1. |
- Carlsson, Fredrik, 1974-, et al.
(author)
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Increased heat resistance in mycelia from wood fungi prevalent in forests characterized by fire : a possible adaptation to forest fire.
- 2012
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 116:10, s. 1025-1031
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Journal article (peer-reviewed)abstract
- AbstractForest fire has for a long time been the major stand replacing/modifying disturbance in boreal forests. For organisms to adopt to this phenomenon different strategies for protective measurements has evolved. This study focuses on the organism group of wood fungi, and one of several possibilities for adaptation to forest fire - increased heat resistance in the mycelia. 16 species of wood fungi where selected and sorted a priori according to their prevalence for fire affected substrate. These were isolated and re-inoculated on pine wood before testing. Experiments where done in a series where the mycelia was exposed to 100, 140, 180, 220°C for 5, 10, 15, 20, 15 min. A very clear difference was found, the group containing species with a prevalence for a fire affected substrate had a much higher survival rate over all combinations of time and temperature compared to species with a more general ecology. This data suggests that increased heat resistance in mycelia could be a possible adaptation to forest fire. This in turn has major impacts on the ecology and population dynamics of wood fungi. An increase in temperature could shift the population structure in a log, allowing minor non fruiting mycelia content to expand on the expense of earlier dominant colonizers. Furthermore this study has implications on how to control prescribed restoration burning events. When burning areas where the dead wood content is dominated by early decay stages, loss of species can be avoided by proper management.
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2. |
- Corcoran, Padraic, et al.
(author)
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Quantifying functional heterothallism in the pseudohomothallic ascomycete Neurospora tetrasperma
- 2012
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 116:9, s. 962-975
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Journal article (peer-reviewed)abstract
- Neurospora tetrasperma is a pseudohomothallic filamentous ascomycete that has evolved from heterothallic ancestors. Throughout its life cycle, it is predominantly heterokaryotic for mating type, and thereby self-fertile. However, studies of N. tetrasperma have revealed the occasional production of self-sterile asexual and sexual spores of a single-mating type, indicating that it can be functionally heterothallic. Here, we report the extensive sampling and isolation of natural, heterokaryotic, strains of N. tetrasperma from the United Kingdom (UK): 99 strains were collected from Surrey, England, and four from Edinburgh, Scotland. We verified by phylogenetic analyses that these strains belong to N. tetrasperma. We isolated cultures from single germinated asexual spores (conidia) from 17 of these newly sampled UK strains from Surrey, and 16 previously sampled strains of N. tetrasperma from New Zealand (NZ). Our results show that the N. tetrasperrna strains from the UK population produced a significantly greater proportion of self-sterile, homokaryotic conidia than the NZ population: the proportion of homokaryotic conidia was 42.6 % (133/312 spores) and 15.3 % (59/386) from the UK and the NZ populations, respectively. Although homokaryons recovered from several strains show a bias for one of the mating types, the total ratio of mat A to mat a mating type in homokaryons (UK: 72/61, NZ 28/31) did not deviate significantly from the expected 1:1 ratio for either of these populations. These results indicate that different populations exhibit differences in their life cycle characteristics, and that a higher degree of outcrossing might be expected from the UK population. This study points to the importance of studying multiple strains and populations when investigating life history traits of an organism with a complex life cycle, as previously undetected differences between populations may be revealed.
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3. |
- Grenville-Briggs, Laura J., et al.
