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.
2008
Authors
Øystein Johnsen Igor A. Yakovlev Daniel Kwaku A. Asante Anne Eskild Nilsen Harald Kvaalen Carl Gunnar FossdalAbstract
In forest trees, environmental conditions during the reproduction can greatly influence progeny performance. We here suggest that temperature during zygotic embryogenesis and seed maturation regulates an “epigenetic memory” in the progeny, involving differential expression of genes that may regulate bud phenology, cold acclimation and embryogenesis in Norway spruce. Conditions colder than normal advance the timing whilst temperatures above normal delay the onset of these processes. The altered performance lasts for many years. The seedlings actually remember the temperatures and photoperiod prevailing during zygotic embryogenesis and seed maturation. We show for the first time that regenerated plants, cloned through somatic embryogenesis, express a memory of the temperatures applied during embryo development whilst growing in a common greenhouse environment. The warmer the in vitro temperature applied, the later the regenerated plants formed terminal buds in the common environment the second growth season. The differences were very large, and similar in size to a provenance separation of 4 – 6 degrees of latitude. To study a molecular mechanisms of a memory from embryo development identical crosses were performed, seed were produced in different temperature regimes (cold and warm embryonic history) and seedling were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two subtracted cDNA libraries, forward and revers, representing genes predominantly expressed in plants growing from seeds obtained after embryogenesis in cold environment (CE) and warm environment (WE) after short day treatment (going to bud set). Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs were unknown. So obtained subtracted libraries is a good source of candidate genes. We used quantitative RT–PCR to study the expression patterns of 34 chosen candidate genes. Just two putative genes among them with no matching in the Database and one reverse transcriptase show constitutively differential expression in progeny from CE and WE
Authors
Igor A. Yakovlev Daniel Kwaku A. Asante Carl Gunnar Fossdal Jouni Partanen Olavi Junttila Øystein JohnsenAbstract
The initiation of growth and dormancy represents critical ecological and evolutionary trade-offs between survival and growth in most perennial plants and represents one of the most basic adaptations of trees to their environment. It is likely that they regulates differently: apical bud set and dormancy induction regulates by perception of short-day signal, but bud burst regulates mostly by temperature signals. We tried to dissect these processes on phenotypical and molecular levels. Seedlings for dormancy analysis were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two SSH cDNA libraries, forward and reverse, representing genes predominantly expressed in plants after short day (SD) treatment (going to bud set) and continue growing at LD. Subtracted libraries had been partially sequenced for candidate genes seeking. Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs in LD library were represented by photosynthesis related genes and just nearly 6% in SD library. High differences were found in RNA synthesis and RNA processing, protein degradation, defense and transporting genes and also in transposable elements. Each library contains large number of unknown genes (mostly in SD). So obtained subtracted libraries is a good source of candidate genes, differently expressed during regulation of bud set. Bud burst initiation was studied on grafts from 15- and 30-year old Norway spruce within 3 time-points during autumn in natural (outdoor) and “forcing” (1 week, 12 h light and 20°C constant) conditions using earlier developed candidate genes (Yakovlev et al., 2007). We used quantitative RT–PCR to study the expression patterns of 58 chosen genes related for bud set and 34 genes – for bud burst. By the experiment conditions we could study only delayed genes and constitutively expressed early genes. Among the candidate genes found, the most interesting ones were the transcription factors, calcium censors, signaling, cold- and water stress related genes. The putative role of the studied genes in development regulation bud set and bud burst is discussed.
Authors
Vidar Selås Ronny Steen Sverre Kobro Terje Lislevand Ingvar StenbergAbstract
In Norway, a positive relationship between spring numbers of lesser spotted woodpecker (Dendrocopos minor) and previous June temperatures has been interpreted as an effect of temperatures on woodpecker survival and reproduction during the breeding season. This article considers the possibility that woodpecker numbers are related to the abundance of the moth Argyresthia goedartella in the current year. Larvae and pupae of A. goedartella are important food for lesser spotted woodpeckers in early spring when few other surface-living invertebrates are available. The occurrence of this moth depends on the flowering of birch (Betula spp.) and alder (Alnus glutinosa), which in turn is influenced by June temperatures in the preceding year. Spring numbers of the lesser spotted woodpecker in two regions of Norway were compared with a trapping index of A. goedartella and weather variables assumed to influence the woodpeckers' breeding success and adult survival. The best multiple regression model included December temperatures and moth indices, supporting the hypothesis of a strong impact of A. goedartella on spring survival. Conservation strategies for the lesser spotted woodpecker should therefore focus not only on minimum areas of deciduous forests with decaying wood, but also on the availability of the moths' host trees, birch and alder.
