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.
2008
Sammendrag
Carbon from complex and structural plant molecules has long been considered more efficiently retained in soils than that of soluble molecules. This dominant paradigm is now being challenged by data emerging from recent isotopic-labeling and compoundspecific isotopic studies. We recently demonstrated that large proportions of plantresidue lignin decompose within a year of incorporation to soils, and that soilextracted lignin has a turnover time of about 20 years (Rasse et al, 2006). In contrast, turnover time of soil-extracted polysaccharides can reach 40 years (Gleixner et al., 2002). Long-term incubation studies have shown that C from labeled glucose is better conserved in certain soil types than C from more complex molecules such as cellulose (e.g. Vinten et al, 2002). These studies suggest that the initial decomposability of plant molecules has limited impact on the long-term fate of their constitutive C in soils. Here we will present a new model where soluble molecules have a competitive advantage over structural molecules for the long-term preservation of their constitutive C in soils. Implementation of compound-specific data in quantitative soil models will also be discussed.
Forfattere
Guro BrodalSammendrag
Ut fra økonomiske hensyn og politiske føringer dyrkes korn i store sammenhengende jordbruksområder med liten grad av vekstskifte, og etterhvert med til dels lite jordarbeiding av hensyn til miljø og vannkvalitet. En slik dyrkningsstrategi kan medføre høyere risiko for utvikling av mykotoksiner (soppgifter) i kornet i tillegg til å øke behovet for bruk av kjemiske plantevernmidler mot ugras og kornsjukdommer.
Sammendrag
Ut fra økonomiske hensyn og politiske føringer dyrkes korn i store sammenhengende jordbruksområder med liten grad av vekstskifte, og etterhvert med til dels lite jordarbeiding av hensyn til miljø og vannkvalitet. En slik dyrkningsstrategi kan medføre høyere risiko for utvikling av mykotoksiner (soppgifter) i kornet i tillegg til å øke behovet for bruk av kjemiske plantevernmidler mot ugras og kornsjukdommer.
Forfattere
Hans Ragnar Norli Agnethe ChristiansenSammendrag
Cereals often give interfering peaks originating from fatty acids and their alkyl esters. The amount of interferences can be so high, that in addition to mask the target pesticides, the retention times increases and makes identification difficult. Standard QuEChERS cleanup with 25 mg/ml of PSA/ml of acetonitrile extract, or increasing the amount of PSA up to 300 mg/ml is not enough to remove the fatty acids. By adding calcium chloride to the extract, the polarity was changed in such a way that the polar pesticides were recovered in acceptable rates and fatty acids were not coextracted. By also include a freeze out step more unpolar fatty acid alkyl esters and plant sterols was removed.
Forfattere
Stein Rune Karlsen Anne Tolvanen Eero Kubin Jarmo Poikolainen Kjell Arild Høgda Bernt Johansen Fiona S. Danks Paul Eric Aspholm Frans Emil Wielgolaski Olga MakarovaSammendrag
Northern Fennoscandia is an ecologically heterogeneous region in the arctic/alpine-boreal transition area. Phenology data on birch from 13 stations and 16-day MODIS-NDVI composite satellite data with 250 m resolution for the period 2000 to 2006 were used to map the growing season. A new combined pixel-specific NDVI threshold and decision rule-based mapping method was developed to determine the onset and end of the growing season. A moderately high correlation was found between NDVI data and birch phenology data. The earliest onset of the growing season is found in the narrow strip of lowland between the mountains and the sea along the coast of northern Norway. The onset follows a clear gradient from lowland to mountain corresponding to the decreasing temperature gradient. In autumn, the yellowing of the vegetation shows a more heterogeneous pattern. The length of the growing season is between 100 and 130 days in 55% of the study area.
