| 1. |
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| 2. |
- Dalin, Frida, 1984-, et al.
(författare)
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Clinical and immunological characteristics of Autoimmune Addison's disease : a nationwide Swedish multicenter study
- 2017
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 102:2, s. 379-389
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Studies on clinical and immunological features of Autoimmune Addison's disease (AAD) are needed to understand the disease burden and increased mortality.OBJECTIVE: To provide upgraded data on autoimmune comorbidities, replacement therapy, autoantibody profiles and cardiovascular risk factors.DESIGN, SETTING AND PARTICIPANTS: Cross sectional, population-based study. 660 AAD patients were included utilizing the Swedish Addison Registry (SAR) 2008-2014. When analyzing cardiovascular risk factors, 3,594 individuals from the population-based survey in Northern Sweden, MONICA (MONItoring of Trends and Determinants of CArdiovascular Disease), served as controls.MAIN OUTCOME MEASURE: Prevalence of autoimmune comorbidities and cardiovascular risk factors. Autoantibodies against 13 autoantigens were determined.RESULTS: Sixty percent of the SAR cohort consisted of females. Mean age at diagnosis was significantly higher for females than for males (36.8 vs. 31.1 years). The proportion of 21-hydroxylase autoantibody positive patients was 83% and 62% of patients had one or more associated autoimmune diseases, more frequently coexisting in females (p<0.0001). AAD patients had lower BMI (p<0.0001) and prevalence of hypertension (p=0.027) compared with controls. Conventional hydrocortisone tablets were used by 89% of patients; with the mean dose 28.1±8.5 mg/day. The mean hydrocortisone equivalent dose normalized to body surface was 14.8±4.4 mg/m(2)/day. Higher hydrocortisone equivalent dose was associated with higher incidence of hypertension (p=0.046).CONCLUSIONS: Careful monitoring of AAD patients is warranted to detect associated autoimmune diseases. Contemporary Swedish AAD patients do not have increased prevalence of overweight, hypertension, T2DM or hyperlipidemia. However, high glucocorticoid replacement doses may be a risk factor for hypertension.
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| 3. |
- Adomas, Aleksandra, et al.
(författare)
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Comparative analysis of transcript abundance in Pinus sylvestris after challenge with a saprotrophic, pathogenic or mutualistic fungus
- 2008
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Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 28:6, s. 885-897
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Tidskriftsartikel (refereegranskat)abstract
- To investigate functional differences in the recognition and response mechanisms of conifer roots to fungi with different trophic strategies, Pinus sylvestris L. was challenged with a saprotrophic fungus Trichoderma aureoviride Rifai. The results were compared with separate studies investigating pine interactions with a pathogen, Heterobasidion annosum (Fr.) Bref. sensu stricto and an ectomycorrhizal symbiont, Laccaria bicolor Maire (Orton). Global changes in the expression of 2109 conifer genes were assayed 1, 5 and 15 days after inoculation. Gene expression data from a cDNA microarray were analyzed by the 2-interconnected mixed linear model statistical approach. The total number of genes differentially expressed compared with the uninfected control was similar after challenge with the pathogen and the ectomycorrhizal symbiont, but the number of differentially expressed genes increased over time, for H. annosum, and decreased for L. bicolor. Inoculation of pine roots with T aureoviride resulted overall in a much lower number of genes with changed transcript levels compared with inoculation with H. annosum or L. bicolor. Functional classification of the differentially expressed genes revealed that the ectomycorrhizal fungus triggered transient induction of defence-related genes. The response and induction of defence against the pathogen was delayed and the magnitude increased over time. Thus, there were specific transcriptional responses depending on whether the conifer roots were challenged with mutualistic, saprotrophic or pathogenic fungi. This suggests that pine trees are able to recognize diverse fungal species and specifically distinguish whether they are pathogenic, neutral or beneficial microbial agents.
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| 4. |
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| 5. |
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| 6. |
- Andersson, Pierre, et al.
(författare)
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B-norsteroids from Hymenoscyphus pseudoalbidus
- 2012
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Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 17, s. 7769-7781
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Tidskriftsartikel (refereegranskat)abstract
- Two viridin-related B-norsteroids, B-norviridiol lactone (1) and B-norviridin enol (2), both possessing distinct unprecedented carbon skeletons, were isolated from a liquid culture of the ash dieback-causing fungus Hymenoscyphus pseudoalbidus. Compound 2 was found to degrade to a third B-norsteroidal compound, 1β-hydroxy-2α-hydro-asterogynin A (3), which was later detected in the original culture. The proposed structure of 1 is, regarding connectivity, identical to the original erroneous structure for TAEMC161, which was later reassigned as viridiol. Compound 2 showed an unprecedented 1H-13C HMBC correlation through an intramolecular hydrogen bond. The five-membered B-ring of compounds 1–3 was proposed to be formed by a benzilic acid rearrangement. The known compound asterogynin A was found to be formed from 3 by a β-elimination of water. All compounds were characterized by NMR spectroscopy, LC-HRMS and polarimetry.
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| 7. |
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| 8. |
- Andersson, Pierre, et al.
(författare)
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Viridin-like steroids from Hymenoscyphus pseudoalbidus
- 2013
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 86, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- Three furanosteroids were isolated from the ash dieback causing fungus Hymenoscyphus pseudoalbidus along with the known compounds viridiol and demethoxyviridiol. The compounds were characterized by 1D and 2D NMR spectroscopy, LC-HRMS and polarimetry. (C) 2012 Elsevier Ltd. All rights reserved.
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| 9. |
- Arhipova, Natalija, et al.
(författare)
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Decay, yield loss and associated fungi in stands of grey alder (Alnus incana) in Latvia
- 2011
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Ingår i: Forestry. - : Oxford University Press (OUP). - 0015-752X .- 1464-3626. ; 84, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- The significance of grey alder (Alnus incana (L.) Moench.) as a fast-growing renewable source for energy and wood production has increased during the last decade. The aims of this study were to: (1) estimate the incidence of stem decay in A. incana stands, (2) measure the extent of decay within individual stems, (3) estimate the impact of decay on wood yield and (4) identify decay-causing fungi. In total, 4344 recently cut A. incana stumps were examined on 46 clearfelled areas in different regions of Latvia. The incidence of decayed stumps varied from 1 to 54 per cent. In addition, 175 living trees were cut to measure the extent of decay within the stems. The length of decay columns varied from 0.4 to 20.6 m and that of spongy rot from 0 to 18.0 m. In total, 354 isolates representing 70 fungal taxa and 1129 isolates representing 131 fungal taxa were obtained from decayed stumps and living stems, respectively. The present study shows that decay and associated fungi are important factors determining biomass production and quality in A. incana stands and that their impact should be seriously considered when cultivating this tree species in the future.
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| 10. |
- Arhipova, Natalija, et al.
