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.
2024
Forfattere
Fernanda Leiva Florent Abdelghafour Muath K Alsheikh Nina Elisabeth Nagy Jahn Davik Aakash ChawadeSammendrag
Common scab (CS) is a major bacterial disease causing lesions on potato tubers, degrading their appearance and reducing their market value. To accurately grade scab-infected potato tubers, this study introduces “ScabyNet”, an image processing approach combining color-morphology analysis with deep learning techniques. ScabyNet estimates tuber quality traits and accurately detects and quantifies CS severity levels from color images. It is presented as a standalone application with a graphical user interface comprising two main modules. One module identifies and separates tubers on images and estimates quality-related morphological features. In addition, it enables the extraction of tubers as standard tiles for the deep-learning module. The deep-learning module detects and quantifies the scab infection into five severity classes related to the relative infected area. The analysis was performed on a dataset of 7154 images of individual tiles collected from field and glasshouse experiments. Combining the two modules yields essential parameters for quality and disease inspection. The first module simplifies imaging by replacing the region proposal step of instance segmentation networks. Furthermore, the approach is an operational tool for an affordable phenotyping system that selects scab-resistant genotypes while maintaining their market standards.
Sammendrag
Climate change is already reducing carbon sequestration in Central European forests dramatically through extensive droughts and bark beetle outbreaks. Further warming may threaten the enormous carbon reservoirs in the boreal forests in northern Europe unless disturbance risks can be reduced by adaptive forest management. The European spruce bark beetle (Ips typographus) is a major natural disturbance agent in spruce-dominated forests and can overwhelm the defences of healthy trees through pheromone-coordinated mass-attacks. We used an extensive dataset of bark beetle trap counts to quantify how climatic and management-related factors influence bark beetle population sizes in boreal forests. Trap data were collected during a period without outbreaks and can thus identify mechanisms that drive populations towards outbreak thresholds. The most significant predictors of bark beetle population size were the volume of mature spruce, the extent of newly exposed clearcut edges, temperature and soil moisture. For clearcut edge, temperature and soil moisture, a 3-year time lag produced the best model fit. We demonstrate how a model incorporating the most significant predictors, with a time lag, can be a useful management tool by allowing spatial prediction of future beetle population sizes. Synthesis and Applications: Some of the population drivers identified here, i,e., spruce volume and clearcut edges, can be targeted by adaptive management measures to reduce the risk of future bark beetle outbreaks. Implementing such measures may help preserve future carbon sequestration of European boreal forests.
Forfattere
Theresa Weigl Jorunn Børve Emily Follett Ingunn Øvsthus Carl Gunnar Fossdal Hanne Larsen Siv Fagertun RembergSammendrag
Det er ikke registrert sammendrag
Sammendrag
STOPPest-prosjektet har som mål å få frem ny kunnskap om rollene til ulike aktører innen dagens plantehelsesystem for å minimere biologisk risiko. En av arbeidspakkene i prosjektet fokuserer på de fysiske kontrollene som skal utføres av importerte planter for å sikre at de er frie for medfølgende planteskadegjørere. I den aktuelle arbeidspakken ble det i 2021 undersøkt totalt 168 planteprøver fra importsendinger for innhold av sjukdomsorganismer (plantepatogener). Plantematerialet kom fra Nederland, Italia, Tyskland, Spania og Portugal. Ved fire ulike importsteder/lokaliteter ble prøvene tatt ut av NIBIO etter at importsendingene først hadde blitt kontrollert av importørene sitt mottakerapparat. Dette ble gjort for å kartlegge om dagens fysiske kontroll utført av importørene kan avdekke sjukdomsorganismer i samme grad som NIBIO med tilgang til spesialister (plantepatologer) og moderne analysemetoder. I prosjektet var det i 2021 ekstra fokus på Phytophthora. Dette er en slekt med fremmede, invaderende planteskadegjørere