The development of a species‐specific test to detect <i><scp>H</scp>ymenoschyphus pseudoalbidus</i> in ash tissues

Gherghel, Felicia; Fussi, Barbara; Donges, Kathrin; Haustein, M.; Jakob, Karl M.; Müller, Karsten; Piškur, Barbara; Hauptman, Tine; Lenz, Heike D.; Konnert, Monika; Kost, Gerhard; Rexer, Karl‐Heinz

doi:10.1111/efp.12078

Cited by 13 publications

(12 citation statements)

References 25 publications

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“…In the Ukraine, this fungus was detected in litter, in ash petioles from the previous year (Davydenko et al 2013). It was also detected in ash wood in Slovenia (Gherghel et al 2014) and in the bark and buds of living ash branches in New Zealand (Chen 2012). The present results suggest that its frequency increases in stems and twigs with advanced necrosis, which categorizes the fungus rather as a secondary invader or saprotroph.…”

Section: Occurrence Of Other Frequent Fungal Speciesmentioning

confidence: 98%

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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Section: Occurrence Of Other Frequent Fungal Speciesmentioning

confidence: 98%

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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“…Not only the screening for candidates is important but also the characterization of the underlying resistance mechanisms, to evaluate which genetic material can be utilized for further breeding [9] and to prove the robustness of the observed partial resistance when new virulent strains evolve. Also in south-eastern Germany [25] and other countries, a high level of fungal genetic variation was already found [34] and the virulence of the different strains has to be proven in the future. The survival of potentially resistant trees is endangered not only by the infections with new evolving virulent strains of H. fraxineus itself, but also by secondary pathogens, like the ash bark beetles or other species of Armillaria that can be increasingly found in weakened ash stands as it was proven in this study.…”

Section: Discussionmentioning

confidence: 99%

“…From a total of 74 trees, 40 successful isolations on malt agar supplemented with antibiotic (20 g¨L´1 malt extract, 100 mg¨L´1 streptomycin and 15 g¨L´1 agar) were performed. In earlier studies, the presence of the fungus was also confirmed by PCR analysis for six study sites [25]. In each pole stand, except for Freising, one tree was felled and samples from three symptomatic branches were used for DNA extraction.…”

Section: Isolation and Cultivation Of H Fraxineus From Infected Branmentioning

confidence: 92%

“…In all young growth stands, the presence of H. fraxineus as a causal agent of the disease was confirmed by its isolation and its subsequent cultivation out of infected branches (Table 3). Furthermore, PCR analysis from six isolates out of six study sites were performed and provided additional information on the genetic heterogeneity of the species [25]. For pole and matured forests, branches from one tree within each study site were harvested and with one exception the presence of the fungus was confirmed by PCR analysis ( Table 3).…”

Section: Development Of Vitality In Ash Stands From 2010 To 2014mentioning

confidence: 99%

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Development of Ash Dieback in South-Eastern Germany and the Increasing Occurrence of Secondary Pathogens

Lenz

Bartha

Straßer

et al. 2016

Forests

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Abstract:Since its first identification in Poland in 2006, the ascomycete Hymenoscyphus fraxineus has caused massive dieback of Fraxinus excelsior in the countries of eastern, northern and central Europe. This work shows the development, expansion, and severity of the disease in south-eastern Germany for a period of four years, starting in 2010. Differences between habitats, as well as age classes have been captured. The presence and the amount of potentially resistant trees were proven over the years, to determine how high the resistance level might be. Typical disease symptoms are the wilting of leaves, necrotic lesions in the bark and reddish discolorations of branches and stems. In addition, stem necroses also appear by infection with species of Armillaria. Therefore, special attention has been given to Armillaria species in affected ash stands but also to other secondary pathogens, like ash bark beetles. It is shown that breeding galleries of Hylesinus fraxini are only found in trees that have recently died and thus Hylesinus fraxini is still acting as a secondary opportunistic pathogen. In contrast, Armillaria spp. can be considered as serious pathogens of weakened ash trees. In different ash stands, typical symptoms of infection can be found. A relationship between stem base necrotic lesions and vitality was examined. It is shown that necrotic lesions severely contribute to accelerating the mortality of ash trees. In addition to the high infection pressure by H. fraxineus, the high inoculum of Armillaria in the soil facilitates further infections and, thus, likewise endangers the survival of potentially resistant trees. In the following years, forest conversion and seed harvest in affected ash stands will have to be urgently considered to avoid tree gaps on a large scale. Furthermore, infection assays of potentially resistant trees with ensuing breeding programmes should be initially started for the conservation of this ecologically and economically important tree species.

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“…This is important for breeding programs to ensure a wide genetic base, particularly since analyses based on microsatellites revealed genetic variation in H. fraxineus populations (BENGTSSON et al, 2012;FUSSI et al, 2012;GHERGHEL et al, 2013) and genotype dependent differences in the pathogen -tree interaction might be expected.…”

Section: Genetic Differences Between Susceptible and Less Susceptiblementioning

confidence: 99%

Genetic analysis of European common ash (Fraxinus excelsior L.) populations affected by ash dieback

Fussi

Konnert

2014

Silvae Genetica

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European common ash is an important component of mixed forest ecosystems in Bavaria and is considered a valuable tree species under climate change. The first aim of the present study was to assess the genetic diversity within and between ash populations in Bavaria in comparison with neighboring regions. Because ash stands have been heavily attacked by ash shoot disease in the last few years, the second aim of the study was to detect genetic differences between susceptible and less susceptible trees (trees with defoliation up to 30%) within populations. Altogether 41 populations were investigated using nuclear and chloroplast microsatellites. The results showed high genetic variation within and high genetic differentiation between ash populations. Higher chloroplast microsatellite variation was detected instead populations from south-eastern Bavaria compared to other regions. The comparison of susceptible and less susceptible groups of individuals within each population revealed medium to high genetic differences in some cases. For the observed heterozygosity, higher values were found for the group of less susceptible trees compared to the group of all trees or to the group of susceptible trees within populations. This could be a first indication that individuals with a higher heterozygosity might be able to withstand ash dieback in a better way compared to homozygotic individuals. Within the group of less susceptible trees a relatively wide genetic base exists whereupon a future breeding programme can be built. Thus it is of utmost importance for the species to maintain less affected trees in order to keep the genetic potential for future adaptation processes within ash populations, seed production and regeneration.

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The development of a species‐specific test to detect Hymenoschyphus pseudoalbidus in ash tissues

Cited by 13 publications

References 25 publications

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

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

Development of Ash Dieback in South-Eastern Germany and the Increasing Occurrence of Secondary Pathogens

Genetic analysis of European common ash (Fraxinus excelsior L.) populations affected by ash dieback

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