(author)
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A family of small tyrosine rich proteins is essential for oogonial and oospore cell wall development of the mycoparasitic oomycete Pythium oligandrum
- 2013
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 117:3, s. 163-172
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Journal article (peer-reviewed)abstract
- The mycoparasitic oomycete Pythium oligandrum is homothallic, producing an abundance of thick-walled spiny oospores in culture. After mining a cDNA sequence dataset, we identified a family of genes that code for small tyrosine rich (Pythium oligandrum small tyrosine rich (PoStr)) proteins. Sequence analysis identified similarity between the PoStr proteins and putative glycine-rich cell wall proteins from the related plant pathogenic oomycete Pythium ultimum, and mating-induced genes from the oomycete Phytophthora infestans. Expression analysis showed that PoStr transcripts accumulate during oospore production in culture and immunolocalisation indicates the presence of these proteins in oogonial and oospore cell walls. PoStr protein abundance correlated positively with production of oogonia as determined by antibiotic-mediated oogonia suppression. To further characterise the role of PoStr proteins in P. oligandrum oospore production, we silenced this gene family using homology-dependent gene silencing. This represents the first characterisation of genes using gene silencing in a Pythium species. Oospores from silenced strains displayed major ultrastructural changes and were sensitive to degradative enzyme treatment. Oogonia of silenced strains either appeared to be arrested at the mature oosphere stage of development or in around 40 % of the structures, showed a complete suppression of oospore formation. Suppressed oogonia were highly vacuolated and the oogonium wall was thickened by a new inner wall layer. Our data suggest PoStr proteins are probably integral structural components of the normal oospore cell wall and play a key role in oospore formation.
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4. |
- Kosawang, Chatchai, et al.
(author)
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Zearalenone detoxification by zearalenone hydrolase is important for the antagonistic ability of Clonostachys rosea against mycotoxigenic Fusarium graminearum
- 2014
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 118:4, s. 364-373
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Journal article (peer-reviewed)abstract
- The fungus Clonostachys rosea is antagonistic against plant pathogens, including Fusarium grarninearum, which produces the oestrogenic mycotoxin zearalenone (ZEA). ZEA inhibits other fungi, and C. rosea can detoxify ZEA through the enzyme zearalenone lactonohydrolase (ZHD101). As the relevance of ZEA detoxification for biocontrol is unknown, we studied regulation and function of ZHD101 in C. rosea. Quantitative reverse-transcription PCR revealed zhd101 gene expression in all conditions studied and demonstrated dose-dependent induction by ZEA. Known inducers of the Polyketide Synthase pathway did not induce zhd101 expression, suggesting specificity of the enzyme towards ZEA. To assess the role of ZHD101 during biocontrol interactions, we generated two Delta zhd101 mutants incapable of ZEA-detoxification and confirmed their defect in degrading ZEA by HPLC. The Delta zhd101 mutants displayed a lower in vitro ability to inhibit growth of the ZEA-producing F. graminearum (strain 1104-14) compared to the wild type. In contrast, all three C. rosea strains equally inhibited growth of the F. graminearum mutant (Delta PKS4), which is impaired in ZEA-production. Furthermore, the Delta zhd101 mutants failed to protect wheat seedlings against foot rot caused by the ZEA-producing F. graminearum. These data show that ZEA detoxification by ZHD101 is important for the biocontrol ability of C. rosea against F. graminearum.
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5. |
- Menkis, Audrius, et al.
(author)
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Archaeorhizomyces borealis sp nov and a sequence-based classification of related soil fungal species
- 2014
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 118:12, s. 943-955
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Journal article (peer-reviewed)abstract
- The class Archaeorhizomycetes (Taphrinomycotina, Ascomycota) was introduced to accommodate an ancient lineage of soil-inhabiting fungi found in association with plant roots. Based on environmental sequencing data Archaeorhizomycetes may comprise a significant proportion of the total fungal community in soils. Yet the only species described and cultivated in this class is Archaeorhizomyces finlayi. In this paper, we describe a second species from a pure culture, Archaeorhizomyces borealis NS99-600(T) (=CBS138755(ExT)) based on morphological, physiological, and multi-locus molecular characterization. Archaeorhizomyces borealis was isolated from a root tip of a Pinus sylvestris seedling grown in a forest nursery in Lithuania. Analysis of Archaeorhizomycete species from environmental samples shows that it has a Eurasian distribution and is the most commonly observed species. Archaeorhizomyces borealis shows slow growth in culture and forms yellowish creamy colonies, characteristics that distinguish A. borealis from its closest relative A. finlayi. Here we also propose a sequence-based taxonomic classification of Archaeorhizomycetes and predict that approximately 500 species in this class remain to be isolated and described.
