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.
2001
Authors
Tore SkrøppaAbstract
No abstract has been registered
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Abstract
In 1996, 7000 ha of pine forests were defoliated by the pine looper Bupalus piniaria in south-western Sweden.The susceptibility of trees of different defoliation classes (0, 30, 60, 90 and 100% defoliation) to beetle-vectored blue-stain fungi was tested in inoculation experiments.Forty and 120-year-old Scots pine trees were inoculated with `single\", i.e. a few inoculations of Leptographium wingfieldii and Ophiostoma minus, two blue-stain fungi associated with the pine shoot beetle Tomicus piniperda. The young trees were also \"mass\" inoculated with L. wingfieldii at a density of 400 inoculation points per m2 over a 60 cm stem belt.Host tree symptoms indicated that only trees with 90100% defoliation were susceptible to the mass inoculation.Single inoculations did not result in any consistent differences in fungal performance between trees of different defoliation classes, regardless of inoculated species or tree age class.Leptographium wingfieldii produced larger reaction zones than O. minus, and both species produced larger lesions in old than in young trees.As beetle-induced tree mortality in the study area occurred only in totally defoliated stands, mass inoculations seem to mimic beetle-attacks fairly well, and thus seem to be a useful tool for assessing host resistance.As even severely defoliated pine trees were quite resistant, host defence reactions in Scots pine seem to be less dependent on carbon allocation than predicted by carbon-based defence hypotheses.
Authors
Svein Ole BorgenAbstract
No abstract has been registered
Authors
Malin Elfstrand Carl Gunnar Fossdal Gunilla Swedjemark David Clapham Olof Olsson Folke Sitbon Praveen Sharma Anders Lönneborg Sara von ArnoldAbstract
In this study we have investigated whether the defensin-like gene spi 1, isolated from Norway spruce, contributes to quantitative disease resistance and is a suitable candidate for utilisation in Norway spruce breeding programmes. The following questions have been raised: (1) Can the putative defense gene, spi 1, improve the defense towards microbial pathogens in a model plant species, tobacco? (2) Is it possible to produce transgenic plants of Norway spruce that overexpress spi 1 and are less susceptible to the pathogenic fungus Heterobasidion annosum? Compared to control plants, tobacco plants expressing spi 1 under an enhanced CaMV 35S promoter permitted less growth of the bacterial pathogen Erwinia carotovora. Embryogenic cultures of Norway spruce were transformed with a similar construct. The general phenotype of regenerated transgenic plants was normal, although it was difficult to maintain certain sublines in culture owing to poor initial growth. Among the transformed plants those with the highest content of SPI 1 displayed reduced fungal growth in the sapwood after inoculation with H. annosum. In conclusion, the spi 1 gene increases resistance in both homologous and heterologous systems.
Abstract
No abstract has been registered
Authors
Mehreteab TesfaiAbstract
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No abstract has been registered
Authors
Gunnar Ogner Guro Randem Torild WickstrømAbstract
Analyses of forest soils are widely used to monitor the effects of human activity on our environment. The overall quality of analytical data must, therefore, be sufficient to answer questions with regard to environmental changes taking place throughout several decades.Three horizons of an air-dried forest soil, was stored at 22 3 C, 3 C and 21 C for up to 1842 d to monitor its stability during storage. At room temperature, soil acidity increased and soil pH in water decreased by 0.1 to 0.3 pH units depending upon the soil horizon.The amount of C, P, and S extracted by 1M ammonium nitrate increased by 94%, 62% and 68%, respectively, after 1842 d. A corresponding increase in exchangeable cations [aluminium(Al), barium(Ba), calcium (Ca), magnesium (Mg), manganese (Mn), strontium (Sr), and zinc (Zn)] ranged from 11 to 23%. Storage at 3 C resulted in a decrease in pH only for mineral soil (10-15 cm layer). At 21 C, no changes in any of the soil-extractable components were found.
Authors
Jan Mulder Heleen A. de Wit Helena W.J. Boonen Lars R. BakkenAbstract
No abstract has been registered