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Control of lateral root development in response to availability of principal mineral nutrients.
Halamková, Daniela ; Tylová, Edita (advisor) ; Smetana, Ondřej (referee)
Lateral roots are, due to their large absorption surface, a part of the root system with significant importance for the plant's ingestion of water and nutrients. Their development depends on heterogeneity of soil environment, which enables the plant to optimize the acquisition of resources under current conditions. The availability of mineral nutrients (type of nutrient, form, distribution in soil and mobility) is one of key factors that determine root system morphogenesis. Another important aspect is the amount of nutrient in the plant; in other words, the plant's current demand for the element. The most important nutrients that influence the architecture of the root system are two macroelements - nitrogen and phosphorus. Both of these elements trigger positive and negative effects on the development of lateral roots. Nitrate, important source of nitrogen, induces two entirely different regulatory mechanisms of lateral root development. Under nitrogen limiting condition, a local stimulation of lateral root elongation is triggered in nitrate-rich patches. This response integrates the signalling pathways of auxin and nitrate. In contrast, high and homogenous availability of nitrate in rhizosphere (≥ 10 mM) causes inhibition of lateral root growth. This systemic inhibitory effect was similarly...
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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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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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Control of lateral root development in response to availability of principal mineral nutrients.
Halamková, Daniela ; Tylová, Edita (advisor) ; Smetana, Ondřej (referee)
Lateral roots are, due to their large absorption surface, a part of the root system with significant importance for the plant's ingestion of water and nutrients. Their development depends on heterogeneity of soil environment, which enables the plant to optimize the acquisition of resources under current conditions. The availability of mineral nutrients (type of nutrient, form, distribution in soil and mobility) is one of key factors that determine root system morphogenesis. Another important aspect is the amount of nutrient in the plant; in other words, the plant's current demand for the element. The most important nutrients that influence the architecture of the root system are two macroelements - nitrogen and phosphorus. Both of these elements trigger positive and negative effects on the development of lateral roots. Nitrate, important source of nitrogen, induces two entirely different regulatory mechanisms of lateral root development. Under nitrogen limiting condition, a local stimulation of lateral root elongation is triggered in nitrate-rich patches. This response integrates the signalling pathways of auxin and nitrate. In contrast, high and homogenous availability of nitrate in rhizosphere (≥ 10 mM) causes inhibition of lateral root growth. This systemic inhibitory effect was similarly...
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