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.
2013
Sammendrag
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Forfattere
Jan Čermák Pavel Cudlin Roman Gebauer Isabella Børja Milena Martinková Zdeněk Stanĕk Jan Koller Jindřich Neruda Nadezhda NadezhdinaSammendrag
Estimates of root absorption magnitude are needed for the balanced management of forest ecosystems, but no methods able to work on the whole tree and stand level were available. Modified earth impedance method was developed recently and here it was tested, by comparing the results with those obtained by combination of several classical methods. Methods We used direct (soil cores, scanning and microscopy) and indirect (sap flow patterns and modified earth impedance) methods in an attempt to estimate the absorptive root area indexes (RAI) at two sites of about 25 and 40-years-old Norway spruce. We considered the geometric surfaces of all scanned fine roots to be equal to the fine root absorptive area (RAIscan). To estimate the potentially physically permeable area of fine roots, we microscopically evaluated the point of secondary xylem appearance and calculated the geometric area of root portions with primary structure (RAImicro). We termed the area of electrically conductive root surface as the active (ion) absorptive area (RAImei) and measured its extent by the modified earth impedance (MEI) method. Results The highest values for absorptive root areas at the two experimental sites we obtained with the scanning method (RAIscan was considered to be 100%), followed by the RAImicro (51%) and RAImei (32%). RAImei reached about 2/3 of RAImicro. The surface area of the ectomycorrhizal hyphae was an order of magnitude larger than that of all fine roots, but the MEI did not measure such increase. Conclusions We showed that the absorptive root area, indirectly estimated by the MEI, provides consistent results that approach the values obtained for fine roots with a primary structure estimated by traditional direct methods. The similar range of the values for the absorptive root surface area obtained by microscopy and by the MEI method indicates that this method is feasible and that it could be used to determine the extent of active absorptive root surface areas in forests.
Forfattere
Igor A. Yakovlev Ari Hietala Pierre-Emmanuel Courty Taina Lundell Halvor Solheim Carl Gunnar FossdalSammendrag
The pathogenic white-rot basidiomycete Heterobasidion irregulare is able to remove lignin and hemicellulose prior to cellulose during the colonization of root and stem xylem of conifer and broadleaf trees. We identified and followed the regulation of expression of genes belonging to families encoding ligninolytic enzymes. In comparison with typical white-rot fungi, the H. irregulare genome has exclusively the short-manganese peroxidase type encoding genes (6 short-MnPs) and thereby a slight contraction in the pool of class II heme-containing peroxidases, but an expansion of the MCO laccases with 17 gene models. Furthermore, the genome shows a versatile set of other oxidoreductase genes putatively involved in lignin oxidation and conversion, including 5 glyoxal oxidases, 19 quinone-oxidoreductases and 12 aryl-alcohol oxidases. Their genetic multiplicity and gene-specific regulation patterns on cultures based on defined lignin, cellulose or Norway spruce lignocellulose substrates suggest divergent specificities and physiological roles for these enzymes. While the short-MnP encoding genes showed similar transcript levels upon fungal growth on heartwood and reaction zone (RZ), a xylem defense tissue rich in phenolic compounds unique to trees, a subset of laccases showed higher gene expression in the RZ cultures. In contrast, other oxidoreductases depending on initial MnP activity showed generally lower transcript levels on RZ than on heartwood. These data suggest that the rate of fungal oxidative conversion of xylem lignin differs between spruce RZ and heartwood. It is conceivable that in RZ part of the oxidoreductase activities of laccases are related to the detoxification of phenolic compounds involved in host-defense. Expression of the several short-MnP enzymes indicated an important role for these enzymes in effective delignification of wood by H. irregulare.
Sammendrag
Shoot dieback disease of European ash caused by the ascomycete Hymenoscyphus pseudoalbidus threatens ash on a continental scale. A spore sampler placed in a diseased ash forest in Southern Norway, coupled with microscopy and DNA-based fungal species-specific real-time PCR assays, was employed to profile diurnal and within-season variation in infection pressure by ascospores of H. pseudoalbidus and the potentially co-existing non-pathogenic Hymenoscyphusalbidus. Hymenoscyphus pseudoalbidus was found to be predominant in the stand. Massive simultaneous liberation, by active discharge of pathogen ascospores in the morning, peaked in mid-Jul. to mid-Aug. Accumulation of pathogen DNA on leaflets of current-year leaves reached a high level plateau phase before appearance of autumn coloration, suggesting that pathogen establishment in leaves is terminated before the onset of leaf senescence.
Sammendrag
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Sammendrag
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Forfattere
Simon Ballance Stefan Sahlstrøm Per Lea Nina Elisabeth Nagy Petter V. Andersen Tzvetelin Dessev Sarah Hull Maria Vardakou Richard FaulksSammendrag
This is a post-peer-review, pre-copyedit version of an article published in [European Journal of Nutrition]. The final authenticated version is available online at: https://doi.org/10.1007/s00394-012-0386-5
Forfattere
Bjørn Arild Hatteland Steffen Roth Arild Andersen Kristin Kaasa Bente Støa Torstein SolhøySammendrag
The present distribution of the invasive slug Arion vulgaris Moquin-Tandon was studied in Norway. This important pest species has spread to many parts of Europe during the last decades, inflicting damage to agriculture and domestic gardens. It was first recorded in Norway in 1988, and has since spread to many parts of the country and is now recorded in 192 municipalities. We surveyed the current distribution by sampling and gathering species records in cooperation with garden societies and local authorities. Based on these records, we present distributional data as well as relative predictions of future distributions based on geoclimatic parameters. Currently, A. vulgaris covers most of coastal southern Norway while it shows a patchy distribution in northern Norway, recorded as far north as Finnsnes in Troms County.
Forfattere
M Ashraful Islam Henrik Lütken Sissel Haugslien Dag-Ragnar Blystad Sissel Torre Jakub Rolcik Søren Rasmussen Jorunn Elisabeth Olsen Jihong Liu ClarkeSammendrag
Euphorbia pulcherrima, poinsettia, is a non-food and non-feed vegetatively propagated ornamental plant. Appropriate plant height is one of the most important traits in poinsettia production and is commonly achieved by application of chemical growth retardants. To produce compact poinsettia plants with desirable height and reduce the utilization of growth retardants, the Arabidopsis SHORT INTERNODE (AtSHI) gene controlled by the cauliflower mosaic virus 35S promoter was introduced into poinsettia by Agrobacterium-mediated transformation. Three independent transgenic lines were produced and stable integration of transgene was verified by PCR and Southern blot analysis. Reduced plant height (21–52%) and internode lengths (31–49%) were obtained in the transgenic lines compared to control plants. This correlates positively with the AtSHI transcript levels, with the highest levels in the most dwarfed transgenic line (TL1). The indole-3-acetic acid (IAA) content appeared lower (11–31% reduction) in the transgenic lines compared to the wild type (WT) controls, with the lowest level (31% reduction) in TL1. Total internode numbers, bract numbers and bract area were significantly reduced in all transgenic lines in comparison with the WT controls. Only TL1 showed significantly lower plant diameter, total leaf area and total dry weight, whereas none of the AtSHI expressing lines showed altered timing of flower initiation, cyathia abscission or bract necrosis. This study demonstrated that introduction of the AtSHI gene into poinsettia by genetic engineering can be an effective approach in controlling plant height without negatively affecting flowering time. This can help to reduce or avoid the use of toxic growth retardants of environmental and human health concern. This is the first report that AtSHI gene was overexpressed in poinsettia and transgenic poinsettia plants with compact growth were produced.
Sammendrag
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