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Lateral root development in response to mineral nutrients; signal mechanisms and pathways.
Halamková, Daniela ; Tylová, Edita (advisor) ; Lhotáková, Zuzana (referee)
TTL3 gene was identified by forward screening of genes involved in lateral root development in Arabidopsis thaliana based on its expression pattern. TTL3 belongs to the TTL (TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE) gene family. The diploma thesis is aimed on characterisation of changes in TTL1, TTL3 a TTL4 promotor activities in response to external conditions (availability of nitrogen or phosphorus) that affect root growth. Obtained data should elucidate possible relation among TTL gene expression activities, root growth rate, and apical meristem activity. Nitrogen or phosphorus deficiency triggered changes in root growth and root system morphology of experimental plants. Short-term nitrogen deficiency stimulated root growth. Short-term phosphorus deficiency induced gradual growth cessation in main root and long laterals. Long-term deficiency reduced root growth of both N-deficient and P-deficient plants compared to control. The root system size of N-deficient and P-deficient plant was almost similar. Determination of promotor activity using β-glucuronidase reporter gene showed changes in expression activity and its localization in response to root growth intensity. TTL4 gene promotor activity was the most responsive. Its activity was generally higher in slowly growing roots, particularly under...
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Mechanisms of extreme drought tolerance in resurrection plants
Termanini, Sebastian ; Lipavská, Helena (advisor) ; Lhotáková, Zuzana (referee)
Drought is one of the abiotic stresses that plants have to fight with from the beginning of their transition to land. However, there is a systematically incoherent group of plants that can solve extreme water scarcityand still effectivelyprosper. A high degree of dehydration involves a number of problems including osmotic stress, the accumulation of reactive oxygen species (ROS), or protein degradation. However, drought-tolerant plants have evolved mechanisms to deal with these problems. For protection against ROS they activate antioxidant enzymes and accumulate non-enzymatic antioxidants, which can quench ROS. These plants use a wide spectrum of amino acids and carbohydrates against the osmotic stresses, ranging from the ubiquitous and abundant carbohydrates like sucrose, till the trehalose scarce in plants. None of the plants relies on a single substance, instead, plants depend on species-specific cocktails of protective agents, through which they acquire their tolerance. The studies of those plants and their mechanisms of tolerance seem to be a perspective way for selection of preferable target genes suitable for the development of crops tolerant to desiccation. Key words: antioxidant systems, dehydration, drought, LEA, octulose, polyols, RFO, resurrection plants, sucrose, trehalose
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Effect of water supply on structure and selected physiological parameters of leaf in woody species.
Horešovská, Michaela ; Lhotáková, Zuzana (advisor) ; Votrubová, Olga (referee)
Woody plants must cope with drought as it is one of the main factors of the ongoing climate change. The ability of woody plants to adapt to this stressor determines whether they will survive in constantly changing environmental conditions. The deciduous trees of European temperate forests are not as adapted to drought as Mediterranean trees and shrubs, and therefore the lack of water is a major stress for them. Leaf turned out to be the most flexible plant organ in its response to drought. The aim of this work is to summarize the knowledge about the effect of water deficit on the anatomical structure of leaf and its selected physiological parameters. The first part of this thesis is focused on the drought affecting European tree species and their various defensive strategies against this factor. It mainly describes the modification of leaf's anatomy structure as their defensive reactions observed in dermal, ground and vascular tissue. The second part of this thesis is devoted to the influence of water deficit on the selected leaf's physiological processes, especially on transpiration and photosynthesis, and the key role of stomata closure on both of these physiological processes. Drought causes changes in leaf anatomical structure and its physiological functions. The leaf's developmental stage at...
