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.
2011
Forfattere
Xiaoren Chen Sonja Klemsdal May Bente BrurbergSammendrag
The oomycete Phytophthora cactorum can cause economically important diseases on numerous host plants worldwide, such as crown rot on strawberry. To explore the molecular mechanisms underlying the pathogenicity of P. cactorum on strawberry, transcriptional analysis of P. cactorum during strawberry infection and cyst germination was performed by applying suppression subtractive hybridization (SSH) and effector-specific differential display (ESDD) techniques. Two SSH cDNA libraries were generated, enriched for P. cactorum genes expressed during infection or during cyst germination, respectively, and 137 unique differentially expressed genes were identified. To specifically select RxLR effector genes from P. cactorum, ESDD was performed using RxLR and EER motif-based degenerate primers. Eight RxLR effector candidate genes as well as 67 other genes were identified out of 124 selected fragments. The expression levels of 20 putatively up-regulated genes were further analyzed using real-time RT-PCR, showing that, indeed 19 of these 20 genes were up-regulated during at least one of the studied developmental stages or during strawberry crown invasion, relative to the mycelium. This study provides a first overview of P. cactorum genes that are up-regulated immediately prior to or during strawberry infection and also provides a novel method for selecting RxLR effector genes from the unsequenced genome of P. cactorum.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Ole Tobias Rannestad May-Guri Saethre Amon P. MaerereSammendrag
The banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is a major pest in banana (Musa spp.) growing areas. The weevil is known to be relatively sedentary and closely associated with its host plant, but little is known about the species" ability to migrate between banana fields and in non-host habitats. Mark-recapture experiments were conducted to assess the weevils" migration potential, possible differences between the sexes, and the relative attractiveness of pseudostem and pheromone baits. One thousand two hundred marked weevils were released in non-host habitat at five distances (5, 10, 20, 40 and 70 m) from fresh pseudostem, and from pitfall traps baited with 45 mg Sordidin. Two hundred males and 200 females were marked and released at five distances (5, 10, 20, 40 and 70 m) from pheromone traps. Distance and distance/bait interactions had a significant effect on recaptured weevils (binary logistic regression). The two baits were almost equally attractive to weevils from 0-10 m, while the pheromone was more attractive from 10-100 m. Distance, bait, and distance/bait interactions had a significant effect on the time elapsed from release to recapture (regression with life data). However, the pattern observed was not consistent. There was no significant difference between males and females with respect to distance or time elapsed from release to recapture.
Forfattere
Frank Asche Kristin Helen Roll Ragnar TveteråsSammendrag
Det er ikke registrert sammendrag
Forfattere
Elisabeth Conrad Louis F Cassar Michael Jones Sebastian Eiter Zita Izaovičová Zuzana Barankova Mike Christie Ioan FazeySammendrag
The involvement of the public in decision-making is established as a key feature of many planning policies. However, there is evidence from the literature of a prevailing gap between participation rhetoric on paper and participation at the operational level. We assess whether this is also the case with landscape policy and review landscape characterization and assessment initiatives in England, Norway, Slovakia and Malta, focusing on five dimensions of good practice: (i) scope of public participation, (ii) representativeness of those involved, (iii) timeliness of public involvement, (iv) extent to which participation is rendered comfortable and convenient for the public, and (v) eventual influence of public input on decisions. Reviewed reporting results indicate weaknesses in the implementation of public participation, with public involvement largely limited to consultation, with few efforts to ensure representativeness of participants, with predominantly late involvement of the public, and with limited influence of the public on outputs. Furthermore, few efforts appear to be made to facilitate participation for the public. Although the cases studied differ, none of them are fully satisfactory in relation to the European Landscape Convention's participatory targets. The reporting of public participation processes thus suggests that practices may fail to match the rhetoric.
Forfattere
Frank Asche Kristin Helen Roll Ragnar TveteråsSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor J. JohansenSammendrag
Dormancy in a potato tuber prevents sprout growth even under optimal sprouting conditions and is the first stage in the physiological ageing process. The intensity and duration of this phase differs between genotypes (cultivars) and may also be affected by environmental conditions both during tuber bulking and early storage. The current study aimed at finding how simulated high latitude growth conditions influence dormancy and the physiological age of tubers to be used as seed potatoes. In a controlled climate at natural light conditions, tubers grown at a low temperature (9°C) had 2-3 weeks shorter dormancy than tubers grown at higher temperatures (15 and 21°C). In tubers grown at artificial light conditions, day-lengths (12, 18 or 24 h) did not affect dormancy significantly. A post-harvest treatment with a low temperature (one month at 4°C and subsequently 18°C) reduced dormancy by 2-3 weeks in tubers from the highest growth temperatures (15 and 21°C) in comparison with constant 18°C post-harvest. After the lowest growth temperature (9°C) the duration of dormancy was not affected by post-harvest temperature treatments. Physiological age was determined by sprouting characteristics after winter storage. At this stage the sprouting capacity was highest in tubers originating from the lowest and the highest growth temperatures. Further, the number of sprouts per tuber was higher in tubers grown at 9°C than at 15 or 21°C. These results were not correlated with duration of dormancy after the various treatments, suggesting that temperatures may affect dormancy and physiological ageing independently. The present results show that dormancy may be shortened by low grow temperatures, and similarly by low post-harvest temperatures at higher growth temperatures.
