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- Andersson, Pierre, et al.
(author)
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B-norsteroids from Hymenoscyphus pseudoalbidus
- 2012
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In: Molecules. - : MDPI AG. - 1420-3049. ; 17, s. 7769-7781
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Journal article (peer-reviewed)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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| 6. |
- Andersson, Pierre, et al.
(author)
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Viridin-like steroids from Hymenoscyphus pseudoalbidus
- 2013
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In: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 86, s. 195-200
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Journal article (peer-reviewed)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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| 7. |
- Arhipova, Natalija, et al.
(author)
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Decay, yield loss and associated fungi in stands of grey alder (Alnus incana) in Latvia
- 2011
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In: Forestry. - : Oxford University Press (OUP). - 0015-752X .- 1464-3626. ; 84, s. 337-348
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Journal article (peer-reviewed)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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| 8. |
- Arhipova, Natalija, et al.
(author)
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Heart-rot and associated fungi in Alnus glutinosa stands in Latvia
- 2012
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In: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 327-336
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Journal article (peer-reviewed)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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- Arnerup Christiansson, Jenny, et al.
(author)
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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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In: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 237, s. 1037-1045
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Journal article (peer-reviewed)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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| 10. |
- Arnerup, Jenny, et al.
(author)
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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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In: Tree Physiology. - : Oxford University Press. - 0829-318X .- 1758-4469. ; 31:11, s. 1262-1272
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Journal article (peer-reviewed)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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