som ofte følger med som blindpassasjerer i rotklumpen på importerte grøntanleggs- og hageplanter. Dersom plantene er symptomfrie, er tilstedeværelse av disse mikroorganismene umulig å oppdage gjennom en fysisk kontroll på importstedet. Derfor ble 150 jordprøver tatt ut av NIBIO til undersøkelser ved laboratoriet på Ås, hvorav 137 prøver var fra planter uten sjukdomssymptomer og dermed ikke kunne mistenkes av importørene som smittet. I tillegg til de 150 jordprøvene tok NIBIO ut 31 prøver fra overjordiske deler av planter (13 av disse prøvene var fra planter der det også ble tatt ut jordprøver) der tidlige/diffuse symptomer på mulig sjukdom var til stede. Kun en av disse 31 prøvene ble plukket ut som mistenkelig av mottakskontrolløren. På disse 31 prøvene ble det funnet mjøldogg (Podosphaera spiraeae) på Japanspirea (Spiraea japonica), Phomopsis sp. på rips (Ribes rubrum) og flere sekundære sopparter. I tillegg til soppinfeksjoner ble bakterien Pseudomonas cichorii identifisert ved fettsyreanalyse fra en bladprøve av villkornell (Cornus sanguinea). Disse patogenene regnes som såkalte kvalitetsskadegjører (RNQP - regulated non-quarantine pests) som det ifølge Matloven og naturmangfoldloven ikke er lov å spre. Av de 150 jordprøvene som ble analysert spesifikt for Phytophthora var det 65 prøver (43.3 %) som hadde Phytophthora i rotklumpen. Totalt ble det funnet 16 Phytophthora-arter. Flere av disse artene, f.eks. P. cactorum, P. cambivora, P. megasperma, P. pini og P. plurivora, er allerede introdusert til norsk natur hvor de gjør skade på trær og busker. To arter, P. multivora og P. × stagnum, var i 2021 ikke rapportert tidligere fra Norge. For majoriteten av de andre artene, mangler det kunnskap om hvor alvorlig risiko de utgjør for norsk natur. Ingen av de 16 Phytophthora-artene er karanteneskadegjørere, men de blir betegnet som kvalitetsskadegjørere. Disse undersøkelsene i STOPPest prosjektet avslører at fremmede, invaderende planteskadegjørere, spesielt i slekta Phytophthora, slipper inn til Norge, og dette går i stor grad under radaren til dagens plantehelsesystems fysiske kontroll. Dette har alt fått, og
Forfattere
Venche Talgø Thomas Jungi Ivan Milenković Tamara Corcobado Martin Pettersson May Bente BrurbergSammendrag
Det er ikke registrert sammendrag
2023
Forfattere
Yupeng Zhang Marcos Viejo Igor A. Yakovlev Torstein Tengs Paal Krokene Timo Hytönen Paul Grini Carl Gunnar FossdalSammendrag
A major challenge for plants in a rapidly changing climate is to adapt to rising temperatures. Some plants adapt to temperature conditions by generating an epigenetic memory that can be transmitted both meiotically and mitotically. Such epigenetic memories may increase phenotypic variation to global warming and provide time for adaptation to occur through classical genetic selection. The goal of this study was to understand how warmer temperature conditions experienced during sexual and asexual reproduction affect the transcriptomes of different strawberry (Fragaria vesca) ecotypes. We let four European F. vesca ecotypes reproduce at two contrasting temperatures (18 and 28°C), either asexually through stolon formation for several generations, or sexually by seeds (achenes). We then analyzed the transcriptome of unfolding leaves, with emphasis on differential expression of genes belonging to the epigenetic machinery. For asexually reproduced plants we found a general transcriptomic response to temperature conditions but for sexually reproduced plants we found less significant responses. We predicted several splicing isoforms for important genes (e.g. a SOC1, LHY, and SVP homolog), and found significantly more differentially presented splicing event variants following asexual vs. sexual reproduction. This difference could be due to the stochastic character of recombination during meiosis or to differential creation or erasure of epigenetic marks during embryogenesis and seed development. Strikingly, very few differentially expressed genes were shared between ecotypes, perhaps because ecotypes differ greatly both genetically and epigenetically. Genes related to the epigenetic machinery were predominantly upregulated at 28°C during asexual reproduction but downregulated after sexual reproduction, indicating that temperature-induced change affects the epigenetic machinery differently during the two types of reproduction.
