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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

Sammendrag

This chapter reviews the historical context, economic importance, objectives and achievements to-date for many of the more important conifers undergoing domestication through genetic improvement programmes around the world. These provide examples of the context in which genomic technologies will have an impact in forestry. Unlike many other crop plants and livestock animals, forest trees have only been exposed to a few cycles of breeding and selection, and most retain very large amounts of genetic variation in natural populations. These factors present both opportunities and hurdles in the effective application of genomic technologies to existing operational breeding programmes.

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Sammendrag

Aspen (Populus tremula L.) is associated with high biodiversity and provides high-quality forage for wild browsing herbivores in boreal and temperate ecosystems. The long-term persistence of aspen in many regions in Scandinavia has been questioned due to the historically high browsing levels. We here review the basic ecology, genetics and life histories of aspen in a browsing context. Browsers can suppress the regeneration of aspen and the relatively short lifespan of the trees result in frequent regeneration cycles and concurrent exposure to browsers. In the long term, browsing may reduce recruitment and delay maturation, increase mortality and ultimately cause a decline of aspen. Norwegian forest inventory data indicate a reduced recruitment rate of young aspen (diameter at breast height; 60–79 mm) during the last 25 years, but it is unclear whether this is all due to browsing. Regeneration may also be hampered by lack of disturbance. Recent genetic studies have shown that aspen may have substantial regeneration by seeds, which allows for effective migration. The main conclusion of this review is that although browsing may affect demography and local abundance of aspen, it is very unlikely to lead to the eradication of the species in Fennoscandia.

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Sammendrag

Background Parthenocarpy is a desirable trait in Capsicum annuum production because it improves fruit quality and results in a more regular fruit set. Previously, we identified several C. annuum genotypes that already show a certain level of parthenocarpy, and the seedless fruits obtained from these genotypes often contain carpel-like structures. In the Arabidopsis bel1 mutant ovule integuments are transformed into carpels, and we therefore carefully studied ovule development in C. annuum and correlated aberrant ovule development and carpelloid transformation with parthenocarpic fruit set. Results We identified several additional C. annuum genotypes with a certain level of parthenocarpy, and confirmed a positive correlation between parthenocarpic potential and the development of carpelloid structures. Investigations into the source of these carpel-like structures showed that while the majority of the ovules in C. annuum gynoecia are unitegmic and anatropous, several abnormal ovules were observed, abundant at the top and base of the placenta, with altered integument growth. Abnormal ovule primordia arose from the placenta and most likely transformed into carpelloid structures in analogy to the Arabidopsis bel1 mutant. When pollination was present fruit weight was positively correlated with seed number, but in the absence of seeds, fruit weight proportionally increased with the carpelloid mass and number. Capsicum genotypes with high parthenocarpic potential always showed stronger carpelloid development. The parthenocarpic potential appeared to be controlled by a single recessive gene, but no variation in coding sequence was observed in a candidate gene CaARF8. Conclusions Our results suggest that in the absence of fertilization most C. annuum genotypes, have parthenocarpic potential and carpelloid growth, which can substitute developing seeds in promoting fruit development.