National Repository of Grey Literature 40 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Evolution of intraspecific diversity of invasive pathogen of alder Phytophthora ×alni
Pecka, Štěpán ; Koukol, Ondřej (advisor) ; Sedlářová, Michaela (referee)
Phytophthora alni s. l. (Peronosporomycetes: Stramenopila) is an invasive pathogen causing phytophthora root and collar rot in alders. It has been known from Europe since the '90s and from the Czech Republic since 2001. Three species were found are known within species complex P. alni s. l. Two of these species hybridized in Europe and created third triploid species called Phytophthora ×alni (Phytophthora alni subsp. alni). Dozens of genotypes have been identified with the help of microsatellites in previous studies, nevertheless only one genotype (Pxa-1) was dominating and most of other genotypes were closely related to it. The trend of increasing or decreasing incidence of this genotype differed among these studies. This thesis compares changes in the P. ×alni population in Vltava basin over the last 14 years during which a significant decrease in number of available hosts of this pathogen took place. Multilocus genotypes were determined using a set of 10 microsatellite markers. Among the 94 P. ×alni isolates reliably genotyped, 23 were of different genotypes. None of these genotypes, however, were found on the same localities repeatedly (except the dominant genotype). Incidence of the dominant genotype increased over time (from 63 % to 86 %). Most of the other genotypes were only slightly...
Infection pathway of Hymenoscyphus fraxineus and its interactions with ash mycobiota
Haňáčková, Zuzana ; Koukol, Ondřej (advisor) ; Adamčíková, Katarína (referee) ; Botella Sánchez, Leticia (referee)
Ash dieback is a disease that affected populations of native ash species throughout Europe at the beginning of the 21st century. It causes necrotic spots on the leaves, necrosis of shoots and branches and, especially in young individuals, the total death of the tree. In particular, F. excelsior is attacked by ash dieback. The causative agent of the disease is the invasive ascomycete fungus from Asia - Hymenoscyphus fraxineus. The aims of this dissertation thesis were as follows: 1) to study population structure of H. fraxineus at different scales - at regional scale (Czech populations) and at the level of particular ash petioles, this latter was to serve as a confirmation of the pathogen infection pathway; 2) to elucidate the effect of H. fraxineus on saprotrophs in the litter (namely H. albidus) and 3) to compare endophytic mycobiota of tolerant and susceptible F. excelsior trees and to test antagonistic interactions of these fungi against the pathogen. Analysis of Czech populations showed lower average gene diversity compared to other European populations with one Czech population differing significantly from the rest due to the lowest allelic richness and very low average gene diversity. The results indicate that despite minimal differences among European populations, local ecological or...
Arthroderma in the fur of wild rodents
Moulíková, Štěpánka ; Kolařík, Miroslav (advisor) ; Koukol, Ondřej (referee)
Arthroderma is the most diverse genus of dermatophytes, fungi causing skin infections. However, the genus is most frequently isolated from soil enriched by keratin sources. In my study, I isolated several strains of Arthroderma from the fur of wild rodents from the Czech Republic. Using polyphasic taxonomy, I characterised the 29 strains genetically (ITS rDNA, tubb and tef1α), morphologically, physiologically, and by mating experiments. In the second part of the study, we used data mining of ITS sequence data from GenBank and GlobalFungi Database to further investigate biogeography and ecology of Arthroderma species. In total, eight Arthroderma species were isolated, including four new species. The geographical distribution of the new species was not restricted to the Czech Republic nor rodents, other strains have been isolated from different animal species and soil from Europe, North America and Asia. Data obtained by data mining confirmed that the genus has diverse ecology - some lineages seem to be closely associated with animals (here described A. rodenticum), while others occur typically in soil. However, low numbers of sequence reads of Arthroderma in soil show that the species are not soil generalists but rather dependent on keratin source. This is the first study using data mining to assess...
Secondary metabolites and antimicrobial effects of neotropical members of the genus Hermatomyces
Ježková, Tereza ; Koukol, Ondřej (advisor) ; Žabka, Martin (referee)
Species of the genus Hermatomyces (Pleosporales) saprotrophs on wood and litter in the tropics. Since the secondary metabolites of this genus have not been investigated so far, this thesis focuses on them. In this thesis, the antifungal properties of the genus Hermatomyces were verified by pairing experiments on agar plates and by testing the minimum inhibitory concentrations of extracts obtained from fungal biomass. The extract of one selected strain, H. reticulatus CCF 5893, was separated by preparative HPLC. The selected biologically active fractions were purified and the chemical structure of the separated compounds was determined by nuclear magnetic resonance analysis and X-ray crystallography. Two compounds were found in this species: palmarumycins C2 and C12, which have antifungal properties. Furthermore, a total of 25 Hermatomyces strains were compared in terms of secondary metabolite production (by testing their minimum inhibitory concentrations and comparing HRMS data). Unique compounds were produced by H. megasporus, which also showed the highest antimicrobial activity of all species and is therefore the most suitable species for further study of antimicrobial compounds of this genus.
