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.
2008
Sammendrag
Aerial dispersal of inoculum is critical to the spread of many plant diseases; including potato late blight (Phytophthora infestans (Pi)), lettuce downy mildew (Bremia lactucae (Bl)) and cucurbit downy mildew (Pseudoperonospora cubensis (Pc)). In addition to relative humidity and temperature, spore survival during aerial dispersal is affected by solar irradiation (SI), in particular during long-distance transport at higher altitudes. We evaluated the potential survival of spores in air by placing detached spores of Pi, Bl and Pc on filter paper in either direct sun or shade at time intervals from 0.5 to 3 h (Pi and Bl), or up to 42 hours (Pc). Thereafter, the filter papers were placed in moist chambers for 15 min prior to incubation on pea agar (Pi) or water agar (Bl and Pc) for 24 h, before the viable spores were enumerated. Spores were considered viable if they exhibited a germ tube or released zoospores. Preliminary results show that no spores of Pi, Bl and Pc germinated after 1, 3 and 30 h exposure to direct sun, with critical SI doses near 700, 2000 and 8500 Wm-2, respectively. In shade, no Pi spores germinated after 3 h, while spores of Bl and Pc were still viable after 3 and 42 h, respectively. In Norway, the potential for long distance distribution of Pi is restricted, but more likely for Bl and Pc. Further experiments will be conducted to find the maximum survival time for spores of these pathogens under Norwegian climatic conditions.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Nadeem Yaqoob Carl Gunnar Fossdal Bao Dzung Diep Halvor SolheimSammendrag
Due to the great economic losses caused by the root and butt-rot pathogen Heterobasidion annosum, developments of efficient control measures are warranted. H. annosum a necrotroph colonize the Norway spruce from inside and is responsible of 10-13 millions Euros losses in Norway alone. Considerable clonal variation has been recorded for Norway spruce in resistance towards H. annosum, but the defence mechanisms contributing to host resistance remain poorly understood. The recent genome sequencing of Populus has made the genus a model to facilitate tree genetics. Genome-wide transcript profiling of Populus tremula upon pathogen attack will now be used, and homologues of Norway spruce genes to defence genes up-regulated in Populus will be identified. Populus-Phellinus tremula pathosystem is selected as P. tremula behaves like H. annosum.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
May Bente BrurbergSammendrag
Research from the last few years in our lab on the two potato pathogens Pectobacterium atrosepticum (Pba) and Clavibacter michiganensis (Cm) will be discussed. This includes studies of plant root affinity of Pba and bacteriocin sensitivity of Cm. For our studies we have used the available genome sequences, a mutation grid, real-time PCR and traditional techniques in biochemistry and microbiology.
Forfattere
Anne Falk Øgaard Anne-Kristin LøesSammendrag
In organic cereal production, restrictions on use of mineral fertilizers will in many cases reduce the P concentration in soil, and short term leys and catch crops will contribute to decrease the risk of P losses due to reduced erosion. However, the current means to control perennial weeds increase the risk of soil erosion and P loss. On organic farms with ruminants, the aim of self-sufficiency with fodder will often cause a low P-surplus, or even a P deficit on the farm level. This will reduce the P content in soil and thereby the P loss to the environment. However, if organic farming develops to include more intensive production systems with high animal densities and purchased fodder, such systems will be prone to the same risks of high P surplus and P losses as conventional farming systems. Outdoor housing for animal welfare is likely to further increase these risks, and environmental concerns such as reducing P losses from agriculture should be considered when organic farming systems are further developed.
Sammendrag
Poinsettia (Euphorbia pulcherrima Willd. Ex Klotzsch), is a contemporary symbol of Christmas in most parts of the world. Today, Europe and North America represent the largest volume of production and sales, but demand is growing quickly in the other regions as poinsettia becomes more popular each year. In Norway, poinsettia is one of the most important pot plants, with a yearly production close to 6 million plants. Its ornamental value and innovation potential have laid the foundation for extensive research in Norway and elsewhere. Poinsettia mosaic virus (PnMV) is a RNA virus that belongs to the family Tymoviridae. Infection of poinsettia plants with PnMV results in mosaic symptoms during parts of the growing season and decrease the commercial value of this ornamental plant. Thus, growers are interested in the potential benefits of growing PnMV-free poinsettias. PnMV-free poinsettia plants can be obtained by heat treatment or in vitro culture of apical meristems, which are time-consuming and cost-ineffective methods. There is thus an urgent need for a new approach, like Agrobacterium-mediated transformation, which can overcome these difficulties. We have therefore developed an Agrobacterium-mediated transformation approach for poinsettia. Transgenic poinsettia plants with improved resistance against PnMV by expressing hairpin RNA constructs which targeted various regions of the virus genome were produced. Mechanical inoculation of PnMV and subsequent enzyme-linked immunosorbent assay (ELISA) confirmed the PnMV resistance. The siRNA analysis has demonstrated gene silencing mediated resistance. The PnMV resistant transgenic poinsettia lines produced are in the process of being commercialized. Because poinsettia is a non-food, non-feed plant and is not propagated through sexual reproduction, this is likely to be more acceptable even in areas where genetically modified crops are currently not cultivated.
Forfattere
Björn Andersson J.E. Yuen G.J.T. Kessel B. Evenhuis L.J. Turkensteen A. Hannukkala A. Lehtinen B. Nielsen S. Ravnskov J.G. Hansen Arne Hermansen May Bente Brurberg Berit NordskogSammendrag
The role of oospores in the epidemiology of potato late blight
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag