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.
2011
Abstract
Twenty cypress accessions were tested for freezing tolerance. After freezing to −15°C, differences among cypress accessions were tested by measuring electrolyte leakage and chlorophyll fluorescence. Based on these data, cypress accessions showing contrasting freezing tolerance were subjected to transcript profiling of candidate genes upon the development of cold hardening, with the ultimate goal of providing a scientific basis for selecting/breeding cypress genotypes with higher tolerance to low temperature. Nine different cypress genes were selected: a heat shock protein, a putative chaperonin, a chlorophyll-binding protein, a serine/threonine protein kinase, a putative exonuclease, a dehydrin, and three senescenceassociated proteins. Transcript levels of these genes were profiled during cold hardening under controlled conditions using real-time reverse-transcription-polymerase chain reaction. While the genes showed regulation patterns common to both cypress accessions, in the case of chaperonin, exonuclease, and some senescence-associated proteins, clonal differences in gene regulation were found. The potential relationship of these differences with cold tolerance is discussed.
Abstract
The causative agent of dieback on European ash (Fraxinus excelsior) was first described as Chalara fraxinea based on cultural morphology because no sexual stage of the fungus was known. Later, based on culturing of ascospores of a candidate teleomorph, morphological comparison and nuclear ribosomal internal transcribed spacer sequencing, the sexual stage of C. fraxinea was assigned as Hymenoscyphus albidus, a native and widespread species in Europe. Recently, the morphological species concept of H. albidus was shown to cover two species that cannot be separated from each other based on teleomorph characters, but which can be distinguished by several DNA markers. As a result, the strains causing ash dieback were reassigned as H. pseudoalbidus. The closely related H. albidus is presumably a non-pathogenic endophyte, but pathogenicity tests to confirm this hypothesis have not yet been performed. Genotyping of herbarium specimens has shown that H. pseudoalbidus was present in Switzerland for at least a decade prior to the epidemic outbreak in Europe. The origin of the ash dieback pathogen, and the general importance of correct pathogen identification to development of effective disease control, are discussed.
Abstract
Fungal hyphae in soil, although crucial in the C-dynamics, are difficult to quantify. Here we present a simple method for fungal biomass assessment and possibility for up-scaling. Originally we used root nets to quantify fine roots in drought-stressed Picea abies stand as described by Lukac and Godbold (2010).Root nets (7 cm wide, mesh size 1 mm) were inserted vertically to 20 cm depth, twice during the course of one year. When root nets were extracted from the soil, large amounts of hyphae were growing on and through the nets in the control plot, whereas little or no hyphae were growing in nets from the drought-stressed plot.This observation led us to consider root nets as a promising tool to quantify hyphae as well. The inert net material together with its regular geometric pattern is well suited for obtaining fungal biomass estimates and provide a material for further molecular analysis of fungal species. We will describe a proposal how to scan the hyphae, calculate the biomass and upscale to the soil volume unit.
Abstract
The osmotic method has been used for many years in Norway and Sweden as a routine method for detection of Pyrenophora teres (anamorph Drechslera teres) and P. graminea (anamorph D. graminea) on barley. The method is based on the ability of Pyrenophora spp. to produce red pigments. However, it cannot distinguish between P. teres and P. graminea because they produce the same pigment. A validation study has been carried out with the aim to provide the necessary documentation for including the method in the International Rules for Seed Testing (ISTA Rules). Seven laboratories participated and each tested 3 x 300 seeds of three barley seed lots. Analyses of the results demonstrate that the method gives sufficient repeatability and there is no particular problem with this test at a laboratory level. Furthermore, in previous studies with the osmotic method organized by a Nordic working group, it has been shown that the osmotic method easily gives reproducible results for Pyrenophora teres/P. graminea in barley when used by experienced laboratories. Moreover, the osmotic method is well suited for routine analyses because it is quick and easy to carry out. The study showed, that if used correctly and with proper equipment the osmotic method for detection of Pyrenophora teres/P. graminea is easy to perform and it showed good conformity amongst laboratories.
Authors
Ragnhild Nærstad Arne Hermansen Vinh Hong Le Grete Lund Abdelhameed Elameen May Bente BrurbergAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Arne StensvandAbstract
The following diseases of roots, stem or shoots of apple are more or less troublesome, but they all seem to be easily spread by planting material. Twig blight and canker caused by Diplodia sp. and Phomopsis sp. are new to Norway, but are thus far not widely distributed. Apple proliferation is widely distributed in the fruit growing areas, while fire blight has not been observed in the fruit areas, although it is widely spread along the western coast of the country. European canker, silver leaf and crown- and collar rot are endemic in the country.
Abstract
odronia canker (Godronia cassandrae f. sp. vaccinii) is a severe disease in young plantings of highbush blueberry (Vaccinium corymbosum L.) in Norway. In Europe, only the imperfect stage (Topospora myrtillii) has been reported, and thus conidia produced in pycnidia are assumed to be important for dissemination of the fungus. The seasonal pattern of production of conidia was investigated in a commercial planting of ‘Jersey" in 1998 and a research planting of ‘Bluecrop" in 1998 to 2000. The disease became apparent in March on shoots infected the preceding growing season, and lesions started to form pycnidia containing conidia in April. Samples of stems with distinct lesions of Godronia canker were collected from the bushes every two to three weeks from early spring to autumn. Stem pieces with lesions were shaken in water to release conidia from the pycnidia, and the numbers of conidia were determined by microscopy. Conidia were present throughout the growing season, but the highest numbers occurred during May, with 106 to more than 107 conidia per lesion. The numbers generally decreased during July to 20 % or less of that found in May, and decreased further during September to around 4 %. Ability to germinate remained high throughout the period conidia were trapped, from April to November/December. Options to manage the disease are discussed.
Abstract
No abstract has been registered
Authors
Jan Svtlík Isabella Børja Toril Drabløs Eldhuset Holger Lange Frank Newell Kidder Douglas Lawrence GodboldAbstract
Fungi are the main degraders of organic matter and are associated symbiotically with over 80% of terrestrial plants (Smith and Read 1997). Thus, the extent of the mycelial network is an indicator of the decomposing or symbiotic activity. Although the importance of fungi in soil is undisputable, the determination of the extent of hyphal mats and the hyphal biomass is difficult to assess. Methods for estimating hyphae in soil are mostly based on the gridline intersect method originally developed to determine the root length or recently by measuring of the ergosterol content, fungal sterol found in the cell membranes....