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.
2014
Sammendrag
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Forfattere
Igor A. Yakovlev YeonKyeong Lee Björn Rotter Jorunn Elisabeth Olsen Tore Skrøppa Øystein Johnsen Carl Gunnar FossdalSammendrag
Embryogenesis is the initial stage of plant life, when the basics of body plan and the post-embryonic development are laid down. Epigenetic memory formed in the Norway spruce embryos permanently affect the timing of bud burst and bud set in progenies, vitally important adaptive traits in this long-lived forest species. The epigenetic memory marks are established in response to the temperature conditions prevailing during zygotic and somatic embryogenesis; the epitype is fixed by the time the embryo is fully developed and is mitotically propagated throughout the tree’s life span. Somatic embryogenesis closely mimics the natural zygotic embryo formation and results in epigenetically different plants in a predictable temperature-dependent manner with respect to altered phenology. Using Illumina-based Massive Analysis of cDNA Ends, the transcriptome changes were monitored in somatic embryos during morphogenesis stage under two different temperatures (18 vs. 30 °C). We found distinct differences in transcriptomes between the genetically identical embryogenic tissues grown under the two epitype-inducing temperatures suggesting temperature-dependent canalizing of gene expression during embryo formation, putatively based on chromatin modifications. From 448 transcripts of genes coding for proteins involved in epigenetic machinery, we found 35 of these to be differentially expressed at high level under the epitype-inducing conditions. Therefore, temperature conditions during embryogenesis significantly alter transcriptional profiles including numerous orthologs of transcriptional regulators, epigenetic-related genes, and large sets of unknown and uncharacterized transcripts.
2013
Sammendrag
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Sammendrag
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Sammendrag
Fruit-set involves a series of physiological and morphological changes that are well described for tomato and Arabidopsis, but largely unknown for sweet pepper (Capsicum annuum). The aim of this paper is to investigate whether mechanisms of fruit-set observed in Arabidopsis and tomato are also applicable to C. annuum. To do this, we accurately timed the physiological and morphological changes in a post-pollinated and un-pollinated ovary. A vascular connection between ovule and replum was observed in fertilized ovaries that undergo fruit development, and this connection was absent in unfertilized ovaries that abort. This indicates that vascular connection between ovule and replum is an early indicator for successful fruit development after pollination and fertilization. Evaluation of histological changes in the carpel of a fertilized and unfertilized ovary indicated that increase in cell number and cell diameter both contribute to early fruit growth. Cell division contributes more during early fruit growth while cell expansion contributes more at later stages of fruit growth in C. annuum. The simultaneous occurrence of a peak in auxin concentration and a strong increase in cell diameter in the carpel of seeded fruits suggest that indole-3-acetic acid stimulates a major increase in cell diameter at later stages of fruit growth. The series of physiological and morphological events observed during fruit-set in C. annuum are similar to what has been reported for tomato and Arabidopsis. This indicates that tomato and Arabidopsis are suitable model plants to understand details of fruit-set mechanisms in C. annuum.
Sammendrag
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Forfattere
Maria Björkman Ishita Ahuja Annette Folkedal Schjøll Nicole van Dam Atle M. Bones Richard MeadowSammendrag
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Forfattere
Maria Björkman Ishita Ahuja Annette Folkedal Schjøll Nicole Van Dam Atle M. Bones Richard MeadowSammendrag
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Sammendrag
Use of genetic materials with a more “southern growth rhythm” has been suggested as one of the measures for adapting our forests to climate change. However, studies on Norway spruce (Picea abies (L.) Karst) provenances and families have shown a possible relationship between phenology (apical growth rhythm) and cambial growth rhythm that might have negative effects on latewood proportion and wood density. We made a detailed study of the xylem formation of four clones during one growth season. The clones were known to express contrasting phenology in terms of timing of bud flush equivalent to two weeks when assessed in 1997. Micro cores from four 20 year old ramets of the four clones, 16 trees in total, were sampled once a week from May to October in 2010. When bud flush were assessed in 2010 there were about one week difference between the most contrasting clones. Temperatures during the spring 2010 were low and flushing started in general late. No relationship was found between the clonal values for timing of bud flush and initiation of xylem formation. Large differences between clones in numbers of formed tracheids were found in later phases of the growing season. Both the rate of cell division and number of formed tracheids varied significantly between clones. Only small differences in latewood percentage were found between the clones. Genetic variation in xylem formation was found, but from this study the genetic variation in xylem formation seems to be independent from the genetic variation in phenology.
Sammendrag
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