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.
2009
Abstract
In natural conditions plants are continuously exposed to number of pathogens both biotrophs and necrotrophs. To understand their defense response at the transcript level two clones C72 and C23 with differential level of resistance from the SwAsp collection were inoculated with a biotroph (Melampsora magnusiana Wagnar) and necrotroph (Ceratocysis spp.) and compared to wounded and healthy controls. Samples were collected in leaves and areas some distance away from the inoculation site to examine the long distance (systemic) defense responses at day, day3 and day14 post treatments. We performed microarray experiments on the necrotrophic and biothrophic interaction compared with the healthy controls and found that the two clones respond in widely different fashions to the treatments applied. Clone C23 showed almost no response to biotroph and necrotroph inoculations after 24 hours while clone 72 gave a clear defense response to both pathogens. We are now in the process of verifying these results and looking at additional time-points using qRT-PCR.
Abstract
No abstract has been registered
Authors
Berit Nordskog David M. Gadoury May Bente Brurberg Tor Håkon Sivertsen R. Kennedy Arne HermansenAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Leif Sundheim Maria-Luz Herrero Trond Rafoss Brita Toppe May Bente Brurberg Trond Hofsvang Christer Magnusson Anne Marte Tronsmo Bjørn ØklandAbstract
Phytophthora ramorum S. Werres, A.W.A.M. de Cook & W.A. Man in‘t Veld is a newly described Phytophthora-species which is considered to be relatively recently introduced to both USA and Europe from an unknown area, or areas, of origin. The pathogen has a wide host range and causes a complexity of disease symptoms generally grouped into three categories: canker, foliage lesion, and dieback. In Europe the pathogen has been reported in 21 countries, Norway included; predominantly on ornamental plants in nurseries, but also outside nurseries in gardens and semi-natural environment, most often on rhododendrons. The Norwegian Food Safety Authority needs a risk assessment of the pest as basis for an evaluation of a future phytosanitary risk management of P. ramorum, including whether the organism should be regulated as a quarantine pest in Norway. On this background the Norwegian Food Safety Authority, in a letter of 22nd August 2008, requested a pest risk assessment of P. ramorum from the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM). The pest risk assessment was adopted by VKM"s Panel on plant health (Panel 9) on a meeting 24th June 2009. VKM"s Panel 9 gives the following main conclusions of the risk assessment: 1) P. ramorum is present but not widely distributed in Norway, and the pest is under official control. The outdoors surveys of P. ramorum in Norway have not been conducted systematically over the whole country, and some uncertainty therefore still remains regarding the current distribution of P. ramorum in the PRA area. 2) The overall probability of entry of P. ramorum into Norway and the overall probability of establishment of P. ramorum in Norway are both rated as high with low levels of uncertainty; 3) In the absence of statutory control the probability for P. ramorum to be spread quickly in the PRA area by trade of host plants for planting is rated as high. The uncertainty of this assessment is low; 4) The part of the PRA area where presence of P. ramorum might result in economically important losses (the endangered area) is assessed to be most of the country of Norway, except where the climate is predicted to be unfavourable for the pest. However, this area must be regarded as a maximum estimate for the endangered area. On the other hand, a narrow and very conservative estimate for the endangered area can be defined based on the geographical distribution of highly susceptible host plants in Norway. This area is gardens and parks with Rhododendron spp., Viburnum spp. and F. sylvatica and areas in the wild into which Rhododendron spp. has spread and woods with F. sylvatica. Woods with F. sylvatica is limited to the county of Vestfold and some small areas in the counties of Aust-Agder and Hordaland; 5) P. ramorum is likely to have moderate economic impact on the nurseries in the PRA area with current phytosanitary measures. Without any such regulations P. ramorum is likely to have major economic impact on the nursery industry of the PRA area. The levels of uncertainties of these assessments are low; 6) With current phytosanitary measures P. ramorum is likely to have moderate economic impact on parks and private gardens in parts of the PRA area. Without any such regulations P. ramorum is likely to have major economic impact in the best climatic zones of the PRA area. The levels of uncertainties of these assessments are low; 7) The impact of P. ramorum in coniferous and mixed forests of the PRA area is likely to be minor. The level of uncertainty of this assessment is medium. The impact of P. ramorum in natural and planted deciduous broadleaf forests of the PRA area is likely to be minor due to the scattered and limited distribution of the most susceptible species. The level of uncertainty of this assessment is medium; 8) The non-commercial and environmental consequences to natural environments in the PRA area are likely to be moderate. The level of uncertainty ...
Abstract
Minirhizotrons, transparent acrylic tubes inserted in the soil, are well suited for long term, non destructive, in situ observations of fine roots. In minirhizotrons, the fine roots are regularly photographed and the root images are visually evaluated according to their status as living, dead or disappeared. This evaluation gives the background for further statistical treatment to estimate the fine root longevity. It is inherent in the minirhizotron technique that a large group of roots will be described as “disappeared” due to grazing, overgrowing by other roots, unclear images or other reasons. Because the fraction of disappeared roots is substantial in some cases, this has consequences for the interpretation of the longevity results. We processed three years of minirhizotron images from Norway spruce stands in southeast Norway (30 yr old) and northern Finland (60 yr old). Of all processed fine roots 32 and 23% was evaluated as disappeared in Norway and Finland, respectively. When roots labelled as disappeared were pooled together with dead ones, the fine root longevity estimates, using the Kaplan Meier method, decreased almost by a factor of two (401 and 433 days), as opposed to labeling them as censored observations (770 and 750 days for Norway and Finland, respectively). Here we demonstrate how the early decision making on the fine root status bears consequences on the resulting longevity estimates. The implications will be discussed
Abstract
No abstract has been registered
Abstract
The chapter reviews the available literature about the adverse effects of excess nickel on plants and their adaptation mechanisms. The study is focused on forest ecosystems exposed to extreme air pollution from the nickel-processing industry in Northern Fennoscandia. Long-term deposition of heavy metals and sulphur has caused strong soil contamination and severe damage to trees and ground vegetation, their structure, composition and chemistry. Tree leaves, branches and bark as well as dwarf shrubs, mosses and lichens show clearly elevated concentrations of nickel and copper in the surroundings of the smelters. Multivariate analyses show that changes in the element composition of plants depend both on air pollution and on natural factors. Besides direct input of pollutants from atmosphere, soil contamination and nutritional disturbance contribute significantly to the observed changes. Despite decline in emissions, extreme pool of heavy metals accumulated in surface soils is expected to influence plant metabolism and chemistry over a long period of time.
Abstract
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.
Authors
Holger Lange Nicholas Clarke O. Janne Kjønaas Wenche Aas Kjell Andreassen Isabella Børja Harald Bratli Susanne Eich-Greatorex Toril Drabløs Eldhuset Kjersti Holt Hansen Tonje Økland Ingvald Røsberg Trine Aulstad Sogn Volkmar TimmermannAbstract
No abstract has been registered