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Physiological mechanisms of abiotic stress tolerance in Sorghum bicolor
Kratochvíl, Jan ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Current agriculture is facing a serious challenge of decreasing precipitation and irregular occurrence of drought periods including their unfavorable distribution during the vegetation season. This leads to growing interest in planting highly drought-resistant crops like sorghum. In comparison with other crops, sorghum excels in low water demand, though exhibits high susceptibility to low temperatures, which hampers its spread to new regions. Surprisingly, there is not enough information about the nature of sorghum's reaction to cold exposure. The aim of this diploma thesis was to describe reactions of young sorghum plants exposed to cold stress, low water availability and their combination and to verify the possibility of plant hardening through previous low-stress load. The special focus was paid to changes in carbohydrate metabolism, which plays generally very important role in plant defense reactions. The other analyzed physiological traits were leaf tissue osmotic potential, proline content and basic morphometric characteristics. Experimental design consisted of pot experiments conducted in growth chambers and the experiments performed under controlled conditions in vitro, using two sorghum genotypes "Ruzrok" and "01Z1800012". Both genotypes exhibited similar response to stress treatment....
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Abiotic Stress Adaptation in Plantago: mechanisms of tolerance
Dvořáková, Iveta ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Plants are exposed to many adverse factors during their life cycles. Abiotic stresses are significantly limiting plant growth and development. Abiotic stress response mechanisms involve compatible solute synthesis (e.g. sugars, sugar alcohols and amino acids). The aim of this study was to characterise the responses of plants from Plantago genus to different abiotic stresses (drought, salinity, cold and stress combination). The complete plants grew under in vitro conditions. I compared morphological parameters, selected metabolic parameters (carbohydrates balance and proline accumulation) under optimal conditions and stress exposure. This study was focused on plants from genus Plantago, because they differ from each other in their tolerance to the salinity. Both, the glycophyte and the halophyte species are described within this genus. Plantains produce besides widespread soluble carbohydrates (sucrose, glucose, fructose) also sugar alcohol sorbitol, which has been reported as a significant component of the stress response. In addition, the reaction of plants to different carbon and energy sources was tested. More severe growth inhibition of the glycophyte Plantago lanceolata compared to the halophyte P. maritima was observed under salt treatment. Significant accumulation of sorbitol was observed...
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Variability and mechanisms of exodermis differentiation in plant roots
Blascheová, Zuzana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Environmental conditions affect the formation of apoplastic barriers (endodermis and exodermis) in roots. This was shown on many species in many research papers. The exodermal layer is more variable in response to stress conditions than endodermal layer. Cadmium toxicity, as many other stresses, induces faster development of apoplastic barriers. Most of research papers published so far, however characterized only the response of main root to this type of stress factor. Lateral roots, an important part of the root system absorptive surface, are neglected and there is not much information about their response to cadmium stress. The pattern of apoplastic barriers development was therefore analysed in main and also in lateral roots of various size and position on maternal root axis. We found significant differences in response to cadmium stress among these different root types. Then we summed up the differences between these types of roots. Short lateral roots were generally more responsive to cadmium stress, cadmium affected root branching as well as differentiation of apoplastic barriers in lateral roots. These results help us to better understand the response of complex roots system to environmental conditions. In the second part of this work, the role of CASP genes in exodermal development was...
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Root apoplastic barriers in adverse environmental conditions.
Blascheová, Zuzana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Differentiation of apoplastic barriers in roots is affected by adverse environmental conditions (e.g. heavy metal toxicity, salinity or flooding). The apoplastic barriers, exodermis and endodermis, differ from each other in response to environmental conditions. The exodermis is more affected by these conditions and its occurence is more variable. The presence of differentiated barriers affects root transport features like uptake, accumulation and entrance of polutants or nutrients. Key words: apoplastic barriers, heavy metals, differentiation, root, Casparian strips, suberin lamellae
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Cellular mechanisms of differentiation of root apoplastic barriers
Namyslov, Jiří ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Apoplastic barriers (exodermis and endodermis) are primarily used to regulate the free movement of substances within apoplast due to modifications of cell walls. While at the anatomical level, the barriers are studied for a long time, only recently the molecular mechanisms that are behind the emergence of these modifications are gradually identified. The most important modifications are Casparian strips that fill the space between the adjacent cells in exodermis and endodermis. Casparian strips are lignin-based structures formed with the help of CASP proteins located in equatorial region of plasmalema (called CSD membrane domain). In addition to CASP proteins, the formation of Casparian strip involves activity of site-specific enzymes of lignin synthesis (PER64 peroxidase, NADPH oxidase RBOHF). In these cell layers shortly after differentiation of Casparian strips, the deposition of suberin occurs between plazmalema and primary cell wall leading to formation of suberin lamellae also serving to block the apoplast. Next step of differentiation is the formation of U-shaped tertiary thickenings that are formed by deposition of secondary cell wall, whose formation mechanism in the root endodermis is not yet well-known. Processes responsible for formation of apoplastic barriers are thus related to the...
