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.
2026
Authors
Petter Öhrn Mats Berlin Jan-Olov Weslien Malin Elfstrand Paal Krokene Anna Maria Jönsson Audrius MenkisAbstract
Background and aims Drought weakens tree defenses, predisposing Norway spruce (Picea abies) to spruce bark beetle (Ips typographus) attack. The extreme 2018 summer drought in Sweden triggered an unprecedented bark beetle outbreak. Our objective was to quantify how weather, soil moisture, and tree provenance influence Norway spruce defense capacity to a necrotrophic beetle-associated pathogen. Methods Trees at three sites in Sweden were inoculated with the phytopathogenic fungus Leptographium europhioides on four occasions during each of the 2019 and 2021 growing seasons. At each site, we inoculated spruce provenances of Swedish or East European origin, with early and late spring bud burst, respectively. Tree defense capacity, expressed as the extent of necrotic lesion formation following fungal inoculation, was used as a proxy for resistance to bark beetle attack. Results Spruce defense capacity (i.e. lesion size) differed with water availability (both precipitation and soil moisture conditions) but not with the timing of spring bud burst. There were within-season differences, with trees having less efficient defenses (producing larger lesions) in the early season (June). On intermediate soil moisture sites, lesions were larger in 2019 than in 2021. In both years, there was a significant negative correlation between lesion size and water availability in the autumn of the previous year. Conclusion Spruce defense capacity varied with local environmental conditions but not with provenance phenology. Variations between study years reflected the sensitivity of spruce defenses to climatic variability and the partial recovery of tree resistance 3 years after the 2018 drought.
Abstract
No abstract has been registered
Authors
Mandeep PoudelAbstract
No abstract has been registered
Abstract
The soil-borne oomycete Phytophthora cactorum causes crown rot, a major disease of the allo-octoploid strawberry (Fragaria × ananassa Duch., 2n = 8× = 56) that limits cultivation worldwide. Resistance to P. cactorum is a highly desirable trait but is typically quantitative and moderately heritable. A better understanding of the genetic basis of resistance to crown rot is essential for developing durable crown rot-resistant cultivars. We conducted a genome-wide association study (GWAS) using multi-locus models on 100 wild strawberry accessions from South and North America. The accessions were genotyped using the Axiom™ 50 K strawberry SNP array and mapped to the F. × ananassa cv. Royal Royce v. 1.0 reference genome. Testing for resistance to P. cactorum revealed a wide range of phenotypes. A single genetic marker, AX-184528282, located on chromosome 7B, was strongly associated with resistance to P. cactorum and explained 53% of the observed phenotypic variation. This marker was present in several highly resistant exotic Fragaria accessions that represent potential donors for introgression of favorable alleles into modern strawberry cultivars. In addition, several strong candidate resistance genes were identified within the 2 Mb genomic region surrounding the significant marker. This study advances understanding of resistance to P. cactorum in strawberry and identifies genetic resources that can accelerate the development of crown rot-resistant cultivars through marker-assisted breeding.
2025
Abstract
Methyl jasmonate (MeJA) is known to effectively protect Norway spruce (Picea abies) against pests and pathogens. However, MeJA application to spruce saplings can significantly reduce growth and is not feasible to use in protecting older trees due to cost. Seed treatment with MeJA or other priming stimulants with fewer negatives could be a practical solution to enhance Norway spruce resistance. Therefore, we assessed the potential of Norway spruce seed treatment with MeJA, pipecolic acid (PipA), lignan (Li), and chitosan (Chi) in enhancing the resistance of the emerged seedlings against Botrytis cinerea. For the first time, MeJA seed treatment was shown to reduce the mortality of the seedlings effectively after B. cinerea infection, with a growth reduction as a side effect. To understand the mechanisms underlying this phenomenon, we quantified phenolics, defense hormones, and differential transcript expressions. MeJA seed treatment increased the concentration of the flavan-3-ols catechin and proanthocyanidin B1. Transcriptomic data suggested an increase in oxidative stress protection, cell wall reinforcement, and pathogenesis-related protein production. Our data also suggested an antagonistic relationship in hormonal signaling between abscisic acid (ABA) and jasmonic acid (JA)/ethylene (ET). Overall, our findings indicated MeJA seed treatment enhanced resistance of young seedlings against B. cinerea via a multitude of defense responses, modulated by complex regulatory systems.