(författare)
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Heart-rot and associated fungi in Alnus glutinosa stands in Latvia
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- The interest in Alnus glutinosa (L.) Gaertn. as plantation species has increased during last years, but its prospects should be evaluated from the perspective of forest health. The aims of the present study were to: (1) estimate the incidence of stem decay in Latvian A. glutinosa stands, (2) measure the extent of decay within individual stems and on a stand level and (3) identify decay-causing fungi. In four A. glutinosa stands, 450 trees were randomly sampled with an increment borer and the presence/absence of decay was recorded. As a result, 112 sound-looking and 338 decayed trees were detected, and a corresponding number of wood samples were collected for fungal isolations. A total of 34 stems with decay symptoms were cut to measure the extent of internal decay. The incidence of decayed stems in studied stands was 75.1% on average. The length of the decay column was 7.7 +/- 5.4 m on average, and that of spongy rot was 4.2 +/- 4.5 m on average, implying that yield losses for fully stocked 80-years-old A. glutinosa stand would comprise 49.2% of the total stand volume, and the losses from spongy rot alone -30.5%. In total, 1134 isolates representing 68 fungal taxa were obtained. The most common decay-causing fungi were Inonotus radiatus and Armillaria sp.
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| 11. |
- Arnerup Christiansson, Jenny, et al.
(författare)
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The primary module in Norway spruce defence signalling against H. annosum s.l. seems to be jasmonate-mediated signalling without antagonism of salicylate-mediated signalling
- 2013
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Ingår i: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 237, s. 1037-1045
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Tidskriftsartikel (refereegranskat)abstract
- A key tree species for the forest industry in Europe is Norway spruce [Picea abies (L.) Karst.]. One of its major diseases is stem and butt rot caused by Heterobasidion parviporum (Fr.) Niemelä & Korhonen, which causes extensive revenue losses every year. In this study, we investigated the parallel induction of Norway spruce genes presumably associated with salicylic acid- and jasmonic acid/ethylene-mediated signalling pathways previously observed in response to H. parviporum. Relative gene expression levels in bark samples of genes involved in the salicylic acid- and jasmonic acid/ethylene-mediated signalling pathways after wounding and inoculation with either the saprotrophic biocontrol fungus Phlebiopsis gigantea or with H. parviporum were analysed with quantitative PCR at the site of the wound and at two distal locations from the wound/inoculation site to evaluate their roles in the induced defence response to H. parviporum in Norway spruce. Treatment of Norway spruce seedlings with methylsalicylate, methyljasmonate and inhibitors of the jasmonic acid/ethylene signalling pathway, as well as the Phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid were conducted to determine the responsiveness of genes characteristic of the different pathways to different hormonal stimuli. The data suggest that jasmonic acid-mediated signalling plays a central role in the induction of the genes analysed in this study irrespective of their responsiveness to salicylic acid. This may suggest that jasmonic acid-mediated signalling is the prioritized module in the Norway spruce defence signalling network against H. parviporum and that there seems to be no immediate antagonism between the modules in this interaction.
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| 12. |
- Arnerup, Jenny, et al.
(författare)
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The pathogenic white-rot fungus Heterobasidion parviporum triggers non-specific defence responses in the bark of Norway spruce
- 2011
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Ingår i: Tree Physiology. - : Oxford University Press. - 0829-318X .- 1758-4469. ; 31:11, s. 1262-1272
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Tidskriftsartikel (refereegranskat)abstract
- Norway spruce [Picea abies (L.) Karst.] is one of the economically most important conifer species in Europe. The major pathogen on Norway spruce is Heterobasidion parviporum (Fr.) Niemelä & Korhonen. To achieve a better understanding of Norway spruce's defence mechanisms, transcriptional responses in bark to H. parviporum infection were compared with the response to wounding using cDNA-amplified fragment length polymorphism. The majority of the recovered transcript-derived fragments (TDFs) showed a similar expression pattern for infection and wounding treatment, although inoculated samples showed an enhanced reaction. Genes related to systemic acquired resistance, e.g., PR1, accumulated after H. parviporum infection. Simultaneously, several transcripts involved in various aspects of jasmonic acid (JA)- and ethylene (ET)-mediated signalling accumulated. Genes involved in the ubiquitin/proteasome system were also regulated. Expression patterns have been confirmed by quantitative polymerase chain reaction. The expression patterns of the isolated TDFs suggest that infection with H. parviporum in Norway spruce induces a broad defence, with many similarities to non-specific defence responses in angiosperms. The parallel induction of salicylic acid- and JA/ET-mediated pathways implies spatially separated responses in different cell layers, with and without hyphal contact. A set of TDFs were analysed in an independent experiment with unrelated material treated with wounding or with inoculation with H. parviporum or Phlebiopsis gigantea, verifying the original observations and underlining the non-specific defence responses. In addition, our data suggest that rerouting of carbon in secondary metabolism is an integral part of Norway spruce induced defence. We report the sequences of three 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase genes (PaDAHP1, PaDAHP2 and PaDAHP3) and their relative expression in response to wounding and infection with H. parviporum and P. gigantea. The results clearly indicate differential regulation of the three DAHPs in the induced defence responses in Norway spruce. This study gives insights into the central mechanisms in the induced defences in Norway spruce.
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| 13. |
- Arnerup, Jenny, et al.
(författare)
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Variation in growth of Heterobasidion parviporum in a full-sib family of Picea abies
- 2010
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Ingår i: Scandinavian Journal of Forest Research. - : Taylor & Francis. - 0282-7581 .- 1651-1891. ; 25:2, s. 106-110
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Tidskriftsartikel (refereegranskat)abstract
- Heterobasidion parviporum (Fr.) Niemelä & Korhonen and Heterobasidion annosum (Fr.) Bref. sensu lato are some of the major forest pathogens in the northern hemisphere causing root and butt rot to conifers. The relative susceptibility to H. parviporum was investigated in a full-sib family of Norway spruce [Picea abies (L.) Karst.] by inoculating a set of 252 cloned progenies from a controlled cross. Four ramets of each progeny were used and the 2-year-old rooted cuttings were incubated for 6 weeks under greenhouse conditions. The condition of the cuttings was assessed visually and all the plants were in excellent vigour with no mortality recorded during the experiment. To score the relative susceptibility, lesion length in the inner bark and fungal growth in the sapwood were measured. Among the progenies, significant differences were found for fungal growth in the sapwood (p<0.0005). There was no significant difference for lesion length; however, there was a significant positive correlation between fungal growth and lesion length. The broad-sense heritability was 0.11 for fungal growth. This shows that the genetic component for susceptibility to H. parviporum can be detected even within a full-sib family of Norway spruce and that there is a potential for mapping quantitative trait loci for this trait in Norway spruce.
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| 14. |
- Assefa, Addisu, et al.
(författare)
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Characterization of Pyrofomes demidoffii from Ethiopian Afromontane forests
- 2015
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 263-273
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Tidskriftsartikel (refereegranskat)abstract
- Pyrofomes demidoffii is a basidiomycetous fungus that causes a white heart rot in living junipers (Juniperus spp.). Morphological characters and genetic variation in species of Pyrofomes were investigated for specimens from Ethiopia, Tanzania, Macedonia, USA and Costa Rica. In addition, the behaviour of isolates from Ethiopia was studied in vitro. The Ethiopian specimens had relatively larger basidiospores than collections from other countries and showed a high sequence similarity in the ITS region of rDNA sequences with most of strains evaluated in this study (95-100%), but only 89-92% with P.demidoffii from the USA. Phylogenetic analysis of ITS-5.8S rDNA sequences resulted in two well-supported (99-100% bootstrap value), separate clades of P.demidoffii. Deeper branches were less well supported (bootstrap<90%), but the two geographically and phylogenetically separated clades within P.demidoffii may still represent sister groups. For Ethiopian strains, the temperature optimum was between 20 and 25 degrees C and the pH optimum was around 5.0. A phylogenetic study with additional genetic markers and with a more representative collection of samples is needed.