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Sorbitol role in abiotic stress response
Dvořáková, Iveta ; Konrádová, Hana (advisor) ; Janská, Anna (referee)
Many adverse factors affect plants during their life cycle. This bachelor thesis is focused on the influence of abiotic stress on plants. Attention is paid to drought and salinity stresses which are the main causes of osmotic stress, and to the mechanisms which help plants to cope with these adverse factors. Common reaction of plants to osmotic stress is synthesis and accumulation of substances which contribute to keeping cell integrity. These substances are called compatible solutes. This thesis is focused on sorbitol - sugar alcohol belonging to this group of substances. In plants that synthesize sorbitol naturally, it provides advantage under exposure to abiotic stresses as it serves as an osmoticum and/or an osmoprotectant and reduces oxidative stresses. Finally, based on the knowledge about participation of sugar alcohols in the stress reactions, modifications of plant metabolisms potentially increasing stress tolerance are discussed. Powered by TCPDF (www.tcpdf.org)
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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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Carbon allocation in evergreen and decidious temperate tree species under the elevated concentration CO2 and O3
Neuwirthová, Eva ; Albrechtová, Jana (advisor) ; Konrádová, Hana (referee)
An ongoing increase in atmospheric CO2 concentrations and tropospheric O3 is expected in coming years. These changes are mostly caused by anthropogenic activities and influence remarkably not only plants but the climate on the Earth. Physiological processes in plants determining carbon assimilation and allocation in plant organs are changing in a consequence of variations of these gases in the environment. Tree species represent importatnt C pools and changes in C allocation may effect their sink capability in the global C cycle.Increased CO2 concentration in the atmosphere often leeds to incereased rate of photosynthesis lowered photorespiration what in turn may lead to enhanced C storage in plant biomass. The C storage into sinks is mediated through the assimilation organs, which are disturbed by O3. Ozone is toxic to plants and trees are due to their longevity exposed to ozone influence repeatedly for long term. The response to increased CO2 and O3 concentrations, is the most commonly investigated on two typical representatives of European temperate species: deciduous European beech (Fagus sylvatica L.) and coniferous Norway spruce (Picea abies L. Karst.) The aim of the present review was to summarize the knowledge about the effects of increased concentrations of CO2 and O3 acting separately or in...
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Possibilities and Utilisation of Objective Personality Tests of the Vienna Tests System for Detection of Individual Risk-Tendency
Konrádová, Hana ; Niederlová, Markéta (advisor) ; Šípek, Jiří (referee)
The theoretical part of this thesis addresses key concepts related to the individual tendency to take risks - it introduces how this trait is embedded in the concept of personality, establishes essential theoretical issues related to risk and risk-tendency, as well as related important terms, research and authors in the field in question. The key issues, too, are methods of risk behaviour detection with emphasis on current trends in psychodiagnostics, thus in the following part the fields of computerized psychodiagnostics and of objective personality tests are discussed. The paper's empirical section is focused on the utilization of Vienna Test System (VTS) in this area. Objective personality tests used for detection of risk-tendency were analysed and validised using the SPARO method and data gained during interviews. Empirically produced results suggest that the validity of the methods used is equivocal. One of the main conclusions of this thesis, therefore, is that VTS methods' potential to determine risk behaviour seems to be rather limited and its further research should be conducted in the future. Keywords: risk, risk-tendency, personality, objective personality tests, computerized testing, Vienna Test System
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Somatic embryogenesis of conifers: description of structural development
Kadlecová, Marie ; Albrechtová, Jana (advisor) ; Konrádová, Hana (referee)
Somatic embryogenesis is a very important tool of in vitro cultivation, therefore, it has recently devoted adequate attention. Stages of somatic embryogenesis involve several consecutive steps: induction of embryogenic culture and its proliferation, maturation of embryo, desiccation, germination and subsequent transfer of embryos into young seedlings. All of these steps are directly influenced by many factors, such as a choice of the original explant, time of cultivation, physical conditions or the composition of the culture medium. There are still emerging new studies describing how the culture conditions and, thus, the quality of embryos could be improved. An important prerequisite for further improving the quality of somatic embryos is good knowledge of aculture protocol, i.e. right concentrations of amended substances in the culture medium, the timing of each step, using the suitable explants etc. Another very important thing is good knowledge of development of all anatomical structures established during embryogenesis. Only then it will get closer to the point when somatic embryos will not arise only in the laboratory, but could be successfully used in practice. The object of this work is to summarize existing knowledge about development of all anatomical structures during somatic...
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