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.
2009
Sammendrag
Two mature clones of Norway spruce (Picea abies (L.) Karst.) shown to have different level of resistance towards inoculation of Heterobasidion parviporum were compared with respect to spatiotemporal expression of transcripts related to biosynthesis of lignin, stilbenes and other phenolic compounds in response to fungal inoculation and physical wounding. Both clones responded to H. parviporum and physical wounding at transcriptional and chemical levels. Taxifolin, detected in the resistant clone only, increased in concentration following both wounding and inoculation. Concentrations of stilbenoid glucosides were highest in the susceptible clone. Following wounding or inoculation, concentrations of these glucosides increased in the susceptible clone, and quantities of their corresponding aglycones increased dramatically in both clones close to the treatment point. Significant changes in transcription were detected over the entire lesion length for all transcripts, and only the changes in a few transcripts indicated a response to inoculation with H. parviporum differing from that caused by wounding alone. The resistant clone had higher basal concentrations of lignin (LTGA) compared to the susceptible clone; concentrations increased in both clones after wounding and wounding plus inoculation treatments, but remained consistently higher in the resistant clone, suggesting higher lignin levels in the cell walls compared to the susceptible clone. In addition, the transcript level in the same clones was also measured the following year and we saw indications of primed defences for a number of gene products likely resulting from the inoculations performed 12 months prior.
Sammendrag
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Forfattere
Maria HerreroSammendrag
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Forfattere
Maria HerreroSammendrag
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Sammendrag
For agurkmjøldogg gis en oversikt over symptomer/skadevirkning, vertplanter, overlevelse og spredning og bekjempelse.
Forfattere
Linda Hjeljord Maria HerreroSammendrag
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Forfattere
Brita Toppe Maria HerreroSammendrag
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Forfattere
Nadeem Yaqoob Igor A. Yakovlev Paal Krokene Harald Kvaalen Halvor Solheim Carl Gunnar FossdalSammendrag
Clonal variation towards resistance has been observed in Norway spruce Heterobasidion annosum s.l. (H.a). H.a. is the main cause of root rot and has a severe economic impact on an economically important conifer tree species. Annual financial losses are in the hundreds of millions of Euros annually. Less susceptible clones appear to have an efficient system of recognizing the pathogen and initiating early defense signalling events. Active defense responses can be started locally and transmitted systemically. This work focus on the expression both spatially (systemically) and temporally in this pathosystem. Two-year-old, somatic saplings of the Norway spruce clone were challenged with H.a., wounded, methyl jasmonate painted and compared to untreated controls and ninety plants were used for the experiment. Stem samples were collected at 1, 3, 6 and 13 days post inoculation (d.p.i). The stem of the saplings were divided into sections along its length and the bark and wood separated from each other at time of collection. In order to see local response an area of 1cm including the site of inoculation was collected, while the spatial (systemic) response was assessed in sections collected at distances of 3 and 6cm away from the site of inoculation. The separated bark and wood were analysed for differential gene expression by qRT-PCR, and the results from peroxidases (PaPX3 and PaPX2) and a chitinase (PaChi4) are presented. Both local and systemic up- and down-regulation were observed at the transcriptional level in both bark and wood, up to 2000 fold local increase in expression was observed for PaChi4.
Sammendrag
Crown rot caused by Phytophthora cactorum is an important disease in commercial strawberry production worldwide. The level of resistance varies greatly between cultivars, and many of the most commonly grown cultivars are quite susceptible to P. cactorum. Adequate soil drainage, clean planting material and use of highly resistant cultivars are the most important measures against crown rot. Previous work at our institute has involved evaluation of methods to screen for resistance, cultivar and progeny screening, and use of induced resistance against the disease. That work also included a genetic study of P. cactorum isolates from various host plants and different geographic origins. P. cactorum has many host plants, but it turned out that isolates causing crown rot of strawberry differs genetically from those with other host origin. A project was recently initiated, where one of the main goals has been to identify molecular markers for resistance against P. cactorum in strawberry. Genotypes of diploid Fragaria species have been screened for resistance, and the progeny from a cross between a susceptible and a resistant genotype will be evaluated by the end of this year. Commercially grown strawberry is very heterozygous and octoploid. Diploid Fragaria species are therefore useful as model organisms. The Fragaria genus has a conserved organisation, and hopefully information obtained from the study of diploid genotypes can be transferred to cultivated Fragaria x ananassa and possibly to other important crop plants in Rosaceae.
Sammendrag
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