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.
2002
Abstract
A quantitative multiplex real-time PCR procedure was developed to monitor the dynamics in Norway spruce (Heterobasidion annosum) pathosystem. The assay reliably detected down to 1 pg of H. annosum DNA and 1 ng of host DNA in multiplex conditions. As a comparative method for quantifying fungal colonization,we applied the ergosterol assay. There was a very high correlation between the results obtained with the two methods, this strengthening the credibility of both assays. The advantages and disadvantages of these assays are discussed.
Abstract
Determining the level of pathogenic fungi and other microorganisms during colonization of the host is central in phytopathological studies. A direct way to monitor fungal hyphae within the host is microscopic examination, but chitin and ergosterol-levels are commonly used to indirectly measure the amount of fungus present. Recently real-time PCR technology is being used to follow infection agents in host tissues. We study the molecular basis of host defense responses, using the coniferous host Norway spruce infected with the pathogen Heterobasidion parviporum as the experimental system. This basidiomycete and the closely related pathogen H. annosum are the major root rot causing pathogens in conifers. To screen host material for differential resistance towards H. parviporum, it is a necessity to quantify the fungal colonization of the host tissues. Therefore, we aimed to develop and compare the sensitivity of a real-time PCR to an ergosterol based method for determining the rate of colonization, and applied the methods to rank the infection level of the pathogen on the spruce clones 053 and 589. We developed a quantitative multiplex real-time PCR procedure that reliably detecting down to 1pg H. parviporum DNA and 1ng host DNA. There was a very high correlation between the fungal-biomass/total-biomass and fungal-DNA/total-DNA rankings obtained with ergosterol and real-time PCR, strengthening the credibility of both methods. Based on both ergosterol and real-time PCR, it was clear that the clone 053 was hosting more fungal biomass than clone 589. The results indicate that this real-time procedure can be a useful method to screen different spruce material for their relative resistance to the pathogen H. parviporum.
Abstract
One of our main interests is to learn about the molecular basis of host defense responses, using the coniferous host Norway spruce infected with the pathogen Heterobasidion parviporum as the experimental system. This basidiomycete and the closely related pathogen H. annosum are the major root rot causing pathogens in conifers.To screen host material for differential resistance towards H. parviporum, it is a necessity to quantify the fungal colonization of the host tissues. Therefore, we aimed to develop and compare the sensitivity of a real-time PCR to an ergosterol based method for determining the rate of colonization. We developed a quantitative multiplex real-time PCR procedure that reliably detecting down to 1pg H. parviporum DNA and 1ng host DNA.There was a very high correlation between the fungal-biomass/total-biomass and fungal-DNA/total-DNA rankings obtained with ergosterol and real-time PCR, strengthening the credibility of both methods. The results indicate that this real-time procedure can be a useful method to screen different spruce material for their relative resistance to the pathogen H. parviporum.
