| 1. |
- Polme, S., et al.
(författare)
-
FungalTraits: a user-friendly traits database of fungi and fungus-like stramenopiles
- 2020
-
Ingår i: Fungal Diversity. - : Springer Science and Business Media LLC. - 1560-2745 .- 1878-9129. ; 105:1, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- The cryptic lifestyle of most fungi necessitates molecular identification of the guild in environmental studies. Over the past decades, rapid development and affordability of molecular tools have tremendously improved insights of the fungal diversity in all ecosystems and habitats. Yet, in spite of the progress of molecular methods, knowledge about functional properties of the fungal taxa is vague and interpretation of environmental studies in an ecologically meaningful manner remains challenging. In order to facilitate functional assignments and ecological interpretation of environmental studies we introduce a user friendly traits and character database FungalTraits operating at genus and species hypothesis levels. Combining the information from previous efforts such as FUNGuild and Fun(Fun) together with involvement of expert knowledge, we reannotated 10,210 and 151 fungal and Stramenopila genera, respectively. This resulted in a stand-alone spreadsheet dataset covering 17 lifestyle related traits of fungal and Stramenopila genera, designed for rapid functional assignments of environmental studies. In order to assign the trait states to fungal species hypotheses, the scientific community of experts manually categorised and assigned available trait information to 697,413 fungal ITS sequences. On the basis of those sequences we were able to summarise trait and host information into 92,623 fungal species hypotheses at 1% dissimilarity threshold.
|
|
| 2. |
- Agostinelli, Marta, et al.
(författare)
-
Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback
- 2021
-
Ingår i: Frontiers in Forests and Global Change. - : Frontiers Media S.A.. - 2624-893X. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- For the last two decades, large-scale population decline of European ash (Fraxinus excelsior) has occurred in Europe because of the introduction of the alien fungal pathogen, Hymenoscyphus fraxineus, from East Asia. Since European ash is a keystone species having critical importance for biodiversity, and only a small percentage of the ash population appears to show some tolerance against the pathogen, the loss of ash trees means that other associated organisms, especially those with high or obligate associations to ash, are at risk of further species declines. In this study, we used high throughput DNA sequencing and multivariate analysis to characterize: (i) the mycobiome in aerial tissues (i.e., leaf, bark, and xylem) of ash trees showing different phenotypic response to ash dieback, (ii) the temporal variation in fungal communities across the growing season, and (iii) the similarity in fungal community structure between ash and other common trees species that may serve as an ecological niche substitute for ash microfungi. Results showed that fungal communities differed among the three tissue types, susceptibility classes, in time and between sites. Trophic analysis of functional groups using the FUNGuild tool indicated a higher presence of pathotrophic fungi in leaves than in bark and xylem. The share of pathotrophic fungi increased along a gradient of low to high disease susceptibility in both bark and xylem tissue, while the proportion of symbiotrophic fungi correspondingly decreased in both tissue types. Neighboring, alternative host trees did not share all the fungal species found in ash, however, most microfungi uniquely associated to ash in this study are generalists and not strictly host specific. The progressive disappearance of ash trees on the landscape imposes a high risk for extinction of Red-listed macrofungal species, and breeding for resistance against ash dieback should help sustain important biodiversity associated to ash. Microfungal diversity though may be less prone to such demise since most ash-associated endophytes appear to occur on a broad range of host species.
|
|
| 3. |
- Agostinelli, Marta, et al.
(författare)
-
Pedunculate Oaks (Quercus robur L.) Differing in Vitality as Reservoirs for Fungal Biodiversity
- 2018
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Ecological significance of trees growing in urban and peri-urban settings is likely to increase in future land-use regimes, calling for better understanding of their role as potential reservoirs or stepping stones for associated biodiversity. We studied the diversity of fungal endophytes in woody tissues of asymptomatic even aged pedunculate oak trees, growing as amenity trees in a peri-urban setting. The trees were classified into three groups according to their phenotypic vitality (high, medium, and low). Endophytes were cultured on potato dextrose media from surface sterilized twigs and DNA sequencing was performed to reveal the taxonomic identity of the morphotypes. In xylem tissues, the frequency and diversity of endophytes was highest in oak trees showing reduced vitality. This difference was not found for bark samples, in which the endophyte infections were more frequent and communities more diverse than in xylem. In general, most taxa were shared across the samples with few morphotypes being recovered in unique samples. Leaf phenolic profiles were found to accurately classify the trees according to their phenotypic vitality. Our results confirm that xylem is more selective substrate for endophytes than bark and that endophyte assemblages in xylem are correlated to the degree of host vitality. Thus, high vitality of trees may be associated with reduced habitat quality to wood-associated endophytes.
|
|
| 4. |
- Andersson, Pierre, et al.