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| 15. |
- Assefa, Addisu, et al.
(författare)
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Corynelia uberata as a threat to regeneration of Podocarpus falcatus in Ethiopian forests: spatial pattern and temporal progress of the disease and germination studies
- 2015
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Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 64, s. 617-626
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Tidskriftsartikel (refereegranskat)abstract
- The order Coryneliales includes several fungi such as Corynelia spp. that are pathogenic to trees in the Podocarpaceae. The aim of this study was to assess the spatial pattern and temporal progress of disease caused by Corynelia uberata on Podocarpus falcatus in Ethiopian forests and to evaluate the germination potential of seed retrieved from fruit infected by C.uberata. Corynelia uberata was found on leaves, young stems and/or on fruit of P.falcatus in Ethiopian forests. Spatial analysis in the Adaba-Dodola forest showed that disease intensity of C.uberata was significantly higher in non-WAJIB' blocks (disturbed forest) than WAJIB' blocks (sustainably managed forest) (P<00001). In the temporal disease progress study, a significantly higher incidence and severity of disease on fruit was recorded during the wet season relative to dry season (P<00001). The green milk stage of fruit exhibited significantly higher mean incidence (P<00001) and severity (P<00001) of disease compared to other growth stages of fruit. The disease incidence and severity in general, as well as on different fruit growth stages, were highly correlated (P<00001, R(2)095). Germination rate of seed decreased significantly with an increase in the level of fruit infection by C.uberata (P<00001). Thus, C.uberata can apparently influence germination of seed and may pose a threat to the regeneration of P.falcatus from seeds in Ethiopian forests.
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| 16. |
- Assefa, Addisu, et al.
(författare)
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Global diversity and taxonomy of the Inonotus linteus complex (Hymenochaetales, Basidiomycota): Sanghuangporus gen. nov., Tropicoporus excentrodendri and T. guanacastensis gen. et spp. nov., and 17 new combinations
- 2016
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Ingår i: Fungal Diversity. - : Springer Science and Business Media LLC. - 1560-2745 .- 1878-9129. ; 77, s. 335-347
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Tidskriftsartikel (refereegranskat)abstract
- Although Inonotus linteus complex is placed in thegenus Inonotus, its perennial basidiocarps with a dimitic hyphalsystem, at least in the trama, distinguish the complex from otherspecies in the genus, which have an annual habit and amonomitic hyphal system. The species number of Inonotuslinteus complex has been increased in China and tropicalAmerica in recent publications. However, whether species inthis complex belong to Inonotus has not specifically been addressed.To explore the phylogenetic placement of species ofInonotus linteus complex, we performed a comprehensivestudy using morphological and phylogenetic data based onglobal samples. nLSU (53 with 13 new) and ITS (70 with 18new) datasets were used to produce the phylogenetic results.Taking into consideration the phylogenies inferred from thenLSU and ITS datasets, Inonotus is a polyphyletic genus comprisingat least three clades. Clade A, the core Inonotus clade,contains the generic type, Inonotus hispidus, while Clades Band C comprise species from the Inonotus linteus complex.Morphological and phylogenetic evidence indicates thatClades B and C are new genera, and Sanghuangporus andTropicoporus are introduced in this study. Ten species are transferredto Sanghuangporus and seven to Tropicoporus.Tropicoporus excentrodendri and T. guanacastensis spp. nov.are described, and their distinctive characters are discussed.Keys to the two new genera and the Inonotus sensu stricto,and to species of each new genus are provided.
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| 17. |
- Baeten, Lander, et al.
(författare)
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Identifying the tree species compositions that maximize ecosystem functioning in European forests
- 2019
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 56:3, s. 733-744
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Tidskriftsartikel (refereegranskat)abstract
- 1. Forest ecosystem functioning generally benefits from higher tree species richness, but variation within richness levels is typically large. This is mostly due to the contrasting performances of communities with different compositions. Evidence-based understanding of composition effects on forest productivity, as well as on multiple other functions will enable forest managers to focus on the selection of species that maximize functioning, rather than on diversity per se.2. We used a dataset of 30 ecosystem functions measured in stands with different species richness and composition in six European forest types. First, we quantified whether the compositions that maximize annual above-ground wood production (productivity) generally also fulfil the multiple other ecosystem functions (multifunctionality). Then, we quantified the species identity effects and strength of interspecific interactions to identify the "best" and "worst" species composition for multifunctionality. Finally, we evaluated the real-world frequency of occurrence of best and worst mixtures, using harmonized data from multiple national forest inventories.3. The most productive tree species combinations also tended to express relatively high multifunctionality, although we found a relatively wide range of compositions with high- or low-average multifunctionality for the same level of productivity. Monocultures were distributed among the highest as well as the lowest performing compositions. The variation in functioning between compositions was generally driven by differences in the performance of the component species and, to a lesser extent, by particular interspecific interactions. Finally, we found that the most frequent species compositions in inventory data were monospecific stands and that the most common compositions showed below-average multifunctionality and productivity.4. Synthesis and applications. Species identity and composition effects are essential to the development of high-performing production systems, for instance in forestry and agriculture. They therefore deserve great attention in the analysis and design of functional biodiversity studies if the aim is to inform ecosystem management. A management focus on tree productivity does not necessarily trade-off against other ecosystem functions; high productivity and multifunctionality can be combined with an informed selection of tree species and species combinations.
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| 18. |
- Bagger, Alexander, et al.
(författare)
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Ab Initio Cyclic Voltammetry on Cu(111), Cu(100) and Cu(110) in Acidic, Neutral and Alkaline Solutions
- 2019
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Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical reactions depend on the electrochemical interface between the electrode surfaces and the electrolytes. To control and advance electrochemical reactions there is a need to develop realistic simulation models of the electrochemical interface to understand the interface from an atomistic point-of-view. Here we present a method for obtaining thermodynamic realistic interface structures, a procedure we use to derive specific coverages and to obtain ab initio simulated cyclic voltammograms. As a case study, the method and procedure is applied in a matrix study of three Cu facets in three different electrolytes. The results have been validated by direct comparison to experimental cyclic voltammograms. The alkaline (NaOH) cyclic voltammograms are described by H* and OH*, while in neutral medium (KHCO3) the CO3* species are dominating and in acidic (KCl) the Cl* species prevail. An almost one-to-one mapping is observed from simulation to experiments giving an atomistic understanding of the interface structure of the Cu facets. Atomistic understanding of the interface at relevant eletrolyte conditions will further allow realistic modelling of electrochemical reactions of importance for future eletrocatalytic studies.
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| 19. |
- Bakys, Remigijus, et al.
