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.
2024
Abstract
1. Root and butt rot caused by pathogenic fungi in the genera Heterobasidion and Armillaria is a pressing issue in managed Norway spruce forests. The disease results in financial losses for the forest owners and reduces the volume of wood that can be used in long-lived products. Pathogenic wood decay fungi spread either with the aid of airborne spores or via mycelial growth among neighbouring trees, the latter leading to clustering (tendency of decayed trees to be in close proximity relative to their neighbouring trees) of decay-affected trees in forests. Understanding the spatial patterns of the decay-affected trees at the forest stand level is vital for designing management strategies to address this problem. 2. We examined decay clustering in 273 clear-cut Norway spruce stands in Norway using harvester-recorded data on spatial occurrence of decayed and healthy Norway spruce trees. We tested clustering using three global-cluster tests that account for population density and distribution, evaluating clustering without identifying specific cluster locations. 3. The proportions of clustered and non-clustered stands differed depending on the statistical test used for clustering assessment, resulting in overall agreement of 32.8% for clustered and 36.9% for non-clustered. Clustered stands exhibited a median cluster distance (maximum distance between the decay-affected trees within a cluster) of 12 m (Inter-Quantile Range, IQR, 6–20 m) and a median of 6 (IQR 3–16) nearest neighbour trees (number of decayed trees forming a cluster), estimates comparable with prior studies focused on assessment of trees infected by mycelial spread of the same fungal individual. The decay incidence in the clustered stands was 16.24%, while the non-clustered stands had a butt-rot incidence of 20.97%. In clustered stands the average number of trees per hectare was higher (693) than in non-clustered stands (553). 4. Synthesis and applications: Our study demonstrates that Norway spruce stands display a diverse range of spatial patterns of butt rotted trees. We found that higher densities of Norway spruce trees probably facilitate the vegetative spread of pathogenic wood decay fungi, leading to clustering of decay-affected trees. To disrupt the spread of decay fungi between tree generations, precision planting of trees other than Norway spruce around infested stumps of prior generation trees has been recommended by earlier studies. We discussed the potential of using harvester-derived geoposition data for butt-rotted trees upon planning and execution of forest regeneration.
Authors
Trygve S. Aamlid Sigridur Dalmannsdottir Marit Jørgensen Kristoffer Herland Hellton Akhil Reddy Pashapu Ievina Sturite Mallikarjuna Rao Kovi Helga Amdahl Carl Gunnar Fossdal Odd Arne RognliAbstract
Timothy ( Phleum pratense L.) is the predominant forage grass species in the northern parts of the Nordic region. Because of the long andharsh winters and a short growing season, most of it with continuous light, the need for locally adapted timothy seed has been recognizedfor more than a century. However, the seed production of timothy in these marginal environments is unpredictable with acceptable seedyield and quality on average only every third year. Thus, a multiplication scheme for the northern cultivars was established with only pre-basic seed produced in the north, and basic and certified seed produced further south to secure enough seed of good quality. In recentdecades this scheme has been more or less abandoned with continous generations produced in the south. Farmers are complaining andare questioning whether the cultivars has changed and lost winter hardiness. We studied freezing and ice-encasement tolerance of generations of the the northern timothy cultivars ‘Engmo’ (old landrace) and ‘Noreng’(synthetic) multiplied for one, two or three generations in Central, Southern and Northern Norway. The trials introduce very largedifferences in mean temperature, growing degree days and photoperiod between place of parental origin and sites of multiplication so theeffects on fitness observed could arise from both selection and and induced epigenetic changes. Large changes (loss) in freezing and ice-encasement tolerance were observed, especially at the southern location in the first generation.The cultivars behaved differently and there were significant interactions. The extreme phenotypic changes observed might be explained bygenetic selection or epigenetic memory of the environmental conditions experienced during seed production, or a combination of the two.We are currently analysing GBS data of all generations and this will be used to test whether genetic shifts has occured during themultiplication in the different environments.
Abstract
No abstract has been registered
Authors
Pål Melbye Trygve S. Aamlid Karin Juul Hesselsøe Wendy Marie Waalen Sigridur Dalmannsdottir Pia Heltoft Thomsen Marit Almvik Carl Johan Lönnberg Håkan Blusi Michelle DaCosta Eric Watkins Tatsiana Espevig Anne Friederike Borchert Michael BekkenAbstract
No abstract has been registered
Authors
Trygve S. Aamlid Tatsiana Espevig Karin Juul Hesselsøe Wendy Marie Waalen Pia Heltoft Thomsen Anne Friederike Borchert Marit Almvik Michael Bekken Monica Fongen Sigridur Dalmannsdottir Carl Johan Lönnberg Håkan Blusi Michelle DaCosta Eric WatkinsAbstract
No abstract has been registered
Abstract
No abstract has been registered
2023
Abstract
Crown rot, caused by Phytophthora cactorum, is a devastating disease of strawberry. While most commercial octoploid strawberry cultivars (Fragaria × ananassa Duch) are generally susceptible, the diploid species Fragaria vesca is a potential source of resistance genes to P. cactorum. We previously reported several F. vesca genotypes with varying degrees of resistance to P. cactorum. To gain insights into the strawberry defence mechanisms, comparative transcriptome profiles of two resistant genotypes (NCGR1603 and Bukammen) and a susceptible genotype (NCGR1218) of F. vesca were analysed by RNA-Seq after wounding and subsequent inoculation with P. cactorum. Differential gene expression analysis identified several defence-related genes that are highly expressed in the resistant genotypes relative to the susceptible genotype in response to P. cactorum after wounding. These included putative disease resistance (R) genes encoding receptor-like proteins, receptor-like kinases, nucleotide-binding sites, leucine-rich repeat proteins, RPW8-type disease resistance proteins, and ‘pathogenesis-related protein 1’. Seven of these R-genes were expressed only in the resistant genotypes and not in the susceptible genotype, and these appeared to be present only in the genomes of the resistant genotypes, as confirmed by PCR analysis. We previously reported a single major gene locus RPc-1 (Resistance to Phytophthora cactorum 1) in F. vesca that contributed resistance to P. cactorum. Here, we report that 4–5% of the genes (35–38 of ca 800 genes) in the RPc-1 locus are differentially expressed in the resistant genotypes compared to the susceptible genotype after inoculation with P. cactorum. In particular, we identified three defence-related genes encoding wall-associated receptor-like kinase 3, receptor-like protein 12, and non-specific lipid-transfer protein 1-like that were highly expressed in the resistant genotypes compared to the susceptible one. The present study reports several novel candidate disease resistance genes that warrant further investigation for their role in plant defence against P. cactorum.
Authors
May Bente Brurberg Anupam Gogoi Bikal Ghimire Erik Lysøe Mandeep Poudel Håvard Eikemo Jahn Davik Arne StensvandAbstract
No abstract has been registered
Authors
Anupam Gogoi Bikal Ghimire Erik Lysøe Mandeep Poudel Håvard Eikemo Jahn Davik Arne Stensvand May Bente BrurbergAbstract
No abstract has been registered
Authors
Anupam Gogoi Bikal Ghimire Erik Lysøe Mandeep Poudel Håvard Eikemo Jahn Davik Arne Stensvand May Bente BrurbergAbstract
No abstract has been registered