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.
2010
Forfattere
Tao Zhao Paal Krokene Niklas Björklund Bo Långström Halvor Solheim Erik Christiansen Anna-Karin Borg-KarlsonSammendrag
Constitutive and inducible terpene production is involved in conifer resistance against bark beetles and their associated fungi. In this study 72 Norway spruce (Picea abies) were randomly assigned to methyl jasmonate (MJ) application, inoculation with the bluestain fungus Ceratocystis polonica, or no-treatment control. We investigated terpene levels in the stem bark of the trees before treatment, 30 days and one year after treatment using GC–MS and two-dimensional GC (2D-GC) with a chiral column, and monitored landing and attack rates of the spruce bark beetle, Ips typographus, on the trees by sticky traps and visual inspection. Thirty days after fungal inoculation the absolute amount and relative proportion of (+)-3-carene, sabinene, and terpinolene increased and (+)-α-pinene decreased. Spraying the stems with MJ tended to generally increase the concentration of most major terpenes with minor alteration to their relative proportions, but significant increases were only observed for (−)-β-pinene and (−)-limonene. Fungal inoculation significantly increased the enantiomeric ratio of (−)-α-pinene and (−)-limonene 1 month after treatment, whereas MJ only increased that of (−)-limonene. One year after treatment, both MJ and fungal inoculation increased the concentration of most terpenes relative to undisturbed control trees, with significant changes in (−)-β-pinene, (−)-β-phellandrene and some other compounds. Terpene levels did not change in untreated stem sections after treatment, and chemical induction by MJ and C. polonica thus seemed to be restricted to the treated stem section. The enantiomeric ratio of (−)-α-pinene was significantly higher and the relative proportions of (−)-limonene were significantly lower in trees that were attractive to bark beetles compared to unattractive trees. One month after fungal inoculation, the total amount of diterpenes was significantly higher in putative resistant trees with shorter lesion lengths than in putative susceptible trees with longer lesions. Thus, terpene composition in the stem bark may be related to resistance of Norway spruce against I. typographus and C. polonica.
Sammendrag
The anamorph genus Leptographium Lagerberg and Melin includes species that are typically bark beetleassociated fungi, with teleomorphs in Grosmannia. During a survey of ophiostomatoid fungi in Norway, two unusual species, that fit the broader morphological description of Leptographium, were isolated directly from the rootfeeding beetles, Dryocetes authographus and Hylastes cunicularius, as well as from roots infested by these insects. The first of these could be distinguished from other described species based on a sparse sporulation, black spore drops and chlamydospores in older cultures. This species also produces a Hyalorhinocladiella synanamorph. The second species was characterised by distinctly curved conidia. Based on these unusual morphological characteristics and distinct DNA sequences, these fungi were recognised as new taxa for which the names Leptographium chlamydatum sp. nov. and L. curvisporum sp. nov. are provided.
Forfattere
Paal KrokeneSammendrag
The interaction between conifers, ophiostomatoid fungi and bark beetles is a key factor in conifer ecosystems worldwide, since combined beetle-fungus attacks may cause massive tree mortality, huge economical losses and landscape-level ecological changes. For more than a century researchers have been arguing about who is responsible for tree mortality in bark beetle attacked trees - the beetles themselves or their associated fungi. As in many such polarized debates the best answer probably lies somewhere in between the extremes. The beetles are obviously central in tree killing, as they are actively selecting suitable host trees, short-circuiting tree defenses by boring straight into the relatively defenseless cambial area, and causing mechanical damage to the phloem. However, ophiostomatoid fungi are equally obvious contributors to tree death since nearly all tree-killing bark beetles are associated with such fungi, these fungi are able to colonize and kill healthy phloem and sapwood far beyond the beetle tunnels, and many fungi can kill healthy trees in experimental mass-inoculations. Thus, the trees are facing a beetle-fungus complex that probably acts synergistically to overwhelm tree defenses. The beetles’ mass-attack strategy is central to the success of the beetle-fungus complex, since multiple attacks deplete tree defenses and speed up tree-killing.
Sammendrag
Det vert her rapportert frå forsøk med lagring av eple av sorten Aroma i kontrollert atmosfære ved ulike temperaturar og oksygennivå. Det var dårlegare fruktkvalitet og meir alderssamanbrot i eple lagra i vanleg luft samanlikna med lågt oksygennivå. Mengd bitterrote (den mest vanlege lagersjukdomen i forsøka) var også noko påverka av oksygennivået, men resultata her var ikkje heilt eintydige.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
The increased occurrence of Fusarium toxins during recent years in Norwegian cereals, especially deoxynivalenol (DON) in spring wheat and DON and T-2/HT-2 toxins in oats (see abstract by Hofgaard et al), is a serious challenge for the cereal industry and farmers. Contamination levels above regulatory or advisory maximum limits have frequently been detected. In Norway, many farmers bring their grain directly to the buyer at harvest, and, in a time and cost perspective, it is not realistic to test all grain lots for mycotoxin content by chemical analysis. In order to reduce the risk of cereal grain lots with unacceptable Fusarium toxin content entering the feed and food chain, a three-step screening strategy has been developed in close cooperation with the cereal industry. 1 Toxin risk (DON, T-2/HT-2) in cereal fields will be predicted by models based on information on climatic conditions and agronomic/cultivation practice (see abstract by Elen et al). 2 Grain from "high-risk" fields will be analysed for mycotoxins by a rapid "on-site" test method (lateral flow tests) before the grain enters the silo/storage/mill. 3 Samples from lots with toxin levels close to the defined maximum limits (based on analyses in step 2) can be forwarded to chemical analyses for precise decision of the mycotoxin concentrations.
Sammendrag
I "Fusariumprosjektet" ved Bioforsk Plantehelse har vi i løpet av en 4 års periode (2006-2009) samlet inn kornprøver fra partier med norskprodusert havre og vårhvete med tilhørende opplysninger om klima og dyrkningsmessige forhold. Kornprøvene er videre analysert for innhold av 17 ulike mykotoksiner. Ved å sammenstille og analysere data og informasjon om de ulike kornprøvene, har vi kartlagt ulike faktorer som kan ha betydning for utvikling av mykotoksiner i kornet. Dataene er videre brukt for å utvikle varslingsmodeller for Fusarium-mykotoksiner i korn, og for utprøving av ulike hurtigmetoder som er utviklet for å måle innhold av mykotoksiner i korn.
Forfattere
Guro BrodalSammendrag
Det er ikke registrert sammendrag
Forfattere
Guro BrodalSammendrag
Det er ikke registrert sammendrag