(författare)
-
Viridin-like steroids from Hymenoscyphus pseudoalbidus
- 2013
-
Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 86, s. 195-200
-
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.
|
|
| 5. |
|
|
| 6. |
- Blomquist, Mimmi, et al.
(författare)
-
Size matters but is big always better? Effectiveness of urea and Phlebiopsis gigantea as treatment against Heterobasidion on Picea abies stumps of variable size
- 2020
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 462
-
Tidskriftsartikel (refereegranskat)abstract
- Heterobasidion is a severe threat to coniferous forests in the northern hemisphere. Accurate forest management is needed to safeguard the economic values at stake. In this paper we investigate the efficacy of stump treatment with urea and Phlebiopsis gigantea as control treatment in Norway spruce against airborne Heterobasidion infections. The aim of this study was to examine the infection frequency, i.e. frequency of stumps infected by airborne spores, and efficacy of the stump treatments after performing precommercial thinning and final felling, representing highly variable stump diameters. Today treatment after these cuttings are not standard practice across the world.From a total of 27 Norway spruce stands in the southern and mid-regions of Sweden, five precommercial thinning stands and five final felling stands with infection frequencies higher than an economical threshold for treatment, 20%, were selected. In these stands, the efficacy of stump treatment using urea and P. gigantea against Heterobasidion spp. was assessed on stumps of variable diameter. Wooden discs from stumps were analyzed for airborne infections of Heterobasidion spp. 7-8 weeks after treatment. To evaluate the efficacy of treatments, we used the following three different measurements; infection frequency (proportion of infected stumps), relative infected stump area and number of Heterobasidion colonies per square dm, which were tested using three different statistical models each represented by an efficacy value. Overall, untreated stumps were infected to a higher extent than treated stumps, and most infections were found in untreated stumps from final fellings. Treatment with P. gigantea was more efficient for larger sized stumps than small. In precommercial thinnings, urea performed better and had higher mean efficacy values (92-94%) compared to P. gigantea (59%-72%). In final fellings there were no significant differences between the treatments, both had high efficacy values (urea 95.5-99.8% vs P. gigantea 90-98%).Our findings point at the need for accurate stump treatment after precommercial thinning and final felling, when infection rates are likely to be high. Urea seems to be more effective than the biological control agent P. gigantea in controlling Heterobasidion infections in stumps created in precommercial thinnings. We therefore recommend to use urea in precommercial thinnings if possible. In final fellings either urea or P. gigantea can be used.
|
|
| 7. |
- Blomquist, Mimmi, et al.
(författare)
-
The potential of biological control against Heterobasidion root rot is not realized in practical forestry
- 2023
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 531
-
Tidskriftsartikel (refereegranskat)abstract
- For about 25 years, forest managers in Sweden have been treating stumps following harvesting with Phlebiopsis gigantea, retailed as Rotstop (R) S gel, against spore infections of Heterobasidion, which cause root rot in order to minimize losses in timber production. However, not all forest managers trust the efficacy of stump treatment and this fact has hindered widespread adoption of stump treatment using P. gigantea. In this study, we evaluated stump treatment in the field during commercial thinning operations across 15 sites, by assessing the degree of stump coverage and subsequent infection levels in stump discs. In total, 45 % of all stumps were infected with Heterobasidion spp.. Nineteen percent of all stumps were considered to have full (100 %) coverage by Rotstop (R) S but contractors failed to achieve the manufacturers stipulated minimum coverage (85 %) in approximately 1/3 of all stumps. Using PCR, we could only detect the presence of P. gigantea in 73 % of the tested stumps. Large variation occurred between stump coverage and the recovery of P. gigantea in wood chip samples collected from stump discs across sites. In the worst case, we detected P. gigantea in only three out of ten treated stumps at one site. Despite this discrepancy we saw a clear reduction of the size of Heterobasidion infections on stumps where stump treatment coverage was more than 85 % of the stump surface.Our results suggest that forest operators in Sweden repeatedly fail to either apply a spore solution of P. gigantea or cover enough of the stumps to provide the desired protection. The outcome of such sub-standard application, could further undermine the usage of biological control agents in forestry and limit any potential control against Heterobasidion spp..