Authors
Geir Kjølberg Knudsen Maria Bengtsson Sverre Kobro Gunnhild Jaastad Trond Hofsvang Peter WitzgallAbstract
Apple fruit moth Argyresthia conjugella is a specialist seed predator of rowan Sorbus aucuparia. Large-scale synchronous fluctuation of seed production in rowan (i.e. named masting) drives the apple fruit moth to seek alternative host plants such as apple, during years when rowan berries are not available for oviposition. The role of plant volatile compounds in the attraction of gravid apple fruit moth females is studied in a laboratory wind tunnel. Volatiles from rowan branches with green berries stimulate female moths to fly upwind and to land at the odour source. By contrast, females are not attracted to rowan branches without green berries, and they are not attracted to apple, demonstrating that the chemical stimulus from rowan berries is required for attraction. Attraction to synthetic compounds identified from rowan, anethole and 2-phenyl ethanol confirms the role of plant volatiles in host finding. These two compounds, however, show a discrepant behavioural effect in wind tunnel and field tests. Field traps baited with 2-phenyl ethanol capture female moths but anethole does not produce significant captures. Wind tunnel tests produce the opposite results: moths fly upwind towards the anethole lure, whereas 2-phenyl ethanol is not attractive at all. Wind tunnel attraction to 2-phenyl ethanol is achieved by adding odour from a rowan branch without berries, which is not attractive on its own. This finding demonstrates that interaction with the background odour contributes to the behavioural effect of plant volatile stimuli in the field.
Authors
Silja Korhonen-Sande Erlend NybakkAbstract
No abstract has been registered
Authors
Arild Andersen An Tran Thi Thien Einar NordhusAbstract
The present distribution and host plant preferences of the polyphagous pest species Liriomyza sativae, L. huidobrensis, L. trifolii and L. bryoniae within the different provinces of Vietnam is discussed. For each species also the possible further spread within Vietnam is discussed.
Abstract
No abstract has been registered
Abstract
In this project plant and vegetation preferences of two Norwegian dairy cattle breeds with different selection history were studied. The Norwegian dairy breed Blacksided Trønder and Nordland Cattle (STN) has never been selected efficiently for higher milk production. The other breed, however, the Norwegian Red (NR), has mainly been selected for this. Two herds both consisting of STN and NR cows, were studied. To examine the animals\" plant preferences, faeces samples were collected and analysed for plant fragments. Vegetation maps were also used to find possible differences in grazing preferences. Breed differences with regard to recorded plant fragments in the faeces samples were significant for Nardus stricta, a species characteristic for nutrient poor but mostly species rich vegetation types in the studied areas, vegetation types of high importance for the biodiversity especially in one of the areas. STN had the highest share of Nardus stricta. Altogether the results of the study indicate that a higher producing cattle breed might prefer to graze more nutrient rich vegetation areas compared to a lower yielding cattle breed, when grazing less nutrient and base rich - but species rich grasslands.
Abstract
No abstract has been registered
Abstract
The current report is a background for a Pest Risk Assessment (PRA) of the bark beetle species Ips amitinus in the PRA area of Norway, following the International Standards for Phytosanitary Measures ISPM 11 (FAO 2004). The report is based on updated information about distribution, pathogenicity and ecological information, which add to a previous PRA for this species. It is concluded that the risk of establishment is high with the current import and management practices. I. amitinus may potentially cause significant tree damage alone or in interaction with Ips typographus; however, the outcome is very much dependent on scenarios of climate development and population dynamics.