All orchid species studied so far have been shown to participate in orchideoid mycorrhizal symbiosis. Morover, this symbiosis is absolutely vital component of their life cycle. Exchange of nutrients occurs between symbionts where the fungi provides the orchid with energy and carbon supply at least in its early developmental stages. This study focuses on the possible role of trehalose in this transfer. In vitro experiments have showed in five species from three different subfamilies of Orchidaceae family that they can utilize trehalose comparably with sucrose and glucose. Thus, the ability of trehalose utilization seems to be conserved among orchids. Trehalase enzyme activity was localized histochemically in orchid mycorrhizas. The activity strongly colocalized with colonized tissue supporting a hypothesis that trehalose transfer occurs in this site and is mediated by trehalase. Using bioinformatic methods, trehalase gene duplications were identified in many taxons of Embryophyta including three orchid species. Interestingly, highest number of trehalase gene copies was identified in genome of orchid Dactylorhiza majalis. Trehalose utilization, high trehalase activity in mycorrhizas and trehalase gene duplications in some orchids together indicate that trehalose transfer in orchid myccorhizas...

Arbuscular mycorrhizal (AM) symbiosis, a widespread plant-fungal relationship, is based on reciprocal resource exchange. The functioning of this fragile relationship balances on the scale from mutualism to parasitism, depending on the specific context. The thesis aims to interlink the functioning of AM symbiosis both with the composition of AM fungal communities and with different abiotic conditions. The thesis is divided into a methodological and a factual part and consists of three publications and one manuscript. All experiments were conducted in greenhouse conditions with medic (Medicago sp.) as host plant. Host plants were inoculated with single AM fungal species in Paper I and II, and with a synthetic AM fungal community of five species in Paper III and IV. The host plant identity, the amount of phosphorus (P) in substrate and the type of substrate played an important role for the achievement of mutualistic AM symbiosis, as demonstrated in Paper I. Paper II showed that mitochondrial and nuclear qPCR markers can be used alternatively for the quantification of particular AM fungal species. However, intraradical fungal biomass was better related to copy numbers of nuclear DNA than of mitochondrial DNA. The functioning of AM symbiosis was modulated by the availability of P, light and water,...

Invasive plants represent an important topic of study in current ecology because of their effects on whole ecosystems. The plants interact with the soil including soil biota, with the other plants in the community and with other organisms, eg. herbivores. Invasive plants often differ from non- invasive plants in nutrient utilization and can thus affect soil pH as well. They may also differ in the way they interact with mycorrhizal fungi that help the plants with nutrient uptake. In this study, the effect of invasive and native plants on soil properties is compared. Congeneric pairs of species, where one species is native and the other invasive, are compared. The native species are chosen so that they are dominant and therefore comparable to the invasive plants in the new environment. The evaluated soil properties are pH value and content of elemental nutrients from abiotic properties, and the amount of mycorrhizal fungi propagules and their spreading rate in soil from the biotic properties. In this study, the invasive and native plants differ only in the content of exchangeable phosphorus and potassium. Content of these two nutrients and one of the indicators of mycorrhizal fungi differ within the pairs of species as well. For most soil properties, the genus of the plant plays the main role, not...

Perhaps all orchids are mycotrophic at early developmental stages, while majority of species photosynthesize at adulthood and only about 200 species remain fully mycotrophic for the whole life. Mycotrophy affects orchids at many levels. In this thesis, I focus on four aspects of orchid biology, which could be connected with mycotrophy: (i) systematics, (ii) genome size and endoreduplication, (iii) regulation of seed germination and (iv) mechanism of transfer of carbon and energy from fungi to orchids. There are over 27,000 recently recognized orchid species, nevertheless new ones are still discovering and old ones are revisiting. In this work I present a description of new species, Cleisostoma yersinii, and its morphological, anatomical, ecological and systematic characterization. Phylogeny reconstruction confirmed relationship with C. birmanicum. In the subtribe Podochileae, I reappraised the genus Campanulorchis to establish monophyletic but also morphologically defined group. For both abovementioned genera I prepared the artificial identification key. In the genus Dactylorhiza I revised taxa present in our country and I prepared an identification key which firstly mentions D. maculata subsp. elodes from Czech Republic. Orchid species diversity is probably reflected in genome structure. Results...

