scholarly journals Genomic basis of European ash tree resistance to ash dieback fungus

2019 ◽  
Author(s):  
Jonathan J. Stocks ◽  
Carey L. Metheringham ◽  
William Plumb ◽  
Steve J. Lee ◽  
Laura J. Kelly ◽  
...  
Keyword(s):  
Sequence Data ◽  
Seed Source ◽  
Source Zone ◽  
Whole Genome Sequence ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
A Genome ◽  
Ash Trees ◽  
Gp Model ◽  
European Ash

SummaryPopulations of European ash trees (Fraxinus excelsior) are being devastated by the invasive alien fungus Hymenoscyphus fraxineus, which causes ash dieback (ADB). We sequenced whole genomic DNA from 1250 ash trees in 31 DNA pools, each pool containing trees with the same ADB damage status in a screening trial and from the same seed-source zone. A genome-wide association study (GWAS) identified 3,149 single nucleotide polymorphisms (SNPs) associated with low versus high ADB damage. Sixty-one of the 203 most significant SNPs were in, or close to, genes with putative homologs already known to be involved in pathogen responses in other plant species. We also used the pooled sequence data to train a genomic prediction (GP) model, cross-validated using individual whole genome sequence data generated for 75 healthy and 75 damaged trees from a single seed source. Using the top 30% of our genomic estimated breeding values from 200 SNPs, we could predict tree health with over 90% accuracy. We infer that ash dieback resistance in F. excelsior is a polygenic trait that should respond well to both natural selection and breeding, which could be accelerated using GP.

First report of Diplodia fraxini and Diplodia subglobosa causing canker and dieback of Fraxinus excelsior in Slovenia

Plant Disease ◽  
2021 ◽  
Author(s):  
Benedetto T. Linaldeddu ◽  
Carlo Bregant ◽  
Lucio Montecchio ◽  
Ana Brglez ◽  
Barbara Piškur ◽  
...  
Keyword(s):  
Sequence Data ◽  
Fungal Species ◽  
Pathogenicity Test ◽  
Limited Information ◽  
Internal Transcribed Spacer Region ◽  
Ash Dieback ◽  
Fungal Isolation ◽  
Hymenoscyphus Fraxineus ◽  
Botryosphaeriaceae Species ◽  
European Ash

Over the last decades the vitality and productivity of European ash trees in Slovenia has been seriously impacted by the onset of canker and dieback disease symptoms on young and old trees, primarily identified as ash dieback caused by Hymenoscyphus fraxineus. Given the limited information available about the aetiology of this emerging disease, a study was carried out to isolate, identify and characterize the fungal species involved in the observed ash symptoms. Field surveys were conducted in five forest sites where 50 symptomatic branch samples were collected. All samples were inspected and used for fungal isolation. Based on morphology, colony appearance and DNA sequence data of the internal transcribed spacer region (ITS), 125 fungal colonies belonging to five species were isolated and identified. Only a few symptomatic ash samples yielded colonies of H. fraxineus, whereas Botryosphaeriaceae species were isolated with a high frequency, with Diplodia fraxini as the dominant species. A pathogenicity test proved that all isolated species were pathogenic on European ash, causing bark lesions and wood discoloration. All Botryosphaeriaceae species isolated in this study are reported for the first time on European ash in Slovenia.

scholarly journals Decline of Fraxinus excelsior L. in parks of Saint Petersburg: Who is to blame – Hymenoscyphus fraxineus or Diplodia spp.?