|
|
| 8. |
- 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.
|
|
| 9. |
|
|
| 10. |
- Cleary, Michelle
(författare)
-
A glimmer of hope - ash genotypes with increased resistance to ash dieback pathogen show cross-resistance to emerald ash borer
- 2023
-
Ingår i: New Phytologist. - 0028-646X .- 1469-8137. ; 240, s. 1219-1232
-
Tidskriftsartikel (refereegranskat)abstract
- Plants rely on cross-resistance traits to defend against multiple, phylogenetically distinct enemies. These traits are often the result of long co-evolutionary histories. Biological invasions can force naive plants to cope with novel, coincident pests, and pathogens. For example, European ash (Fraxinus excelsior) is substantially threatened by the emerald ash borer (EAB), Agrilus planipennis, a wood-boring beetle, and the ash dieback (ADB) pathogen, Hymenoscyphus fraxineus. Yet, plant cross-resistance traits against novel enemies are poorly explored and it is unknown whether na_ive ash trees can defend against novel enemy complexes via cross-resistance mechanisms.To gain mechanistic insights, we quantified EAB performance on grafted replicates of ash genotypes varying in ADB resistance and characterized ash phloem chemistry with targeted and untargeted metabolomics.Emerald ash borer performed better on ADB-susceptible than on ADB-resistant genotypes. Moreover, changes in EAB performance aligned with differences in phloem chemical profiles between ADB-susceptible and ADB-resistant genotypes.We show that intraspecific variation in phloem chemistry in European ash can confer increased cross-resistance to invasive antagonists from different taxonomic kingdoms. Our study suggests that promotion of ADB-resistant ash genotypes may simultaneously help to control the ADB disease and reduce EAB-caused ash losses, which may be critical for the long-term stability of this keystone tree species.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Cleary, Michelle
(författare)
-
Citizen science can enhance strategies to detect and manage invasive forest pests and pathogens
- 2023
-
Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 11
-
Forskningsöversikt (refereegranskat)abstract
- Incorporating a citizen science approach into biological invasion management strategies can enhance biosecurity. Many citizen science projects exist to strengthen the management of forest pest and pathogen invasions within both pre- and post-border scenarios. Besides the value of citizen science initiatives for early detection and monitoring, they also contribute widely to raising awareness, informing decisions about eradication and containment efforts to minimize pest and pathogen spread, and even finding resistant plant material for restoration of landscapes degraded by disease. Overall, many projects actively engage citizens in the different stages of forest pest and pathogen invasions, but it is unclear how they work together across all stages of the entire biological invasion process to enhance biosecurity. Here we provide examples of citizen science projects for each stage of the biological invasion process, discuss options for developing a citizen science program to enhance biosecurity, and suggest approaches for integrating citizen science into biosecurity measures to help safeguard forest resources in the future.
|
|
| 14. |
- Cleary, Michelle
(författare)
-
Cryptic Risks to Forest Biosecurity Associated with the Global Movement of Commercial Seed
- 2019
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The import and export of tree seed carries with it risks of inadvertent introduction of pests and pathogens to hitherto unaffected regions. Although trade in seed of specified trees is regulated, phytosanitary requirements for most tree species are minimal, even those related to the most important forest tree species in a given region. A better understanding of the microbiome associated with seed intended for commercial production or ornamental use, and their potential risk with the transport from the source origin of distributors, will help regulatory agencies implement measures to safeguard seed health and avoid trade-related spread of potentially harmful pathogens. In this study we used high-throughput sequencing to show that highly diverse fungal communities were associated with seed of 14 different Pinus species obtained from seed banks (seed orchards) and retail sources (online distributors) in North America and Europe. Fungal diversity differed among the 23 seedlots tested. Community composition did not relate to the species of Pinus nor the country of origin. Assigned potential functions based on sequence identity using FUNGuild provided an overall understanding of the likely life strategies of fungal operational taxonomic units (OTUs). Of those sequences classified to a trophic level, 453 were plant pathogens, with the Dothideomycetes having the highest prevalence. The most common plant pathogens included Sydowia polyspora, Lasiodiplodia theobromae, Diplodia intermedia and Diplodia sapinea that were detected from the majority of Pinus species. The evidence presented here illustrates an urgent need for plant protection authorities, practitioners and the general public to recognize the potential risk of introducing harmful pathogens through innocent transport of seed.
