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
Forfattere
Marit Larsen Sekse Sonja KlemsdalSammendrag
Rognebærmøllen (Argyresthia conjugella) er den viktigaste insektskadegjeraren på eple i Skandinavia. Rognebærmøllen legg egga sine på rognebær om våren og larvene lever i rognebæra. Fruktproduksjonen i rogn er syklisk, og kvart andre til fjerde år er det for lite bær for rognebærmøllen å leggje egg på. I år med lite rognebær legg rognebærmøllen egga sine på eple i staden. Larvene gneg seg inn i epla og etterlet seg brunfarga gangar. Luktesansen er viktig for mange insekt når dei skal lokalisere vertsplanter. Nokre planter skil ut spesifikke luktstoff som insekta kjenner igjen, men i dei fleste tilfelle er det ikkje så enkelt. Dei fleste planter skil ut mange vanlege luktstoff. Tanken er då at insekta kjenner att vertsplantene gjennom ei blanding av ulike luktstoff, og ikkje basert på eit bestemt luktstoff. Desse luktstoffa er gjerne vanlege i mange planter og må vera til stades i rett blandingsforhold. Luktorganet til insekta er antennene. Antennene er dekka av små hår, sensilla (Fig. 1). Desse håra har små porer i overflata som luktstoffa kan kome inn gjennom. Inne i kvart av desse små håra er det ei eller fleire nerveceller. Desse nervecellene kjenner igjen ulike luktstoff og sender beskjed vidare til hjernen. Nervecellene har protein (luktreseptorar) i cellemembranen som kjenner igjen luktstoff. Nokre luktreseptorar er svært spesifikke medan andre kjenner igjen eit større utval av luktstoff. Når eit luktstoff bind til ein luktreseptor vil det føre til ein nerveimpuls.
Forfattere
Marit Sekse Sonja KlemsdalSammendrag
Luktesansen er viktig for mange insekt når dei skal lokalisere vertsplanter. Auka kunnskap om den genetiske kontrollen av sanseorgana vil kunne opne for nye tilnærmingar til kontroll av insektskadegjerarar.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Progenies from a natural stand of Picea abies planted on a forest site with heterogeneous growth conditions were characterized for genetic and environmental control of internodal and whorl branch formation and lammas growth. The progenies studied were 27 years old from seed and planted in a randomized complete block experiment. Internodes and whorls studied were located in the top section of the trees. Significant genetic variation (p<0.01) was found for a number of internodal and whorl branches. Block means for the length of internodes, a strong indicator for the site index in respective blocks, were correlated strongly with branch dimensions (r >= 0.90), intermediately with the frequency of lammas growth (r = 0.81) and number of branches in whorls (r = 0.68), and only weakly with the number of internodal branches per length unit of internode (r = 0.25). A strong environmental effect on branch dimensions was supported by the relative size of variance components. The results show that the environmental effect expressed by site index dominates the control of branch dimensions, while the number of branches is under stronger genetic control in P. abies.
Forfattere
Mari Mette Tollefsrud Roy Kissling Felix Gugerli Øystein Johnsen Tore Skrøppa Rachid Cheddadi W.O. van der Knaap Magorzata Lataowa Ruth Terhürne-Berson Thomas Litt Thomas Geburek Christian Brochmann Christoph SperisenSammendrag
Norway spruce (Picea abies [L.] Karst.) is a broadly distributed European conifer tree whose history has been intensively studied by means of fossil records to infer the location of full-glacial refugia and the main routes of postglacial colonization. Here we use recently compiled fossil pollen data as a template to examine how past demographic events have influenced its modern genetic diversity...
Sammendrag
Rhodiola rosea is widely distributed in Norway, but so far limited knowledge exists on the level of genetic diversity. To initiate a selective breeding program, Amplified Fragment Length Polymorphism (AFLP) analysis was used to estimate genetic diversity within the Norwegian R. rosea germplasm collection. AFLP analysis of 97 R. rosea clones using five primer combinations gave a total of 109 polymorphic bands. We detected high percentage of polymorphic bands (PPB) with a mean of 82.3% among the clones of R. rosea. Each of the 97 R. rosea clones could be unambiguously identified based on these primer combinations. Estimates of genetic similarities were obtained by the Dice coefficient, and a final dendrogram was constructed with the Unweighted Pair Group Method with Arithmetic mean (UPGMA). Genetic similarity based on the AFLP data ranged from 0.440 to 0.950 with a mean of 0.631. This genetic analysis showed that there was no close genetic similarity among clones related to their original growing county. No gender-specific markers were found in the R. rosea clones. Analysis of molecular variance (AMOVA) revealed a significantly greater variation within regions (92.03%) than among regions (7.97%). A low level of genetic differentiation (F-ST=0.043) was observed, indicating a high level of gene flow, which had a strong influence on the genetic structure at different counties. Our results indicate high gene flow among R rosea clones that might be a result of seed dispersal rather than cross-pollination. Further world-wide studies are required to compare the level of genetic diversity and more studies in R. rosea detailing the consequences of different patterns of gene flow (pollen spread and dispersal of seeds and clonal plants) will be useful for characterization of roseroot. (C) 2008 Elsevier Ltd. All rights reserved.
