loss, mass density loss and changes in equilibrium moisture content are not well elucidated. The physical and chemical alterations are crucial when linking microstructural characteristics with macroscopic mechanical properties. In the present article, a consistent set of physical, chemical and mechanical characteristics is presented, which were measured on the same sample before and after fungal degradation. In the first part of this two-part contribution, elucidating microstructure/stiffness-relationships of degraded wood, changes in physical and chemical data are presented, which were collected from specimens of Scots pine (Pinus sylvestris) sapwood degraded by Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) for up to 28 weeks degradation time. A comparison of mass loss with corresponding mass density loss demonstrated that mass loss entails two effects: firstly, a decrease in sample size (more pronounced for G. trabeum), and secondly, a decrease of mass density within the sample (more pronounced for T. versicolor). These two concurrent effects are interrelated with sample size and shape. Hemicelluloses and cellulose are degraded by G. trabeum, while T. versicolor was additionally able to degrade lignin. In particular because of the breakdown of hemicelluloses and paracrystalline parts of cellulose, the equilibrium moisture content of degraded samples is lower than that in the initial state