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Evolutionary forces of Central European taxa of the genus Dactylorhiza
Bílá, Klára ; Urfus, Tomáš (advisor) ; Figura, Tomáš (referee)
Genus Dactylorhiza, comprising green terrestrial orchids, belongs to of the most taxonomically complex groups of Europeran flora. Basic species often hybridise between each other and there is a lot of taxonomically challenging hybrids and hybridogenous lineages. Essential parental species of majority of hybrids and hybridogenous lineages are D. incarnata, D. maculata and D. fuchsii. Sister genus of Dactylorhiza is Gymnadenia which shares some similar features with Dactylorhiza species. Dactylorhiza viridis, formerly classified into the genus Coeloglossum, is the earliest diverged species. Diversity centre probably takes place in the Mediterranean Basin from where Dactylorhiza species migrated back to the Central Europe in postglacial. Major force of the genus evolution is polyploidisation which together with hybridisation leads to establishment of allopolyploid lineages. Unique feature of many orchids (including genus Dactylorhiza) is partial endoreduplication, which somatic endopolyploidisation of certain part of genome takes place. Pollination type is also important for Dactylorhiza microevolution. Deceptive flowers of Dactylorhiza genus are mainly pollinated by naive bumlebees but even beetles or ants can be pollinators. Majority of Dactylorhiza species are threatened by habitat loss during last decades....
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Effect of drought on plant-soil interactions
Secká, Gabriela ; Münzbergová, Zuzana (advisor) ; Florianová, Anna (referee)
There are feedback processes happening between plants and the soil, called plant-soil feedback (PSF), during which the plants affect the physical, chemical and biological properties of the soil and the soil in turn affects not only fitness of individual plant types, but also interspecific interactions. The influence of PSF can manifest either instantaneously or with a delay, and it has a lot of external factors affecting it. The aim of my work was literary research, which focuses on the effects of drought on PSF. Frequent and repeating droughts, which are one of the consequences of climate change, affect not only the processes happening in ecosystems, but also individual organisms present in them, including microorganisms living in the soil. Intense droughts mainly cause temperature increases, decreases in soil moisture and soil degradation. The consequences of the drought include lowering of the primary productivity of plants and changes in the composition of soil and plant ecosystems. These changes, which influence the PSF, manifest as either positive or negative feedback.
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The role of biotic interactions in plant invasions
Štajerová, Kateřina ; Pyšek, Petr (advisor) ; Prach, Karel (referee) ; Richardson, David M. (referee)
- ABSTRACT - The loss of co-adapted and gain of novel biotic interactions during the invasion process influence the success or failure of introduced plants. Within the present thesis, I studied diverse biotic interactions, specifically the relationships between plants and their herbivores, pollinators, fungi, and resident plant communities, and how biotic interactions can be utilized in planning effective science-based management. With my collaborators, we combined the community and biogeographical approach with the reciprocal transcontinental comparison between Eurasia and North America, based on primary data collected in the field. Of numerous hypotheses for the striking success of invasive plants, the enemy release hypothesis (ERH) is one of the most frequently tested. It asserts that the greater performance of introduced plants in non-native ranges is due to the absence, or decrease, in regulation by natural enemies that are left behind in the native range. Our results, in a broad sense, supported ERH, but we found that the magnitude of herbivore damage is context-dependent, related to the feeding guild and origin of both herbivores and plant species and that the increased plant performance in a new range might also be related to other factors, such as the shift in plant competition. Of animal-plant...
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Fungi associated with tree roots
Charvátová, Markéta ; Baldrian, Petr (advisor) ; Gryndler, Milan (referee)
In contrast to the bulk soil environment, plant roots represent a habitat with higher nutrient availability due to the supply of photosynthesis-derived C-containing compounds. The roots thus support the life of various microorganisms that use such compounds, but the root-associated microbes in the same time may face a limitation in N and P availability. Unlike bacteria, many filamentous fungi are able to transport these compounds from soil and their mycelia thus typically extend into this environment. Ectomycorrhizal fungi are a typical example of this nutrition strategy. Tree roots produce exudates, that differ in thein composition for each species and they can also differ among individuals. It causes a high diversity of root-associated fungi. Soil is also inhabited by parasitic and saprotrophic fungi. Composition and activity of microbial communisies in the rhizosphere differ from the bulk soil. This work points at the differences of the rhizosphere and builk soil, the importance mycorrhizal fungi and it presents an overview of fungal species that have been found on the roots of spruce - Picea abies. Key words: fungi, mycorrhiza, soil, rhizosphere, Picea abies
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The role of trehalose in mycorrhizal associations
Šoch, Jan ; Ponert, Jan (advisor) ; Hála, Michal (referee)
Mycorrhizal symbiosis is a widely spread phenomenon in nature. A translocation of nutrients occurs between symbionts with disaccharide trehalose playing a key role in the process. However, this saccharide fulfils many important roles in metabolism of fungi and plants. Fungi use trehalose mainly as storage and transport saccharide. On the other hand, trehalose occurs in extremely low amounts in plants where it acts as a signal molecule. Thus it is likely that the saccharide could be used by the fungus to manipulate plant metabolism on a physical interface between symbionts. Trehalose has a similar function in many parasitic interactions. In most cases of mycorrhizal associations trehalose synthesis creates a carbon sink in mycelium which leads to saccharide transfer from the host plant to the fungus. Completely different situation occurs in the types of mycorrhizal symbiosis, where saccharides are translocated from a fungus to a plant. Some plants can utilize trehalose effectively as a sole source of energy. Consequently, the question raises - could such plants gain fungal trehalose on purpose as a source of energy and carbon? This review aims to assess and discuss the mentioned possibilities considering available literature. Key words: mycorrhiza, orchids, parazitism, saccharides, sink, symbiosis,...
