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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.

2019

Sammendrag

Vi har tatt i bruk nye metoder innen plantemetabolomikk for å påvise og identifisere forsvarsstoff i gran og presenterer her noen resultater fra dette arbeidet. Hvert fjerde tre i skogen er angrepet av råtesopp. Rotråtesopp angriper treet gjennom rota og spiser opp kjerneveden på sin vei oppover i stammen. Den delen av trestokken som er angrepet av rotråte kan ikke lenger brukes til byggematerialer og skognæringen lider store tap. Kan de soppangrepne trestammene brukes til andre formål? Vi vet grana produserer en mengde forsvarsstoffer som en reaksjon på soppangrepet. Kan forsvarsstoffene utnyttes til å lage nye plantevernmidler, trebeskyttelsesmidler eller legemidler?

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Sammendrag

Shallot (Allium cepa var. aggregatum) is an important vegetable crop belonging to the genus Allium. The present study attempted to develop an efficient droplet-vitrification cryopreservation method for shallot ‘10603’ shoot tips. In vitro stock shoots were maintained on Murashige and Skoog (1962) medium (MS) supplemented with 30 g L-1 sucrose, 0.5 mg L-1 BAP, 0.1 mg L-1 NAA and 8 g L-1 agar (pH=5.8). Shoot tips (2.0-3.0 mm in length) were excised from 4-week-old stock shoots and stepwise precultured with increased sucrose concentrations from 0.3 to 0.5 M, each concentration for 1 day. The precultured shoot tips were then loaded for 20 min with a solution composed of 2 M glycerol and 0.5 M sucrose, before exposure to PVS3 for 3 h at room temperature. Dehydrated shoot tips were transferred onto aluminum foils (2×0.8 cm), prior to direct immersion into liquid nitrogen (LN) for cryostorage. For thawing, frozen aluminum foils were moved from LN and immediately transferred into unloading solution composed of liquid MS containing 1.2 M sucrose. After incubation at room temperature for 20 min, shoot tips were post-cultured on solidified MS medium containing 0.3 M sucrose for 2 days and then transferred onto a recovery medium for shoot regrowth. With this procedure, 94% shoot tips survived, and 58% shoot tips regenerated into shoots following cryopreservation.

Sammendrag

Invasive alien species and new plant pests are introduced into new regions at an accelerating rate, due to increasing international trade with soil, plants and plant products. Exotic, plant pathogenic oomycetes in soil from the root zone of imported plants pose a great threat to endemic ecosystems and horticultural production. Detecting them via baiting and isolation, with subsequent identification of the isolated cultures by Sanger sequencing, is labour intensive and may introduce bias due to the selective baiting process. We used metabarcoding to detect and identify oomycetes present in soil samples from imported plants from six different countries. We compared metabarcoding directly from soil both before and after baiting to a traditional approach using Sanger-based barcoding of cultures after baiting. For this, we developed a standardized analysis workflow for Illumina paired-end oomycete ITS metabarcodes that is applicable to future surveillance efforts. In total, 73 soil samples from the rhizosphere of woody plants from 33 genera, in addition to three samples from transport debris, were analysed by metabarcoding the ITS1 region with primers optimized for oomycetes. We detected various Phytophthora and Pythium species, with Pythium spp. being highly abundant in all samples. We also found that the baiting procedure, which included submerging the soil samples in water, resulted in the enrichment of organisms other than oomycetes, compared to non-baited soil samples.

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Sammendrag

Potato soft rot Pectobacteriaceae (SRP) cause large yield losses and are persistent in seed lots once established. In Norway, different Pectobacterium species are the predominant cause of soft rot and blackleg disease. This work aimed to evaluate the potential of real-time PCR for quantification of SRP in seed tubers, as well as investigating the status of potato seed health with respect to SRP in Norway. A total of 34 seed potato lots, including certified seeds, was grown and monitored over three consecutive years. All seed lots contained a quantifiable amount of SRP after enrichment, with very few subsamples being free of the pathogens. A high SRP prevalence based on a qPCR assay, as well as a high symptom incidence in certified seeds were observed, suggesting that current criteria for seed certification are insufficient to determine tuber health and predict field outcomes. Pectobacterium atrosepticum was the most abundant species in the examined seed lots and present in all lots. Consistently good performance of first generation seed lots with respect to blackleg and soft rot incidence, as well as low quantity of SRP in these seed lots demonstrated the importance of clean seed potatoes. Weather conditions during the growing season seemed to govern disease incidence and SRP prevalence more than seed grade. The impact of temperature, potato cultivar and Pectobacterium species on tuber soft rot development were further examined in tuber infection experiments, which showed that temperature was the most important factor in nearly all cultivars. Large-scale quantification of latent infection and predictive models that include contributing factors like weather, infecting bacterial species and cultivar are needed to reduce soft rot and blackleg.

Sammendrag

Complex communities of microorganisms influence plant and agroecosystem health and productivity. Bacteria and fungi constitute a major part of the wheat head microbiome. A microorganism’s ability to colonize or infect a wheat seed is influenced by interacting microbiome. In Norway, wheat seed lots are routinely analysed for the infestation by Fusarium head blight and seedling blight diseases, such as Fusarium and Microdochium spp., and glume blotch caused by Parastagonospora nodorum using traditional methods (plating grain on PDA, recording presence or absence of fungal colonies) The purpose is to decide if the seed quality is suitable for sowing and whether seed treatment is needed. This method is time consuming, require knowledge within fungal morphology, and do not facilitate identification to species level in all cases. Molecular methods such as sequencing could allow detection and quantification of “all” microbial DNA, only limited by the specificity of the primers. Microbial profiling (metabarcoding) can be very time and cost-effective, since a mixture of many samples can be analysed simultaneously for both fungi and bacteria, and other microbes if required. In our project “Phytobiome” we used metabarcoding to analyse microbial communities in wheat heads and verify this information with results from qPCR and plate studies for a more complete study. Around 150 spring wheat seed lots from the years 2016-2017 (including two cultivars) were selected for analysis. One of the main objectives was to find microorganisms associated with seed germination. We will present findings from this work, but also some challenges when using PCR-based sequencing methods, especially regarding Fusarium head blight fungi.