Authors
Benedicte Riber Albrectsen Kristiina Mäkinen Lovely Mahawar Arti Mishra Isaac Kwesi Abuley Isalyne Veillon Apsara Indhu Gopan Radha Sivarajan Sajeevan Svante Resjö Erik Andreasson Erland Liljeroth Peter Marhavý Simeon Rossmann Jens Grønbech HansenAbstract
Based on discussions within the Northern Tubers of Potato network (N’TOP-net), this review highlights northern Scandinavia’s potential for sustainable, low pest seed potato production. While long transport distances currently limit large-scale supply for consumption or processing, low pest pressure and stricter EU plant protection regulations increase its value for seed production. Climate change is expected to extend the growing season, driving renewed interest in Northern Scandinavia’s role in European food security. Finland exemplifies this potential, and parts of northern and central Sweden—historically suppliers of disease-free seed potatoes, even exported to Brazil—offer expansion opportunities. Nordic potato production, key biotic stressors, and opportunities for regional cooperation are examined, with a focus on novel farming practices, breeding innovations, and disease surveillance to improve resilience and sustainability. Despite shared values in cultivar selection, certification, and potato preferences, Nordic production strategies remain uncoordinated for long-term sustainability. We advocate for transnational, interdisciplinary collaboration to enhance Europe’s food security through joint efforts in three key areas: (1) soil-conserving farming, (2) breeding for adaptation to longer day length and resistance traits, and (3) transnational pest and disease surveillance. A Nordic potato initiative can strengthen European cooperation on sustainable production amid climate change. However, as policies must balance the benefits of longer growing seasons with emerging risks such as pests, droughts, and flooding, coordinated research, regulatory adaptation, and climate resilience investments are essential for safeguarding seed potato quality, food security, and supply chain stability.
Authors
Theresa Weigl Jorunn Børve Emily Follett Melissa Magerøy Hanne Larsen Carl Gunnar Fossdal Siv Fagertun RembergAbstract
The effect of harvest timing on postharvest ripening was investigated by changes in ethylene production, expression of ethylene biosynthesis genes MdACS1, MdACS6, (1-aminocyclopropane-1-carboxylic acid synthase 1 and 6) and the ACS degradation promoting gene MdETO1 (Ethylene overproducer 1). Apple fruit of two cultivars, ‘Red Aroma’ and ‘Rubinstep’, were harvested at three time points, early, middle, and late, at two-week intervals. Fruit were either treated with 1 ppm 1-Methylcyclopropene (1-MCP) or remained untreated, and stored at 4 °C in regular atmosphere. Late harvested, untreated apples reached peak ethylene production after the shortest time in cold storage ('Red Aroma' in week five, 'Rubinstep' in weeks nine and ten), while early harvested, untreated fruit reached their peak after a longer time ('Red Aroma' in week eight, 'Rubinstep' in weeks 13 and 14). Early harvested fruit experienced greater firmness loss and a higher increase in SCC/TA ratio during cold storage. Senescence in late harvested, untreated fruit was evident from low ethylene production after simulated shelf-life and increased physiological disorders in ‘Rubinstep’. In 1-MCP-treated fruit, ethylene production increased toward the end of storage, particularly in early harvested fruit, indicating a decline in 1-MCP efficacy over time. Gene expression analysis showed strong induction of MdACS1 during climacteric ripening. MdETO1 positively correlated with MdACS1 gene expression, suggesting positive co-regulation. The expression of MdACS6 was negatively correlated with simulated shelf-life and with 1-MCP treatment, suggesting regulation by temperature and metabolic state. Overall, harvest timing and 1-MCP strongly influenced the changes in fruit physiology during postharvest storage.