(författare)
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Investigations concerning the role of Chalara fraxinea in declining Fraxinus excelsior
- 2009
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Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 58, s. 284-292
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Tidskriftsartikel (refereegranskat)abstract
- A study was carried out to clarify the role of the fungus Chalara fraxinea in decline of Fraxinus excelsior, which is observed on a large scale in central and northern Europe with high incidence of tree mortality. The aims of this work were: (i) to check for the presence of C. fraxinea in various tissues of declining F. excelsior by agar culture isolations and by direct analysis of plant tissues using molecular techniques (DNA extraction, ITS-PCR, cloning, ITS sequencing and T-RFLP); (ii) to study fungal communities inhabiting tissues with symptoms; and (iii) to test the pathogenicity of C. fraxinea to F. excelsior. Chalara fraxinea was isolated from 93% of stem cankers, 91% of necrotic leaf stalks, 27-28% of bark wounds and 30% of visually healthy leaf stalks. Molecular analyses of necrotic leaves, leaf stalks and bark revealed the presence of 25 different fungal taxa, 14 of which were detected in all three types of tissue sample. Chalara fraxinea was the second most common species (61% of samples), and only Cryptococcus foliicola occurred more often (70%). All eight of the tested C. fraxinea isolates induced necroses in bark and cambium on each of 86 inoculated trees, and all controls remained healthy. Average length of necroses caused by different C. fraxinea strains varied from 4.2 to 8.9 cm, but the differences were statistically insignificant. Instead, differences in resistance of individual trees to C. fraxinea were observed.
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| 20. |
- Bakys, Remigijus, et al.
(författare)
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Occurrence and pathogenicity of fungi in necrotic and non-symptomatic shoots of declining common ash (Fraxinus excelsior) in Sweden
- 2009
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Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 128, s. 51-60
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Tidskriftsartikel (refereegranskat)abstract
- Currently, massive dieback of Fraxinus excelsior is observed in countries of eastern, northern and central Europe, and the reasons for it are unclear. The aims of the present work were (a) to study fungal communities in declining F. excelsior crowns; (b) to clarify role of fungi in the decline. Shoots from symptomatic crowns were collected in four localities in central Sweden, and distributed into the following categories: (a) visually healthy; (b) initial necroses; (c) advanced necroses; (c) dead tops. The most frequently isolated fungi were Gibberella avenacea, Alternaria alternata, Epicoccum nigrum, Botryosphaeria stevensii, Valsa sp., Lewia sp., Aureobasidium pullulans and Phomopsis sp., and these taxa were consistently found in shoots of all four symptomatic categories. Forty-eight taxa of other fungi were isolated, and fungal diversity was not exhausted by the sampling effort. The same taxa of fungi were dominant in F. excelsior shoots of different symptomatic categories, and moderate to high similarity of fungal communities was observed in shoots despite the symptoms. Forty-four isolates from 24 fungal taxa were used for artificial inoculations of 277 1-year-old F. excelsior seedlings in bare root nursery. After 2 years, only four fungi caused symptomatic necroses of bark and cambium: A. alternata, E. nigrum, Chalara fraxinea and Phomopsis sp. The most pathogenic was C. fraxinea, inducing symptoms on 50% of inoculated trees, while three other fungi caused necroses on 3-17% of inoculated trees. Infection biology of C. fraxinea and environmental factors determining susceptibility of F. excelsior to decline deserve future investigations.
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| 21. |
- Bakys, Remigijus, et al.
(författare)
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Root rot, associated fungi and their impact on health condition of declining Fraxinus excelsior stands in Lithuania
- 2011
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 26, s. 128-135
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Tidskriftsartikel (refereegranskat)abstract
- Dieback of Fraxinus excelsior L. associated with Chalara fraxinea is observed in Europe, and in some areas dying trees exhibit symptoms of root and butt rot. Our study was conducted (1) to estimate the impact of the rot on F. excelsior dieback severity; (2) to identify fungi colonizing roots of dieback-affected trees; (3) to check their pathogenicity to F. excelsior; and (4) to estimate sprouting incidence and sprout health condition in relation to presence/absence of rot. The extent of rot was measured in 33 trees with different dieback intensity, 150 fungal isolations were attempted from roots of 50 trees, 26 fungi were tested for pathogenicity to 286 saplings, and sprouting was evaluated for 328 stumps on three clear-felled sites. Root rot was mainly caused by Armillaria cepistipes, and the extent of rot correlated positively with dieback severity although it played a secondary role in tree decline. Four years after tree felling, root rot had a negative impact on sprouting frequency, yet rot did not enter sprouts from stumps, and when experimentally inoculated, fungi associated with root rot in mature ash had no visible impact on tree vigor, showing that after formation of sprouts, rot does not affect the subsequent phytosanitary condition. Sprouts on investigated sites exhibited Chalara dieback symptoms on leaves and bark irrespectively of presence/absence of rot, indicating that vigorous natural regeneration of F. excelsior in dieback-affected areas could not be expected.
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| 22. |
- Bengtsson, Stina, et al.
(författare)
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Detection of Chalara fraxinea from tissue of Fraxinus excelsior using species-specific ITS primers
- 2010
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 40, s. 111-115
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Tidskriftsartikel (refereegranskat)abstract
- P>Chalara fraxinea (teleomorph: Hymenoscyphus albidus) is known as a serious pathogen of Fraxinus excelsior, causing massive dieback of trees in Europe. The fungus is able to cause latent infections, and has been previously detected as an endophyte in asymptomatic tissues. Chalara fraxinea is a slow grower in culture, and is thus likely to be overgrown by faster growing fungi whenever pure culture isolations are being attempted. This study reports species-specific ITS primers allowing fast and reliable detection of the pathogen directly from infected tissues of F. excelsior.
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| 23. |
- Bengtsson, Stina, et al.
(författare)
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Population structure of Hymenoscyphus pseudoalbidus and its genetic relationship to Hymenoscyphus albidus
- 2012
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 5, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- The ascomycete fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea) is responsible for ash dieback currently expanding over large parts of Europe. Our objective was to investigate the genetic structure of H. pseudoalbidus and to examine its relationship to the species H. albidus, known as a saprotroph. The study comprised 181 isolates of H. pseudoalbidus collected within the diseased area, 17 H. albidus isolates from six apothecia, collected outside the diseased area in Norway, and nine apothecia of H. pseudoalbidus collected in Sweden. By analysis of microsatellite markers developed for this study, combined with AP-PCR using the M13 primer, we demonstrated sexual heterothally in H. pseudoalbidus, detected high gene flow and low geographic structure of the H. pseudoalbidus population and found indications of a founder effect. Also, substantial genetic differences were detected between the two species of fungi; only four of seven microsatellite markers developed for H. pseudoalbidus were amplified for H. albidus, and no alleles were shared among the species. Furthermore, AP-PCR banding patterns were distinctly different for the two species. We conclude that even though the two fungi have a similar habitat and are morphologically virtually identical, they do not share a recent common ancestor. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.
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| 24. |
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| 25. |
- Bengtsson, Stina, et al.