Forfattere
jihong liu clarkeSammendrag
Det er ikke registrert sammendrag
Forfattere
Marit Larsen Sekse Sonja KlemsdalSammendrag
The apple fruit moth (Argyresthia conjugella) is a serious pest in apples. It is a specialist seed predator of rowan, but the females will lay eggs on apples when rowan berries are scarce. Olfaction is important for many insect species in locating host plants. The odorant detection results from the association of odorous ligands with specific olfactory receptors, which are located in the membrane of the olfactory neurons. The aim of this work is to identify and characterize the odorant receptor genes and the genes involved in the regulation of the circadian olfactory response rhythm in the female apple fruit moth. In order to identify ORs, and other genes involved in olfaction, in the apple fruit moth a library of mRNA up-regulated in the antenna compared to the legs was made using subtractive hybridization. So far 37 of the clones containing sequences that were found to be up-regulated in the antenna, out of in total 1045 clones, have been sequenced. BLAST searches were performed (BLASTx and BLASTn) to try to identify the transcripts. Those sequences that did not give a useful hit in the blast searches were translated to protein sequences in all six reading frames and the possible protein sequences were investigated for the presence of trans-membrane domains. The blast searches yielded useful hits for most of the sequences. 20 sequences were assigned to be probable odorant binding proteins and these seem to represent 12 different genes. Seven sequences were assigned to be glutathione S-transferases and 1 sequence were assigned to be cytochrome P450. Seven sequences gave no useful hits in the blast searches. These sequences seemed to represent 4 different genes and 2 of these have were predicted to contain transmembrane domains. These are possible odorant receptors.
Forfattere
Arne SteffenremSammendrag
Wood based products come from a renewable resource playing an important part of the carbon cycle and are therefore regarded environmentally friendly compared to many other alternatives. We might therefore expect a more intensive use of the timber resource in the future. An increase in the supply and net value of timber products from a given area requires more intensive and cost efficient forest management. However, a faster growth rate in general and an increase in the juvenile wood proportion specifically, might come in conflict with the desirable wood quality. Tree breeding programs for Norway spruce (Picea abies L. Karst.) aim to follow up the general demands by providing forestry with plant materials that have superior growth and high wood quality. It is therefore important to establish a better knowledge of the potential of improving wood quality characters in this species through breeding. Characteristics important for structural strength and dimensional stability in conifers are wood density, spiral grain, microfibril angle (MfA) in the S2 layer in the secondary cell wall, branch characteristics and stem straightness. We have studied the genetic variation and correlation patterns for these traits and the direct end-use performance of clearwood samples in terms of stiffness (MOE) and strength (MOR) in four studies of Norway spruce (Paper I-IV). Wood quality traits of defect free wood were studied in Paper I and II. The materials used were 28 and 29 year old progeny trials planted in South East Norway on fertile soils. Significant genetic variation was found for wood density, MfA and spiral grain in both studies (p < 0.05). MOE and MOR, measured by static bending, were studied in one of the materials and the genetic variation was found to be highly significant (p < 0.01). There was also significant genetic variation (p < 0.05) in MOE estimated (MOEest) from wood density and the x-ray diffractometry pattern from the S2 layer obtained by SilviScan®-3. Genetic parameters were estimated in Paper II with large standard errors. The parameters must therefore be used with caution and preferably with support from other studies. We could confirm earlier studies of high genetic variation and low genotype by environment interactions (GxE) for wood density and spiral grain. Parameter estimates for MfA and MOEest, from one site, suggest that these are under moderate to strong genetic control in Norway spruce. Phenotypic correlations between growth traits (height and diameter growth) and wood quality traits were negative for wood density, positive for MfA and negative for MOEest. Genetic relationships showed the same trends for diameter growth, but not for height growth. The genetic and environmental variation in branch characteristics (Paper III and IV) were studied in three sets of progeny trials that were 22, 28 and 29 years old from planting. Stem straightness was studied in the 22-year old trial only. The branch diameter was highly influenced by site index and spacing. Number of branches formed and stem straightness seems to be under stronger genetic control. Individual tree heritabilities for growth traits, branch diameter and stem straightness were estimated in the 22-year old progeny trial planted at two sites. The trials were planted with different spacing, which allowed us to study genotype by spacing interactions. Heritability for growth traits and branch diameter across sites were moderate (0.14 - 0.19) compared to the higher values found for stem straightness (0.28). GxE, and thereby genotype by spacing interactions were not important for any of the traits. Heritability for number of branches, estimated from one of the sites, was 0.24. There was a strong and positive genetic correlation between growth traits and branch diameter. The presence of genetic variation for most wood quality traits suggests that these can be improved by tree breeding. However, genetic correlations with growth traits indicate that selection solely for growth might have adverse effects on wood quality. It is therefore important to balance the gain in growth and wood quality. Implementation of several adversely correlated traits in a breeding program reduces its efficiency. It is therefore essential that tree breeding, silvicultural practices and forest industrial needs interact when developing tree breeding programs to obtain an optimal strategy for selection and utilization of improved plant materials.
Forfattere
Maria Herrero Brita Toppe Trond RafossSammendrag
In November 2002, P.ramorum was detected for the first time in Norway (1). It was isolated from Rhododendron catawbiense imported earlier the same year. After the first detection the Norwegian Food Safety Authority has carried out surveys from 2003 to 2006. The surveys were first directed to nurseries and garden centres. Most of the positive findings were on Rhododendron spp., but one sample of Pieris japonica, one of Kalmia sp., one of Syringa sp. and one of Viburnum sp. were also positive. In 2005 and 2006, P. ramorum was isolated from well-established viburnum and rhododendron plants in private gardens, parks and public greens. Infections were detected on well-established plants from 9 different outdoor sites. While the positive samples from nurseries were spread over the country, the positives found on well-established plants were concentrated in and around the cities of Bergen and Stavanger on the southwestern coast of Norway. This part of the country has cool summers, mild winters and more than 2000 mm of annual precipitation. In 2006, P. ramorum was found in private gardens in the eastern part of the country on young recently introduced plants. P. ramorum was found in 12 import shipments, mainly on rhododendron, but also on a viburnum sample.