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Vertical gradient of Hymenoscyphus fraxineus spore dispersal at infected locality in Boršov nad Vltavou
ŠTOIDL, Petr
Hymenoscyphus fraxineus is a pathogenic sac fungus causing ash tree necrosis throughout Europe, spreading predominantly through the air using ascospores. The aim of this thesis was to quantitatively describe the occurrence of spores of the causative agent of ash trees necrosis at different heights above the source of infection. The results were subsequently used to consider the inoculum potential of this pathogenic fungus for longer distance spreading using air currents. The qPCR method was used for the detection and quantification of DNA concentration. Based on a statistical analysis of the obtained molecular data a dependence of the occurrence of different amounts of H. fraxineus on height was proved. The main contribution of this thesis lies in charting the range of the H. fraxineus pathogen spread in the air column which is directly related to the range of spores to greater distances.
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Micropropagation of common ash (Fraxinus excelsior L.)
Šedivá, Jana ; Havrdová, Ludmila ; Maršík, Petr
The aim of the methodology is to provide an optimized process of micropropagation of common ash, which can support the production of its elite genotypes with a higher degree of tolerance to the invasive fungal pathogen Hymenoscypus fraxineus causing our domestic species of ash (Fraxinus excelsior and F. angustifolia) so called necrosis of ashes (known in Europe as " ash dieback "). The methodology includes two integrated in vitro propagation techniques, which are based either on juvenile plant material (from seeds) or on adult trees using apical buds.
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Analýza vnitrodruhové proměnlivosti jasanu ve vztahu k jeho chřadnutí
Bohdálek, Michal
Population of common (Fraxinus excelsior L.) and narrow-leaved ash (Fraxinus angustifolia Vahl.) in Europe are currently haunted by the pathogenic fungus Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz & Hosoya, originating in the Far East. The objective of present study is to analyze whether and how the provenance of reproductive material influences the tolerance of the both ash species against this invasive pathogen. Our study was carried out in the research plot Zámeček near Kroměříž with 16 provenances of common ash from all of the Czech Republic and 2 provenances of narrow-leaved ash from the Morava valley at the age of 22 years. The experiment was established by the Forestry and Game Research Institute in Jíloviště-Strnady. In the field, we measured height and diameter, and assessed the stem quality, bud burst and intensity of infection by H. fraxineus (using a certified methodology) of individual trees and provenances. Then, we analyzed mutual relationships of the growth, morphology, phenology and intensity of infection. It resulted in interesting findings: we found provenances of common ash originating from more northerly localities (higher latitude) less intensively infected by H. fraxineus and flushing later than others. Less infected individuals were higher and had better stem quality at the same time. It is interesting that provenances from warmer sites revealed bigger breast-height diameter.
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Occurrence of putative dsRNA mycoviruses in Ash Dieback Causal Agent
Čermáková, Vendula
Thanks to environmental changes, globalization, long distance trade and plant transport, invasive organisms have become a major threat for world biodiversity and ecosystem services. Over the last 20 years, common European ash trees (Fraxinus excelsior L., Fraxinus angustifolia Vahl. etc.) have been subjected to heavy dieback and mortality because of the introduction and spread of the ascomycetous fungal pathogen Hymenoscyphus pseudoalbidus Queloz (syn. Chalara fraxinea Kowalski). Once the disease is established, its management is hardly possible. Therefore, one of the main objectives of European researchers is to find effective and respectful control methods, such as biological control. The discovery of viruses which reduce the virulence of the chestnut blight fungus Cryphonecria parasitica (Murr.) Barr., has intensively stimulated the research of fungal viruses as potential biological control agents (BCA). The occurrence of putative dsRNA particles in the decaying fungus H. pseudoalbidus was investigated as an important indicator of the mycoviruses' presence. In total, 106 samples of this pathogen were obtained from eight different European countries. According to the results, dsRNA segments were confirmed in 32.1 % of examined samples (two similarly sized at 2--2.5 kb and a third one of approximately 5 kb). Statistical results have revealed no significant relation between the presence of dsRNA and growth rate, colour or any other characteristic of the mycelium.
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