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Fungal symbioses in roots of the seagrass genus Posidonia: distribution, phenotypic and genetic variability and potential ecophysiological significance
Borovec, Ondřej ; Vohník, Martin (advisor) ; Gryndler, Milan (referee) ; Adamec, Lubomír (referee)
Plant roots host a wide spectrum of endophytic fungi ranging from parasites through neutralistic fungi to mutualistic mycorrhizal fungi. In most of terrestrial ecosystems, these groups of symbiotic fungi are well documented. However, much less is known about fungal endophytes of aquatic plants, especially the only group of submerged marine plants, seagrasses. We focused on roots of the seagrass species Posidonia oceanica which is a Mediterranean endemite. Its roots hosted an abundant presence of endophytic fungi. We examined the roots using optical and electron microscopy in order to study its morphology. We isolated the mycobionts and determined their taxonomic classification. A specific symbiosis of P. oceanica roots and dark coloured septate fungus has been recorded all over a vast area of the Mediterranean spreading from southern Spain to south Turkey. The fungus forms distinctive and typical structures: superficial hyphae occasionally forming hyphal sheaths or dense hyphal nets, intraradical hyphae colonizing extracellular space and, occasionally, primary cortex cells, and finally intracellular microsclerotia. The colonization pattern of the fungi resembles dark septate endophytes (DSE), group of fungi commonly found in roots of both terrestrial and freshwater plants. In our following studies, we...
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Orchids as a model for research in ecophysiological adaptations of mycoheterotropic plants
Ponert, Jan ; Lipavská, Helena (advisor) ; Gryndler, Milan (referee) ; Chrtek, Jindřich (referee)
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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Interaction of ectomycorrhizal and ericoid mycorrhizal host plants via ectomycorrhizal, ericoid mycorrhizal and pseudomycorrhizal fungi
Fendrych, Matyáš ; Albrechtová, Jana (advisor) ; Gryndler, Milan (referee)
Abstract 9. Abstract Roots of ectomycorrhizal and ericoid mycorrhizal plants are believed to be colonized by fungi belonging to different taxonomic groups. However, both frequent isolations of ericoid mycorrhizal fungi from ectomycorrhizal root tips and a few recent studies (Vrålstad et al. 2000, 2002b, Piercey et al. 2002, Hambleton & Sigler 2005) indicate that there is a group of mycobionts colonizing both types of roots. Ectomycorrhizal morphotype Piceirhiza bicolorata was shown to be induced by Meliniomyces sp. belonging to the Rhizoscyphus ericae aggregate (Vrålstad et al. 2000). The ability to colonize roots of potentially ectomycorrhizal and ericoid plants simultaneously was proven in in vitro experiments in the case of Rhizoscyphus ericae (Pirecey et al. 2002) and Cadophora finlandica (VillarrealRuiz et al. 2004). DSE fungi ("dark septate endophytes", formerly termed pseudomycorrhizal) represent another group of mycobionts colonizing both ericoid and potentially ectomycorrhizal plant roots. In the present work, we inoculated roots of ericoid (Vaccinium myrtillus) and potentially ectomycorrhizal plants (Picea abies, Pinus sylvestris and Betula nana) with typically ectomycorrhizal and ericoid mycorrhizal fungi and...
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Plant sugar metabolism and arbuscular mycorrhizal symbiosis
Konečný, Jan ; Jansa, Jan (advisor) ; Gryndler, Milan (referee)
The study of arbuscular mycorrhizal symbiosis (AMS) - the mutualist relationship between the most of land plants and evolutionary old fungal group Glomeromycota - is becoming a prestigious topic. The prevalence of and extent of physiological action of AMS on plants is very interesting for the plant biology itself, but its importance grows, notably in time of global climate change, frequent soil degradation and ascending exhaustion of mineral fertilizer reserves. Although the flows in AMS of some minerals, like of phosphorus was enlightened, carbon exchange between the symbionts is still poorly understood. In this experimental work, I utilized the boom of molecular and bioinformatic methods in the quest for completely unexplained carbon flows. The organisms used include barrel medic (Medicago truncatula), the model legume for symbiotic relationships, biotic, and abiotic stresses; Rhizophagus irregularis, the widely used fungus for such experimental studies of AMS; and Sinorhizobium meliloti, the nodulating nitrogen-fixing bacterium compatible with the barrel medic. Two variants - mycorrhizal (M+) and non-mycorrhizal (NM) plants were subjected to several levels of analysis. I have checked the variants, did the measurements of phosphorus and nitrogen contents, as well as I probed the plants with...
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Ecophysiological significance of root-fungus symbioses in Mediterranean seagrasses
Borovec, Ondřej ; Vohník, Martin (advisor) ; Gryndler, Milan (referee)
Seagrasses are the only group of submerged plants that are permanently growing in marine environment. They play an important role in the sea bottom ecosystem. Seagrasses are primary producers capable of accumulation and deposition of carbon. They influence water flow at the sea bottom and form symbioses with variety of organisms. Our knowledge of symbiotic interactions of seagrasses is still limited even though several studies of the topic have been carried out in recent years. Unlike most of terrestrial plants, seagrasses are generally considered as plants that do not form any specific associations with mycorrhizal or endophytic fungi. Surprisingly, we have discovered a novel fungal endophytic association in roots of Mediterranean endemic seagrass species Posidonia oceanica (L.) Delile. Morphology of this symbiotic fungi strongly resembles common symbiotic fungi of terrestrial plants, dark septate endophytes (DSE). We sampled roots of P. oceanica in large area of the Mediterranean from southeastern Spain to Albania and described range and taxonomical classification of the endophyte using microscopy, in vitro cultivation and molecular determination. Roots of P. oceanica in whole area of study are colonized by mere two endophytic fungal species. Over 90 % of the fungal symbionts belong to a single...
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