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
Authors
Nadeem Yaqoob Jan Karlsson Benedicte Riber Albrectsen Halvor Solheim Carl Gunnar FossdalAbstract
Plants are exposed to a variety of pathogens in their natural habitats. To understand the key processes of defense responses in aspen (Populus tremulae) at the transcript level two clones C72 and C23 with differential level of resistance from the SwAsp collection were inoculated with a foliar rust (Melampsora magnusiana Wagnar). Leaf samples were collected from adjacent areas of the inoculation site to examine the long distance (systemic) defense responses at day1, day3 and day14 post treatments. We performed microarray experiments on the biothrophic interaction, on comparison with the healthy controls we found that the two clones respond in a widely different fashion to the rust. Clone C23 showed almost no response to biotroph after 24 hours while clone 72 gave a clear defense response to the pathogen. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) showed a significant differential expression patterns in susceptible and resistant colnes. Chitinase, cinnamic acid reductase and the iaa genes showed signification up-regulation in resistant clone. The level of expression was 5.9 delta threshold cycles in chitinase gene at day14. Data analysis from extracted total phenolics and condensed tannins verify the results of cDNA arrays and qRT-PCR.
Authors
Igor A. Yakovlev Ari M. Hietala Pierre-Emmanuel Courty Francis Martin Jan Stenlid Halvor Solheim Carl Gunnar FossdalAbstract
The genome H. annosum s.l. was sequenced by JGI to a 8.23X coverage and assembled into 39 scaffolds with a total size of 33.7 Mb covering more than 98% of the whole genome. Based of genome sequence we annotated a number of genes for fungal enzymes that are believed to participate in lignin degradation, including: laccases (Lcc18 genes), manganese peroxidases (MnP8 genes) and hydrogen peroxide forming enzymes such as glyoxal oxidases (GLOX5 genes), quinone oxidoreductases (QOR17 genes) and aryl alcohol oxidases (AAO16 genes), which is in concordance with these gene family sizes observed in other sequenced white-rot fungi. We studied the genomic organisation and phylogeny of these genes as well as their expression using NimbleGen arrays and qRT-PCR. Transcript profiling using whole-genome oligo arrays and qRT-PCR revealed that some transcripts were very abundant in lignin-rich media (Lcc5 15, MnP2, GLOX4, QOR2 10, AAO9), in cellulose-rich media (lcc2, 7 16, MnP3 4, GLOX3, QOR4 6, AAO2, 7 10), in wood (Lcc3, MnP4, QOR2, GLOX1, AAO10) or in the free-living mycelium grown liquid culture (Lcc1, 3, 10 13), suggesting specific functions of these genes, which need to be studied further.
Authors
Jihong Liu Clarke Carl Jonas Jorge Spetz Sissel Haugslien Merete Dees Roar Moe Dag-Ragnar BlystadAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Traditional wood preservatives based on biocides are effective against wood-deteriorating organisms because of their toxicity. By contrast, modified woods are non-toxic by definition. To investigate the efficiency of various wood modifications, quantitative real-time polymerase chain reaction (qPCR) was used to profile the DNA amounts of the white-rot fungus Trametes versicolor (L.) [Lloyd strain CTB 863 A] during an 8-week-long growth period in treated Pinus sylvestris (L.) sapwood. The studied wood was modified by acetylation, furfurylation, and thermal treatment. The traditional wood preservatives bis-(N-cyclohexyldiazeniumdioxy)-copper (Cu-HDO) and chromated copper arsenate (CCA) were used as references, whereas untreated P. sylvestris (L.) sapwood served as a control. The maximum levels of fungal DNA in native wood occurred at the end of the experiment. For all wood treatments, the maximum fungal DNA level was recorded after an incubation period of 2 weeks, followed by a decline until the end of the trial. For the preservative-treated woods, Cu-HDO showed the lowest level of fungal DNA throughout the experiment, indicating that exploratory hyphal growth is limited owing to the phytotoxicity of the treatment. The other treatments did not inhibit the exploratory hyphal growth phase. We conclude that qPCR studies of hyphal growth patterns within wood should provide a powerful tool for evaluating and further optimizing new wood protection systems.