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The effect of mycorrhiza on production of plant secondary metabolites
Pikorová, Markéta ; Albrechtová, Jana (advisor) ; Rydlová, Jana (referee)
Mycorhizal symbiosis, mutualistic relationship between symbiotic fungus and plant roots, is ranked among important interspecies interactions. It is indicated that about 90% terrestrial vascular plants live in this symbiosis. Arbuscular mycorrhiza (AM) is the most often occurring type of mycorrhiza and simultaneously the most often occurring type of symbiosis of higher plants. Approximately 80% of all of plant species form this symbiosis. By symbiotic coexistence with fungus plant often gains benefits as for example higher tolerance against stress factors, resistance against pathogens or improvement of nutrient uptake. In recent years in series of works is detected that mycorrhiza positively influences production of plant secondary metabolites. This influence can display quantitativelyby increase of metabolite in plant and also qualitatively by change spectrum of substances produced. These substances can have importance in different spheres for human. Medicinal research regularly extends spectum of substances with bioactive effect which have origin just in the plant secondary metabolism. Target of this thesis is, by the form of literary retrieval, to create an overview of recent state of research regarding of influence of mycorhizal symbiosis on content of secondary metabolites in plants, especially...
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Change of structure and function of a fungal comunnities in the soil environment after the end of the flowassimilates with Norway spruce (Picea abies)
Charvátová, Markéta ; Baldrian, Petr (advisor) ; Mrnka, Libor (referee)
The decomposition of plant biomass is associated with changes of the associated fungal community which is crucial in the process of degradation due to their production of extracellular enzymes. Moreover, fungal communities as well as enzymatic activity are specific for soil microhabitats. This thesis focused on the importance of fungi associated with the roots of Norway spruce (Picea abies) trees. Forest with dominating Norway spruce, located in the School Forest Enterprise Křtiny area in Moravia, was selected for the experiment. The aim of this thesis was to compare the community composition of fungi in the roots, rhizosphere and bulk soil and to describe the gradual development of this community after the death of the roots. The next aim was to isolate, describe and characterize those fungi that decomposed roots 5 and 9 months after tree harvest. Identification of fungal isolates was based on DNA sequencing. Degradation capabilities were determined as the activity of enzymes involved in the degradation of lignocellulose. Composition of fungal communities was described by sequencing of environmental DNA on the Illumina platform. Before the flow of assimilates from the live trees stopped, communities of ectomycorrhizal fungi dominated with 60 % of all sequences. Increased abundance of saprotrophic...
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Physiological mechanisms of sorghum adaptation to abiotic stresses
Kratochvíl, Jan ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Sorghum is a traditional crop, which has been grown especially in the countries of Africa and Asia. It is used as a food, fodder, source of fiber and energy. Because of its tolerance to various abiotic stresses, especially drought, sorghum is often called "the camel of crops", and there are a lot of studies trying to clarify the basis of this tolerance. Nowadays, suitable sorghum genotypes are considered as an alternative in other parts of the world (North and Middle America, Europe) or to widen the planting areas. The first part of this thesis summarizes results of current studies aimed on sorghum physiological responses to drought, high salinity, extreme temperatures, aluminium toxicity and the combination of these stresses. The second part explains the ways how to alleviate effect of stresses on the plant. It includes the application of various compounds and genetic modifications. Powered by TCPDF (www.tcpdf.org)
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The role of trehalose in mycorrhizal associations
Šoch, Jan ; Ponert, Jan (advisor) ; Hála, Michal (referee)
Mycorrhizal symbiosis is a widely spread phenomenon in nature. A translocation of nutrients occurs between symbionts with disaccharide trehalose playing a key role in the process. However, this saccharide fulfils many important roles in metabolism of fungi and plants. Fungi use trehalose mainly as storage and transport saccharide. On the other hand, trehalose occurs in extremely low amounts in plants where it acts as a signal molecule. Thus it is likely that the saccharide could be used by the fungus to manipulate plant metabolism on a physical interface between symbionts. Trehalose has a similar function in many parasitic interactions. In most cases of mycorrhizal associations trehalose synthesis creates a carbon sink in mycelium which leads to saccharide transfer from the host plant to the fungus. Completely different situation occurs in the types of mycorrhizal symbiosis, where saccharides are translocated from a fungus to a plant. Some plants can utilize trehalose effectively as a sole source of energy. Consequently, the question raises - could such plants gain fungal trehalose on purpose as a source of energy and carbon? This review aims to assess and discuss the mentioned possibilities considering available literature. Key words: mycorrhiza, orchids, parazitism, saccharides, sink, symbiosis,...
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