The use of molecular markers for the study of the impact of global change on fungal communities
Faltysová, Julie ; Baldrian, Petr (advisor) ; Koukol, Ondřej (referee)
Fungi are an essential part of life on Earth. Besides their main role in decomposition of organic matter, they belong among key symbiotic organisms and they take part in providing a range of ecosystem processes important for humankind such as primary production and with that related food availability or soil water regulation. For the study of fungal distribution, we often use a method called DNA metabarcoding which combines the use of specific molecular markers, most commonly universal fungal ITS, and high-throughput sequencing. The importance of the method has been rising in the current time of changing environment and it has helped us observe changes in fungal communities due to global change. It seems that primarily various climatic factors such as warming, changes in rainfall patterns and nitrogen deposition have strongly influenced community and fungal guilds composition. Consequently, these changes may potentially have an impact on ecosystem functioning so that their overall balance can be in threat. Key words: molecular markers, DNA metabarcoding, fungal community, warming, climate change, nitrogen deposition
Characterization of fungal community in spruce (Picea abies) litter using cultivation and T-RFLP
Kolářová, Zuzana ; Koukol, Ondřej (advisor) ; Brabcová, Vendula (referee)
Fungi have a key role in the decomposition of coniferous litter and affect nutrient cycling in forest ecosystems. Therefore, great emphasis is placed on exploring the diversity of these organisms. The aim of this thesis was to describe fungal diversity in spruce litter and revealed temporal development of this community in a forest regenerating after bark beetle outbreak. Another objective was to compare sites with different length of bark beetle damage. The study area was located in the Bohemian Forest mountain range. Litter bags with spruce needles were placed on the forest soil and several samplings were performed in the course of three years. Diversity of fungi and changes in the fungal community were assessed by two methods: cultivation of needles on 2ř MEA and fingerprinting method T-RFLP. In total 71 fungal species were obtained from needles during a three-year succession by cultivation approach. Using T-RFLP 122 different fragments were generally recorded. The dominant species were Scleroconidioma sphagnicola, Thysanophora penicillioides, Hormonema dematiodes, Ceuthospora pinastri, species of genus Chalara, Trichoderma polysporum, Mycena galopus and unknown species Helotiales sp. 1. Primary saprotrophs occured in the community mainly in first 8 months and then were replaced by basidiomycetes....
Diversity, phylogeny and ecology of members of the family Geastraceae
Zehnálek, Petr ; Koukol, Ondřej (advisor) ; Kříž, Martin (referee)
The family Geastraceae is a group of Fungi with global distribution and with saprophytic manner of nutrition. Its members have basic characters of class Gasteromycetes, which no longer exists. The fruitbodies have angiocarpous morphology and peridia are well developer and very distinct in their functions. Star-shaped mature fruitbody is the most typical character of these interesting mushrooms. This bachelor's thesis deals with family Geastraceae. Its object is give a basic overview about the actual state of knowledge of this group of Fungi. It is group that is known from all continets besides from Antarctica. The members of family Geastraceae are saprophytes and they are found in different forest and non-forest habitats. The members of this familia are characterized by their morphology with a special terms and it will be described in details. Other aim is a recapitulation historical development family Geastraceae in system of Basidiomycota. Several recent molecular phylogenetic studies brought some new surprising knowledges about taxonomy of the family Geastraceae and the membership of some genera was questioned.
Interactions of microscopic fungi and testate amoebae in Norway spruce litter
Konvalinková, Tereza ; Koukol, Ondřej (advisor) ; Nováková, Alena (referee)
Both testate amoebae and fungi are common inhabitants of coniferous litter. Their interactions in this environment were rarely studied, although they reach high biodiversity and can play a significant role in nutrient cycling in this environment. In this study, a cultivation of litter needles in the damp chambers was used to investigate interactions between fungi and testate amoebae. Observation of spruce litter needles in environmental scanning electron microscope was used to better characterize testate amoebae communities directly on the needles. Additionally, two experiments changing the biotic conditions in the microcosm were used to follow a principle of the interactions. Three species of testate amoebae from litter needles were able to colonize the filter paper on the bottom of the damp chambers. Occurrence of Phryganella acropodia and Assulina muscorum on the filter paper was significantly fuelled by the presence of mycelium. Assulina muscorum was associated with the fungal spores and Arcella discoides was attracted by sporulating colonies of Cladosporium spp. in the damp chambers. By contrast, no association of putatively mycophagous Phryganella acropodia with fungal spores was observed. Arcella discoides was attracted both by live and death mycelium in additional experiment. Interestingly, the...

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