Abstract
We have recently found that Norway spruce (Picea abies (L.) Karst.) can rapidly adjust its adaptive performance, probably through an epigenetic mechanism. This appears to employ a kind of long-term memory of temperature sum and (probably) photoperiod from the time of its embryo development. In our research we made identical controlled crosses and produced seed lots under controlled temperature and day-length conditions and later observed phenology, growth and hardiness traits in the progenies. It was repeatedly found that temperature conditions during seed set, in particular, influence the phenotypes of the offspring; seedlings from seeds produced under warm conditions have later terminal bud set and reduced autumn frost hardiness than those from seed produced under colder conditions, and thus perform like a more southern provenance. When embryonic clones were derived from mature zygotic embryos and were cultured at different temperatures, the plants cultured under warm in vitro temperature were the last to set bud and grew taller than those cultured at lower temperatures. Progenies produced in Norway by Central European mother trees had a bud set curve skewed towards that of the local Norwegian performance. A comparison of the performance of seedlings from seeds collected in the same provenance regions in 1970 and 2006 shows that the more recent seed lots consistently produce taller seedlings with a later bud set, probably due to higher temperatures during seed production in 2006. The effect of reproductive environment has been shown to persist for years. It mimics the variation between provenances from different latitudes and altitudes and may explain much of the observed variability in bud set and early height growth between natural populations of Norway spruce. The observed phenomenon suggests an epigenetic mechanism in the developing embryo, either zygotic or somatic, that senses environmental signals such as temperature and influences adaptive traits. Research is underway to understand the molecular basis of this mechanism. We will discuss the implications of this epigenetic phenomenon for the interpretation of provenance differences, for tree breeding and for its possible role in adaptation to climate change.
2009
Authors
Belachew Asalf Tadesse Håvard Eikemo Andrew Dobson Anne-Marte Tronsmo Cecilie Hagen David M. Gadoury Robert C Seem Arne StensvandAbstract
Several non-chemical control agents are now registered and available for control of powdery mildews. However, there is little or no information about their efficacy against strawberry powdery mildew, caused by Podosphera aphanis. Trials were conducted to compare the performance of non-chemical control agents to chemical fungicides under laboratory, greenhouse and high plastic tunnel conditions. The treatments included: AQ10 (active ingredient is Ampelomyces quisqualis, a hyperparasite on powdery mildew), AQ10 + Silwet Gold (organosilicon adjuvant, enhances distribution and wetting), Vacciplant (active ingredient is laminarin, an extract from brown algae), JMS Stylet oil (mineral oil), Rape seed oil + detergent, Thiovit (wettable sulphur), Topas 100 EC (penconazole) + Candit (kresoximmethyl) and water as control. In the greenhouse, one quarter of the recommended dose was used either daily in one experiment or three times per week in another. In the field, half of recommended rates were applied twice weekly. Both in the greenhouse and tunnel experiments, the chemical control Topas + Candit and AQ10 + Silwet Gold significantly reduced disease severity. AQ10,Vacciplant and Thiovit were moderately effective when applied daily in the greenhouse trial, but not significantly different from the water control when applied three time per week in the greenhouse and twice a week in the tunnel experiment. In the plastic tunnel, the JMS stylet oil and Rape seed oil + detergent treatments caused severe phytotoxic reaction (necrosis). AQ10 used alone had the poorest performance in the tunnel. This indicated that the spreader either enhances the effect of AQ10 and/or the spreader itself had an effect. In laboratory experiments with powdery mildew grown on strawberry leaflets in Petri dishes, spore germination after treatments with water, Stylet oil, Candit and Thiovit were 74, 53, 8 and 7%, respectively. The effect of Thiovit found in the laboratory was not reflected in the greenhouse and plastic tunnel trials. We will further explore the protectant, curative and eradicative effects of the compounds included here.
Abstract
No abstract has been registered
Authors
Ole Martin Eklo Marit Almvik Randi Bolli Trond Børresen Terje Haraldsen Lars Egil Haugen Roger Holten Gunnhild RiiseAbstract
This is a final report for the project Norwegian Scenarios II, part two, that has been performed in collaboration between Bioforsk Plant Health and Plant Protection, The Norwegian University of Life Sciences and the Norwegian Food Safety Authority. The aim of the project was to establish Norwegian scenarios for the models PRZM and MACRO and to use them for approval of new pesticides.
Authors
Belachew Asalf Tadesse Arne Stensvand David M. Gadoury Robert C Seem Andrew Dobson Anne-Marte TronsmoAbstract
Development of ontogenic resistance to powdery mildew (Podosphaera aphanis) in strawberry fruit has not been quantified, and thus cannot be exploited in disease management programs. Four commercially-relevant strawberry cultivars were evaluated for ontogenic resistance to powdery mildew. Fruits were inoculated at one of the four growth stages: flowering, green, white and early pink fruit. There was a significant difference between and within cultivars at the bloom and green stage of inoculations (P <0.05) for both disease incidence and severity. On average 16.4, 39.5, 48.7, and 60.3 % of the fruits inoculated at bloom developed powdery mildew in cultivars Elan, Korona, Frida and Inga, respectively. None of the cultivars developed powdery mildew when inoculated at the pink stage. It may be concluded that flowers and green fruits of strawberry were much more susceptible to powdery mildew infection than white and pink fruits. The high susceptibility of cultivars at the flower and early green stages seemed coincident with the succulent nature of the fruits at these stages, making it easy for penetration and establishment of mildew. Control measures targeting at these critical windows of fruit susceptibility are likely to reduce yield loss.