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Paal Krokene - One of the best experts on this subject based on the ideXlab platform.
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Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts
The ISME Journal, 2019Co-Authors: Tao Zhao, Suresh Ganji, Christian Schiebe, Björn Bohman, Paal Krokene, Philip Weinstein, Anna-karin Borg-karlson, C. Rikard UneliusAbstract:Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Tree-killing bark beetles vector numerous symbiotic Blue-Stain Fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these Fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the Fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C d-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic Fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.
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Table_1_Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis.doc
2018Co-Authors: Yue Pan, Paal Krokene, Tao Zhao, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far.
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Image_1_Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis.JPEG
2018Co-Authors: Yue Pan, Paal Krokene, Tao Zhao, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far.
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Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis
Frontiers Media S.A., 2018Co-Authors: Paal Krokene, Tao Zhao, Yue Pan, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far
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anatomical and chemical defenses of conifer bark against bark beetles and other pests
New Phytologist, 2005Co-Authors: Vincent R. Franceschi, Paal Krokene, Erik Christiansen, Trygve KreklingAbstract:Contents Summary 1 I. Introduction 2 II. Integrating defense strategies 2 III. Constitutive defense systems: first tier of defense 4 IV. Inducible defense systems: second tier of defense 11 V. Genetics and physiology of bark defense 13 VI. Bark beetles: diminutive but deadly 15 VII. The arms race: coevolution of conifer defense and bark beetle strategies 15 VIII. Bark-beetle-vectored Blue-Stain Fungi: multiple attacks against multiple defenses 17 IX. Conclusions 18 Acknowledgements 19 References 19 Summary Conifers are long-lived organisms, and part of their success is due to their potent defense mechanisms. This review focuses on bark defenses, a front line against organisms trying to reach the nutrient-rich phloem. A major breach of the bark can lead to tree death, as evidenced by the millions of trees killed every year by specialized bark-invading insects. Different defense strategies have arisen in conifer lineages, but the general strategy is one of overlapping constitutive mechanical and chemical defenses overlaid with the capacity to up-regulate additional defenses. The defense strategy incorporates a graded response from ‘repel’, through ‘defend’ and ‘kill’, to ‘compartmentalize’, depending upon the advance of the invading organism. Using a combination of toxic and polymer chemistry, anatomical structures and their placement, and inducible defenses, conifers have evolved bark defense mechanisms that work against a variety of pests. However, these can be overcome by strategies including aggregation pheromones of bark beetles and introduction of virulent phytopathogens. The defense structures and chemicals in conifer bark are reviewed and questions about their coevolution with bark beetles are discussed.
Tao Zhao - One of the best experts on this subject based on the ideXlab platform.
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Ophiostomatales (Ascomycota) associated with Tomicus species in southwestern China with an emphasis on Ophiostoma canum
Journal of Forestry Research, 2019Co-Authors: Pan Yue, Chen Peng, Huihong Zhang, Tao ZhaoAbstract:Ophiostomatalean Fungi may facilitate bark beetle colonization and reproduction. In the present study of the fungal community associated with bark beetle species belonging to Tomicus in Yunnan, China, six ophiostomatalean Fungi (Ophiostoma canum, O. ips, O. tingens, Leptographium yunnanense, Leptographium sp. 1 and Leptographium sp. 2) were isolated from the beetles or their galleries; O. canum was the most common fungal species. The distribution of O. canum was associated with stands heavily damaged by Tomicus species and a higher percentage of valid galleries of Tomicus yunnanensis and T. minor in Yunnan pine (Pinus yunnanensis). After inoculation of Yunnan pine with the fungus, a phloem reaction zone formed and monoterpenes accumulated in the phloem. These results suggested that O. canum was pathogenic to Yunnan pine and that the wide distribution of the fungus might be beneficial to reproduction of pine shoot beetles in Yunnan pine. However, because the reaction zone and monoterpene accumulation were mild, fungal damage of Yunnan pine might be limited. A more integrated study considering all the fungal species should be done to better understand the interactions among bark beetles, Blue-Stain Fungi, and the tree hosts in the region.
