Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2012
Forfattere
YeonKyeong Lee Igor A. Yakovlev Carl Gunnar Fossdal Øystein Johnsen Jorunn Elisabeth OlsenSammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Forfattere
Igor A. Yakovlev Carl Gunnar Fossdal Tore Skrøppa Jorunn Elisabeth Olsen Anne Hopen Jahren Øystein JohnsenSammendrag
Conifers are evolutionarily more ancient than their angiosperm counterparts, and thus some adaptive mechanisms and features influenced by epigenetic mechanisms appear more highly displayed in these woody gymnosperms. Conifers such as Norway spruce have very long generation times and long life spans, as well as large genome sizes. This seemingly excessive amount of genomic DNA without apparent duplications could be a rich source of sites for epigenetic regulation and modifications. In Norway spruce, an important adaptive mechanism has been identified, called epigenetic memory. This affects the growth cycle of these trees living in environments with mild summers and cold winters, allowing them to adapt rapidly to new and/or changing environments. The temperature during post-meiotic megagametogenesis and seed maturation epigenetically shifts the growth cycle programme of the embryos. This results in significant and long-lasting phenotypic change in the progeny, such as advance or delay of vital phenological processes of high adaptive value, like bud break and bud set. This phenomenon is not only of important evolutionary significance but has clear practical implications for forest seed production and conservation of forest genetic resources. The underlying molecular mechanism that causes the ‘memory’ in long-lived woody species is currently under investigation. Here we summarize the information related to epigenetic memory regulation in gymnosperms, with special emphasis on conifers. The molecular mechanism behind this is still unknown but transcriptional changes are clearly involved. Epigenetic regulation may be realized through several mechanisms, including DNA methylation, histone modification, chromatin remodelling, small non-coding RNAs and transposable element regulation, of which non-coding RNAs might be one of the most important determinants.
Forfattere
Igor A. Yakovlev YeonKyeong Lee Bjørn Rotter Tore Skrøppa Øystein Johnsen Jorunn Elisabeth Olsen Carl Gunnar FossdalSammendrag
Epigenetic memory marks establishment in Norway spruce occur exclusively during embryogenesis in response to environmental impact, and the epitype is fixated by the time the embryo is fully developed without a change in the DNA sequence. We started large scale studies aimed on identifying and characterizing of genes and regulatory elements involved in the initiation, maintenance, and heritability of epigenetic memory using candidate genes and next generation sequencing approaches. Molecular mechanisms of formation of epigenetic memory were studied on the same full-sibs family zygotic embryo in vitro cultures developed in cold (18°C) and warm (30°C) environmental conditions from proliferation till mature embryo stages. Initially we had found large set (64) of Arabidopsis epigenetic regulator gene homologs in spruce. In general, known epigenetic related genes are very well represented among spruce ESTs. Analysis of the transcription patterns of these genes using RT-PCR in epigenetically different embryogenic samples reveal specific transcription patterns on different stages of embryogenic development dependent on epitype. We are expecting to determine certain stages during embryogenesis when epigenetic memory marks are forming. At the same time, nearly no differences in transcription levels of studied genes had been found in seedlings (4 month old), originated from full-sib families clearly differed in epigenetic response. Using MACE (massive cDNA 3-end sequencing) deep mRNA sequencing on the Illumina GSII platform, we analyzed P. abies transcriptomes by comparison warm and cold originated “embryonic epitypes” developed in cold and warm environmental conditions. Significant differences in transcriptomes between epitypes revealed by high-throughput sequencing will be discussed.
