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.
2005
Authors
Carl Gunnar Fossdal Ari M. HietalaAbstract
The root-rot causing fungus Heterobasidion annosum can attack both spruce and pine trees and is the economically most damaging pathogen in northern European forestry. We have monitored the Heterobasidion annosum S-type (fairly recently named H. parviporum) colonization rate and expression of host chitinases and other host transcripts in Norway spruce material with differing resistances. Transcript levels of three chitinases, representing classes I, II and IV, were monitored with real-time PCR. We have also transferred a Class IV chitinase to Arabidopsis as well as its promotor in GFP and YFP reporter constructs. Ramets of two 33 -year-old clones differing in resistance were employed as host material and inoculation and wounding was performed. Multiplex real-time PCR detection of host and pathogen DNA was also performed to follow the colonization of the host tissues by the pathogen and the collapse in host DNA levels in infected regions. Host defense transcript levels, as an indicator of the host defense response, were monitored with singleplex real-time PCR. Three days after inoculation, comparable colonization levels were observed in both clones in the area immediately adjacent to inoculation. Fourteen days after infection, pathogen colonization was restricted to the area immediately adjacent to the site of inoculation for the strong clone (589), but had progressed further into the host tissue in the weak clone (409). Transcript levels of the class II and IV chitinases increased following wounding or inoculation, while the transcript level of the class Ichitinase declined following these treatments. Transcript levels of the class II and class IV chitinases were higher in areas immediately adjacent to the inoculation site in 589 than in similar sites in 409 three days after inoculation, suggesting that the clones differ in the rate of pathogen perception and host defense signal transduction. This an earlier experiments using mature spruce clones as substrate indicate that it is the speed of the host response and notmaximum amplitude of the host response that is the most crucial component in an efficient defense in Norway spruce toward pathogenic fungi such as H. annosum.
Abstract
No abstract has been registered
Authors
Nina Jøhnk Ari M. Hietala Carl Gunnar Fossdal David B. Collinge Mari-Anne NewmanAbstract
To study the mechanisms of inducible disease resistance in conifers, changes in transcript accumulation in roots of Norway spruce (Picea abies (L.) Karst.) seedlings exposed to the root rot pathogen Ceratobasidium bicorne Erikss. and Ryv. (anamorph: Rhizoctonia sp.) were monitored by differential display (DD). Because C. bicorne attacks root tips, a desiccation treatment was added to exclude genes induced by pathogen-related desiccation stress. The DD analysis was defined by the use of 11 sets of primers, covering about 5% of the transcriptome. A comparison of gene expression in control, desiccation- and pathogen-stressed roots revealed 36 pathogen-induced gene transcripts. Based on database searches, these transcripts were assigned to four groups originating from spruce mRNA (25 transcripts), rRNA (five transcripts), fungal mRNA (two transcripts) and currently unknown cDNAs (four transcripts). Real-time PCR was applied to verify and quantify pathogen-induced changes in transcript accumulation. Of the 18 transcripts tested, nine were verified to be Norway spruce gene transcripts up-regulated from 1.3- to 66-fold in the infected roots. Four germin-like protein isoforms, a peroxidase and a glutathione S-transferase, all implicated in oxidative processes, including the oxidative burst, were predicted from sequence similarity searches. Seven class IV chitinase isoforms implicated in fungal cell wall degradation and a nucleotide binding site-leucine rich repeat (NBS-LRR) disease resistance protein homologue related to pathogen recognition were identified. Several transcript species, such as the NBS-LRR homologue and the germin-like protein homologues, have not previously been identified as pathogen-inducible genes in gymnosperms.
Authors
Jørgen Aleksander Mølmann Øystein Johnsen Olavi Junttila Jorunn Elisabeth OlsenAbstract
No abstract has been registered
Abstract
In this study modified wood samples were tested according to the extended standardised test procedures of ENV 807 (3 types of soils). A Round Robin test was carried out at two laboratories: Swedish National Testing and Research Institute and Norwegian Forest Research Institute.The different soil types used were conifer forest soil (pH 4.6), soil from the Simlngsdalen test field (pH 5.2) and garden compost soil (pH 7.4). The wood modifications used were furfurylation (Visorwood), acetylation and heat treatment (Thermowood). Other materials tested were linseed oil impregnated pine, reference preservative (CC and CCA) treated pine and Robinia psuedoaccacia heartwood.A dynamic MOE (MOEdyn) test device based on measurement of ultrasonic pulse propagation was used for non-destructive decay strength evaluation during the incubation period. The MOE values were correlated to measured decay mass loss of the test specimens after different periods of exposure to the soils. Type of fungal attack was also evaluated using light microscopy.Results from preliminary studies indicate that ultrasound seems to be an excellent tool for evaluation of early brown rot decay. It also seems to be feasible for detecting white rot. However it does not seem to be very accurate in evaluating early stages of soft rot decay.
Authors
Morten Eikenes Monica Fongen Line Roed Yngve StenstrømAbstract
In recent years chitosans have been investigated as a natural chemical for wood preservation against fungal decay, and chitosan in aqueous solutions has been used in impregnation studies. To evaluate the retention of chitosan after an impregnation process and to evaluate the fixation of chitosan in wood a method for determination of chitosan in wood and water samples has been developed based on acidic hydrolysis of chitosan to glucosamine followed by online derivatization by o-phthalaldehyde, chromatographic separation and fluorescent detection. For wood samples the method was linear up to 45 mg gK1 chitosan in wood and had a recovery of 86%. The yield of chitosan in water was 87% at 1% (w/v) concentration.
Abstract
In recent years chitosans have been investigated as a natural chemical for wood preservation against fungal decay, and chitosan in aqueous solutions has been used in impregnation studies. To evaluate the retention of chitosan after an impregnation process and to evaluate the fixation of chitosan in wood a method for determination of chitosan in wood and water samples has been developed based on acidic hydrolysis of chitosan to glucosamine followed by online derivatization by o-phthalaldehyde, chromatographic separation and fluorescent detection. For wood samples the method was linear up to 45mgg−1 chitosan in wood and had a recovery of 86%. The yield of chitosan in water was 87% at 1%(w/v) concentration.
Abstract
Animal health and health handling were studied in organic dairy farms separated into three groups according to time of conversion. The study showed differences in both health and health handling between the groups and especially so for the earliest converters.
Abstract
Animal health and health handling were studied in organic dairy farms separated into three groups according to time of conversion. The study showed differences in both health and health handling between the groups and especially so for the earliest converters.
Authors
Mekjell MelandAbstract
No abstract has been registered