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.
2021
Forfattere
Jorunn BørveSammendrag
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Forfattere
Carla Cruz-Paredes Tomas Diera Marie Louise Davey Maria Monrad Rieckmann Peter Christensen Majbrit Dela Cruz Kristian Holst Laursen Erik J. Joner Jan H. Christensen Ole Nybroe Iver JakobsenSammendrag
Arbuscular mycorrhizal fungi (AMF) are important in plant nutrient uptake, but their function is prone to environmental constraints including soil factors that may suppress AMF transfer of phosphorus (P) from the soil to the plant. The objective of this study was to disentangle the biotic and abiotic components of AMF-suppressive soils. Suppression was measured in terms of AMF-mediated plant uptake of 33P mixed into a patch of soil and treatments included soil sterilization, soil mixing, pH manipulation and inoculation with isolated soil fungi. The degree of suppression was compared to volatile organic compound (VOC) production by isolated fungi and to multi-element analysis of soils. For a selected suppressive soil, sterilization and soil mixing experiments confirmed a biotic component of suppression. A Fusarium isolate from that soil suppressed the AMF activity and produced greater amounts than other fungal isolates of the antimicrobial VOC trichodiene (a trichothecene toxin precursor), beta-chamigrene, alpha-cuprenene and p-xylene. These metabolites deserve further attention when unravelling the chemical background behind the suppression of AMF activity by soil microorganisms. For the abiotic component of suppression, soil liming and acidification experiments confirmed that suppression was strongest at low pH. The pH effect might be associated with changed availability of specific suppressive elements. Indeed 33P uptake from the soil patches correlated negatively to Al levels and Al toxicity seems to play a major role in the AMF suppressiveness at pH below 5.0–5.2. However, the documentation of a biotic component of suppression for both low and high pH soils leads to the conclusion that biotic and abiotic components of suppression may act in parallel in some soils. The current insight into the components of soil suppressiveness of the AMF activity aids to develop management practices that allow for optimization of AMF functionality.
Sammendrag
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Forfattere
Jørgen A.B. MølmannSammendrag
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Forfattere
Oskar PuschmannSammendrag
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Sammendrag
Plant-parasitic nematodes (PPN) cause significant yield reduction in commercial pineapple (Ananas comosus) worldwide. In Kenya, few nematode studies have been conducted, although the main commercial pineapple producer has sole dispensation to use Telone II (1,3-Dichloropropene) indicating the magnitude of the nematode problem. This study was conducted with the aim to investigate the population densities and diversity of nematodes in two commercial plantations with two contrasting management practices. We additionally assessed the influence of crop age and compared this with nearby smallholder pineapple production systems. Soil and root samples were collected from fields of different ages in each commercial plantation and from 29 smallholder fields. A total of 18 genera were associated with pineapple, with a relatively greater diversity found in smallholder than commercial farms. The most prevalent genus was Meloidogyne spp. (M. javanica) followed by Helicotylenchus spp., Tylenchus spp. and Aphelenchoides spp. PPN densities were higher in relatively older fields of 24 and 36 months than from fallow and 3-month-old fields. Regression analysis additionally demonstrated the rise of PPN densities with age of pineapple fields, especially Meloidogyne spp., while free-living nematode densities declined. This study provides an indication of the high level of PPN infection in pineapple in Kenya, which would constitute an important factor contributing to low yields. The study confirms an obvious need for pineapple producers to control PPN to improve crop yields.
Forfattere
Tommi Nyman Elena Papadopoulou Eeva Ylinen Saskia Wutke Craig T. Michell Ludmila Sromek Tuula Sinisalo Elena Andrievskaya Vyacheslav Alexeev Mervi KunnasrantaSammendrag
Three subspecies of the ringed seal (Pusa hispida) are found in northeastern Europe: P. h. botnica in the Baltic Sea, P. h saimensis in Lake Saimaa in Finland, and P. h. ladogensis in Lake Ladoga in Russia. We investigated the poorly-known cestode helminth communities of these closely related but ecologically divergent subspecies using COI barcode data. Our results show that, while cestodes from the Baltic Sea represent Schistocephalus solidus, all worms from the two lakes are identified as Ligula intestinalis, a species that has previously not been reported from seals. The observed shift in cestode communities appears to be driven by differential availability of intermediate fish host species in marine vs. freshwater environments. Both observed cestode species normally infect fish-eating birds, so further work is required to elucidate the health and conservation implications of cestode infections in European ringed seals, whether L. intestinalis occurs also in marine ringed seals, and whether the species is able to reproduce in seal hosts. In addition, a deep barcode divergence found within S. solidus suggests the presence of cryptic diversity under this species name.
