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.
2018
Authors
Isabella Børja Kjell Andreassen Jan Čermák Lise Dalsgaard Arthur Gessler Douglas Lawrence Godbold Rainer Hentschel Zachary E. Kayler Paal Krokene Nadezhda Nadezhdina Sabine Rosner Halvor Solheim Jan Svetlik Mari Mette Tollefsrud Ole Einar TveitoAbstract
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Authors
Sabine Rosner Notburga Gierlinger Matthias Klepsch Bo Karlsson Rob Evans Sven-Olof Lundqvist Jan Svetlik Isabella Børja Lise Dalsgaard Kjell Andreassen Svein Solberg Steven JansenAbstract
Projected climate change scenarios such as frequently occurring dry summer spells are an enormous threat to the health of boreal conifer forests. We identified visible features indicating wood with tracheids predisposed for hydraulic and mechanical dysfunction in Norway spruce, suggest why this is formed during severe summer drought and hypothesised on mechanism that would cause tracheid collapse and stem cracks. Trees from southern Sweden that showed signs of severe reaction to drought, i.e. stem cracks along the trunk, were compared to healthy, undamaged trees. Rings investigated included those formed in 2006, a year with an extremely dry summer season in the study region. In southern Norway, we investigated trees with and without drought-induced top dieback symptoms. We analysed anatomical features such as tracheid lumen diameter, thickness of cell wall and its various layers (S1, S2 and S3), applied Raman imaging in order to get information on the lignin distribution in the cell wall and the compound middle lamellae and performed hydraulic flow and shrinkage experiments. Although tracheids in annual rings with signs of collapse had higher tangential lumen diameters than those in “normal” annual rings, we conclude that collapse of tracheid walls depends mainly on wall thickness, which is genetically determined to a large extent. Spruce trees that produce earlywood with extremely thin cell walls can develop wall collapse and internal cracks under the impact of dry spells. We also present a new diagnostic tool for detecting individuals that are prone to cell wall collapse and stem cracks: Lucid bands, i.e. bands in the fresh sapwood with very thin cell walls and inhomogeneous lignin distribution in the S-layers and the compound middle lamellae that lost their hydraulic function due to periods of severe summer drought. The detection of genotypes with lucid bands could be useful for an early selection against individuals that are prone to stem cracks under the impact of severe summer drought, and also for early downgrading of logs prone to cracking during industrial kiln drying
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Authors
Tonje Økland Jørn-Frode Nordbakken Holger Lange Ingvald Røsberg Kjersti Holt Hanssen Nicholas ClarkeAbstract
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Authors
Mark McMullan Maryam Rafiqi Gemy Kaithakottil Bernardo J. Clavijo Lorelei Bilham Elizabeth Orton Lawrence Percival-Alwyn Ben J. Ward Anne Edwards Diane G.O. Saunders Gonzalo Garcia Accinelli Jonathan Wright Walter Verweij Georgios Koutsovoulos Kentaro Yoshida Tsuyoshi Hosoya Louisa Williamson Philip Jennings Renaud Ioos Claude Husson Ari Hietala Adam Vivian-Smith Halvor Solheim Dan MaClean Christine Fosker Neil Hall James K.M. Brown David Swarbreck Mark Blaxter J. Allan Downie Matthew D. ClarkAbstract
Accelerating international trade and climate change make pathogen spread an increasing concern. Hymenoscyphus fraxineus, the causal agent of ash dieback, is a fungal pathogen that has been moving across continents and hosts from Asian to European ash. Most European common ash trees (Fraxinus excelsior) are highly susceptible to H.fraxineus, although a minority (~5%) have partial resistance to dieback. Here, we assemble and annotate a H.fraxineus draft genome, which approaches chromosome scale. Pathogen genetic diversity across Europe and in Japan, reveals a strong bottleneck in Europe, though a signal of adaptive diversity remains in key host interaction genes. We find that the European population was founded by two divergent haploid individuals. Divergence between these haplotypes represents the ancestral polymorphism within a large source population. Subsequent introduction from this source would greatly increase adaptive potential of the pathogen. Thus, further introgression of H.fraxineus into Europe represents a potential threat and Europe-wide biological security measures are needed to manage this disease.
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Authors
Melissa Magerøy Hugh B. Cross Torstein Tengs Carl Gunnar Fossdal Pierre Petriacq Adam Vivian-Smith Tao Zhao Paal KrokeneAbstract
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