(författare)
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Seasonal Pattern of Lesion Development in Diseased Fraxinus excelsior Infected by Hymenoscyphus pseudoalbidus
- 2014
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Ash dieback is a recent widespread disease on ash (Fraxinus sp.) that is causing important economic and ecological losses throughout Europe. The disease is initiated by the ascomycetous fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea). The main aim of this study was to investigate seasonal pattern of lesion development associated with ash dieback. We present data on the spread of 324 natural lesions in ash shoots, branches and stems surveyed over a 32 month period. Most lesions were active and showed the greatest rate of growth during the summer; however, lesions were active throughout the year. Tree mortality was high, with more than a third of the surveyed trees dying during the study. Although many lesions permanently ceased to develop, the rate at which new lesions emerged was greater than the rate at which lesions entered a resting phase. The most common cause for a lesion going into a permanent state of rest was that it had encountered a branch-base. Genotype analysis showed that multiple infections can occur in a single tree given that different genotypes were identified in different lesions as well as in single lesions. A weak positive correlation was noted between tree health and tree size and a weak negative correlation was noted between tree overall health and lesion activity. The lower limit for H. pseudoalbidus growth in culture was between 4.0 degrees C and 0.5 degrees C.
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| 26. |
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| 27. |
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| 28. |
- Blomberg, Patrik, 1972-
(författare)
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Non-target Effects of Genetically Modified Trees
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To date, few studies have focused on the effects of genetically modified trees (GM trees) on the environment. One concern with GM trees is that they may have unanticipated effects on non-target organisms, i.e. effects on organisms that are not direct targets of the genetically modified trait. The main objective of this thesis was to study potential non-target effects from the interaction between GM trees and natural enemies, including phytopathogens and herbivorous insects. To study this I used a system consisting of GM trees featuring changes in growth-related characteristics, and naturally occurring enemies. The GM trees used were the aspen hybrids Populus tremula x tremuloides: one unmodified wild type clone T89 (control) and transgenic lines with altered expression of gibberellin (GA 20-oxidase), sucrose (SPS) or pectin (PME); and Populus tremula x alba: one unmodified wild type clone INRA 717-1-B4 (control) and lines modified to suppress the activity of the enzymes in the lignin biosynthetic pathway, i.e. CAD, COMT, CCR or CCoAOMT. The natural enemies used were the parasitic phytopathogens Melampsora pinitorqua, M. populnea and Venturia tremulae, and the herbivorous leaf-beetle Phratora vitellinae. To address this question inoculation experiments, feeding preference experiments, analyses of secondary chemistry and field inventories were performed. The results of the studies showed that the GM trees significantly affected the interaction with the natural enemies, both in the laboratory as well as in the field. For instance, both M. pinitorqua and V. tremulae showed an altered disease incidence on the GM trees of P. tremula x tremuloides compared to the unmodified wild type T89, where all tested transgenic lines exhibited altered susceptibility to the pathogens. However, there were also differences in aggressiveness to the aspens depending on pathogen population. The results from the field inventory showed that lines within all tested transgenic construct, COMT, CAD, CCoAOMT and CCR of P. tremula x alba differed significantly from the wild type INRA 717-1-B4 in susceptibility to M. populnea. In addition, the susceptibility to the rust also differed significantly between lines carrying the same transgenic constructs. Furthermore, we found that overexpression of SPS in P. tremula x tremuloides, unintentionally induced changes in plant secondary chemistry, where the GM-line SPS33A exhibited the largest deviation from the wild type T89 in contents of plant phenolics and nitrogen, and that these changes coincide with a concurrent decrease in herbivory by P. vitellinae on this line. I argue that the altered interactions are the result of physiological changes in the trees. They can originate from direct effects i.e. altered expression of the modified trait, indirect effects of the genetic modification process e.g. pleiotropy, or effects from the transformation process e.g. position effects, to which the tested natural enemies respond. The result stresses the importance of further research on the causes and mechanisms responsible for the altered interaction between GM trees and non-target organisms, as well as evaluating the potential environmental effects of cultivation of GM trees in the field. Such research will require collaboration between researchers from different disciplines, such as plant ecology and physiology, functional genomics, proteomics and metabolomics.
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| 29. |
- Boberg, Johanna, et al.
(författare)
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A novel comparative research platform designed to determine the functional significance of tree species diversity in European forests
- 2013
-
Ingår i: Perspectives in Plant Ecology, Evolution and Systematics. - : Elsevier BV. - 1433-8319 .- 1618-0437. ; 15, s. 281-291
-
Tidskriftsartikel (refereegranskat)abstract
- One of the current advances in functional biodiversity research is the move away from short-lived test systems towards the exploration of diversity-ecosystem functioning relationships in structurally more complex ecosystems. In forests, assumptions about the functional significance of tree species diversity have only recently produced a new generation of research on ecosystem processes and services. Novel experimental designs have now replaced traditional forestry trials, but these comparatively young experimental plots suffer from specific difficulties that are mainly related to the tree size and longevity. Tree species diversity experiments therefore need to be complemented with comparative observational studies in existing forests. Here we present the design and implementation of a new network of forest plots along tree species diversity gradients in six major European forest types: the FunDivEUROPE Exploratory Platform. Based on a review of the deficiencies of existing observational approaches and of unresolved research questions and hypotheses, we discuss the fundamental criteria that shaped the design of our platform. Key features include the extent of the species diversity gradient with mixtures up to five species, strict avoidance of a dilution gradient, special attention to community evenness and minimal covariation with other environmental factors. The new European research platform permits the most comprehensive assessment of tree species diversity effects on forest ecosystem functioning to date since it offers a common set of research plots to groups of researchers from very different disciplines and uses the same methodological approach in contrasting forest types along an extensive environmental gradient. (C) 2013 Elsevier GmbH. All rights reserved.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Boberg, Johanna, et al.
(författare)
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Fungal C translocation restricts N-mineralization in heterogeneous environments
- 2010
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 24, s. 454-459
-
Tidskriftsartikel (refereegranskat)abstract
- P>1. In forest soils, fungi generally dominate the decomposer community, but their specific, filamentous physiology is often not recognized in nitrogen (N) cycling models. Many litter degrading fungi form large mycelia and have a well-developed capacity to translocate resources within their mycelia. Fungi may thus connect substrates that differ with respect to carbon (C) and nitrogen (N) availability and, thereby, overcome local resource limitation through translocation.2. Here we test whether the ability of fungi to translocate carbohydrates within their mycelia prevents local C limitation in a low C:N ratio substrate, thereby reducing N mineralization. The capacity of fungi to translocate N to a high C:N ratio substrate in order to increase the decomposition, was also assessed. Two litter decomposing fungi, Marasmius androsaceus and Mycena epipterygia were grown in axenic laboratory microcosms containing spatially separated substrates: pine needles (C:N = 135) and glycine (C:N = 2).3. In the absence of needles both fungi mineralized the glycine N. When connecting the two substrates, both fungi were able to overcome local C-deficiency on the glycine medium by translocating carbohydrates from the needles. In the presence of needles, N mineralization from glycine was negligible, although the glycine was utilized. Only trace amounts of N were translocated from glycine to the needles.4. A basic assumption of N cycling models is that substrates of different qualities decompose in an independent manner. Our observations imply that this assumption may be violated in heterogenic environments dominated by fungi.
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| 34. |
- Boberg, Johanna, et al.
(författare)
-
Life after tree death: Does restored dead wood host different fungal communities to natural woody substrates?