Forfattere
Marie-France Dignac C Rumpel Daniel Rasse M Mendez-Millan H Bahri S Derenne G Bardoux A MariottiSammendrag
How the chemical composition of plant biomolecules controls their dynamics in soils at the long-term scale remains largely unknown. Stabilisation mechanisms in soils might depend upon the chemical nature of organic matter. These mechanisms either involve soil mineral constituents or are related to chemical recalcitrance of specific molecules such as lignins. Physical and physico-chemical protection mechanisms may act differently on above- and belowground tissues of plants, leading to contrasting contributions of these tissues to soil organic matter (SOM). Cutins and suberins are specific for above and the belowground tissues of higher plants, respectively. Their molecular constituents can be used as biomarkers of the inputs of these plant tissues to soils. In this study, the molecular turnover of specifically plant-derived constituents in soils were estimated using compound specific isotopic tracer techniques applied to agricultural lands converted from C3 plant to C4 plant cropping. We assessed the specific residence times of lignins, cutins and suberins in soils, in order to compare the contributions of above- and belowground tissues to SOM. Lignin turnover in soil was faster than that of total organic carbon. Contrasting dynamics in soils were observed among lignin monomers as well as among cutin/suberin markers, which might be related to their chemical nature, their position into the polymeric structure and/or to the plant tissue in which they are present. This study, combining compound specific isotope measurements with a long term field trial helped understanding soil carbon turnover on a molecular level.
Forfattere
Gunnhild Wærsted Takle Ian Toth May Bente BrurbergSammendrag
During the last years, Norway and several other countries have seen an increase in potato blackleg disease caused by the Gram-negative bacterium Pectobacterium atrosepticum (formerly known as Erwinia carotovora ssp. atroseptica). P. atrosepticum has a narrow host range, limited almost exclusively to potato plants in temperate regions, where it also causes soft rot of potato tubers. The pathogen spreads from infected seed tubers to progeny tubers either through the plant or over short distances in the soil. However, little is known about how seed potatoes are initially contaminated with the bacterium and what onsets the infection. Our overall aim is to understand the underlying molecular mechanisms behind potato infection by P. atrosepticum and to find possible means of controlling blackleg disease, as well as providing more knowledge of the overall lifestyle of the bacterium. The sequencing and annotation of the genome of P. atrosepticum strain SCRI1043 (Bell et al., 2004. Proc.Natl.Acad.Sci. 101: 11105-10) as well as a genome-wide mutant library (Holeva et al., 2004. Mol. Plant. Microbe. Interact. 17:943-50) provide valuable tools in examining the molecular aspects of both pathogenesis and environment related factors. Quorum-sensing seems to play an essential role in the pathogenesis of P. athrosepticum, and we are currently studying some of the many genes affected by this regulatory control as well as other putative virulence genes.
Forfattere
Anne-Cathrine Scheen Charlotte Lindqvist Carl Gunnar Fossdal Victor A. AlbertSammendrag
The five mint genera Brazoria, Macbridea, Physostegia, Synandra and Warnockia (Lamioideae: Lamiaceae) are all North American endemics. Together with the monotypic European genus Melittis and the Asian genus Chelonopsis, these taxa have been classified as subtribe Melittidinae. Previous morphological studies have failed to uncover synapomorphic characters for this group.We sequenced the plastid trnL-trnF region and trnS-trnG spacer and the nuclear ribosomal 5S non-transcribed spacer (5S-NTS) to assess phylogenetic relationships within Melittidinae. Standard parsimony and direct optimization (POY) analyses show Melittis, the type genus of the subtribe, as sister to Stachys. Thus, the monophyly of subtribe Melittidinae is not supported either by molecular or morphological data...
Forfattere
Carl Gunnar Fossdal Ari M. Hietala Igor A. Yakovlev Halvor SolheimSammendrag
The root-rot causing fungus Heterobasidion annosum sensu lato is the most devastating pathogen of conifers in Europe. This pathogen enters Norway spruce through the roots and can colonize the tree from within, growing as a saprophyte when established within the dead heartwood and acting as a necrotroph when in contact with living host tissue. Despite the high incidence of damage, trees have defences against this pathogen in the bark and living wood. Furthermore, spruce has a defense against internal attack by forming a reaction zone, in this case the host defense is directed inwardly by the still living sapwood toward the central colonized heartwood. We have studied the host responses to infection in Norway spruce clones at the transcriptional level and found that the speed of recognition and that spatial defense signalling appears to be the hallmarks of trees with high degree of resistance...
Forfattere
Marianne Bechmann Johannes Deelstra Per Stålnacke Hans Olav Eggestad Lillian Øygarden Annelene PengerudSammendrag
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