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6. |
- Saraiva, Marcia, et al.
(author)
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Functional characterization of a tyrosinase gene from the oomycete Saprolegnia parasitica by RNAi silencing
- 2014
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In: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 118:7, s. 621-629
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Journal article (peer-reviewed)abstract
- Here we describe the first application of transient gene silencing in Saprolegnia parasitica, a pathogenic oomycete that infects a wide range of fish, amphibians, and crustaceans. A gene encoding a putative tyrosinase from S. parasitica, SpTyr, was selected to investigate the suitability of RNA-interference (RNAi) to functionally characterize genes of this economically important pathogen. Tyrosinase is a mono-oxygenase enzyme that catalyses the O-hydroxylation of monophenols and subsequent oxidation of O-diphenols to quinines. These enzymes are widely distributed in nature, and are involved in the melanin biosynthesis. Gene silencing was obtained by delivering in vitro synthesized SpTyr dsRNA into protoplasts. Expression analysis, tyrosinase activity measurements, and melanin content analysis confirmed silencing in individual lines. Silencing of SpTyr resulted in a decrease of tyrosinase activity between 38 % and 60 %, dependent on the level of SpTyr-expression achieved. The SpTyr-silenced lines displayed less pigmentation in developing sporangia and occasionally an altered morphology. Moreover, developing sporangia from individual silenced lines possessed a less electron dense cell wall when compared to control lines, treated with GFP-dsRNA. In conclusion, the tyrosinase gene of S. parasitica is required for melanin formation and transient gene silencing can be used to functionally characterize gene S in S. parasitica.
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7. |
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8. |
- Vinnere Pettersson, Olga, et al.
(author)
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Phylogeny and intraspecific variation of the extreme xerophile, Xeromyces bisporus
- 2011
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In: Fungal Biology. - Oxon, United Kingdom : Elsevier. - 1878-6146 .- 1878-6162. ; 115:11, s. 1100-1111
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Journal article (peer-reviewed)abstract
- The filamentous ascomycete Xeromyces bisporus is an extreme xerophile able to grow down to a water activity of 0.62. We have inferred the phylogenetic position of Xeromyces in relation to other xerophilic and xerotolerant fungi in the order Eurotiales. Using nrDNA and betatubulin sequences, we show that it is more closely related to the xerophilic food-borne species of the genus Chrysosporium, than to the genus Monascus. The taxonomy of X. bisporus and Monascus is discussed. Based on physiological, morphological, and phylogenetic distinctiveness, we suggest that Xeromyces should be retained as a separate genus.
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9. |
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10. |
- Andersson, Björn, et al.
(author)
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Genetic analysis of Phytophthora infestans populations in the Nordic European countries reveals high genetic variability
- 2011
-
In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 115, s. 335-342
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Journal article (peer-reviewed)abstract
- Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). The pathogen is highly adaptable and to get an overview of the genetic variation in the Nordic countries, Denmark, Finland, Norway and Sweden we have analyzed 200 isolates from different fields using nine simple-sequence repeat (SSR) markers. Forty-nine alleles were detected among the nine SSR loci and isolates from all four Nordic countries shared the most common alleles across the loci. In total 169 multi-locus genotypes (based on seven loci) were identified among 191 isolates. The genotypic diversities, quantified by a normalized Shannon's diversity index (H(s)), were 0.95 for the four Nordic countries. The low F(ST) value of 0.04 indicates that the majority of variation is found within the four Nordic countries. The large number of genotypes and the frequency distribution of mating types (60% A1) support the hypothesis that sexual reproduction is contributing notably to the genetic variation of P. infestans in the Nordic countries. (C) 2011 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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11. |
- Menkis, Audrius, et al.