Forfattere
Yupeng Zhang Guangxun Fan Tuomas Toivainen Torstein Tengs Igor A. Yakovlev Paal Krokene Timo Hytönen Carl Gunnar Fossdal Paul GriniSammendrag
Plants must adapt with increasing speed to global warming to maintain their fitness. One rapid adaptation mechanism is epigenetic memory, which may provide organisms sufficient time to adapt to climate change. We studied how the perennial Fragaria vesca adapted to warmer temperatures (28°C vs. 18°C) over three asexual generations. Differences in flowering time, stolon number, and petiole length were induced by warmer temperature in one or more ecotypes after three asexual generations and persisted in a common garden environment. Induced methylome changes differed between the four ecotypes from Norway, Iceland, Italy, and Spain, but shared methylome responses were also identified. Most differentially methylated regions (DMRs) occurred in the CHG context, and most CHG and CHH DMRs were hypermethylated at the warmer temperature. In eight CHG DMR peaks, a highly similar methylation pattern could be observed between ecotypes. On average, 13% of the differentially methylated genes between ecotypes also showed a temperature-induced change in gene expression. We observed ecotype-specific methylation and expression patterns for genes related to gibberellin metabolism, flowering time, and epigenetic mechanisms. Furthermore, we observed a negative correlation with gene expression when repetitive elements were found near (±2 kb) or inside genes. In conclusion, lasting phenotypic changes indicative of an epigenetic memory were induced by warmer temperature and were accompanied by changes in DNA methylation patterns. Both shared methylation patterns and transcriptome differences between F. vesca accessions were observed, indicating that DNA methylation may be involved in both general and ecotype-specific phenotypic variation.
Forfattere
Eline Seim Varna Thangavel Arti Rai Magne Nordang Skårn May Bente Brurberg Tage ThorstensenSammendrag
Det er ikke registrert sammendrag
Forfattere
Carl Gunnar Fossdal Igor A. Yakovlev Marcos Viejo Paul Grini Paal Krokene Yupeng Zhang Jorunn Elisabeth OlsenSammendrag
Det er ikke registrert sammendrag
Forfattere
Yupeng Zhang Tuomas Toivainen Kathryn Mackenzie Igor A. Yakovlev Paal Krokene Timo Hytönen Paul Grini Carl Gunnar FossdalSammendrag
Temperature conditions experienced during embryogenesis and seed development may induce epigenetic changes that increase phenotypic variation in plants. Here we investigate if embryogenesis and seed development at two different temperatures (28 vs. 18°C) result in lasting phenotypic effects and DNA methylation changes in woodland strawberry (Fragaria vesca). Using five European ecotypes from Spain (ES12), Iceland (ICE2), Italy (IT4), and Norway (NOR2 and NOR29), we found statistically significant differences between plants from seeds produced at 18 or 28°C in three of four phenotypic features investigated under common garden conditions. This indicates the establishment of a temperature-induced epigenetic memory-like response during embryogenesis and seed development. The memory effect was significant in two ecotypes: in NOR2 flowering time, number of growth points and petiole length were affected, and in ES12 number of growth points was affected. This indicates that genetic differences between ecotypes in their epigenetic machinery, or other allelic differences, impact this type of plasticity. We observed statistically significant differences between ecotypes in DNA methylation marks in repetitive elements, pseudogenes, and genic elements. Leaf transcriptomes were also affected by embryonic temperature in an ecotype-specific manner. Although we observed significant and lasting phenotypic change in at least some ecotypes, there was considerable variation in DNA methylation between individual plants within each temperature treatment. This within-treatment variability in DNA methylation marks in F. vesca progeny may partly be a result of allelic redistribution from recombination during meiosis and subsequent epigenetic reprogramming during embryogenesis.