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.
2016
Sammendrag
The root rot pathogens in Norway spruce (Picea abies) Heterobasidion ssp. cause substantial loss in carbon sequestered in forest and economic revenue for forest owners. To facilitate strategic breeding planning for increased resistance against this pathogen in particular, the blue stain fungus Endoconidiophora polonica, growth and wood quality traits (wood density and spiral grain), we estimated additive genetic parameters, correlations and the potential response from selection. Parameters were estimated from a progeny trial series established at two sites (25 years from planting) and their parents in a seed orchard (43 years from grafting). A standard half-sib analysis based on progenies and a parent–offspring regression was used for estimation of heritabilities. Resistance against the pathogens was measured as lesion length under bark after inoculations in phloem. Heritability values varied with site and estimation procedure from 0.06 to 0.33, whereas the phenotypic variance (as CV P ) is high and fairly stable around 40–50 %. Heritability values for wood density and spiral grain in the same material varied from 0.32 to 0.63. The highest heritability values were generally obtained from parent–offspring regression. There is no evidence of resistance traits being genetically correlated with growth or wood quality traits. Wood density is negatively correlated with stem diameter. Implications for breeding are discussed.
Forfattere
Mari Mette Tollefsrud Tor Myking Jørn Henrik Sønstebø Vaidotas Lygis Ari Hietala Myriam HeuertzSammendrag
During post glacial colonization, loss of genetic diversity due to leading edge effects may be attenuated in forest trees because of their prolonged juvenile phase, allowing many migrants to reach the colonizing front before populations become reproductive. The northern range margins of temperate tree taxa in Europe are particularly suitable to study the genetic processes that follow colonization because they have been little affected by northern refugia. Here we examined how post glacial range dynamics have shaped the genetic structure of common ash (Fraxinus excelsior L.) in its northern range compared to its central range in Europe. We used four chloroplast and six nuclear microsatellites to screen 42 populations (1099 trees), half of which corresponded to newly sampled populations in the northern range and half of which represented reference populations from the central range obtained from previously studies. We found that northern range populations of common ash have the same chloroplast haplotypes as south-eastern European populations, suggesting that colonization of the northern range took place along a single migration route, a result confirmed by the structure at the nuclear microsatellites. Along this route, diversity strongly decreased only in the northern range, concomitantly with increasing population differentiation and complex population substructures, a pattern consistent with a leading edge colonization model. Our study highlights that while diversity is maintained in the central range of common ash due to broad colonizing fronts and high levels of gene flow, it profoundly decreases in the northern range, where colonization was unidirectional and probably involved repeated founder events and population fluctuations. Currently, common ash is threatened by ash dieback, and our results on northern populations will be valuable for developing gene conservation strategies.
Forfattere
Hadush Tsehaye Beyene Abdelhameed Elameen Anne Marte Tronsmo Leif Sundheim Arne Tronsmo Dereje Assefa May Bente BrurbergSammendrag
Amplified fragment length polymorphism (AFLP) was used to study the genetic variation among 80 F. verticillioides isolates from kernels of Ethiopian maize, collected from 20 different maize growing areas in four geographic regions. A total of 213 polymorphic fragments were obtained using six EcoRI/MseI primer combinations. Analysis of the data based on all 213 polymorphic AFLP fragments revealed high level of genetic variation in the F. verticillioides entities in Ethiopia. About 58% of the fragments generated were polymorphic. The genetic similarity among F. verticillioides isolates varied from 46% to 94% with a mean Dice similarity of 73%. Unweighted Pair Group Method with Arithmetic Average (UPGMA) analysis revealed two main groups and four subgroups. The principal coordinate analysis (PCO) also displayed two main groups that agreed with the results of UPGMA analysis, and there was no clear pattern of clustering of isolates according to geographic origin. Analysis of molecular variance: (AMOVA) showed that only 1.5% of the total genetic variation was between geographic regions, while 98.5% was among isolates from the same geographic regions of Ethiopia. Eighty distinct haplotypes were recognized among the 80 isolates analyzed. Hence, breeding efforts should concentrate on quantitative resistance that is effective against all genotypes of the pathogen.
Sammendrag
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Forfattere
Lise GrøvaSammendrag
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Forfattere
Tage ThorstensenSammendrag
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Forfattere
Tage ThorstensenSammendrag
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Forfattere
Tage ThorstensenSammendrag
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Forfattere
Tage ThorstensenSammendrag
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Forfattere
Mallikarjuna Rao Kovi Stephen Byrne Liv Østrem Petter Marum Torben Asp Odd Arne RognliSammendrag
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