2020 ◽  
Vol 73 (1) ◽  
pp. 43-51
Author(s):  
Dmitrii A. Shabunin ◽  
Andrey V. Selikhovkin ◽  
Elena Yu. Varentsova ◽  
Dmitry L. Musolin
Keyword(s):  
Light Microscopy ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Saint Petersburg ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
Fallen Leaves ◽  
European Ash

Abstract The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens “the entry of infection” and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

scholarly journals Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback

2021 ◽  
Vol 4 ◽  
Author(s):  
Marta Agostinelli ◽  
Diem Nguyen ◽  
Johanna Witzell ◽  
Michelle Cleary
Keyword(s):  
Large Scale ◽  
Population Decline ◽  
Keystone Species ◽  
Fungal Species ◽  
Fraxinus Excelsior ◽  
Fungal Communities ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
European Ash

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.

scholarly journals Situation and perspectives of European ash (Fraxinus spp.) in Ukraine: focus on eastern border

2019 ◽  
Vol 25 (2) ◽  
pp. 193-202
Author(s):  
Kateryna V Davydenko ◽  
Valentyna Borysova ◽  
Olena Shcherbak ◽  
Yevhen Kryshtop ◽  
Valentyna Meshkova
Keyword(s):  
Pathogenic Fungus ◽  
Total Mortality ◽  
Fraxinus Excelsior ◽  
Bacterial Disease ◽  
Eastern Region ◽  
Ash Dieback ◽  
Epicormic Shoots ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
European Ash

The health condition of European ash (Fraxinus excelsior) stands in Ukraine has become worse since 2006. Firstly, in 2011 an alien invasive pathogenic fungus Hymenoscyphus fraxineus was identified in the eastern part of the country and, subsequently, its presence was confirmed in the western and central parts. The aims of our research were to evaluate the health of ash trees and identify the main causes of ash decline in different regions of Ukraine with emphasis on ash dieback and its association with collar rots.    Results showed that since 2013 the number of trees with ash dieback symptoms has been gradually increasing, reaching up to 92 % in 2018. Total mortality due to ash dieback was up to 9 % in 2018. Disease intensity remains high in northern and central Ukraine comparing with the east. Branch dieback, collar rots, epicormic shoots and bacterial disease of ash occurred more often in the eastern region, some symptoms were observed simultaneously. Ash bark beetle galleries, as well as foliage browsing insects, were found mostly in weakened and/or dying trees.    It was indicated that collar rots significantly increase the mortality of ash trees. Armillaria spp. fungi were found to be frequently associated with ash dieback on living stems and fallen trees in 2017, causing high rates of mortality in the northern and central regions. For further ash conservation and breeding programmes, resistant trees in severely damaged regions should be selected to preserve genetic diversity in ash populations.                                                       Keywords: Fraxinus excelsior, ash dieback, collar rot, bacterial disease, epicormic shoots, Hymenoscyphus fraxineus, Armillaria spp.

scholarly journals Estimating mortality rates of European ash ( Fraxinus excelsior ) under the ash dieback ( Hymenoscyphus fraxineus ) epidemic

2018 ◽  
Vol 1 (1) ◽  
pp. 48-58 ◽  
Author(s):  
Tim L. R. Coker ◽  
Jiří Rozsypálek ◽  
Anne Edwards ◽  
Tony P. Harwood ◽  
Louise Butfoy ◽  
...  
Keyword(s):  
Mortality Rates ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
European Ash

scholarly journals Diversity of secoiridoid glycosides in leaves of UK and Danish ash provide new insight for ash dieback management

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
John D. Sidda ◽  
Lijiang Song ◽  
Jack L. Parker ◽  
David J. Studholme ◽  
Christine Sambles ◽  
...  
Keyword(s):  
Emerald Ash Borer ◽  
Structural Diversity ◽  
Feeding Deterrents ◽  
Leaf Extracts ◽  
Ash Dieback ◽  
Sample Group ◽  
Ash Trees ◽  
Secoiridoid Glycosides ◽  
The Uk ◽  
European Ash

