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.
2006
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Forfattere
Anna Holefors Anne Katrine Ree Rosnes Lars Morten Opseth Carl Gunnar Fossdal Jorunn Elisabeth OlsenSammendrag
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Forfattere
Bruno Mezzetti Maurizio Battino Jan Schaart Christopher J. Atkinson Rolf Nestby Jahn DavikSammendrag
Tilnærminger gjennom foredling og bioteknologi blir fortløpende brukt for å øke innholdet av spesifike bioaktive komponenter i planter, men å styre plantemetabolismen slik at man forbedrer produktene er fremdeles vanskelig. Det er imidlertid en økende klarhet i at multiple gen- og omgivelses-faktorer påvirker produksjon og akumulering av bioaktive forbindelser, men disse forholdene er skjelden med i bildet når f.eks bær blir markedsført.
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Forfattere
Paal KrokeneSammendrag
Bark beetles and associated phytopathogenic fungi elicit defence responses in conifers that may interfere with beetle establishment and development. Norway spruce is serving as a useful model species for studies of induced defences elicited by beetle attacks, fungal inoculation, and treatment with chemical elicitors.When trees are pretreated with a sublethal dose of fungal inoculations or with the phytohormone methyl jasmonate they become much more resistant to subsequent bark beetle attacks or artificial mass inoculations with fungi. This induced disease resistance follows dose-response dynamics, is nonspecific with respect to the pretreatment organism, appears to be nonsystemic, takes weeks rather than days to become activated, and can also be activated by mechanical wounding alone.Application of methyl jasmonate to Norway spruce stems induces a massive increase in terpene levels and external resin flow on the stem, whereas no increase is observed in soluble phenolics. Methyl jasmonate-application also leads to significantly less bark beetle colonization, with shorter parental galleries and fewer eggs laid in treated bark. There were also reductions in the number of beetles produced and the mean dry weight per beetle in methyl jasmonate-treated bark. Furthermore, fewer beetles were attracted to conspecifics tunneling in MJ-treated bark.The exact mechanisms responsible for induced resistance in Norway spruce and other conifers have not been determined, but inducible anatomical defense responses such as changes in polyphenol-containing parenchyma cells (PP cells) in the phloem and induction of traumatic resin duct formation in the sapwood seem to play an important role.
Sammendrag
When conifers such as Picea abies Karst. (Norway spruce) are attacked by insects or pathogens, they often respond by producing increased quantities of terpenoid oleoresin. This response can be mimicked in young P. abies seedlings by treatment with methyl jasmonate (MJ). In this study, we determined the effects of MJ on terpenoids and other chemical defenses of mature P. abies, and investigated whether this treatment protected trees against attack by the blue-stain fungus Ceratocystis polonica (Siem.) C. Moreau, the most important fungal associate of the spruce bark beetle Ips typo-graphus L. Methyljasmonate treatment induced the formation of traumatic resin ducts in the developing xylem, enhanced resin flow and stimulated increased accumulation of monoterpenes, sesquiterpenes and diterpene resin acids. However, only minor changes were detected in terpene composition in response to MJ treatment and no changes in soluble phenolic concentration were measured. There was much variability in the timing and degree of response to MJ among clones. The observed chemical and anatomical changes in response to MJ treatment were correlated with increased resistance to C. polonica, suggesting that terpenoid oleoresin may function in defense against this pathogen.