- 2018
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 409, s. 863-871
-
Tidskriftsartikel (refereegranskat)abstract
- In Europe, enhancing the amount of dead wood, and thereby promoting habitats for saproxylic species, is one of the most commonly applied restorative treatments in intensively managed forests. This study examines whether the different tree-level treatments utilized to increase the amount of dead wood (girdling, chainsaw felling, and uprooting) have an effect on the wood-inhabiting fungi in the logs of Scots pine (Pinus sylvestris). We also investigate whether the structure (diversity and composition) of these communities differ from those that occur in pine wood substrates that have been uprooted naturally. The study was conducted within currently protected forests that have been previously managed for timber production. Both fungal DNA (for sequence-based identification) and the presence of sporocarps of polypore fungi were surveyed from the logs. Based on the results, greater number of species were associated with the girdled logs compared to the other types of dead wood. The method of felling the trees (uprooting vs. chainsaw-felling) also resulted in differences in community composition, but this mainly concerned the sporocarp occurrence of polypore fungi. Fungal communities on naturally uprooted dead wood had more variation to the restored logs. Overall, our results suggest that restoration of dead wood can provide substrates for many fungi, including Red Listed polypores, and successfully contribute to achieving some of the restoration targets. However, to capture most of the variation in natural fungal communities, several methods should be used together when artificially increasing the amount of dead wood in forest ecosystems.
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| 35. |
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| 36. |
- Boberg, Johanna, et al.
(författare)
-
Nitrogen and Carbon Reallocation in Fungal Mycelia during Decomposition of Boreal Forest Litter
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:3, s. e92897-
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal forests are characterized by spatially heterogeneous soils with low N availability. The decomposition of coniferous litter in these systems is primarily performed by basidiomycete fungi, which often form large mycelia with a well-developed capacity to reallocate resources spatially-an advantageous trait in heterogeneous environments. In axenic microcosm systems we tested whether fungi increase their biomass production by reallocating N between Pinus sylvestris (Scots pine) needles at different stages of decomposition. We estimated fungal biomass production by analysing the accumulation of the fungal cell wall compound chitin. Monospecific systems were compared with systems with interspecific interactions. We found that the fungi reallocated assimilated N and mycelial growth away from well-degraded litter towards fresh litter components. This redistribution was accompanied by reduced decomposition of older litter. Interconnection of substrates increased over-all fungal C use efficiency (i.e. the allocation of assimilated C to biomass rather than respiration), presumably by enabling fungal translocation of growth-limiting N to litter with higher C quality. Fungal connection between different substrates also restricted N-mineralization and production of dissolved organic N, suggesting that litter saprotrophs in boreal forest ecosystems primarily act to redistribute rather than release N. This spatial integration of different resource qualities was hindered by interspecific interactions, in which litters of contrasting quality were colonised by two different basidiomycete species. The experiments provide a detailed picture of how resource reallocation in two decomposer fungi leads to a more efficient utilisation of spatially separated resources under N-limitation. From an ecosystem point of view, such economic fungal behaviour could potentially contribute to organic matter accumulation in the litter layers of boreal forests.
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| 37. |
- Boberg, Johanna, et al.
(författare)
-
Nitrogen availability affects saprotrophic basidiomycetes decomposing pine needles in a long term laboratory study
- 2011
-
Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 4, s. 408-416
-
Tidskriftsartikel (refereegranskat)abstract
- Fungi, especially basidiomycetous litter decomposers, are pivotal to the turnover of soil organic matter in forest soils. Many litter decomposing fungi have a well-developed capacity to translocate resources in their mycelia, a feature that may significantly affect carbon (C) and nitrogen (N) dynamics in decomposing litter. In an eight-month long laboratory study we investigated how the external availability of N affected the decomposition of Scots pine needles, fungal biomass production, N retention and N-mineralization by two litter decomposing fungi - Marasmius androsaceus and Mycena epipterygia. Glycine additions had a general, positive effect on fungal biomass production and increased accumulated needle mass loss after 8 months, suggesting that low N availability may limit fungal growth and activity in decomposing pine litter. Changes in the needle N pool reflected the dynamics of the fungal mycelium. During late decomposition stages, redistribution of mycelium and N out from the decomposed needles was observed for M. epipterygia, suggesting autophagous self degradation. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.
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| 38. |
- Boberg, Johanna, et al.
(författare)
-
Skadegörarna utmanar skogen
- 2014
-
Ingår i: Future Forests Syntes.
-
Annan publikation (populärvet., debatt m.m.)abstract
- Invasiva skadegörare är främmande arter som som hamnat i en ny miljö och därigenom ofta orsakar stor skada. Skadegörare i skog består till största delen av olika insekter och svamp-patogener som orsakar sjukdomar. Introduktionen av invasiva skadegörare till Europas skogar har mer än fördubblats under de senaste 100 åren. De invasiva skadegörarna sprids effektivt via handeln med växter och växtmaterial, men även i förpackningsmaterial, som lastpallar. Svamppatogener introduceras oftast genom import av levande plantor medan skadliga insekter som barkborrar och nematoder oftast transporteras med trä och träprodukter. Den potentiella kostnaden orsakade av invasiva skadegörare är enorm. Att hantera almsjukan, en patogen som påverkat ett trädslag med liten utbredning i Sverige, har uppskattats kosta 20-54 miljoner kronor per år. Inkluderas värdeförluster ökar kostnaden med upp till 37 gånger! Skulle de dominerande trädslagen gran eller tall hotas av en invasiv art på liknande sätt som almen skulle kostnaderna snabbt kunna blir mycket stora. Dessutom går stora värden i kulturlandskapet och i biologisk mångfald förlorade.
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| 39. |
- Brodde, Laura, et al.
(författare)
-
A Reliable and Simple Method for the Production of Viable Pycnidiospores of the Pine Pathogen Diplodia sapinea and a Spore-Based Infection Assay on Scots Pine
- 2023
-
Ingår i: Plant Disease. - 0191-2917 .- 1943-7692. ; 107, s. 3370-3377
-
Tidskriftsartikel (refereegranskat)abstract
- Diplodia sapinea is a globally distributed opportunistic fungal pathogen of conifers that causes severe production losses in forestry. The fungus frequently colonizes pine trees as an endophyte without causing visible symptoms but can become pathogenic when the host plant is weakened by stress, such as drought or heat. Forest damage might therefore further increase due to the effects of climate change. The future development of control strategies depends on a better understanding of the fungus' biology, which requires experimental methods for its investigation in the laboratory. An efficient, standardized protocol for the production and storage of highly viable pycnidiospores was developed, and a spore-based infection method was devised. We compared infection rates of dormant and actively growing, wounded, or nonwounded Scots pine seedlings inoculated with in vitro-produced spores and mycelium from agar-plugs. Spores were a much more efficient inoculum for causing disease symptoms on wounded plants than the conventional agar plug. The application of spores on nonwounded plants lead to high rates of asymptomatic infection, suggesting endophytic fungal development. These methods enable standardized spore infection and virulence assays and promote D. sapinea as a model organism for studying the switch from endophytic to pathogenic life styles of forest pathogens.
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| 40. |
- Brodde, Laura, et al.