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Increasing plant drought resistance by priming methods: the role of antioxidant capacity changes
Popelářová, Anna ; Lipavská, Helena (advisor) ; Lhotáková, Zuzana (referee)
When there is a lack of water in the soil, the plant is subject to stress during which reactive oxygen species (ROS) are formed and the water content in the tissues decreases. ROS cause oxidative damage, which the plant tries to prevent by antioxidation systems action. The osmotic adjustment process ensures water maintenance in the plant. Priming can be thought of as a treatment of plants aimed at increasing stress resistance. This thesis is mainly focused on summarizing information related to priming in connection with drought tolerance improvement and related changes in the activities and amount of antioxidation systems and osmolytes. So far, seed priming methods are probably the most explored, these include hydropriming, osmopriming and priming with elicitors. Priming in the vegetative phase of growth is mainly associated with the application of elicitors. Transgenerational priming has an impact on the progeny of treated plants. Priming-induced changes are species-specific and in some cases may affect the plants for a longer period.
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Norway spruce chloroplast ultrastructure - heterogeneity within a needle.
Glanc, Natália ; Lhotáková, Zuzana (advisor) ; Kutík, Jaromír (referee)
6 Abstract Temperate forests serve as long term carbon storage and are affected by increasing carbon dioxide (CO2) concentration in the atmosphere. Norway spruce (Picea abies (L.) Karst.) is the most abundant conifer in the forests of the Czech Republic, therefore I studied the response of its photosynthetic aparatus to elevated CO2 concentration. The aim of my thesis was to analyze the impact of CO2 concentration on chloroplast ultrastructure in both shaded and exposed needles, focusing on the volume density of starch in the median cross-sections of mesophyll cell chloroplasts. The next aim of the study was to test whether the chloroplasts of the first subepidermal layer of mesophyll are representative for the whole needle with respect to starch volume density. The study was performed on eleven years-old Norway spruce trees that had been exposed to ambient or elevated concentration of CO2 for six years; the experiment had been carried out at the Bílý Kříž experimental station in the Beskids Mountains in cultivation chambers with automatically adjustable windows. First year needles of trees grown under abient (382-395ppm) or elevated (700 ppm) CO2 concentration were collected in October 2011. The needles were used to prepare ultrathin sections and the images of median chloroplast cross-sections were...
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The role of NO in plant senescence
Kramná, Barbara ; Wilhelmová, Naďa (advisor) ; Lhotáková, Zuzana (referee)
1 Abstract Nitric oxide (NO) is a lipophilic free radical gaseous molecule able to readily diffuse through membranes and thus influence the adjacent cells from its source. It belongs among important physiological modulators of a plant life despite of its short life span, which is in most cases, only a few seconds. NO influences plants during their whole life cycle and predominantly acts via a modulation of gene expression or post-translation modifications. An enzymatic production of NO has been documented in apoplast, cytosol and organels such as mitochondria, chloroplasts and peroxisomes, apart from its spontaneous production in reducting conditions. The possible cytoprotective or cytotoxic effects of NO in plant cells depends on its concentration. High concentrations have been proved to be rather cytotoxic. Plant senescence is often accompanied by a vast oxidative damage, which results in high concentrations of ROS, such as O2∙- and H2O2, lipid peroxidation and a decrease of antioxidant enzymes activities. NO has been proved to retard or entirely prevent a senescent phenotype of stress-treated plants. Thus a role as a negative regulator of plant senescence has been proposed for it. The most often method used for NO level modulation in plant tissues is an exogenous aplication of various NO donors. Other...
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Laboratory spectroscopy for selected Krkonoše Mts. tundra vegetation species
Tomcová, Jana ; Červená, Lucie (advisor) ; Lhotáková, Zuzana (referee)
Laboratory spectroscopy for selected Krkonoše Mts. tundra vegetation species The diploma thesis is focused on testing the methodologies of measuring the reflectance of grasses from the tundra of Krkonoše Mountains (Nardus stricta, Molinia caerulea, Calamagrostis villosa). The spectoradiometer ASD FieldSpec 4 Wide-Res with added contact probe ASD Plant Probe is used for measurements. Since it is not common to measure such narrow leaves that do not cover the whole FOV, the thesis is looking for methodologies that are the most repeatable and influenced by a minimum of errors. Factors influencing the measurement results are also monitored. Furthermore, the differentiation of the studied species is observed based on their spectral properties. Based on the measured data the medians and standard deviations are calculated and compared among each other. An analysis of variance (ANOVA) is used to determine the bands where the influence of individual factors is more apparent and where the individual grasses are distinguishable. As the most suitable methodologies for measuring grasses depend on the grasses structures and properties, the best methodology is different for each of selected species. The two layer leaf measurement is most suitable for the Nardus stricta, the measurement of the abaxial sides of leaves fits...