(author)
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Phylogenetic relationships in European Ceriporiopsis species inferred from nuclear and mitochondrial ribosomal DNA sequences
- 2010
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 114, s. 350-358
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Journal article (peer-reviewed)abstract
- The aim of this work was to clarify taxonomy and examine evolutionary relationships within European Ceriporiopsis species using a combined analysis of the large subunit (nLSU) nuclear rRNA and small subunit (mtSSU) mitochondrial rRNA gene sequences. Data from the ITS region were applied to enhance the view of the phylogenetic relationships among different species. The studied samples grouped into four complex clades, suggesting that the genus Ceriporiopsis is polyphyletic. The generic type Ceriporiopsis gilvescens formed a separate group together with Ceriporiopsis guidella and Phlebia spp. in the phlebioid clade. In this clade, the closely related species Ceriporiopsis resinascens and Ceriporiopsis pseudogilvescens grouped together with Ceriporiopsis aneirina. C. resinascens and C. pseudogilvescens have identical LSU and SSU sequences but differ in ITS. Ceriporiopsis pannocincta also fell in the phlebioid clade, but showed closer proximity to Gloeoporus dichrous than to C. gilvescens or C. aneirina C. pseudogilvescens C. resinascens group. Another clade was composed of a Ceriporiopsis balaenae Ceriporiopsis consobrina group and was found to be closely related to Antrodiella and Frantisekia, with the overall clade highly reminiscent of the residual polyporoid clade. The monotypic genus Pouzaroporia, erected in the past for Ceriporiopsis subrufa due to its remarkable morphological differences, also fell within the residual polyporoid clade. Ceriporiopsis subvermispora held an isolated position from the other species of the genus. Therefore, the previously proposed name Gelatoporia subvermispora has been adopted for this species. Physisporinus rivulosus appeared unrelated to two other European Physisporinus species. Moreover, Ceriporiopsis (=Skeletocutis) jelicii grouped in a separate clade, distinct from Ceriporiopsis species. Finally, the ITS data demonstrated the-proximity of some Ceriporiopsis species (Ceriporiopsis portcrosensis and Ceriporiopsis subsphaerospora) to Skeletocutis amorpha. (C) 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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12. |
- Mgbeahuruike, Anthony Christian, et al.
(author)
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Differential expression of two hydrophobin genes (Pgh1 and Pgh2) from the biological control agent Phlebiopsis gigantea
- 2012
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 116, s. 620-629
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Journal article (peer-reviewed)abstract
- Phlebiopsis gigantea has been widely used as the biocontrol fungus against the root and butt rot disease of conifers caused by Heterobasidion annosum. We investigated the regulation of two hydrophobin genes (Pgh1 and Pgh2) in strong and weak antagonistic isolates of the biological control agent P. gigantea under diverse substrate conditions. Transcript abundance of Pgh1 was higher in single cultures of strong performing isolates than in the weak performing isolates at the early and late stages of the fungal growth (P = 0.05). Higher fold transcript changes of Pgh1 and Pgh2 were observed in the strong performing isolates at the early stage of the antagonistic interaction on modified Norkrans sawdust agar medium compared to the weak performing isolates. Higher transcript abundance of the two genes was also observed during growth in submerged compared to surface agar cultures (P < 0.003 and P = 0.0001 for Pgh1 and Pgh2, respectively). No correlation between antagonistic ability and sequence characteristics of either gene was found but a significant correlation was found between some strong performing isolates and the expression of Pgh1. Regulatory patterns of both Pgh1 and Pgh2 suggest a role during early stages of interaction between the two fungi and their potential roles in the biological control process is discussed. (C) 2012 British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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13. |
- Olsson, Pål Axel, et al.
(author)
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Elemental composition in vesicles of an arbuscular mycorrhizal fungus, as revealed by PIXE analysis.
