| 1. |
- Eriksson, Louise, 1973-, et al.
(författare)
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Invasive forest pathogens in Europe : Cross-country variationin public awareness but consistency in policy acceptability
- 2019
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Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; 48:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Political action can reduce introductions of diseases caused by invasive forest pathogens (IPs) and public support is important for effective prevention. The public’s awareness of IP problems and the acceptability of policies aiming to combat these pathogens were surveyed in nine European countries (N = 3469). Although awareness of specific diseases (e.g., ash dieback) varied, problem awareness and policy acceptability were similar across countries. The public was positive towards policies for informational measures and stricter standards for plant production, but less positive towards restricting public access to protected areas. Multilevel models, including individual and country level variables, revealed that media exposure was positively associated with awareness of IP problems, and strengthened the link between problem awareness and policy acceptability. Results suggest that learning about IPs through the media and recognizing the associated problems increase policy acceptability. Overall, the study elaborates on the anthropogenic dimension of diseases caused by IPs.
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| 2. |
- Faldt, Jenny, et al.
(författare)
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Influence of fungal infection and wounding on contents and enantiomeric compositions of monoterpenes in phloem of Pinus sylvestris
- 2006
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 32:8, s. 1779-1795
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Tidskriftsartikel (refereegranskat)abstract
- To identify chemical resistant markers induced by fungal or mechanical injury, young trees of Scots pine (Pinus sylvestris) were subjected to inoculations of blue stain fungi associated with the pine shoot beetles Tomicus piniperda and T. minor. Among the 20 trees selected for chemical analyses, 16 were divided into four groups: one as control and three were pretreated by wounding only, or by inoculation with either the blue stain fungus Leptographium wingfieldii or Ophiostoma canum. Four wk after pretreatment, all 16 pretreated trees were mass-inoculated with L. wingfieldii. The absolute and relative amounts, as well as the enantiomeric compositions of monoterpene hydrocarbons in the phloem, were determined via a small sample of the phloem before and after the pretreatment and mass inoculation, by using two-dimensional gas chromatography (2D GC) and GC-mass spectrometry (MS). After mass inoculation, the absolute amounts of most of the monoterpenes decreased in the phloem sampled > 20 cm from the fungal infection, and were higher in the phloem sampled within the infected reaction zone. The relative amounts of both (-)-beta-pinene and (-)-limonene increased in phloem samples taken > 20 cm above the fungal inoculation in the preinoculated trees compared with phloem sampled from the remaining four control trees. The enantiomeric compositions of beta-pinene and limonene changed, after fungal growth, at defined distances from the inoculation site: the proportion of the (-)-enantiomers was highest in the phloem sampled > 20 cm from the fungal inoculation. Four wk after pretreatment, monoterpene production in the phloem at the site of inoculation was more enhanced by L. wingfieldii than by O. canum. However, the different virulence levels of the fungi did not affect the enantiomeric composition of the monoterpenes. The biosynthesis of monoterpene enantiomers is discussed in relation to induced pathogen resistance.
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| 3. |
- Mageroy, Melissa H., et al.
(författare)
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Priming of inducible defenses protects Norway spruce against tree‐killing bark beetles
- 2020
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Ingår i: Plant, Cell and Environment. - : John Wiley & Sons. - 0140-7791 .- 1365-3040. ; 43:2, s. 420-430
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Tidskriftsartikel (refereegranskat)abstract
- Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short–lived model plants such as Arabidopsis, but little is known about this phenomenon in long‐lived plants like spruce. We compared the effects of pre‐treatment with sub‐lethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48‐year‐old Norway spruce (Picea abies) trees to mass attack by a tree‐killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees, but largely avoided fungus‐inoculated trees and MeJA‐treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91‐fold higher terpene concentrations compared to untreated trees, while application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus‐inoculated trees is a result of direct induction of defenses while resistance in MeJA‐treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.
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| 4. |
- Zhao, Tao, et al.
(författare)
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Induced Terpene Accumulation in Norway Spruce Inhibits Bark Beetle Colonization in a Dose-Dependent Manner
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:10, s. e26649-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tree-killing bark beetles (Coleoptera, Scolytinae) are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization. Methods: To test for inhibitory effects of induced terpenes on colonization by the spruce bark beetle Ips typographus (L.) we inoculated 20 mature Norway spruce Picea abies (L.) Karsten trees with a virulent fungus associated with the beetle, Ceratocystis polonica (Siem.) C. Moreau, and investigated induced terpene levels and beetle colonization in the bark. Results: Fungal inoculation induced very strong and highly variable terpene accumulation 35 days after inoculation. Trees with high induced terpene levels (n = 7) had only 4.9% as many beetle attacks (5.1 vs. 103.5 attacks m(-2)) and 2.6% as much gallery length (0.029 m m(-2) vs. 1.11 m m(-2)) as trees with low terpene levels (n = 6). There was a highly significant rank correlation between terpene levels at day 35 and beetle colonization in individual trees. The relationship between induced terpene levels and beetle colonization was not linear but thresholded: above a low threshold concentration of similar to 100 mg terpene g(-1) dry phloem trees suffered only moderate beetle colonization, and above a high threshold of similar to 200 mg terpene g(-1) dry phloem trees were virtually unattacked. Conclusion/Significance: This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance. This knowledge could be useful for developing management strategies that decrease the impact of tree-killing bark beetles.
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| 5. |
- Zhao, Tao, et al.
(författare)
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Storm-induced tree resistance and chemical differences in Norway spruce (Picea abies)
- 2011
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Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 68:3, s. 657-665
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Tidskriftsartikel (refereegranskat)abstract
- Windstorm is one of the most destructive environmental disturbance factors on forests, but its influence on conifer defense chemistry and susceptibility to insects and diseases is not well understood.
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| 6. |
- Zhao, Tao, et al.
(författare)
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The influence of Ceratocystis polonica inoculation and methyl jasmonate application on terpene chemistry of Norway spruce, Picea abies
- 2010
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 71:11-12, s. 1332-1341
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Tidskriftsartikel (refereegranskat)abstract
- 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 (+)-alpha-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 (-)-beta-pinene and (-)-limonene. Fungal inoculation significantly increased the enantiomeric ratio of (-)-alpha-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 (-)-beta-pinene, (-)-beta-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 (-)-alpha-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.
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