National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Potassium in plant osmoregulation
Kholová, Kateřina ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Potassium is very mobile in plants and is transported across membranes using transporters and channels. It is present in the ionic form K+ in plants. Also, in the form of this ion, K+ is taken up by plants from the soil solution. The uptake is mediated by the transporter HAK5 and by the channel AKT1. The transfer of K+ to the xylem is provided by the channel SKOR and the transporter KUP7. The role of potassium as an osmotically active element is crucial. K+ helps to regulate the amount of water in the cells and thus to maintain the turgor. Turgor is important for maintaining the shape of the plant cells and for its growth. Stomatal guard cells are used as a model system for describing processes related to the K+ osmotic function. Movement of K+ is involved in the regulation of opening and closing of stomata on the principle of turgor changes. Transport of K+ into guard cells is provided by channels KAT1, KAT2, AKT1 and AKT2. On the contrary, K+ release is mediated by the channel GORK on the plasma membrane and TPK1 on the tonoplast. K+ supports also the transport of assimilates in the phloem, where the channel AKT2 plays a role. The osmotic functions of K+ are the main topic of this bachelor thesis, which summarizes current knowledge about transport mechanisms necessary for the function of K+ as osmotically...
Effect of exodermis differentiation on nutrient uptake localization in root
Janoušková, Jana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants are able to cope with changing environmental conditions or withstand its adverse effects due to their plastic development. One way to adapt to fluctuating amounts of nutrients and water in the environment or the presence of toxic substances is to regulate the movement of substances between the plant and the environment. Beside other, this regulation is also possible at the level of the root system, by the formation of apoplastic barriers endodermis and exodermis. Some species posses endodermis only, in others exodermis in hypodrermal layers of the root can be found. These barriers differentiate in three stages and prevent free movement of coumpounds though apoplast. The transport to the symplast is the key point of regulating the uptake of substances into the plant and the endodermis is the fundamental structure. The presence of exodermis, however, affects the apoplast permeability of the surface root layers and can therefore influence the involvement of the primary cortex cells in the uptake of substances from the environment. In this work the impact of phosphate deficiency on the formation of apoplastic barriers was studied focusing on exodermis and the effect of its differentiation on the occurrence of membrane transporters and involvement of primary cortex cells in the uptake of...
Mechanisms of resistance of plants from the genus Coffea to abiotic stresses
Skřivánek, Jakub ; Konrádová, Hana (advisor) ; Tylová, Edita (referee)
The genus Coffea is so specific by its distribution, requirements for environmental conditions and economic importance for humans that it is increasingly being studied as a model plant material. The thesis in the form of literary research is worked out in the context of the emerging climatic changes in order to give a comprehensive overview of the physiological responses of plants of the genus Coffea to three abiotic stresses - heat, cold and drought. The partial goal was to compare the resistance to these stresses of two economically significant species - Coffea arabica and Coffea canephora. We cannot generally say which species is more resilient, it always depends on a particular stress. Essential parts of the reaction to these stresses have proved to be carbohydrate accumulation and content dynamics. Key words: carbohydrates, climate change, Coffea, drought, extreme temperatures, stress
Potassium deficiency in plants - signs and responses
Štočková, Hana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants receive K+ mainly from the soil through the root system. In soil, K+ occurs primarily in minerals such as mica and potassium feldspar. The availability of K+ for plant uptake depends on the form in which K+ occurs in soil. There are forms directly available, slowly available, and unavailable for plant and the transition of K+ between these pools may occur. In plant, K+ is very mobile and it occurs in high amount in cells. It is the most prominent cytoplasmic cation. It affects high number of metabolic processes, including photosynthesis, osmoregulation, and activation of enzymes. K+ shortage can cause changes in plant morphology, anatomy and metabolism. K+ deficiency can be manifested by leaf deformation, decreased leaf area, necrosis, short internodes, reduced rate of photosynthesis, etc. K+ deficient plant is also more vulnerable to pathogens and its resistance to abiotic stress factors such as drought, low temperatures, or salinity is decreased. Deficiency of K+ reduces the biomass and overall yield in agricultural crops, so K+ fertilizers, both soil and foliar, are needed. The thesis focuses on the manifestations of K+ deficiency in plants and summarizes the recent findings on mechanisms of K+ deficiency perception and signal pathways leading to the response to this deficiency. Key...
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....
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...
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...
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
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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