Cryptic speciation in <i>Hymenoscyphus albidus</i>

In the past the root rot pathogen Roesleria subterranea (Ascomycota) was generally considered as a minor parasite, a view with which we were often confronted during field work in German winegrowing regions where this ascomycete recently caused serious problems in established vineyards and at replant sites. To irrevocably demonstrate that R. subterranea is not a minor, but a primary pathogen of grapevines (and fruit trees) a pest risk analysis was carried out according to the guidelines defined by EPPO standard series PM 5, which defines the information needed, and contains standardised, detailed key questions and a decision support scheme for risk analysis. Following the provided decision scheme, it becomes apparent that R. subterranea must be considered as a serious, primary pathogen for grapevines and fruit trees that can cause massive economic losses. Based on the literature, the pathogen seems to be ubiquitous in wine growing regions in cool climates of the northern hemisphere. It is likely that because of its growth below ground, the small fruiting bodies, and ambiguous symptoms above ground, R. subterranea has been overlooked in the past and therefore, has not been considered as primary pathogen for grapevine. Available published information together with experience from field trials was implemented into a diagnostic decision scheme which will, together with the comprehensive literature provided, be the basis (a) to implement quick and efficient diagnosis of this pathogen in the field and (b) to conduct risk analysis and management in areas where R. subterranea has not established yet.

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“…The taxonomy of R. subterranea was recently revised based on both morphological and rDNA data (Kirchmair et al 2008 (Queloz et al 2010).…”

Section: Methodsmentioning

confidence: 99%

Is Roesleria subterranea a primary pathogen or a minor parasite of grapevines? Risk assessment and a diagnostic decision scheme

Neuhauser

Huber²,

Kirchmair

2011

Eur J Plant Pathol

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“…Its teleomorph, based on morphological features, was initially designated as Hymenoscyphus albidus (Kowalski and Holdenrieder 2009a). Further research based on DNA sequences of isolates from Switzerland and other European countries revealed that H. albidus represents an aggregate of two clearly delimited species (Queloz et al 2011). One was related to the non-pathogenic H. albidus sensu stricto, which had been known in Europe since 1850 (Kowalski and Holdenrieder 2009a;Baral and Bemmann 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The second was described as a new cryptic species, Hymenoscyphus pseudoalbidus, with Ch. fraxinea as its anamorph (Queloz et al 2011). A new taxonomic designation was made by , who stated that under the rules for the naming of fungi with pleomorphic life cycles, adopted in July 2011 (Hawksworth 2014), the nomenclaturally correct name for the fungus causing the current ash dieback in Europe is Hymenoscyphus fraxineus with the basionym Chalara fraxinea, and Hymenoscyphus pseudoalbidus as a taxonomic synonym of H. fraxineus.…”

Section: Introductionmentioning

confidence: 99%

Fungi on stems and twigs in initial and advanced stages of dieback of European ash (Fraxinus excelsior) in Poland

Kowalski¹,

Kraj²,

Bednarz³

2016

Eur J Forest Res

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F. excelsior is affected by dieback in the major part of its natural geographical range in Europe, which results in economic and ecological losses. The disease is caused by the ascomycetous fungus Hymenoscyphus fraxineus, a pathogen introduced to Europe most probably from East Asia. This paper presents data on fungi identified on F. excelsior trees representing two different stages of ash dieback in Poland. Fungal communities were identified in initial necrotic lesions on living stems and twigs using the classical method of isolation on malt extract agar and morphological and molecular analyses. In dead apical parts of stems and twigs, fungi were identified by microscopic analyses of fruit bodies formed in situ. Seventy-one fungal taxa were found in 720 samples with symptoms of initial or advanced necrosis. The most common fungus detected in initial necrotic lesions in each forest site was Hymenoscyphus fraxineus (59.2 % of analysed samples). Other frequently isolated fungi included Alternaria alternata, Diaporthe eres, Diplodia mutila, Fusarium avenaceum, F. lateritium and Phomopsis spp. Fruit bodies on dead apical parts of stems and twigs were produced mostly by Diaporthe eres, Diplodia mutila, Lophiostoma corticola, Phomopsis spp., Sirodothis sp. and Valsa cypri. Fungal communities from different sites were similar, as shown by high Sørensen similarity index values. Greatest variation in fungal community structure at the initial necrotic stage was realized by D. mutila and F. avenaceum, and at the advanced necrotic stage by D. eres, D. mutila and Phomopsis spp. Data show a close affinity of certain fungi to site, suggesting geographical relatedness. The ecological effects of distribution of the invasive H. fraxineus and of other fungi sporulating on diseased ash trees in Europe are discussed.

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“…In 2010, the fungus Hymenoscyphus pseudoalbidus (Helotiales, Ascomycota) was proven to be the causal agent of ash dieback (Queloz et al, 2011, Zhao et al, 2012, a disease that has rapidly spread across Europe in the course of the last 20 years. This notorious pathogen can only be found in ash trees (Fraxinus) and is responsible for severe dieback of the European ash (Fraxinus excelsior).…”

Section: Introductionmentioning

confidence: 99%

Hymenosetin, a 3-decalinoyltetramic acid antibiotic from cultures of the ash dieback pathogen, Hymenoscyphus pseudoalbidus

et al. 2014

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A 3-decalinoyltetramic acid, for which the trivial name hymenosetin is proposed, was isolated from crude extracts of a virulent strain of the ash dieback pathogen, Hymenoscyphus pseudoalbidus (= "Chalara fraxinea"). This compound was produced only under certain culture conditions in submerged cultures of the fungus. Its planar structure was determined by NMR spectroscopy and by mass spectrometry. The absolute stereochemistry was assigned by CD spectroscopy and HETLOC data. Hymenosetin exhibited broad spectrum antibacterial and antifungal activities (including strong inhibition of MRSA, as well as moderate cytotoxic effects.So far, the metabolite proved inactive in assays for evaluation of phytotoxicity, whereas viridiol, another secondary metabolite known from H. pseudoalbidus, was regarded as phytotoxic principle of the pathogen against its host, Fraxinus excelsior. Further studies will show whether hymenosetin constitutes a defence metabolite that is produced by the pathogenic fungus to combat other microbes and fungi in the natural environment.

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Cryptic speciation in Hymenoscyphus albidus

Cited by 219 publications

References 36 publications

Is Roesleria subterranea a primary pathogen or a minor parasite of grapevines? Risk assessment and a diagnostic decision scheme

Is Roesleria subterranea a primary pathogen or a minor parasite of grapevines? Risk assessment and a diagnostic decision scheme

Fungi on stems and twigs in initial and advanced stages of dieback of European ash (Fraxinus excelsior) in Poland

Hymenosetin, a 3-decalinoyltetramic acid antibiotic from cultures of the ash dieback pathogen, Hymenoscyphus pseudoalbidus

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