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
- Cleary, Michelle, et al.
(författare)
-
Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight
- 2022
-
Ingår i: Molecular Plant Pathology. - : Wiley. - 1464-6722 .- 1364-3703.
-
Tidskriftsartikel (refereegranskat)abstract
- Lecanosticta acicola is a pine needle pathogen causing brown spot needle blight that results in premature needle shedding with considerable damage described in North America, Europe, and Asia. Microsatellite and mating type markers were used to study the population genetics, migration history, and reproduction mode of the pathogen, based on a collection of 650 isolates from 27 countries and 26 hosts across the range of L. acicola. The presence of L. acicola in Georgia was confirmed in this study. Migration analyses indicate there have been several introduction events from North America into Europe. However, some of the source populations still appear to remain unknown. The populations in Croatia and western Asia appear to originate from genetically similar populations in North America. Intercontinental movement of the pathogen was reflected in an identical haplotype occurring on two continents, in North America (Canada) and Europe (Germany). Several shared haplotypes between European populations further suggests more local pathogen movement between countries. Moreover, migration analyses indicate that the populations in northern Europe originate from more established populations in central Europe. Overall, the highest genetic diversity was observed in south-eastern USA. In Europe, the highest diversity was observed in France, where the presence of both known pathogen lineages was recorded. Less than half of the observed populations contained mating types in equal proportions. Although there is evidence of some sexual reproduction taking place, the pathogen spreads predominantly asexually and through anthropogenic activity.
|
|
| 18. |
- Cleary, Michelle
(författare)
-
Effects of Host Variability on the Spread of Invasive Forest Diseases
- 2017
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 8
-
Forskningsöversikt (refereegranskat)abstract
- Biological invasions, resulting from deliberate and unintentional species transfers of insects, fungal and oomycete organisms, are a major consequence of globalization and pose a significant threat to biodiversity. Limiting damage by non-indigenous forest pathogens requires an understanding of their current and potential distributions, factors affecting disease spread, and development of appropriate management measures. In this review, we synthesize innate characteristics of invading organisms (notably mating system, reproduction type, and dispersal mechanisms) and key factors of the host population (namely host diversity, host connectivity, and host susceptibility) that govern spread and impact of invasive forest pathogens at various scales post-introduction and establishment. We examine spread dynamics for well-known invasive forest pathogens, Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, Hosoya, comb. nov., causing ash dieback in Europe, and Cryphonectria parasitica, (Murr.) Barr, causing chestnut blight in both North America and Europe, illustrating the importance of host variability (diversity, connectivity, susceptibility) in their invasion success. While alien pathogen entry has proven difficult to control, and new biological introductions are indeed inevitable, elucidating the key processes underlying host variability is crucial for scientists and managers aimed at developing effective strategies to prevent future movement of organisms and preserve intact ecosystems.
|
|
| 19. |
- Cleary, Michelle
(författare)
-
First report of Lecanosticta acicola on non-native Pinus mugo in southern Sweden
- 2019
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 49
-
Tidskriftsartikel (refereegranskat)abstract
- In 2017, severe symptoms of brown spot needle blight, similar to those caused by Lecanosticta acicola, were observed on needles of non-native Pinus mugo var. Hesse planted in an arboretum in southern Sweden. Microscopic characterization and molecular diagnostics of isolates obtained from diseased needles confirmed the identity of L. acicola. This is the first report of the quarantine pathogen L. acicola in Sweden. Subsequent surveys are urgently needed to assess the presence and extent of the L. acicola invasion in Scots pine (Pinus sylvestris) stands in Sweden and other Scandinavian countries.
|
|
| 20. |
- Cleary, Michelle, et al.