Sammendrag
Plants with roots and soil clumps transported over long distances in plant trading can harbor plant pathogenic oomycetes, facilitating disease outbreaks that threaten ecosystems, biodiversity, and food security. Tools to detect the presence of such oomycetes with a sufficiently high throughput and broad scope are currently not part of international phytosanitary testing regimes. In this work, DNA metabarcoding targeting the internal transcribed spacer (ITS) region was employed to broadly detect and identify oomycetes present in soil from internationally shipped plants. This method was compared to traditional isolation-based detection and identification after an enrichment step. DNA metabarcoding showed widespread presence of potentially plant pathogenic Phytophthora and Pythium species in internationally transported rhizospheric soil with Pythium being the overall most abundant genus observed. Baiting, a commonly employed enrichment method for Phytophthora species, led to an increase of golden-brown algae in the soil samples, but did not increase the relative or absolute abundance of potentially plant pathogenic oomycetes. Metabarcoding of rhizospheric soil yielded DNA sequences corresponding to oomycete isolates obtained after enrichment and identified them correctly but did not always detect the isolated oomycetes in the same samples. This work provides a proof of concept and outlines necessary improvements for the use of environmental DNA (eDNA) and metabarcoding as a standalone phytosanitary assessment tool for broad detection and identification of plant pathogenic oomycetes.
Forfattere
Ida Marie Luna Fløystad Paul Eric Aspholm Katja Häkli Per John Aslaksen Anti Per Anders Eira Ann Maret Eira Johan Henrik Gaup Nikolai Pedersen Ingrid Helle Søvik Snorre Hagen Hans Geir EikenSammendrag
DNA-overvåking av brunbjørn i et totalt 650 km2 stort område i Karasjok kommune i Troms og Finnmark ble utført med hårfeller med luktstoff i 2 måneder fra juni til august i 2020. Overvåkingen ble utført i tre deler; et hårfelleprosjekt sentralt i Karasjok, et hårfelleprosjekt i Anàrjohka og et hårfelleprosjekt utført av et elgjaktlag i jaktfelt 28. Vi brukte et 5 x 5 km rutesystem med totalt 26 ruter med én hårfelle i hver rute, og der hårfellen ble flyttet etter en måned til en annen lokalitet i samme rute. I tillegg var to hårfeller plassert på geografiske punkt av elgjaktlag i 2 uker. Det ble samlet inn til sammen 58 hårprøver fra hårfellene (i tillegg til 9 ekskrementprøver). For de 16 hårfellene sentralt plassert i Karasjok var 24 av de 48 innsamlede prøvene (50 %) positive for brunbjørn i DNA-analysen ved laboratoriet på NIBIO Svanhovd. Fra disse prøvene ga 22 prøver en fullstendig identifiserende DNA-profil som viste 8 ulike bjørner (3 hannbjørn og 5 hunnbjørn). Bjørnetettheten ble estimert til 0,20 bjørn/10km2 som er i samsvar med forrige år. Totalt ble det funnet 11 ulike bjørneindivider (5 hannbjørn og 6 hunnbjørn) for de 3 hårfelleprosjektene. Av disse 11 var 9 bjørner tidligere påvist, mens 2 av bjørnene (2 hannbjørner) var nye. Hårfelleprosjektetene bidrar med unik geografisk og tidsmessig informasjon om bjørneaktivitenen i området, og 4 av de 11 påviste bjørnene var i 2020 kun påvist igjennom hårfelleprosjektene.
Forfattere
Volkmar TimmermannSammendrag
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