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.
2012
Forfattere
Gunn Strømeng May Bente Brurberg Maria Herrero Willy Couanon Arne Stensvand Isabella Børja Venche TalgøSammendrag
Tidlig på våren i 2012 ble det observert døde og døende trær av gråor i vannkanten langs Årungen i Ås kommune (Akershus). På stammene var det tjærefargede flekker, et symptom som gjerne forbindes med angrep av plantepa¬togene arter innen slekten Phytophthora. Fram til 1990-tallet var det ikke kjent at Phytophthora kunne angripe or, men i 1993 ble dette oppdaget i England, hvor tusenvis av oretrær har blitt ødelagt av denne sjukdomsorganismen. Det er en egen art, Phytophthora alni, som angriper or. Den er senere funnet i mange europeiske land og i Nord-Amerika. I august 2012 påviste vi P. alni for første gang i Norge på prøver fra gråor ved Årungen.
Forfattere
Toril Drabløs Eldhuset Nina Elisabeth Nagy Daniel Volařík Isabella Børja Roman Gebauer Igor A. Yakovlev Paal KrokeneSammendrag
Purpose: Drought-induced tree susceptibility is a major risk associated with climate change. Here we report how an 11-week drought affected tracheid structure, gene expression, and above- and belowground growth in 5-year-old Norway spruce trees (Picea abies) under controlled conditions. Results: The canopy of trees subjected to severe drought had significantly less current-year needle biomass, and fewer tracheids and tracheid rows in current-year shoots compared to fully watered control trees. Belowground tissues were more strongly affected by drought than aboveground tissues. In fine roots (<2 mm diameter) severe drought significantly reduced root biomass, root diameter, root length density and root surface area per soil volume compared to the control. Tracheid diameter and hydraulic conductivity in fine roots were significantly lower and tracheid flatness higher in trees subjected to severe drought than in control trees, both for long and short roots. Transcripts of the drought-related dehydrins PaDhn1 and PaDhn6 were strongly upregulated in stem bark and current-year needles in response to drought, whereas PaDhn4.5 was down-regulated. Conclusions: This study demonstrates that drought reduces biomass and hydraulic conductivity in fine roots and needles. We suggest that the ratio between PaDhn6 and PaDhn4.5 may be a sensitive marker of drought stress in Norway spruce.
Forfattere
Muath Alsheikh-Yousef Gage Koehler Robert Wilson Jens Rohloff Anita Sønsteby Jahn Davik Stephen K, RandallSammendrag
A crucial consideration for strawberry producers in Norway and other northern countries is winter freezing damage. A long-term goal of the Norwegian strawberry breeding is to increase winter hardiness and to improve fruit quality. Due to the complexity involved in regulating and enhancing freezing tolerance, the progress in the improvement of cultivars using traditional screening methods have had limited success. Thus, the development of molecular markers for freezing hardiness would facilitate the selection work for this trait. In this effort, we have developed and adopted state-of-art molecular tools to investigate cold response in strawberry plants during the acclimation phase resulting in the identification of a large number of genes, proteins, and distinct metabolites that correspond to cold/freezing tolerance in strawberry. To identify proteins responsible for freezing tolerance in strawberry we have examined alterations in protein levels in strawberry varieties that differ in cold tolerance using either 2-DE gel analysis followed by LC-MS/MS analysis or a shotgun MS/MS approach. Proteomic analysis suggested 30 potential biomarkers that showed significant changes in the cultivated strawberry in response to cold. In addition, GC-MS-based metabolite profiling revealed the up-regulation of carbohydrates, polyols, amino acids, TCA intermediates, and other distinct secondary metabolites after cold treatment. Transcriptional analysis of the cold acclimated samples also confirmed the regulation upon cold-treatment with varietal differences in strawberry. Moreover, several F2-populations from the model F. vesca parents diverging in cold tolerance have been developed in order to facilitate mapping of QTLs by performing GBS analyses. The knowledge attained from these endeavors is expected to expedite breeding of strawberries to achieve freezing tolerant lines and provide an integrative understanding of the molecular pathways that underlie this characteristic. * Rohloff et al. (2012) Metabolite profiling reveals novel multi-level cold responses in the model Fragaria vesca. Phytochemistry 79:99-109. * Koehler et al. (2012) Proteomic study of low temperature responses in strawberry cultivars (Fragaria x ananassa) that differ in cold tolerance. Plant Physiology 159:1787–1805 * Davik et al., (2012) Low temperature tolerance in diploid strawberry species (Fragaria ssp.) and its correlation to alcohol dehydrogenase levels, dehydrin levels, and central metabolism constituents. Planta (in press; DOI: 10.1007/s00425-012-1771-2).