(författare)
-
First Report of Phytophthora gonapodyides Causing Stem Canker on European Beech (Fagus sylvatica) in Southern Sweden
- 2016
-
Ingår i: Plant Disease. - 0191-2917 .- 1943-7692. ; 100, s. 2174-2175
-
Tidskriftsartikel (refereegranskat)abstract
- Since 2010, extensive crown transparency of European beech (Fagus sylvatica) has been recorded in southern Sweden, with Phytophthora cambivora, P. plurivora, and P. cactorum as well as associated climatic triggers believed to be the major factors involved. In 2015, a different Phytophthora sp. was isolated from three F. sylvatica trees showing characteristic bleeding canker symptoms in Pildammsparken in Malmö, Sweden. Small sections of inner phloem were dissected at the interface between necrotic and healthy tissue, directly plated onto PAR(PH)-V8 selective medium containing 0.250 g/liter sodium ampicillin, 0.01 g/liter benomyl, 0.05 g/liter hymexazol, 0.1 g/liter PCNB, 0.05 g/liter pimaricin, and 0.01 g/liter rifamycin, and incubated at 20°C in darkness. Growing hyphae were later transferred to PDA and incubated at 20°C in the dark. The colony pattern was stellate. The average radial growth rate at 20°C was 0.6 cm/day. These morphological features are similar to that previously described for P. gonapodyides (Corcobado et al. 2010; Erwin and Ribeiro 1996; Jung et al. 1996). The isolates grown on PDA formed irregularly branched hyphae. Nonpapillate, elongated-ovoid to obpyriform sporangia (∼50 × 40 µm) were produced after 7 days by incubating on V8 agar culture (nonsterile soil water). DNA was extracted from mycelia and the identity of P. gonapodyides was confirmed by sequencing the internal transcribed (ITS) spacer region of the rDNA with the primers ITS4/ITS6 (GenBank accession nos. KX055998, KX055999, and KX056000). BLAST search showed 99 to 100% identity with reference sequences of P. gonapodyides deposited in GenBank. Pathogenicity on F. sylvatica was confirmed in a greenhouse experiment using two different isolates of P. gonapodyides. Mycelial plugs of 3-week-old cultures of each isolate grown on PDA were inoculated on the stems of 1-year-old seedlings at two locations, separated by 20 cm, by aseptically excising a small 5-mm flap of bark, inserting the mycelial plug along the cambium, and adding a droplet of Milliq H2O before sealing the wound with Parafilm. Ten seedlings were inoculated for each isolate. Controls consisted of stem-wound inoculation with a sterile plug of PDA, and no wounding at all. After 7 weeks, lesion length was measured. All seedlings inoculated with P. gonapodyides showed distinct necrotic lesions, whereas control treatments did not show any symptoms of disease. The average cumulative lesion length on seedlings inoculated with P. gonapodyides was significantly higher than on the wounded control treatment (25.4 mm ± 1.66 vs. 0.4 mm ± 0.01; P < 0.0001 for isolate 1 and 28.9 mm ± 1.42 vs. 0.4 mm ± 0.01; P < 0.001 for isolate 2). Koch's postulates were fulfilled by successfully reisolating the pathogen from infected seedlings. To our knowledge, this is the first report of P. gonapodyides causing disease on trees in Sweden. P. gonapodyides has been noted previously in Denmark (Erwin and Ribeiro 1996), and has been traditionally regarded as a weak parasite with saprophytic abilities, usually associated with aquatic environments such as rivers, riparian areas, and wetlands (Brasier et al. 2003). We cannot exclude that recent climatic triggers such as high summer precipitation coupled with mild winter temperatures have favored conditions to multicyclic spread of P. gonapodyides via zoospores, or that increased average age of beech stands has contributed to their higher susceptibility to weaker pathogens. Damage caused by P. gonapodyides however might be underestimated as it also can inhibit seed germination and is known to cause root rot and stem lesions in Quercus robur and Q. ilex (Corcobado et al. 2010; Jung et al. 1996). The newly reported damage caused by P. gonapodyides on F. sylvatica trees in southern Sweden is alarming particularly since beech is a dominant and ecologically important hardwood species that is widely used in forestry and as a planted ornamental in urban and landscape settings. Furthermore, other hosts such as Alnus glutinosa, Q. petraea, Q. robur (Jung et al. 1996), Picea abies, Betula spp., Acer spp., Tilia spp. (Jung et al. 2009), and Salix spp. (Brasier et al. 2003), also common in southern Sweden, may face an increased risk of damages caused by P. gonapodyides in the future.
|
|
| 21. |
- Cleary, Michelle, et al.