- 2011
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 115:7, s. 643-648
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Journal article (peer-reviewed)abstract
- We investigated element accumulation in vesicles of the arbuscular mycorrhizal (AM) fungus Glomus intraradices, extracted from the roots of inoculated leek plants. The elemental composition (elements heavier than Mg) was quantified using particle-induced X-ray emission (PIXE), in combination with scanning transmission ion microscopy (STIM). In vesicles, P was the most abundant of the elements analysed, followed by Ca, S, Si and K. We analysed 12 vesicles from two root systems and found that the variation between vesicles was particularly high for P and Si. The P content related positively to Si, Zn and K, while its relation to Cl fitted to a negative power function. Vesicle transects showed that P and K were present in central parts, while Ca was present mainly near the vesicle surfaces. The results showed that P is an important part (0.5% of the dry weight) of the vesicle content and that the distribution of some elements, within mycelia, may be strongly correlated.
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14. |
- Ramesh, Vetukuri, et al.
(author)
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Silencing of the PiAtvr3a effector-encoding gene from Phytophthora infestans by transcriptional fusion to a short interspersed element
- 2011
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 115, s. 1225-1233
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Journal article (peer-reviewed)abstract
- Phytophthora infestans is the notorious oomycete causing late blight of potato and tomato. A large proportion of the P. infestans genome is composed of transposable elements, the activity of which may be controlled by RNA silencing. Accumulation of small RNAs is one of the hallmarks of RNA silencing. Here we demonstrate the presence of small RNAs corresponding to the sequence of a short interspersed retrotransposable element (SINE) suggesting that small RNAs might be involved in silencing of SINEs in P. infestans. This notion was exploited to develop novel tools for gene silencing in P. infestans by engineering transcriptional fusions of the PiAvr3a gene, encoding an RXLR avirulence effector, to the infSINEm retroelement. Transgenic P. infestans lines expressing either 5'-infSINEm::PiAvr3a-3' or 5'-PiAvr3a::SINEm-3' chimeric transcripts initially exhibited partial silencing of PiAvr3a. Over time, PiAvr3a either recovered wild type transcript levels in some lines, or became fully silenced in others. Introduction of an inverted repeat construct was also successful in yielding P. infestans transgenic lines silenced for PiAvr3a. In contrast, constructs expressing antisense or aberrant RNA transcripts failed to initiate silencing of PiAvr3a. Lines exhibiting the most effective silencing of PiAvr3a were either weakly or non-pathogenic on susceptible potato cv. Bintje. This study expands the repertoire of reverse genetics tools available for P. infestans research, and provides insights into a possible mode of variation in effector expression through spread of silencing from adjacent retroelements. Crown Copyright (C) 2011 Published by Elsevier Ltd on behalf of The British Mycological Society. All rights reserved.
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15. |
- Rineau, Francois, et al.
(author)
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Liming in a beech forest results in more mineral elements stored in the mantle of Lactarius subdulcis ectomycorrhizas.
- 2010
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 114:11-12, s. 1007-1014
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Journal article (peer-reviewed)abstract
- Liming is a forest practice used to counteract forest decline induced by soil acidification. It consists of direct Ca and Mg input in forest soil and restores tree mineral nutrition, but also causes drastic changes in nutrient availability in soil. Ectomycorrhizal (ECM) fungi significantly contribute in nutrient uptake by trees, and can recover them through organic acid secretion or through enzymatic degradation of organic matter. The symbiotic fungi use their extraradical mycelium for nutrient uptake, and then store them into the ECM mantle. In this study we measured how liming influences element contents in the mantle of Lactarius subdulcis ECMs, an abundant and particularly active in oxalate and laccase secretion in beech stands. For this purpose we used SEM observation coupled with energy- (EDX) and wavelength-dispersive-X-ray microanalyses (WDX). Results showed that ECM mantles of this species presented significantly higher Ca, Mg, Mn, K, Si, Al and Fe contents in limed plots. The nutrient amounts of L. subdulcis ECMs were significantly different between individuals for all the elements, showing a differential storage ability between individuals. The storage role of the ECM mantle can be interpreted in two different ways: i) a detoxification role for Al or heavy metals and ii) an increased potential nutrient resource by the fungus, which can benefit the tree.