Forfattere
Md Hafizur Rahman Trine Lund Ian BrycesonSammendrag
Salinity increase has been one of the major problems for traditional agricultural practices in coastal Bangladesh for several decades, but very few studies have been conducted on effects of salinity on agrobiodiversity in this area. This study investigated the salinity effects on agro-biodiversity in rice (Oryza sativa L.), vegetables, and fruit trees in three coastal, rural villages; Putia (Satkhira district), Srifaltala (Bagerhat district) and Hogolbunia (Khulna district). Information was collected by participatory rural appraisal methods including transect walks, group discussions, key informant interviews, and 121 personal interviews from July to December 2006. The study revealed that increased salinity had significant negative impacts on the overall agro-biodiversity. From 1975 to 2006 the number of indigenous rice varieties declined from seventeen to zero in Putia, from twelve to nine in Hogolbunia and from fifteen to two in Srifaltala. The encroachment of shrimp ponds near the homestead, and cultivation of high yielding, salt-tolerant rice varieties contributed to the decline of indigenous rice varieties. The occurrence of vegetable and fruit tree species declined from 1975 to 1990. The farmers appeared generally unaware of the importance of conservation of seeds and local landraces. This paper highlights factors directly and indirectly influencing farmers’ agricultural practices, and contributes to the discussion as to how environmental changes influence agro-biodiversity conservation and food production. The large reduction in agro-biodiversity, largely induced by increasing salinity, is alarming and threatens the Bangladeshi farmers’ ability to continue crop cultivation and thus their livelihood.
Forfattere
Roman Gebauer Daniel Volařík Josef Urban Isabella Børja Nina Elisabeth Nagy Toril Eldhuset Paal KrokeneSammendrag
Conifers and other trees are constantly adapting to changes in light conditions, water/nutrient supply and temperatures by physiological and morphological modifications of their foliage. However, the relationship between physiological processes and anatomical characteristics of foliage has been little explored in trees. In this study we evaluated needle structure and function in Norway spruce families exposed to different light conditions and transpiration regimes. We compared needle characteristics of sun-exposed and shaded current-year needles in a control plot and a thinned plot with 50% reduction in stand density. Whole-tree transpiration rates remained similar across plots, but increased transpiration of lower branches after thinning implies that sun-exposed needles in the thinned plot were subjected to higher water stress than sun-exposed needles in the control plot. In general, morphological and anatomical needle parameters increased with increasing tree height and light intensity. Needle width, needle cross-section area, needle stele area and needle flatness (the ratio of needle thickness to needle width) differed most between the upper and lower canopy. The parameters that were most sensitive to the altered needle water status of the upper canopy after thinning were needle thickness, needle flatness and percentage of stele area in needle area. These results show that studies comparing needle structure or function between tree species should consider not only tree height and light gradients, but also needle water status. Unaccounted for differences in needle water status may have contributed to the variable relationship between needle structure and irradiance that has been observed among conifers.
Forfattere
jihong liu clarke Even Sannes Riiser Ingrid Holtsmark Sonja Klemsdal Sadhu Leelavathi Andreas Lössl Vanga S. Reddy Nagothu U. Sekhar Hege Særvold Steen Sathyamangalam Swaminathan Rebekka ØvstegårdSammendrag
Dengue viruses (Flavivirus) are mosquito-borne human pathogens with a worldwide prevalence. There are four antigenically-related dengue virus serotypes, DEN-1 to DEN-4, which cause serious problems of morbidity and mortality. Dengue is emerging rapidly as one of the most important public health problems in countries of the Asia-Pacific region with nearly 1.8 billion people in the region at risk, compared to an estimated total of 2.5 billion globally (WHO 2009). The disease has resulted in widespread social and economic problems, especially among the poor, who are the most vulnerable group. There is currently no vaccine to prevent dengue virus infection making it difficult to control and manage the disease, although considerable efforts have been made, including vector control, sanctions, law enforcement and public education (www.who.int). A DEN vaccine must be tetravalent, as immunity to a single serotype does not offer cross-protection against the other serotypes the yeast Pichia pastoris. In this study, we aim to develop a similar envelope domain III (EDIII)-based chimeric antigen which elicits neutralizing antibodies against all four DEN serotypes. The antigen will be expressed in tobacco chloroplasts, aiming for a cost-effective and safe production system by joint efforts of Indo-Norwegian bilateral collaboration.