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.
2006
Authors
Halvor SolheimAbstract
Norway spruce suffers from serious root and butt rot problems from sea level up to the timber line in Norway. In this paper the most common fungi causing white rot is presented with special notes on gross characteristics of the rot. During the meeting we visited a stand near the timberline where logging was ongoing. Isolations were done from nearly hundred rotten logs and the results are presented.
2005
Authors
Magnus Karlsson Ari M. Hietala Harald Kvaalen Åke Olson Halvor Solheim Jan Stenlid Carl Gunnar FossdalAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
*Strawberry Fragaria × ananassa (cv. Korona) was inoculated with Botrytis cinerea by dipping berries in a conidial suspension. *Colonization by the pathogen was monitored using real-time PCR, ELISA and ergosterol assays, the first showing the highest sensitivity. The expression of pathogen B-tubulin and six polygalacturonases (Bcpg1-6) and three host defence genes (polygalacturonase-inhibiting protein (FaPGIP) and two class II chitinases) were monitored using real-time RT-PCR. *The maximum transcript levels of the host defence genes occurred at 16 h postinoculation (hpi) at the presumed initial penetration stage. The unique transcript profile of Bcpg2 over the 96-h incubation time and its high transcript levels relative to those of the other Bcpgs at 8-24 hpi suggest that the gene has a specific role in the penetration stage. *Bcpg1 was expressed constitutively at a relatively high level in actively growing mycelia throughout the experimental period. Comparison of the transcript profiles indicated that Bcpg1 and Bcpg3-6 were coordinately regulated.
Abstract
Rhizoctonia solani was frequently isolated in the Italian Alps from ursery-grown European beech (Fagus sylvatica) seedlings displaying symptoms of cotyledon rot. Koch?s postulates were verified and mode of infection of the associated isolates was investigated with light and scanning electron microscopy. Population structure of the pathogen was investigated by scoring the anastomosis reaction type in pairings between different isolates from the same seedbed. One pathogen genotype showed a large distribution area within the seedbed, this implying that the inoculum had been building up in the seedbed over a longer time period. Hyphal anastomosis tests and sequence analysis of the internal transcribed spacer (ITS) region of ribosomal DNA indicated that the pathogen belongs to AG 2-1 of R. solani. ITS sequence analysis indicates that the isolates from beech are closely related to R. solani isolates causing a disease on tulip. The striking similarities between the two diseases are discussed.
Abstract
This paper describes the use of quantitative real-time PCR for monitoring colonization of birch wood (Betula pubescens) by the white-rot fungus Trametes versicolor in an EN113 decay experiment. The wood samples were harvested after 4, 8, 12, 16 and 20 weeks of incubation.The mass loss was in the range of 440%. Chitin and ergosterol assays were conducted for comparison. Second-order polynomial fits of the mass loss of decayed wood versus chitin, ergosterol and DNA gave correlations (r2) of 0.87, 0.61 and 0.84, respectively. Compared to the other two assays employed, real-time PCR data correlated best with the relative mass loss of decayed samples 48 weeks after inoculation, while the saturation and decline of DNA-based estimates for fungal colonization 1620 weeks after inoculation indicated that the DNA assay is not suited for quantification purposes in the late stages of decay.The impact of conversion factors, extraction efficiency, inhibitory compounds and background levels in relation to the three detection assays used is discussed.
Abstract
In spring 2002, extensive damages were recorded in southeast Norway on nursery-grown Norway spruce seedlings that had either wintered in nursery cold storage or had been planted out in autumn 2001. The damages were characterised by leader shoot dieback and necroses on the upper or lower part of the 2001-year-shoot. Gremmeniella abietina and Phomopsis sp. were frequently isolated from the diseased seedlings. RAMS (random amplified microsatellites) profiling indicated that the G.abietina strains associated with diseased nursery seedlings belonged to LTT (large-tree type) ecotype, and inoculation tests confirmed their pathogenicity on Norway spruce. Based on sequence analysis of the internal transcribed spacer (ITS) regions of ribosomal DNA, the Phomopsis strains associated with diseased seedlings do not represent any characterized Phomopsis species associated with conifers. Phomopsis sp. was not pathogenic in inoculation tests, this implying it may be a secondary colonizer. ITS-based real-time PCR assays were developed in order to detect and quantify Gremmeniella and Phomopsis in the nursery stock. We describe here the Gremmeniella - associated shoot dieback symptoms on Norway spruce seedlings and conclude that the unusual disease outburst was related to the Gremmeniella epidemic caused by the LTT type on large pines in 2001.
Authors
Axel Schmidt Zeneli Gazmend Ari Hietala Carl Gunnar Fossdal Paal Krokene Erik Christiansen Jonathan GershenzonAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Lisbeth Mehli Trygve D. Kjellsen Frances M. Dewey Ari M. HietalaAbstract
Strawberry Fragariax ananassa (cv. Korona) was inoculated with Botrytis cinerea by dipping berries in a conidial suspension. The colonization of the pathogen was monitored with real-time PCR, ELISA and ergosterol assays, the first showing the highest sensitivity. The expression of pathogen -tubulin and six polygalacturonases (Bcpg1-6) and three host defense genes (polygalacturonase inhibiting protein (FaPGIP) and two class II chitinases) were monitored with real-time RT-PCR. The maximum transcript levels of the host defense genes occurred at 16 hours post inoculation (hpi), at the presumed initial penetration stage.The unique transcript profile of Bcpg2 over the 96-hour-long incubation time and its high transcript levels relative to those of the other Bcpgs at 8 to 24 hpi suggest that the gene has a specific role in the penetration stage.Bcpg1 was constitutively expressed at a relatively high level in actively growing mycelia throughout the experimental period. Comparison of the transcript profiles indicated that Bcpg1 and Bcpg3-6 were co-ordinately regulated.