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Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts
The ISME Journal, 2019Co-Authors: Tao Zhao, Suresh Ganji, Christian Schiebe, Björn Bohman, Paal Krokene, Philip Weinstein, Anna-karin Borg-karlson, C. Rikard UneliusAbstract:Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Tree-killing bark beetles vector numerous symbiotic Blue-Stain Fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these Fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the Fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C d-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic Fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.
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Table_1_Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis.doc
2018Co-Authors: Yue Pan, Paal Krokene, Tao Zhao, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far.
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Image_1_Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis.JPEG
2018Co-Authors: Yue Pan, Paal Krokene, Tao Zhao, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far.
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Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis
Frontiers Media S.A., 2018Co-Authors: Paal Krokene, Tao Zhao, Yue Pan, Min Qiao, Peng ChenAbstract:Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three Blue-Stain Fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three Fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far
Halvor Solheim - One of the best experts on this subject based on the ideXlab platform.
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the ophiostoma clavatum species complex a newly defined group in the ophiostomatales including three novel taxa
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2016Co-Authors: Robert Jankowiak, Caterina Villari, Riikka Linnakoski, Halvor Solheim, Thomas Kirisits, Wilhelm Z De BeerAbstract:Two species of Blue-Stain Fungi with similar morphologies, Ophiostoma brunneo-ciliatum and Ophiostoma clavatum, are associates of bark beetles infesting Pinus spp. in Europe. This has raised questions whether they represent distinct taxa. Absence of herbarium specimens and contaminated or mistakenly identified cultures of O. brunneo-ciliatum and O. clavatum have accentuated the uncertainty regarding their correct identification. The aim of this study was to reconsider the identity of European isolates reported as O. brunneo-ciliatum and O. clavatum by applying DNA-based identification methods, and to provide appropriate type specimens for them. Phylogenetic analyses of the ITS, βT, TEF-1α and CAL gene sequences revealed that the investigated isolates represent a complex of seven cryptic species. The study confirmed that ITS data is insufficient to delineate species in some Ophiostoma species clusters. Lectotypes and epitypes were designated for O. clavatum and O. brunneo-ciliatum, and three new species, Ophiostoma brunneolum, Ophiostoma macroclavatum and Ophiostoma pseudocatenulatum, are described in the newly defined O. clavatum-complex. The other two species included in the complex are Ophiostoma ainoae and Ophiostoma tapionis. The results suggest co-evolution of these Fungi in association with specific bark beetles. The results also confirm the identity of the fungus associated with the pine bark beetle Ips acuminatus as O. clavatum, while O. brunneo-ciliatum appears to be mainly associated with another pine bark beetle, Ips sexdentatus.
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effects of growth and virulence of associated blue stain Fungi on host colonization behaviour of the pine shoot beetles tomicus minor and t piniperda
Plant Pathology, 2001Co-Authors: Halvor Solheim, Paal Krokene, Bo LangstromAbstract:The pine shoot beetles Tomicus minor and T. piniperda are common in the Nordic countries. Of these, T. piniperda may attack and kill living but severely stressed trees, whereas T. minor has never been reported to be individually responsible for killing live trees. Both species are associated with Blue-Stain Fungi: T. minor with Ophiostoma canum and T. piniperda with Leptographium wingfieldii and Ophiostoma minus. The growth of these Fungi was studied in phloem and sapwood of live Scots pine trees, on malt agar, and on malt agar under oxygen-deficient conditions. Leptographium wingfieldii was more virulent (i.e. caused more extensive host symptoms) grew more quickly on malt agar, and was less affected by oxygen-deficient growth conditions than either O. minus or O. canum. Ophiostoma canum was least virulent. In low-density inoculations it induced lesions similar to those induced by sterile control inoculations; it grew very slowly on malt agar and stopped growing after <30 mm under oxygen-deficient conditions. Ophiostoma minus was intermediate in all respects. The different virulence of the Blue-Stain Fungi associated with the two pine shoot beetles may explain the lower level of aggressiveness in T. minor.