(författare)
-
First report of Pleuroceras pseudoplatani on Acer rubrum, A. griseum, A. saccharinurn, A. negundo, A. circinatum and A. macrophyllum in Scotland
- 2018
-
Ingår i: Forestry Chronicle. - : Canadian Institute of Forestry. - 0015-7546 .- 1499-9315. ; 94, s. 147-150
-
Tidskriftsartikel (refereegranskat)abstract
- In September 2016, large necrotic lesions were observed on the foliage of several maples in Aberdeenshire, Scotland. Symptoms resembled giant leaf blotch disease caused by Pleuroceras pseudoplatani (formerly Gnomonia pseudoplatani; Ophiognomia pseudoplatani) on sycamore maple (Acer pseudoplatanus), a common disease in Europe. Other than A. pseudoplatanus, no other Acer species have previously been reported as hosts for this pathogen. Symptomatic leaves were collected from Acer rubrum, A. rubrum var. Somerset, A. griseum, A. saccharinum, A. negundo, A. macrophyllum, and A. circinatum, and the known host of P pseudoplatani, A. pseudoplatanus. Next generation sequencing was used to determine presence of the suspected P. pseudoplatani and other associated fungi in symptomatic leaves. P pseudoplatani was predominant in all symptomatic samples with 99-100% identity with reference ITS sequences of P pseudoplatani deposited in GenBank (NCBI). This is the first report of P. pseudoplatani associated with leaf blotch on Acer species other than A. pseudoplatanus. The newly reported damage on North American Acer species may be of particular concern because of the economic importance of maples for timber products, syrup production and as ornamental trees in urban landscapes. Precautions should be taken to limit trade of plants from infested areas in Europe.
|
|
| 22. |
- Cleary, Michelle
(författare)
-
FORMATION OF TRAUMATIC RESIN DUCTS IN THE PHLOEM OF WESTERN REDCEDAR (THUJA PLICATA) ROOTS FOLLOWING ABIOTIC INJURY AND PATHOGENIC INVASION BY ARMILLARIA OSTOYAE
- 2011
-
Ingår i: IAWA Journal. - : Brill. - 0928-1541 .- 2294-1932. ; 32, s. 351-359
-
Tidskriftsartikel (refereegranskat)abstract
- Anatomical changes involved in traumatic phloem resin duct (TPRD) formation in western redcedar (Thuja plicata) roots were examined following abiotic wounding and fungal invasion by Armillaria ostoyae. Following necrophylactic periderm formation, hyperplasia and expansion of a band of phloem parenchyma cells occurred in close proximity to the vascular cambium and schizogenous and lysigenous separation of its derivatives resulted in a series of longitudinal resin ducts in the inner to mid-phloem region. Fungal invasion appeared to amplify traumatic resin duct formation in the phloem. While traumatic cavities in the phloem have been reported for other Cupressaceae, this is the first report documenting TPRD formation in western redcedar.
|
|
| 23. |
- Cleary, Michelle, et al.
(författare)
-
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
-
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.
|
|
| 24. |
- Cleary, Michelle, et al.
(författare)
-
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
-
Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 102, s. 115-125
-
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.
|
|
| 25. |
- Cleary, Michelle, et al.
(författare)
-
Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker
- 2020
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 11
-
Forskningsöversikt (refereegranskat)abstract
- Fusarium circinatum, the causal agent of pine pitch canker (PPC), is currently one of the most important threats ofPinusspp. globally. This pathogen is known in many pine-growing regions, including natural and planted forests, and can affect all life stages of trees, from emerging seedlings to mature trees. Despite the importance of PPC, the global distribution ofF. circinatumis poorly documented, and this problem is also true of the hosts within countries that are affected. The aim of this study was to review the global distribution ofF. circinatum, with a particular focus on Europe. We considered (1) the current and historical pathogen records, both positive and negative, based on confirmed reports from Europe and globally; (2) the genetic diversity and population structure of the pathogen; (3) the current distribution of PPC in Europe, comparing published models of predicted disease distribution; and (4) host susceptibility by reviewing literature and generating a comprehensive list of known hosts for the fungus. These data were collated from 41 countries and used to compile a specially constructed geo-database. A review of 6297 observation records showed thatF. circinatumand the symptoms it causes on conifers occurred in 14 countries, including four in Europe, and is absent in 28 countries. Field observations and experimental data from 138 host species revealed 106 susceptible host species including 85Pinusspecies, 6 non-pine tree species and 15 grass and herb species. Our data confirm that susceptibility toF. circinatumvaries between different host species, tree ages and environmental characteristics. Knowledge on the geographic distribution, host range and the relative susceptibility of different hosts is essential for disease management, mitigation and containment strategies. The findings reported in this review will support countries that are currently free ofF. circinatumin implementing effective procedures and restrictions and prevent further spread of the pathogen.
|
|