(författare)
-
Diplodia sapinea as a contributing factor in the crown dieback of Scots pine (Pinus sylvestris) after a severe drought
- 2023
-
Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 549
-
Tidskriftsartikel (refereegranskat)abstract
- The frequency and impact of drought on global ecosystems have increased within the last century, while drought has affected tree health in many regions. Diplodia sapinea is a widespread, opportunistic pathogen infecting most conifers, causing Diplodia tip blight, thriving on hosts impacted by stress such as drought, heat, or mechanical wounding. In summer of 2018, a large-scale drought was recorded all over Europe. In late summer, pine trees all over Gotland showed crown dieback, where necrotic twigs and needles were found, especially in the upper part of the crowns. Symptoms were consistent with a potential outbreak of D. sapinea. Effects of the combination of drought and Diplodia tip blight on mortality or recovery of Scots pine in Nordic conditions are unknown. This study confirmed the presence and potential contribution of D. sapinea in the observed damages of Scots pine. Shoot blight and drought led to crown defoliation which was observed one year post-drought, while trees showed a clear recovery of newly grown shoots within the second year. Severely affected pines (>70% of the upper third of the crown with shoot blight) showed increased mortality. Recovery of the surviving trees was independent of previous dieback levels. Diplodia sapinea was most abundant in twigs with shoot blight of the symptomatic trees compared to healthy-looking twigs from the same trees and asymptomatic trees in affected and healthy pine stands. Sampling on affected and healthy sites showed possible endophytic infections with low abundance within healthy-looking twigs. Spore deposition of D. sapinea was monitored on healthy and affected sites for two consecutive years after crown damages occurred to confirm the presence of the opportunistic pathogen in the affected region. Spore deposition was observed during all seasons and correlated with high precipitation during sampling. Our observations provide insights into the emergence of Diplodia tip blight in the Northern countries and underline the potential impact of D. sapinea on tree health in the course of a changing climate.
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| 41. |
- Brodde, Laura, et al.
(författare)
-
Diplodia Tip Blight on Its Way to the North: Drivers of Disease Emergence in Northern Europe
- 2019
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Disease emergence in northern and boreal forests has been mostly due to tree-pathogen encounters lacking a co-evolutionary past. However, outbreaks involving novel interactions of the host or the pathogen with the environment have been less well documented. Following an increase of records in Northern Europe, the first large outbreak of Diplodia sapinea on Pinus sylvastris was discovered in Sweden in 2016. By reconstructing the development of the epidemic, we found that the attacks started approx. 10 years back from several isolated trees in the stand and ended up affecting almost 90% of the trees in 2016. Limited damage was observed in other plantations in the surroundings of the affected stand, pointing to a new introduced pathogen as the cause of the outbreak. Nevertheless, no genetic differences based on SSR markers were found between isolates of the outbreak area and other Swedish isolates predating the outbreak or from other populations in Europe and Asia Minor. On a temporal scale, we saw that warm May and June temperatures were associated with higher damage and low tree growth, while cold and rainy conditions seemed to favor growth and deter disease. At a spatial scale, we saw that spread occurred predominantly in the SW aspect-area of the stand. Within that area and based on tree-ring and isotope (delta C-13) analyses, we saw that disease occurred on trees that over the years had shown a lower water-use efficiency (WUE). Spore traps showed that highly infected trees were those producing the largest amount of inoculum. D. sapinea impaired latewood growth and reduced C reserves in needles and branches. D. sapinea attacks can cause serious economic damage by killing new shoots, disrupting the crown, and affecting the quality of stems. Our results show that D. sapinea has no limitations in becoming a serious pathogen in Northern Europe. Management should focus on reducing inoculum, especially since climate change may bring more favorable conditions for this pathogen. Seedlings for planting should be carefully inspected as D. sapinea may be present in a latent stage in asymptomatic tissues.
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| 42. |
- Capador‐Barreto, Hernán D., et al.
(författare)
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Killing two enemies with one stone? : Genomics of resistance to two sympatric pathogens in Norway spruce
- 2021
-
Ingår i: Molecular Ecology. - : John Wiley & Sons. - 0962-1083 .- 1365-294X. ; 30:18, s. 4433-4447
-
Tidskriftsartikel (refereegranskat)abstract
- Trees must cope with the attack of multiple pathogens, often simultaneously during their long lifespan. Ironically, the genetic and molecular mechanisms controlling this process are poorly understood. The objective of this study was to compare the genetic component of resistance in Norway spruce to Heterobasidion annosum s.s. and its sympatric congener Heterobasidion parviporum. Heterobasidion root- and stem-rot is a major disease of Norway spruce caused by members of the Heterobasidion annosum species complex. Resistance to both pathogens was measured using artificial inoculations in half-sib families of Norway spruce trees originating from central to northern Europe. The genetic component of resistance was analysed using 63,760 genome-wide exome-capture sequenced SNPs and multitrait genome-wide associations. No correlation was found for resistance to the two pathogens; however, associations were found between genomic variants and resistance traits with synergic or antagonist pleiotropic effects to both pathogens. Additionally, a latitudinal cline in resistance in the bark to H. annosum s.s. was found; trees from southern latitudes, with a later bud-set and thicker stem diameter, allowed longer lesions, but this was not the case for H. parviporum. In summary, this study detects genomic variants with pleiotropic effects which explain multiple disease resistance from a genic level and could be useful for selection of resistant trees to both pathogens. Furthermore, it highlights the need for additional research to understand the evolution of resistance traits to multiple pathogens in trees.
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| 43. |
- Castaño Soler, Carles, et al.
(författare)
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Optimized metabarcoding with Pacific biosciences enables semi-quantitative analysis of fungal communities
- 2020
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 228, s. 1149-1158
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies have questioned the use of high-throughput sequencing of the nuclear ribosomal internal transcribed spacer (ITS) region to derive a semi-quantitative representation of fungal community composition. However, comprehensive studies that quantify biases occurring during PCR and sequencing of ITS amplicons are still lacking. We used artificially assembled communities consisting of 10 ITS-like fragments of varying lengths and guanine-cytosine (GC) contents to evaluate and quantify biases during PCR and sequencing with Illumina MiSeq, PacBio RS II and PacBio Sequel I technologies. Fragment length variation was the main source of bias in observed community composition relative to the template, with longer fragments generally being under-represented for all sequencing platforms. This bias was three times higher for Illumina MiSeq than for PacBio RS II and Sequel I. All 10 fragments in the artificial community were recovered when sequenced with PacBio technologies, whereas the three longest fragments (> 447 bases) were lost when sequenced with Illumina MiSeq. Fragment length bias also increased linearly with increasing number of PCR cycles but could be mitigated by optimization of the PCR setup. No significant biases related to GC content were observed. Despite lower sequencing output, PacBio sequencing was better able to reflect the community composition of the template than Illumina MiSeq sequencing.
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| 44. |
- Chaudhary, Rajiv, et al.