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Perhaps all orchids are mycotrophic at early developmental stages, while majority of species photosynthesize at adulthood and only about 200 species remain fully mycotrophic for the whole life. Mycotrophy affects orchids at many levels. In this thesis, I focus on four aspects of orchid biology, which could be connected with mycotrophy: (i) systematics, (ii) genome size and endoreduplication, (iii) regulation of seed germination and (iv) mechanism of transfer of carbon and energy from fungi to orchids. There are over 27,000 recently recognized orchid species, nevertheless new ones are still discovering and old ones are revisiting. In this work I present a description of new species, Cleisostoma yersinii, and its morphological, anatomical, ecological and systematic characterization. Phylogeny reconstruction confirmed relationship with C. birmanicum. In the subtribe Podochileae, I reappraised the genus Campanulorchis to establish monophyletic but also morphologically defined group. For both abovementioned genera I prepared the artificial identification key. In the genus Dactylorhiza I revised taxa present in our country and I prepared an identification key which firstly mentions D. maculata subsp. elodes from Czech Republic. Orchid species diversity is probably reflected in genome structure. Results...

Plant symbiosis with arbuscular mycorrhizal (AM) fungi provides many benefits for plants, including increased nutrient uptake, drought tolerance, and belowground pathogen resistance. In order to have a better understanding of the genetic architecture of mycorrhizal symbiosis, we conducted a genome-wide association study (GWAS) by phenotyping a diversity panel of cultivated sunflower (Helianthus annuus) for root colonization under inoculation with the AM fungus Rhizophagus intraradices. This mapping panel consists of 261 inbred lines that capture approximately 90% of the genetic diversity present in the cultivated sunflower germplasm. Using a mixed linear model approach with a high-density genetic map, we determined regions of the genome that are likely associated with AM colonization in sunflower. Additionally, we used a ‘core 12' set of twelve diverse lines (representing approximately 50% of the genetic diversity in the cultivated germplasm) to assess the effect that inoculation with AM fungi has on dried shoot biomass and macronutrient uptake. Colonization rate among lines in the mapping panel ranged from 0 to 70% and was not correlated with mycorrhizal growth response, shoot P response, or shoot K response among the core 12 lines. Association mapping yielded three SNPs that were significantly associated with AM colonization rate. These SNPs explained 19.0%, 14.4%, and 27.9% of the variance in three different metrics used to measure the degree of root colonization. Three genes of interest identified from the significant regions that contained these SNPs are potentially related to plant defense. Overall, our data suggests that candidate genes involved in plant defense may affect AM colonization rates within cultivated sunflower, and that these genes have a large effect size.

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Mycorrhizal networks (MNs), or the networks of fungal mycelia that connect plants to each other, are vital in contributing to the well-being of ecosystems. They not only assist in the transport of nutrients across an ecosystem, but also help protect an ecosystem from disease and adverse conditions. However, more research into these networks is needed and modelling these networks as graphs can help us achieve this. By applying centrality analysis and performing k-core partitioning on these networks, we are able to identify the trees that are most important and central to a MN and observe the effects of removing these trees. We also perform random partitioning on these networks and compare the results to the k-core partitioning results. We found that these networks are fairly resilient to the removal of a single keystone individual, but this can disrupt the interconnectedness of a MN in a dry (xeric) moisture regime. We also found that these networks are less resilient to k-core partitioning. In a network of trees divided up by age cohorts, the maximal k-core subgraph contained a mix of trees that mostly belonged to older cohorts and were linked to one specific fungal genet. This could influence conservation efforts for not only a few older trees, but also some younger trees and potentially specific fungal genets. When removing the maximal k-core subgraphs for networks in dry (xeric) and moist (mesic) moisture regimes, the network became disconnected for the xeric graph and still somewhat connected for the mesic graph. So, mycorrhizal networks could possibly be more resilient to this k-core partitioning in an area where the soil is moist rather than dry.