Authors
Dan AamlidAbstract
Extended summary and conclusions The Pechenganikel combine in the Nikel-Zapolyarny area was established in 1933. During the first 30 years of production, 100 000 tons of sulphur dioxide (SO2) were emitted annually. Since 1971, nickel from the Norilsk ores in Siberia have been processed in the smelters. The Norilsk ore contains more sulphur than the Nikel ore. As a result of the processing of this sulphur-rich ore, emissions of SO2 increased rapidly, reaching 400 000 tons in 1979. Current annual emissions are much lower, about 150 000 tons. However, the present emission is still above the critical level for sensitive biota in the Nikel-Pasvik area. Investigations of soils show that the soil layers are contaminated by heavy metals (nickel and copper). The results also indicate an influence on soil fertility expressed as changes in base saturation (BS), cation exchange capacity (CEC) and soil acidity. According to the calculations (critical loads) future sulphur deposition has to be reduced to very low levels in order to stop the ongoing soil acidification. Air pollution influence has had severe effects on forest vegetation in the Nikel-Pasvik area. Trees, vascular plants, mosses and lichens are all affected. In the close vicinity of the smelters forests are dead or severely damaged. Visible injuries to vegetation caused by SO2 have some years been frequent. Symptoms are recognised on Scots pine (Pinus sylvestris) and downy birch (Betula pubescens), which are the dominant tree species in the region, and on other plants, e.g. dwarf birch (Betula nana) and bilberry (Vaccinium myrtillus). The species composition of the ground vegetation in the forest has been influenced, and epiphytic lichen vegetation has been severely influenced over large areas. Critical levels are exceeded on more than 3200 square kilometres of Russian and Norwegian territory. Air pollution has reduced invertebrate and animal diversity due to lack of forest vegetation and contamination of surface soils in the vicinity of the nickel smelters. Small vertebrates are impacted by an increased heavy metal content in the liver. However, no negative health effects to reindeer are foreseen. Long-term monitoring of water chemistry in lakes and rivers has revealed that extensive surface water acidification has taken place, particularly on the Norwegian side of the border. Critical loads are exceeded in large areas of Sør-Varanger municipality, especially in the Jarfjord area, and in areas situated around Nikel and Zapolyarny. However, on the Russian side, the contamination of lakes by the heavy metals (nickel and copper) is more severe than acidification, especially in the vicinity of the smelters, where damage to fish populations as well as phytoplankton and invertebrate communities are observed. Studies of human health in the Nikel-Pasvik area revealed no major health effects that can be ascribed to the air pollution by nickel and sulphur dioxide in the Nikel-Zapolyarny area or in the Pasvik valley. The most severe effects of air pollution in the border areas between Norway and Russia, caused by sulphur dioxide emission from Nikel and Zapolyarny, on the terrestrial and aquatic ecosystems seem to be on vegetation, surface water and soils, and thus also on other compartments of the ecosystem.
Abstract
No abstract has been registered
Authors
S. Kobro Halvor SolheimAbstract
No abstract has been registered
Authors
Wim de Vries Gert Jan Reinds H.F. van Dobben D. de Zwart Dan Aamlid P. Neville M. Posch J. Auée J.C.H. Voogd E.M. VelAbstract
No abstract has been registered
Authors
Halvor Solheim Jan-Ole SkageAbstract
In a greenery trial of Noble fir in western Norway, most branches had good quality until 1994 when 31 % of the branches were discarded. Since then a high level of losses has been noted and 87 % were discarded in 2000. A survey in 1998 revealed that the needle blight fungus Delphinella abietis was the main cause. It seems that frost did not initiate or maintain the disease in the stand, but generally low temperatures may have been important. Discarded branches with the fungus have been left on the ground and have probably been important in maintaining a high level of attack.
Abstract
Several strong westerly storms hit Western Norway during the winter of 1986-87. We studied the uptake, loss and visible effects of sea salt aerosols in Scots pine and Norway spruce. Foliage of was sampled at distances 0-100 km from the coastline between 59¢ª and 65¢ª N, and analysed for chloride, sodium and other elements. The range of chloride and sodium concentrations in needles was 0.5-5.0, and 0.1-3.0 mg g-1, respectively. The local variation was very large close to the coast. The relation to distance from the sea was improved by using distance from the nearest fjord rather than from the outer coastline. Other elements were less variable and not related to distance from the sea, or to sea salt concentrations. Only 1-10% of the needles sea salt content could be removed by 2 minutes washing in distilled water, and still much less of other elements. The amount of sea salt removed by washing was less related to distance from the sea than was the total content. Visible damage to the foliage occurred at chloride concentrations above 1 mg g-1 in the needles. Our conclusions are that analysis of the needles chloride or sodium content is a robust method for confirming damage to tree foliage by sea salt aerosols. Fjords as well as the ocean are significant sources of sea salt aerosols. Large local variation in salt deposition and damage will occur at a rugged coast. Nutrients and other elements are not significantly affected by the sea salt deposition. The use of chloride or sodium as a tracer for dry deposition should take into account not only the enrichment of these elements in canopy throughfall, but also the accumulation in the needles.
Authors
Halvor SolheimAbstract
No abstract has been registered