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.
2009
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Wolfgang Britz Klaus MittenzweiAbstract
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Wenche DramstadAbstract
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Ari Hietala Nina Elisabeth Nagy Arne Steffenrem Harald Kvaalen Carl Gunnar Fossdal Halvor SolheimAbstract
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Two mature clones of Norway spruce (Picea abies (L.) Karst.) shown to have different level of resistance towards inoculation of Heterobasidion parviporum were compared with respect to spatiotemporal expression of transcripts related to biosynthesis of lignin, stilbenes and other phenolic compounds in response to fungal inoculation and physical wounding. Both clones responded to H. parviporum and physical wounding at transcriptional and chemical levels. Taxifolin, detected in the resistant clone only, increased in concentration following both wounding and inoculation. Concentrations of stilbenoid glucosides were highest in the susceptible clone. Following wounding or inoculation, concentrations of these glucosides increased in the susceptible clone, and quantities of their corresponding aglycones increased dramatically in both clones close to the treatment point. Significant changes in transcription were detected over the entire lesion length for all transcripts, and only the changes in a few transcripts indicated a response to inoculation with H. parviporum differing from that caused by wounding alone. The resistant clone had higher basal concentrations of lignin (LTGA) compared to the susceptible clone; concentrations increased in both clones after wounding and wounding plus inoculation treatments, but remained consistently higher in the resistant clone, suggesting higher lignin levels in the cell walls compared to the susceptible clone. In addition, the transcript level in the same clones was also measured the following year and we saw indications of primed defences for a number of gene products likely resulting from the inoculations performed 12 months prior.
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The soil is considered to be the major Carbon (C) sink in boreal forests, thus determination of soil carbon fluxes is essential for reliable C budgets. Especially partitioning of soil and root respiration is a major challenge. Soil respiration (Rs) consists of autotrophic respiration (Ra, respiration of plant roots and of microorganisms living on root-derived organic C in the rhizosphere) and heterotrophic respiration (Rh, respiration of free-living microorganisms during their decomposition of soil organic matter. In our study we attempted to estimate the contribution of roots to soil respiration by a girdling experiment. The study was established in two Norway spruce (Picea abies) stands, 35 and 65 year old, at Nordmoen, southeast Norway. Four quadratic plots (21m x 21m) were chosen within each of the two stands in spring 2006 and within two plots all trees were girdled. To estimate the contribution of root respiration, we measured CO2 efflux within each plot with a PP EGM-4 gas monitor for CO2, at permanently marked spots during two years (2006 and 2007). In the youngest stand in 2006, Rs in the control plots was higher than in the girdled plots at all measurement occasions. During this period, the mean Rs in the girdled plots was 64.9 % of the mean Rs in the control plots. In 2007, the Rs was highest in the girdled plots on most occasions, but the difference was never significant. In the oldest stand, Rs was also highest in the control plots in 2006 and highest in the girdled stand in most cases in 2007, but the difference was never significant. The implications will be discussed.
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Authors
Dana Daniela Maria Soare Daniela Stefanescu Valentina Cotet Tore Krogstad Marianne Bechmann Florin Oancea Carmen Lupu Florentin ChitoranAbstract
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