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Thorium as an environment stressor for plant growth.
Hrdinová, Aneta ; Lhotáková, Zuzana (advisor) ; Podlipná, Radka (referee)
Thorium is an element belonging to heavy metals, which is characterized by its radioactivity similarly to uranium and radon. Thorium is not commonly used in industry, but becouse of its radioactive properties it has a great potentional for future use in nuclear energetics. Thus, increasing release of Th into the soil, water and atmosphere can be expected in near future and through plant biomass it could become a part of food chains and webs and, thus, to represent a considerable health risks to humans. Studies devoted to research on thorium and its effects on plants has not been published much yet. The majority of these studies focus mainly only on plant abilities to accumulate thorium and/or monitoring distribution of thorium in plant body. But till now, a study is still missing, which would monitor the effect of thorium on the physiological characteristics of plants. Plants of Nicotiana glutinosa (L.) medium Thorium accumulatin were hydroponically cultivated Hoagland nutrient media differedin the presence of thorium, tartaric acid, putrescine and phosphates. In first part of the present study I monitored accumulation of thorium by tobacco plants under the influence of the above-mentioned modifications of media. In the second part, I studied the Th effect on the photosynthetic apparatus (contents...
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Comparison of various approaches to evaluation of tree energetic balance
Tomková, Alžběta ; Pokorný, Jan (advisor) ; Lhotáková, Zuzana (referee)
The thesis deals with the tree energetic balance closely related to the phenomenon of plant transpiration. Living systems have a unique ability to equilibrate gradients in the nature. Storing energy of the incoming solar radiation into a latent heat of water evaporation is an example of such tree feature. It dissipates energy and simultaneously recycles nutrients and water in the ecosystem. There are few possible ways of energy balance detection shown in this work. The thermal imagining can be used as a method for an indirect indication of transpiration - transpiring plants have lower leaf surface temperature. An alternative method for determining the rate of transpiration is a direct measurement of transpiration on leaves or transpiration flow in a tree trunk. However, extrapolation of the above mentioned methods to entire stands can encounter some difficulties. The first part of the thesis presents a description of a physical background of energetic processes and the ways in which plants operate with water, the biotic pump theory is being discussed. The practical part begins with experiments on single leaves. These experiments are carried out to test the usability of the methods for the following experiments, which are performed on the entire living trees. They are focused on the relationship of the...
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Leaf structural changes induced by tropospheric ozone.
Češpírová, Zdeňka ; Lhotáková, Zuzana (advisor) ; Hála, Michal (referee)
Tropospheric ozone is an important pollutant formed by the photochemical reactions of ultraviolet radiation and nitrogenous. Recently, its concentration in the air is increasing due to the promoting climate change and antropogenic activities, mainly because of combustion of the fossil fuels. The ozone is highly reactive molecule degrading to the reactive oxygen species having negative effects on the leaf physiological functions and structure. Ozone penetrates the leaf through the stomata, thereafter it reacts with the cells and their singular compartments. The products formed due to ozone degradation are able to cause the disintegration of plasma membranes and other oxidative damage, for example accumulation of plastoglobuli inside the chloroplasts, changes in the shape of chloroplasts, mitochondria or peroxisomes. At the macroscopic level the visible lesions, chloroses and necroses are observed. In addition, the faster senescence of leaves is observed under the effect of ozone. The main aim of present thesis is to review knowledge of the ozone-induced changes in the leaf structure beginning on the cell structure level and ending at the whole plant body level and to explain physiological mechanisms leading to these damages. Key words: ozone, oxidative stress, leaf structure, mesophyll, reactive...
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