Abstract Secoiridoid glycosides are anti-feeding deterrents of the Oleaceae family recently highlighted as potential biomarkers in Danish ash trees to differentiate between those tolerant and susceptible to the fungal disease ash dieback. With the knowledge that emerald ash borer has recently entered Europe from Russia, and that extensive selection trials are ongoing in Europe for ash dieback tolerant European ash (Fraxinus excelsior), we undertook comprehensive screening of secoiridoid glycosides in leaf extracts of trees tolerant and susceptible to ash dieback sampled from sites in the UK and Denmark. Here we report an unexpected diversity of secoiridoid glycosides in UK trees and higher levels of secoiridoid glycosides in the UK sample group. While it is unlikely that secoiridoid glycosides generally can serve as reliable markers for ash dieback susceptibility, there are differences between tolerant and susceptible groups for specific secoiridoids. We predict that the high levels—and structural diversity—of secoiridoids present in the UK group may provide a robust reservoir of anti-feeding deterrents to mitigate future herbivore threats such as the Emerald ash borer.

scholarly journals Lessons from the Frontline: Exploring How Stakeholders May Respond to Emerald Ash Borer Management in Europe

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 617 ◽  
Author(s):  
Mariella Marzano ◽  
Clare Hall ◽  
Norman Dandy ◽  
Cherie LeBlanc Fisher ◽  
Andrea Diss-Torrance ◽  
...  
Keyword(s):  
Biological Control ◽  
Social Acceptance ◽  
Emerald Ash Borer ◽  
Social Acceptability ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
The Social ◽  
Ash Trees ◽  
The Usa ◽  
Management Approaches

The emerald ash borer (EAB) has caused extensive damage and high mortality to native ash trees (Fraxinus; sp.) in North America. As European countries battle with the deadly pathogen Hymenoscyphus fraxineus (ash dieback) affecting European ash (Fraxinus excelsior), there is concern that the arrival of EAB will signal the demise of this much-loved tree. While Europe prepares for EAB it is vital that we understand the social dimensions that will likely influence the social acceptability of potential management measures, and experiences from the USA can potentially guide this. We draw on differing sources including a literature review, documentary analysis, and consultation with key informants from Chicago and the Twin Cities of Minneapolis and St. Paul. In this paper, we focus on EAB management responses that involve chemical applications, tree felling and replanting, and biological control, and assess their likely social acceptability to stakeholders based on the perceived risks and benefits. Benefits involve protecting specific ash trees and slowing the spread of EAB across the landscape. Risks include collateral harm from insecticide use on human and environmental health, financial costs and liabilities, and the effectiveness of each approach. Biological control and replacing ash with other species are likely to be largely acceptable across contexts and stakeholder groups but pre-emptive felling and insecticide application could be more problematic if seeking widespread social acceptance. Based on our observations from the evidence collected we offer suggestions for approaching EAB management in Europe with a focus on improving prospects of social acceptability. Strong engagement will be necessary to establish the relevance and reason for using different management approaches and to build awareness and trust.

scholarly journals Mapping the genetic basis of diabetes mellitus in the Australian Burmese cat (Felis catus)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Georgina Samaha ◽  
Claire M. Wade ◽  
Julia Beatty ◽  
Leslie A. Lyons ◽  
Linda M. Fleeman ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Genome Wide Association Study ◽  
Genetic Model ◽  
Sequence Data ◽  
Pancreatic Beta Cell ◽  
Whole Genome Sequence ◽  
Cell Dysfunction ◽  
Genome Wide ◽  
A Genome ◽  
Pathologic Features