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growth and virulence of mountain pine beetle associated blue stain Fungi ophiostoma clavigerum and ophiostoma montium
Botany, 1998Co-Authors: Halvor Solheim, Paal KrokeneAbstract:The mountain pine beetle (Dendroctonus ponderosae) is commonly associated with the Blue-Stain Fungi Ophiostoma clavigerum and Ophiostoma montium. Ophiostoma clavigerum is the primary invader of sapwood after beetle infestation and is thought to be the most virulent of the two Fungi. Growth of these Fungi was studied under oxygen-deficient conditions on malt agar in test tubes and Petri dishes. In addition, growth was studied in phloem and sapwood of young living shore pines (Pinus contorta var. contorta) and western white pines (Pinus monticola) inoculated with fungus in low densities (eight inoculations per tree). In test tubes with limited oxygen O. clavigerum grew for a longer time than O. montium. Both Fungi are fast growing on malt agar (maximum growth 4.4n9.0 mm/day), but O. clavigerum grew better at temperatures below 25∞C. The rapid growth and the ability to tolerate low oxygen levels may be important adaptations for O. clavigerum as the primary invader of fresh sapwood. However, although O. clavigerum grew better in the phloem of both tree species, there were no differences between the two Fungi in their ability to colonize the sapwood of the inoculated trees.
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early stages of blue stain fungus invasion of lodgepole pine sapwood following mountain pine beetle attack
Botany, 1995Co-Authors: Halvor SolheimAbstract:Invasion of lodgepole pine sapwood by Blue-Stain Fungi was followed for 7 weeks after infestation by the mountain pine beetle, Dendroctonus ponderosae. During this period all sapwood was heavily st...
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effects of pruning young scots pines on host vigour and susceptibility to leptographium wingfieldii and ophiostoma minus two blue stain Fungi associated with tomicus piniperda
Forest Pathology, 1993Co-Authors: Bo Langstrom, Halvor Solheim, Claes Hellqvist, Rolf GrefAbstract:In a field experiment in central Sweden, the vigour of 25-yr-old Scots pines was manipulated by pruning, prior to inoculation with Leptographium wingfieldii and Ophiostoma minus, two Blue-Stain Fungi associated with Tomicus piniperda. Our main purpose was to correlate fungus invasion and host defence reactions with host vigour. Both Fungi invaded the inner bark and the sapwood at the points of inoculation. L. wingfieldii caused larger lesions in the bark, but O. minus tended to grow faster in the sapwood. The flow of primary resin was related to tree vigour, whereas carbohydrates present in needles and stem phloem were not. Lesion formation and the content or composition of resin acids in lesions did not differ between Fungi or pruning treatments.
Janice E K Cooke - One of the best experts on this subject based on the ideXlab platform.
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genetic and genomic evidence of niche partitioning and adaptive radiation in mountain pine beetle fungal symbionts
Molecular Ecology, 2017Co-Authors: Dario Ojeda I Alayon, Yiyuan Zhang, Clement K M Tsui, Nicolas Feau, Arnaud Capron, Braham Dhillon, Sepideh Massoumi Alamouti, Celia K Boone, Allan L Carroll, Janice E K CookeAbstract:Bark beetles form multipartite symbiotic associations with blue stain Fungi (Ophiostomatales, Ascomycota). These fungal symbionts play an important role during the beetle's life cycle by providing nutritional supplementation, overcoming tree defences and modifying host tissues to favour brood development. The maintenance of stable multipartite symbioses with seemingly less competitive symbionts in similar habitats is of fundamental interest to ecology and evolution. We tested the hypothesis that the coexistence of three fungal species associated with the mountain pine beetle is the result of niche partitioning and adaptive radiation using SNP genotyping coupled with genotype-environment association analysis and phenotypic characterization of growth rate under different temperatures. We found that genetic variation and population structure within each species is best explained by distinct spatial and environmental variables. We observed both common (temperature seasonality and the host species) and distinct (drought, cold stress, precipitation) environmental and spatial factors that shaped the genomes of these Fungi resulting in contrasting outcomes. Phenotypic intraspecific variations in Grosmannia clavigera and Leptographium longiclavatum, together with high heritability, suggest potential for adaptive selection in these species. By contrast, Ophiostoma montium displayed narrower intraspecific variation but greater tolerance to extreme high temperatures. Our study highlights unique phenotypic and genotypic characteristics in these symbionts that are consistent with our hypothesis. By maintaining this multipartite relationship, the bark beetles have a greater likelihood of obtaining the benefits afforded by the Fungi and reduce the risk of being left aposymbiotic. Complementarity among species could facilitate colonization of new habitats and survival under adverse conditions.