Authors
Özgün Candan Onarman Umu Knut Espevig Simeon Rossmann Inger-Lise Akselsen Carl-Henrik Lensjø Alvin Marit Larssen SekseAbstract
No abstract has been registered
Authors
Tomáš Hlásny Roman Modlinger Jostein Gohli Rupert Seidl Paal Krokene Iris Bernardinelli Simon Blaser Gediminas Brazaitis Gailenė Brazaitytė Eckehard G. Brockerhoff György Csóka Laura Dobor Maarten de Groot Mihai‐Leonard Duduman Massimo Faccoli Margarita Georgieva Georgi Georgiev Wojciech Grodzki Henrik Hartmann Anikó Hirka Gernot Hoch Tomasz Jabłoński Hervé Jactel Mats Jonsell Marija Kolšek Markus Melin Slobodan Milanović Constantin Nețoiu Mats Nieberg Bjørn Økland Milan Pernek Michaela Perunová Nick Schafstall Martin Schroeder Gottfried Steyrer Jozef Vakula Thomas Wohlgemuth Tiina Ylioja Andrew M. LiebholdAbstract
Ongoing shifts in climate and land use have altered interactions between trees and insect herbivores, changing biotic disturbance regimes. However, as these changes are complex and vary across host species, insect taxa, and feeding guilds, they remain poorly understood. We compiled annual records of forest insect disturbance from 15 countries in temperate and boreal Europe, spanning the period from 2000 to 2022. The dataset comprises 1361 time series characterizing the dynamics of 50 herbivorous insects. We used this dataset to test whether insect disturbance has systematically changed during the 23‐year period across host trees and feeding guilds, whether it varies along latitudinal and climatic gradients, and whether synchrony exists among species in the same guild or among species sharing the same host. Since 2000, borer disturbance was predominantly concentrated on gymnosperms, while defoliators impacted gymnosperms and angiosperms more evenly. While 85.8% of gymnosperm disturbance was inflicted by a single species, Ips typographus , the majority of disturbances to angiosperms were caused by six different species. Borer impact on gymnosperms has increased in the 21st century, while defoliator impact has decreased across both clades. In contrast to diverging temporal trends, disturbance was consistently greater in warmer and drier conditions across feeding guilds and host types. We identified significant synchrony in insect disturbance within host types and feeding guilds but not between these groups, suggesting shared drivers within guilds and host types. Increasing insect disturbance to gymnosperms may catalyze adaptive transformations in Europe's forests, promoting a shift from historical conifer‐dominated management to broadleaved trees, which are less affected by insect herbivores. Our findings reveal a diversity of trends in insect herbivory, underscoring the need to strengthen monitoring and research in order to better understand underlying mechanisms and identify emerging threats that may not be apparent in currently available data.
Authors
Gry Alfredsen Michael Altgen Mari S. Austigard Johan Mattsson Maria Nunez Lone Ross Sverre Aarseth Tunstad Andreas Treu Igor A. Yakovlev Nanna Bjerregaard PedersenAbstract
A total of 212 iconic wooden cable car pylons were constructed for mining operations in Svalbard, significantly contributing to Longyearbyen's historical identity as a mining town. Fieldwork in Svalbard involved collecting wood samples from 22 of these pylons, targeting wood exposed both aboveground and ground proximity. While the timber used in the constructions was assumed to be untreated Norway spruce (Picea abies), light microscopy revealed that 25% of the timber members were Scots pine (Pinus sylvestris). Wooden beams exposed aboveground showed initial decay over the first 80-90 years, whereas severe fungal decay was observed after about 50 years in wooden poles inserted in the ground. Metabarcoding identified Ascomycetes and Basidiomycetes to be predominating in the wood samples and unveiled new fungal species for Svalbard, including four brown rot, five white rot, and sixteen soft rot species. Macroscopic and microscopic examinations confirmed more advanced decay in ground proximity samples, dominated by brown and soft rot fungi.