Abstract Diabetes mellitus, a common endocrinopathy affecting domestic cats, shares many clinical and pathologic features with type 2 diabetes in humans. In Australia and Europe, diabetes mellitus is almost four times more common among Burmese cats than in other breeds. As a genetically isolated population, the diabetic Australian Burmese cat provides a spontaneous genetic model for studying diabetes mellitus in humans. Studying complex diseases in pedigreed breeds facilitates tighter control of confounding factors including population stratification, allelic frequencies and environmental heterogeneity. We used the feline SNV array and whole genome sequence data to undertake a genome wide-association study and runs of homozygosity analysis, of a case–control cohort of Australian and European Burmese cats. Our results identified diabetes-associated haplotypes across chromosomes A3, B1 and E1 and selective sweeps across the Burmese breed on chromosomes B1, B3, D1 and D4. The locus on chromosome B1, common to both analyses, revealed coding and splice region variants in candidate genes, ANK1, EPHX2 and LOX2, implicated in diabetes mellitus and lipid dysregulation. Mapping this condition in Burmese cats has revealed a polygenic spectrum, implicating loci linked to pancreatic beta cell dysfunction, lipid dysregulation and insulin resistance in the pathogenesis of diabetes mellitus in the Burmese cat.

scholarly journals Dealing with dieback: forest manager attitudes towards developing resistant ash trees in the United Kingdom

2019 ◽  
Vol 92 (5) ◽  
pp. 554-567 ◽  
Author(s):  
Mariella Marzano ◽  
Paul Woodcock ◽  
Christopher P Quine
Keyword(s):  
Native Species ◽  
Ash Dieback ◽  
The United Kingdom ◽  
Hymenoscyphus Fraxineus ◽  
Resistant Varieties ◽  
Ash Trees ◽  
New Varieties ◽  
Time Required ◽  
The Uk ◽  
Past Experiences

Abstract European ash (Fraxinus excelsior L.) is a highly valued native species in the UK and elsewhere. The rapid spread and predicted impact of ash dieback (caused by Hymenoscyphus fraxineus), has led researchers to explore a range of responses from introducing non-native ash to use of Genetic Modification (GM) technologies to develop disease resistance. To support decisions over which approaches should receive further investment to encourage adoption, it is necessary to understand what is acceptable to forest practitioners. Interviews with 22 forest advisors and managers revealed ash is highly valued for the multiple benefits it provides but past experiences with pest and diseases have encouraged a more cautious (‘wait and see’) attitude to approaches for dealing with ash dieback. These practitioners showed a strong interest in the concept of resistant ash but emphasized that any ‘new’ varieties should have similar characteristics, retain genetic diversity and be able to withstand future pests. There was limited support for planting non-native ash and use of GM methods and greater support for traditional breeding, though views varied dependent upon objectives and could evolve with experience countering the disease. There were concerns about the time required to produce resistant varieties and more information was needed about the costs, benefits and impacts of the different approaches. These findings point to the need for continued communication and engagement with stakeholders in the refinement of responses to dieback and any development of resistant ash.

scholarly journals Clinal genomic analysis reveals strong reproductive isolation across a steep habitat transition in stickleback fish

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Quiterie Haenel ◽  
Krista B. Oke ◽  
Telma G. Laurentino ◽  
Andrew P. Hendry ◽  
Daniel Berner
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Sequence Data ◽  
Genomic Analysis ◽  
Whole Genome Sequence ◽  
Adaptive Divergence ◽  
Entire Genome ◽  
High Dispersal ◽  
A Genome ◽  
Habitat Transition

AbstractHow ecological divergence causes strong reproductive isolation between populations in close geographic contact remains poorly understood at the genomic level. We here study this question in a stickleback fish population pair adapted to contiguous, ecologically different lake and stream habitats. Clinal whole-genome sequence data reveal numerous genome regions (nearly) fixed for alternative alleles over a distance of just a few hundred meters. This strong polygenic adaptive divergence must constitute a genome-wide barrier to gene flow because a steep cline in allele frequencies is observed across the entire genome, and because the cline center closely matches the habitat transition. Simulations confirm that such strong divergence can be maintained by polygenic selection despite high dispersal and small per-locus selection coefficients. Finally, comparing samples from near the habitat transition before and after an unusual ecological perturbation demonstrates the fragility of the balance between gene flow and selection. Overall, our study highlights the efficacy of divergent selection in maintaining reproductive isolation without physical isolation, and the analytical power of studying speciation at a fine eco-geographic and genomic scale.

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