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16. |
- Samils, Berit, et al.
(author)
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New genetic markers for identifying Cronartium flaccidum and Peridermium pini and examining genetic variation within and between lesions of Scots pine blister rust in Sweden
- 2011
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 115, s. 1303-1311
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Journal article (peer-reviewed)abstract
- Microsatellite markers were developed as an identification tool and for analysis of the genetic variation in the pathogens Cronartium flaccidum and Peridermium pini, causing Scots pine blister rust in Pinus spp. Six reference aeciospore samples from Finland were used to examine genetic differences between the two pathogens. Genetic variation within and between 27 lesions on Scots pines from seven locations in Sweden was also investigated. Aeciospores were collected from single aecia within the lesions. Reference samples from P. pini were homozygous for all seven microsatellite loci investigated, while the three C. flaccidum samples contained heterozygous loci. These results confirm previous studies, where homozygous aeciospores were indicated to be characteristic for P. pini. The majority of aeciospores had two nuclei in both heterozygotic and homozygotic samples. Five of the Swedish lesions contained only homozygotic aecia, while the aecia in the remaining 22 lesions were heterozygotic. All lesions with homozygotic aecia contained only one single multilocus genotype, while many of the lesions with heterozygotic aecia contained several genotypes. The latter indicates the occurrence of multiple matings within a lesion between the resident spermogonia and alien fertilizing spermatia. (C) 2011. British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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17. |
- Sjöholm, Lina, et al.
(author)
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Genotypic diversity and migration patterns of Phytophthora infestans in the Nordic countries
- 2013
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 117, s. 722-730
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Journal article (peer-reviewed)abstract
- In this study we investigated the genotypic diversity and the migration patterns of Phytophthora infestans in the Nordic countries. Isolates of P. infestans from outbreaks in 43 fields sampled in 2008 were collected using stratified sampling with country, field, and disease foci as the different strata. Microsatellites were used as markers to determine the genotypic variation in the sampled material. The results show a high genotypic variation of P. infestans in the Nordic countries with most of the genotypes found only once among the collected isolates. The major part of the genotypic variation was observed within the fields, with low differentiation between the fields. The observed low association of alleles among loci is consistent with frequent sexual reproduction of P. infestans in the Nordic countries. Coalescence analyses did not support a single common population for the four countries, thus indicating some degree of geographic differentiation. The analyses of migration patterns showed differing levels of gene flow among the Nordic countries. No correlation between migration rates and geographical distance could be seen. This could be explained by different degrees of genetic similarity between the pathogen populations in the different countries. (C) 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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18. |
- Van Der Nest, Magriet, et al.
(author)
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Mutualism and asexual reproduction influence recognition genes in a fungal symbiont
- 2013
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In: Fungal Biology. - : Elsevier BV. - 1878-6146. ; 117, s. 439-450
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Journal article (peer-reviewed)abstract
- Mutualism between microbes and insects is common and alignment of the reproductive interests of microbial symbionts with this lifestyle typically involves clonal reproduction and vertical transmission by insect partners. Here the Amylostereum fungus-Sirex wood-wasp mutualism was used to consider whether their prolonged association and predominance of asexuality have affected the mating system of the fungal partner. Nucleotide information for the pheromone receptor gene rab1, as well as the translation elongation factor 1 alpha gene and ribosomal RNA internal transcribed spacer region were utilized. The identification of rab1 alleles in Amylostereum chailletii and Amylostereum areolatum populations revealed that this gene is more polymorphic than the other two regions, although the diversity of all three regions was lower than what has been observed in free-living Agaricomycetes. Our data suggest that suppressed recombination might be implicated in the diversification of rab1, while no evidence of balancing selection was detected. We also detected positive selection at only two codons, suggesting that purifying selection is important for the evolution of rab1. The symbiotic relationship with their insect partners has therefore influenced the diversity of this gene and influenced the manner in which selection drives and maintains this diversity in A. areolatum and A. chailletii. (C) 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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