Forfattere
Åke Olson Andrea Aerts Fred Asiegbu Lassaad Belbahri Ourdia Bouzid Anders Broberg Björn Canback Pedro M. Coutinho Dan Cullen Kerstin Dalman Giuliana Deflorio Linda T.A. van Diepen Christophe Dunand Sébastien Duplessis Mikael Durling Paolo Gonthier Jane Grimwood Carl Gunnar Fossdal David Hansson Bernard Henrissat Ari Hietala Kajsa Himmelstrand Dirk Hoffmeister Nils Högberg Timothy Y. James Magnus Karlsson Annegret Kohler Ursula Kües Yong-Hwan Lee Yao-Cheng Lin Mårten Lind Erika Lindquist Vincent Lombard Susan Lucas Karl Lundén Emmanuelle Morin Claude Murat Jongsun Park Tommaso Raffaello Pierre Rouzé Asaf Salamov Jeremy Schmutz Halvor Solheim Jerry Ståhlberg Heriberto Vélëz Ronald P. de Vries Ad Wiebenga Steve Woodward Igor A. Yakovlev Matteo Garbelotto Francis Martin Igor V. Grigoriev Jan StenlidSammendrag
• Parasitism and saprotrophic wood decay are two fungal strategies fundamental for succession and nutrient cycling in forest ecosystems. An opportunity to assess the trade-off between these strategies is provided by the forest pathogen and wood decayer Heterobasidion annosum sensu lato. • We report the annotated genome sequence and transcript profiling, as well as the quantitative trait loci mapping, of one member of the species complex: H. irregulare. Quantitative trait loci critical for pathogenicity, and rich in transposable elements, orphan and secreted genes, were identified. • A wide range of cellulose-degrading enzymes are expressed during wood decay. By contrast, pathogenic interaction between H. irregulare and pine engages fewer carbohydrate-active enzymes, but involves an increase in pectinolytic enzymes, transcription modules for oxidative stress and secondary metabolite production. • Our results show a trade-off in terms of constrained carbohydrate decomposition and membrane transport capacity during interaction with living hosts. Our findings establish that saprotrophic wood decay and necrotrophic parasitism involve two distinct, yet overlapping, processes.
Forfattere
Igor A. Yakovlev Gustav Vaaje-Kolstad Ari Hietala Emil Stefanczyk Halvor Solheim Carl Gunnar FossdalSammendrag
No abstract has been registered
Forfattere
Steffi Munack Kathrin Roderer Jurate Kamarauskaite Gabriele Cordara Andre van Eerde Peter Kast Ute KrengelSammendrag
No abstract has been registered
Forfattere
DJ Sargent T Passey N Surbanovski E. Lopez Girona P Kuchta Jahn Davik R. Harrison A Passey AB Whitehouse DW SimpsonSammendrag
No abstract has been registered
Forfattere
Jens Rohloff Muath Alsheikh Gage Koehler Robert Charles Wilson Jahn Davik Stephen K, RandallSammendrag
No abstract has been registered
Sammendrag
The winter hardiness of strawberry cultivars used in perennial production systems varies greatly, although a strong linkage exists between transcriptional and metabolic changes during cold acclimation. Still, little information is available on how plant metabolism adapts to cold and freezing temperatures under natural temperature and light conditions. In order to examine the hardening process of overwintering meristematic tissue in Fragaria x ananassa, crown samples of field-grown cvs. ‘Polka’ and ‘Honeoye’ were consecutively collected over a period of 15 weeks, i.e. from the end of the season (week 35/ end August) until midwinter (week 50/ December). Samples were subjected to qGC MS metabolite profiling to assess the reconfiguration of central metabolism, and characterize the regulation of selected compatible solutes (amino acids, Krebs metabolites, sugars, polyols). Besides changes in amino acid patterns (glutamic acid, aspartic acid, and asparagine), monosaccharide levels (fructose) were strongly enhanced until the end of the acclimation period in cv. ‘Honeoye’ (180-fold compared to start control). In contrast, ‘Polka’ showed a concentration peak (36-fold) in week 47 and a decline towards week 50. Also sucrose levels were steadily enhanced throughout the cold hardening period with averagely 6-fold higher levels in ‘Honeoye’ compared to ‘Polka’, thus underscoring cultivar differences. However, both cultivars showed a clear decline in sucrose levels after week 47. Particularly, the raffinose pathway was affected leading to strongly and transiently increased levels of the precursor galactinol (week 42/ mid October) and the trisaccharide raffinose (weeks 43 to 47/ end October to mid November). While galactinol biosynthesis was obviously earlier induced in cv. ‘Polka’ (week 38) compared to ‘Honeoye’ (week 39), subsequent raffinose production and concentration peaks were clearly delayed in ‘Polka’ (week 47) in contrast to ‘Honeoye’ (week 45). Major metabolic changes in both cultivars coincided with a decrease in daylength below 14 h after week 37 (mid September), and a consistent drop below 10°C average day temperature in week 39 (end September). The effect of temperature and light conditions on metabolic cold acclimation in field-grown strawberry is discussed. Keywords: Winter hardiness, metabolite profiling, quadrupole gas chromatography-mass spectrometry (qGC-MS), temperature, light