(författare)
-
Combining transcriptomics and genetic linkage based information to identify candidate genes associated with Heterobasidion-resistance in Norway spruce
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The Heterobasidion annosum s.l species complex comprises the most damaging forest pathogens to Norway spruce. We revisited previously identified Quantitative Trait Loci (QTLs) related to Heterobasidion-resistance in Norway spruce to identify candidate genes associated with these QTLs. We identified 329 candidate genes associated with the resistance QTLs using a gene-based composite map for Pinaceae. To evaluate the transcriptional responses of these candidate genes to H. parviporum, we inoculated Norway spruce plants and sequenced the transcriptome of the interaction at 3 and 7 days post inoculation. Out of 298 expressed candidate genes 124 were differentially expressed between inoculation and wounding control treatment. Interestingly, PaNAC04 and two of its paralogs in the subgroup III-3 of the NAC family transcription factors were found to be associated with one of the QTLs and was also highly induced in response to H. parviporum. These genes are possibly involved in the regulation of biosynthesis of flavonoid compounds. Furthermore, several of the differentially expressed candidate genes were associated with the phenylpropanoid pathway including a phenylalanine ammonia-lyase, a cinnamoyl-CoA reductase, a caffeoyl-CoA O-methyltransferase and a PgMYB11-like transcription factor gene. Combining transcriptome and genetic linkage analyses can help identifying candidate genes for functional studies and molecular breeding in non-model species.
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| 45. |
- Chaudhary, Rajiv, et al.
(författare)
-
Marker-Trait Associations for Tolerance to Ash Dieback in Common Ash (Fraxinus excelsior L.)
- 2020
-
Ingår i: Forests. - : MDPI. - 1999-4907. ; 11:10
-
Tidskriftsartikel (refereegranskat)abstract
- Common ash (Fraxinus excelsior L.) is a tree species of significant ecological and economic importance that has suffered a devastating decline since the 1990s in Europe. Native ash species are being threatened by the alien invasive fungus Hymenoscyphus fraxineus, which causes ash dieback. The main goal of the study was to develop markers for traits related to tolerance to ash dieback and to investigate whether genotypes selected for tolerance were genetically different from susceptible wild populations. We phenotyped 326 ash trees from Sweden for disease severity and genotyped them using 63 amplicon-derived single-nucleotide polymorphism (SNP) markers derived from genes in 40 scaffolds spanning 8 MB in total, which represents approximately 1% of the ash genome. We used a mixed linear model to test for an association between genotypic variation at these loci and disease severity of ash. In total, two SNPs were found to have significant associations. One non-synonymous SNP associated with the disease severity of ash was found in a gene predicted to encode a subtilisin-related peptidase S8/S53 domain. A second marginally significant marker was associated with an LRR gene. Our results demonstrate an inexpensive time-effective method for generating genomic data that could have potential for use in future tree breeding programs and provide information for marker-assisted selection. Our study also showed a low differentiation between genotypes selected for disease tolerance and the wild population of ash representing a range of susceptibilities to ash dieback, indicating opportunities for further selection without significantly losing genetic diversity in the ash population.
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| 46. |
- Chen, Zhi‑Qiang, et al.
(författare)
-
Early selection for resistance to Heterobasidion parviporum in Norway spruce is not likely to adversely affect growth and wood quality traits in late-age performance
- 2018
-
Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 137:4, s. 517-525
-
Tidskriftsartikel (refereegranskat)abstract
- Infections with Heterobasidion parviporum devalue the Norway spruce timber as the decayed wood does not meet the necessary quality requirements for sawing. To evaluate the incorporation of disease resistance in the Norway spruce breeding strategy, an inoculation experiment with H. parviporum on 2-year-old progenies of 466 open-pollinated families was conducted under greenhouse (nursery) conditions. Lesion length in the phloem (LL), fungal growth in sapwood (FG) and growth (D) were measured on an average of 10 seedlings for each family. The genetic variation and genetic correlations between both LL, FG and growth in the nursery trial and wood quality traits measured previously from 21-year old trees in two progeny trials, including solid-wood quality traits (wood density, and modulus of elasticity) and fiber properties traits (radial fiber width, tangential fiber width, fiber wall thickness, fiber coarseness, microfibril angle and fiber length). For both LL and FG, large coefficients of phenotypic variation (> 26%) and genetic variation (> 46%) were detected. Heritabilities of LL and FG were 0.33 and 0.42, respectively. We found no significant correlations between wood quality traits and growth in the field progeny trials with neither LL nor FG in the nursery trial. Our data suggest that the genetic gains may reach 41 and 52% from mass selection by LL and FG, respectively. Early selection for resistance to H. parviporum based on assessments of fungal spread in the sapwood in nursery material, FG, will not adversely affect growth and wood quality traits in late-age performance.
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| 47. |
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| 48. |
- Cleary, Michelle, et al.
(författare)
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Friend or foe? Biological and ecological traits of the European ash dieback pathogen Hymenoscyphus fraxineus in its native environment
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Hymenoscyphus fraxineus, an introduced ascomycete fungus and primary causal agent of European ash dieback, was investigated on Fraxinus mandshurica trees in its native range in Primorye region of Far East Russia. This evidence is the first report of H. fraxineus on healthy, asymptomatic F. mandshurica trees. High-throughput sequencing revealed 49 distinct fungal taxa associated with leaves of F. mandshurica, 12 of which were identified to species level. Phyllosphere fungal assemblages were similar among sites despite being largely geographically distant. Many organisms comprising the foliar fungal community on F. mandshurica in Far East Russia have similarity to those reported inhabiting F. excelsior in Europe based on previous studies. However, Mycosphaerella sp., the most dominant species in this study and detected in nearly all samples, was associated only with F. mandshurica. Genetic diversity of H. fraxineus was significantly higher in the Far East Russian population than in Europe. In contrast to its aggressive behaviour on Fraxinus excelsior in Europe, H. fraxineus appears to be a benign associate of indigenous F. mandshurica that initially induces quiescent and asymptomatic infections in healthy trees prior to active host colonization normally associated with modification of host tissue during senescence.
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- Cleary, Michelle, et al.
(författare)
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Genotypes of Fraxinus excelsior with different susceptibility to the ash dieback pathogen Hymenoscyphus pseudoalbidus and their response to the phytotoxin viridiol - A metabolomic and microscopic study
- 2014
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 102, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- Eight European ash (Fraxinus excelsior) genotypes with different known susceptibility to Hymenoscyphus pseudoalbidus were tested against the phytotoxin viridiol and their response described at the microscopic and metabolomic level. All ash genotypes were sensitive to the toxin and necrosis was detectable after 24 h. Among the three viridiol concentrations used in the experiment, the lowest concentration (14.7 mu M) yielded markedly lower mean damage scores compared to those resulting from seedlings tested at higher dosages. The highest damage scores were associated with the susceptible ash clones S-101, S-106 and S-125, but also with resistant clone R-104. Three resistant clones (R-131, R-121, and R-118) had lower mean damage scores compared to susceptible clones. Wilting of leaves was more common 48 h after treatment and more pronounced on seedlings with high damage scores. The resulting lesions generally lacked browning of tissue and displayed only surface disruption of cells in direct contact with the toxin. A delay in symptom development was evident on all five resistant clones tested with the two higher concentrations of viridiol. LC-HRMS and MS/MS analyses of ash seedling extracts suggest several secoiridoid compounds as well as compounds related to abscisic acid (ABA) to be produced in response to viridiol. ABA-cysteine and xanthoxin were found at significantly higher concentrations in susceptible clones compared to resistant clones after treatment with viridiol, suggesting a primary role of ABA in response to stress. The results observed in this study suggest that genetic resistance to H. pseudoalbidus among ash genotypes may be explained, in part, by the varied response to phytotoxins produced by the fungus. (C) 2014 Elsevier Ltd. All rights reserved.
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