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Trygve S. Aamlid Siri Fjellheim Abdelhameed Elameen Sonja Klemsdal Kristin Daugstad Hans Martin Hanslin Knut Hovstad Dagmar Hagen Knut Rydgren Line RosefSammendrag
Rapporten viser status for ECONADA-prosjektet ved årsskiftet 2011/2012.
Sammendrag
The outcome of a compatible mycorrhizal interaction is different from that in a compatible plant–pathogen interaction; however, it is not clear what mechanisms are used to evade or suppress the host defence. The aim of this work is to reveal differences between the interaction of Norway spruce roots to the pathogen Ceratocystis polonica and the ectomycorrhizal Laccaria bicolor, examine if L. bicolor is able to evade inducing host defence responses typically induced by pathogens, and test if prior inoculation with the ectomycorrhizal fungus affects the outcome of a later challenge with the pathogen. The pathogen was able to invade the roots and caused extensive necrosis, leading to seedling death, with or without prior inoculation with L. bicolor. The ectomycorrhizal L. bicolor colonised primary roots of the Norway spruce seedlings by partly covering, displacing and convoluting the cells of the outer root cortex, leaving the seedlings healthy. We detected increased total peroxidase activity, and staining indicating increased lignification in roots as a response to C. polonica. In L. bicolor inoculated roots there was no increase in total peroxidase activity, but an additional highly acidic peroxidase isoform appeared that was not present in healthy roots, or in roots invaded by the pathogen. Increased protease activity was detected in roots colonised by C. polonica, but little protease activity was detected in L. bicolor inoculated roots. These results suggest that the pathogen efficiently invades the roots despite the induced host defence responses, while L. bicolor suppresses or evades inducing such host responses in this experimental system.
Forfattere
Sheng-Hong Li Nina Elisabeth Nagy Almuth Hammerbacher Paal Krokene Xue-Mei Niu Jonathan Gershenzon Bernd SchneiderSammendrag
Norway spruce (Picea abies) bark contains specialized phloem parenchyma cells that swell and change their contents upon attack by the bark beetle Ips typographus and its microbial associate, the blue stain fungus Ceratocystis polonica. These cells exhibit bright autofluorescence after treatment with standard aldehyde fixatives, and so have been postulated to contain phenolic compounds. Laser microdissection of spruce bark sections combined with cryogenic NMR spectroscopy demonstrated significantly higher concentrations of the stilbene glucoside astringin in phloem parenchyma cells than in adjacent sieve cells. After infection by C. polonica, the flavonoid (+)-catechin also appeared in phloem parenchyma cells and there was a decrease in astringin content compared to cells from uninfected trees. Analysis of whole-bark extracts confirmed the results obtained from the cell extracts and revealed a significant increase in dimeric stilbene glucosides, both astringin and isorhapontin derivatives (piceasides A to H), in fungus-infected versus uninfected bark that might explain the reduction in stilbene monomers. Phloem parenchyma cells thus appear to be a principal site of phenolic accumulation in spruce bark.
Forfattere
Nina Elisabeth Nagy Simon Ballance Harald Kvaalen Carl Gunnar Fossdal Halvor Solheim Ari HietalaSammendrag
Heterobasidion parviporum, a common pathogenic white-rot fungus in managed Norway spruce forests in northern and central Europe, causes extensive decay columns within stem heartwood of the host tree. Infected trees combat the lateral spread of decay by bordering the heartwood with a fungistatic reaction zone characterized by elevated pH and phenol content. To examine the mode of fungal feeding in the reaction zone of mature Norway spruce trees naturally infected by H. parviporum, we conducted spatial proWling of pectin and hemicellulose composition, and established transcript levels of candidate fungal genes encoding enzymes involved in degradation of the diVerent cell wall components of wood. Colonized inner heartwood showed pectin and hemicellulose concentrations similar to those of healthy heartwood, whereas the carbohydrate proWles of compromised reaction zone, irrespective of the age of fungal activity in the tissue, indicated selective fungal utilization of galacturonic acid, arabinose, xylose and mannose. These data show that the rate of wood decay in the reaction zone is slow. While the up-regulation of genes encoding pectinases and hemicellulases preceded that of the endoglucanase gene during an early phase of fungal interaction with xylem defense, the manganese peroxidase gene showed similar transcript levels during diVerent phases of wood colonization. It seems plausible that the reaction zone components of Norway spruce interfere with both lignin degradation and the associated co-hydrolysis of hemicelluloses and pectin, resulting in a prolonged phase of selective decay.
Sammendrag
Det er ikke registrert sammendrag
Poster – Phytophthora-arter på lignoser i Norge
Maria Herrero, Venche Talgø, May Bente Brurberg, ...
Sammendrag
Det er ikke registrert sammendrag