Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2018
Sammendrag
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Forfattere
Åge Arild NyborgSammendrag
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Bolette BeleSammendrag
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Maria-Luz Herrero Mona SchiefloeSammendrag
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Geir-Harald StrandSammendrag
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Sammendrag
Bark beetles and their symbiotic bluestain fungi kill more trees than all other natural factors and cause great economic losses in Norway spruce and other conifers. The tree's natural defenses are the most important factor maintaining bark beetle-fungus complexes at low, endemic levels. Spraying Norway spruce trees with the plant hormone methyl jasmonate (MeJA) primes tree defenses without eliciting notable induced defenses, but enables the trees to respond much more quickly and strongly when challenged by bark beetles or fungi several weeks after treatment. This phenomenon, known as defense priming, is a form of acquired resistance that enables cost-effective and vigorous defense responses. In field experiments with 50-year-old clonal spruce trees terpene concentrations in the bark increased 60-fold within 24 h after mechanical wounding of MeJA primed trees, compared with a 13-fold increase in unprimed control trees. We also observed altered transcriptional patterns in primed trees using Illumina deep transcriptome sequencing. When wounded, primed trees launched vigorous induced defenses with significant differential regulation of gene transcripts, such as those involved in phenylpropanoid synthesis leading to lignification. Resistance-like genes, such as the NB-LRR coding genes, are also more rapidly induced in primed than in unprimed trees. Transcriptome results from primed but unwounded trees indicate an alteration in the state of the chromatin, resembling changes associated with the activity of the epigenetic machinery creating long-lasting epigenetic marks. We do not know yet how long the primed state is activated in Norway spruce, but our data so far indicate that it may last for at least 3 years.
Forfattere
Nanna B. Svenningsen Stephanie J Watts-Williams Erik J. Joner Fabio Battini Aikaterini Efthymiou Carla Cruz-Paredes Ole Nybroe Iver JakobsenSammendrag
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Forfattere
Patryk Czortek Amy Eycott John-Arvid Grytnes Anna Delimat Jutta Kapfer Bogdan JaroszewiczSammendrag
Changes in the local flora of mountains are often explained by climate warming, but changes in grazing regimes may also be important. The aim of this study was to evaluate whether the alpine flora on summits in the Tatra Mts, Poland and Slovakia, has changed over the last 100 years, and if the observed changes are better explained by changes in sheep grazing or climate. We resurveyed the flora of 14 mountain summits initially investigated in the years 1878–1948. We used ordination methods to quantify changes in species composition. We tested whether changes in plant species composition could be explained by cessation of grazing and climate change, and whether these factors have influenced shifts in Ellenberg’s plant ecological indicator values and Raunkiaer’s life forms. Changes in alpine flora were greater on lower elevation summits, and lower on summits less accessible for sheep. More accessible summits were associated with a decrease in mean values of plant species’ light ecological indicator values over time, and a concurrent increase in temperature and nitrogen ecological indicator values. No significant relationships were found between accessibility for sheep and changes in Raunkiaer’s life-forms. Greater accessibility for sheep (meaning high historical grazing pressure) led to greater compositional changes of mountain summits compared with summits with low accessibility. Our results suggest that cessation of sheep grazing was the main factor causing changes in the species composition of resurveyed mountain summits in the Tatra Mts, while climate change played a more minor role.
Forfattere
Björn Ringselle Erik Bertholtz Ewa Magnuski Lars Olav Brandsæter Kjell Mangerud Göran BergkvistSammendrag
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