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.
2010
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Svein SolbergAbstract
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Measurements of heat production rate have been made on wood samples with the brown rot fungus Postia placenta at different moisture contents. The results clearly indicate that the heat production rate (a measure of respiration rate and activity) is moisture dependent. When the moisture content is decreased, less heat is produced, and when the moisture content is increased, more heat is produced. Isothermal calorimetry seems to be a measurement technique well suited to the study of rot fungal activity as a function of temperature and moisture content.
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Roman Gebauer Josef Urban Isabella Børja Vladimir Gryc H Vavrcik Daniel Volarik Petra RychteckaAbstract
The drought stress presents a significant threat for the forest ecosystems. The climate change brings some extreme climatic conditions including longer and more common periods of the drought into the still more forest stands. Current forest management and consecutively wood processing industry in the Czech Republic is nowadays dependent mostly on the Norway spruce. In the same hand, Norway spruce is probably the most threatened tree species by the climate change. Therefore there is a demand for the suitable methodology to monitor the direct effect of the drought on the trees. Presented publication puts together different methods of the evaluation of the water stress and tries to assess their value for the study of the water stress. Of course, there are dozen of the methods to study the water stress. In this handbook we skipped the difficult and expensive techniques and focused rather on the simple methods, suitable for the field use. Methodology begins with the description of the meteorological measurements with current widely available instrumental techniques (i.e. measurements of the intensity of global radiation, air temperature and humidity, wind speed and precipitation) and continues with the monitoring of the soil water content and soil water potential. Then there is a focus on the direct effect of the water stress on the plant. We began with the plant root system since we believed that the fine roots were the most susceptible part of the tree. The focus was on their morphology, anatomy and biological activity. In the aboveground part of the tree we focused on the development of the hydraulic architecture of the tree on the microscopic level. This theoretical analysis was validated by the in-situ measurements of the sap flow. Direct and immediate effect of the water stress on the plant water status is described in the means of the plant water potential. Similarly to the hydraulic architecture we dealt with both the xylogenesis (on the cellular level) and the stem increment measured (on the tree level) by the logging band dendrometers. Finally we discussed the effect of the plant water status on the mineral nutrition of the tree. To conclude, none of the methods alone can implicate the complexity of the water stress, however the combination of the different views gives rather good insight on the tree condition and enable to predict the further tree development.
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Igor A. Yakovlev Carl Gunnar Fossdal Øystein JohnsenAbstract
The temperature level experienced during zygotic embryogenesis in the conifer Norway spruce effects an epigenetic memory and vital phenological traits in the progeny (Kvaalen & Johnsen, 2008). MicroRNAs (miRNAs) are endogenous small RNAs having large-scale regulatory effects on plant development and could participate in epigenetic regulation of expression in plants. To unravel the possible molecular mechanisms behind this epigenetic phenomenon we prepared two concatemerized small RNA libraries representing smallRNAs expressed in plants from seeds obtained after embryogenesis in cold environment and in a warm environment and made a search of conserved miRNAs found in other plant species. Partial sequencing of the libraries allowed identifying of 199 different small RNAs, with predominant length of 21-nt. Among them were 24 novel candidate miRNAs and 4 conserved. Screening of conserved miRNAs allowed confirming additional 17 miRNAs belonged to 11 miRNA families. Most of the miRNA obtained were related to unknown and “no-hit” genes. The expression of 8 conserved miRNAs (pab-miR156c, 159a, 396a,b, 535, 947, 951 and 858) and 9 predicted miRNAs (miR080, 100, 105, 119, 122, 132, 144a,b and 157) showed significant differences in transcript levels between epigenetically distinct plants. Additionally we confirmed that four selected genes PaLPT4, PaGaMYB, PaMYB10 and PaSPB13 regulated by miRNAs pab-miR100, 858, 159a and 156c, may also be involved in epigenetic memory regulation. Our results suggest that Norway spruce miRNAs are composed of a set of conserved miRNAs and a large proportion of novel non-conserved miRNAs with relatively low expression levels. These findings imply that both kinds of miRNAs might be involved or at least affected by the molecular mechanisms underlying the temperature sensitive epigenetic memory in Norway spruce.
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Nina OpstadAbstract
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