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multilocus species identification and fungal dna barcoding insights from blue stain fungal symbionts of the mountain pine beetle
Molecular Ecology Resources, 2010Co-Authors: Adrianne V Rice, Sean E Bromilow, Janice E K Cooke, Felix A H SperlingAbstract:There is strong community-wide interest in applying molecular techniques to fungal species delimitation and identification, but selection of a standardized region or regions of the genome has not been finalized. A single marker, the ribosomal DNA internal transcribed spacer region, has frequently been suggested as the standard for Fungi. We used a group of closely related blue stain Fungi associated with the mountain pine beetle (Dendroctonus ponderosae Hopkins) to examine the success of such single-locus species identification, comparing the internal transcribed spacer with four other nuclear markers. We demonstrate that single loci varied in their utility for identifying the six fungal species examined, while use of multiple loci was consistently successful. In a literature survey of 21 similar studies, individual loci were also highly variable in their ability to provide consistent species identifications and were less successful than multilocus diagnostics. Accurate species identification is the essence of any molecular diagnostic system, and this consideration should be central to locus selection. Moreover, our study and the literature survey demonstrate the value of using closely related species as the proving ground for developing a molecular identification system. We advocate use of a multilocus barcode approach that is similar to the practice employed by the plant barcode community, rather than reliance on a single locus.
Marc Stevens - One of the best experts on this subject based on the ideXlab platform.
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optimisation of a two stage heat treatment process durability aspects
Wood Science and Technology, 2007Co-Authors: Michiel J Boonstra, J Van Acker, Kegel Edo Vincent, Marc StevensAbstract:Heat treatment of wood at relatively high temperatures (in the range of 150–280°C) is an effective method to improve biological durability of wood. This study was performed to investigate the effect of heat treatment process optimisation on the resistance against fungal attack, including basidiomycetes, molds and blue stain Fungi. An industrially used two-stage heat treatment method under relatively mild conditions (<200°C) was used to treat the boards. Heat treatment of radiata pine sapwood revealed a clear improvement of the resistance against the brown rot Fungi Coniophora puteana and Poria placenta. Increasing process temperature and/or effective process time during the first process stage, the hydro thermolysis, appeared to affect the resistance against C. puteana attack, but the effect on the resistance against P. placenta was rather limited. Heat treated radiata pine showed a limited resistance against the white rot fungus Coriolus versicolor and process variations during the hydro thermolysis stage appeared not to affect this resistance. A clear difference between the resistance of heat treated Scots pine sapwood and heartwood against fungal attack is observed. Scots pine heartwood showed a higher resistance against C. puteana and P. placenta but also against the white rot fungus C. versicolor. Similar results were obtained when heat treated birch was exposed to brown and white rot Fungi. Heat treatment showed an improved resistance against C. puteana attack, especially at higher temperatures during the hydro thermolysis stage. A clear improvement of the durability was also observed after exposure to the white rot fungus C. versicolor and especially Stereum hirsutum. Increasing the process temperature or process time during the hydro thermolysis stage appeared to have a limited effect on the resistance against C. versicolor attack. Heat treated radiata pine and Norway spruce were still susceptible to mold growth on the wood surface, probably due to the formation of hemicelluloses degradation products (e.g. sugars) during heat treatment. Remarkable is the absence of blue stain Fungi on heat treated wood specimen, also because the abandant blue stain Fungi were observed on untreated specimen. Molecular reasons for the resistance of heat treated wood against fungal attack are discussed in detail contributing to a better understanding of heat treatment methods.