|
|
Regulácia vyrastania kotylárnych pupeňov hrachu
Kucsera, Attila
This work was aimed to achieve more details in regulation of cotyledonary bud outgrowth of pea plants (Pisum sativum L.). Plants were studied after decapitation of the apex and removal of cotyledons and their subsequent substitution with agar gels containing different susbstances. Experiments were perform in light and dark conditions. The obtained results proved that auxin could regulate outgrowth of pea cotyledonary buds. Furthermore, sucrose showed partly inhibitory effect on bud outgrowth. This inhibitory effect was pronounced if plants were cultivated in dark. Next experiments showed that cotyledons could regulate apical dominance depending on light or dark conditions.
|
|
|
Růstové korelace u rostlin konopí setého
Michálková, Klára
The teoretical part of my bachelor thesis Growth correlations in cannabis plant is mainly focused on the issue of growth correlations. In the bachelor thesis, concrete examples of growth correlations are characterized including more details on problematics of apical dominance of the stem. The basic botanical, morphological and genetic characteristics of cannabis are also described, including important content substances. In the experimental part, the intensity of shoot branching of intact plants of selected technical and medical cannabis genotypes is investigated. The increase in length of axillary buds of first, second and third node was measured. Within the period of a few days, plant response to decapitation and exogenous auxin application was tested. In technical cannabis there was a strong response to exogenous application of auxin. On the other hand in the most cases of medical cannabis there was a reduced sensitivity to exogenous application of auxin. On the topic of shoot branching it was observed that the branching of medical hemp genotypes is significantly more intensive compared to the varieties od technical cannabis. The results of the grafting experiment then imply that the rootstock of technical cannabis did not influence the intensity of shoot branching of the medical cannabis scion.
|
|
|
Vliv vybraných stanovištních faktorů na proteolytickou aktivitu lesních půd s důrazem na organické a anorganické látky
Holík, Ladislav
PhD thesis focuses on soil biochemistry, namely the effects of organic and inorganic substances on proteolytic ktivity in forest soils. The thesis is composed of several impacted journal articles and two manuscripts. Selected organic compounds feature L- and D-tartaric acid, phenolics, proteinogenic and non-proteinogenic amino acids, auxins and cytokinins, whilst inorganic substances are represented by salts. Furthermore, an article dealing with the effects of different forest management practises on soil enzymatic ktivity (including proteases) is adjoined. Its aim is to monitor the effect of forest regenerative elements (forest stand gaps) on enzymatic ktivity, whereas the intervention into forest ktivity changes the moisture and thermal conditions of the site. The results show that out of the organic substances tested L- and D-tartaric acid, proteinogenic and non-proteinogenic amino acids and auxins have a positive effect on the proteolytic ktivity. Conversely, phenols and cytokinins acted as inhibitors. Soil salinization also had a negative effect on proteolytic ktivity of forest soils. The Influence of forest management through forest regenerative elements on soil protease ktivity was not detected. Potential urease ktivity was the only enzyme that reacted to the change of climatic conditions of forest habitat; however, ktiv not a principal topic of this work.
|
|
|
New insights on auxin metabolism
Helusová, Lenka ; Müller, Karel (advisor) ; Ryšlavá, Helena (referee)
Auxin is the longest known phytohormone with many functions. It participates in the development of embryo, in vegetative and generative development, plant stress reaction, and also in their senescence and death. Activity of auxin in plant cells and tissues is quite often compared to the effect of morphogens, i.e. the effect of substances, whose concentrations induce a strictly defined response in tissue and organ formation. Apart from intercellular and intracellular auxin transport, the main determinants of auxin concentration gradients are its biosynthesis and metabolism. Regardless of the long-lasting study of auxin, the complexity of metabolic pathway regulation is still not well known. The aim of this thesis is to summarize current knowledge of the metabolism of auxin in plants, i.e. its biosynthetic pathways, conjugation and oxidation, and put them into a context with older results.
|
|
|
The evolution of auxin metabolism, signalling and transport in the green lineage (Viridiplantae)
Schmidt, Vojtěch ; Petrášek, Jan (advisor) ; Fendrych, Matyáš (referee)
Phytohormone auxin is an essential coordinator of growth and development within land- plants. Mechanisms of auxin action in algae is still poorly understood, given that related research has begun recently. Current progress is derived mainly from available sequence data, which are necessary for analysis of gene homology with higher plants. In this case with the genes related to auxin action mechanisms, e.g. metabolism, signaling and transport. Auxin biosynthesis predated the split of Chlorophyta and Streptophyta, but tighter regulation of auxin levels is the matter of land-plants. First auxin responses were probably non-transcriptional. Transcription-regulating nuclear signaling pathway assembled from more ancient domains, some of them were identified in Charophyta, but whole pathway was complete after colonization of land. Auxin transport out of the cell was one of the original mechanisms of regulating its levels. More sophisticated auxin carrier system was proposed to evolve in Charophyta, where polar auxin transport was identified. Auxin as a signaling molecule was present in primitive algae groups, but its response spectrum dramatically increased after colonization of land. Future research of auxin action evolution needs more model organisms to be established, especially from Charophyta....
|
|
|
Molecular basis for regulation of cell wall pH in Arabidopsis thaliana
Bogdan, Michal ; Fendrych, Matyáš (advisor) ; Retzer, Katarzyna (referee)
The cell wall is one of the defining parts of the plant cell. Cell walls resist turgor pressure, give plants their rigidity and still allow the cell to grow despite their stiffness. The plant cell wall is a composite material that consists of different elements; thus, the knowledge of the plant cell wall composition helps us understand the impact of the mentioned pH changes. Alterations of plant cell wall properties result in a change of plant cell growth rate. A prime example of this is the modification of wall properties by pH change, termed the acid growth. Although acid growth has been studied for a long time, we still do not fully understand the underlying mechanisms, as we have not yet identified all the agents involved in acid growth and our ability to determine apoplastic pH is limited. Local cell wall pH fluctuations arise also due to plant organs having different roles and being affected by a diverse range of stimuli. Despite the fact that new pH measurement techniques, such as genetically encoded fluorescent probes, were developed in the last two decades, there is still a need to provide a higher spatiotemporal resolution of pH analysis. Key words: Arabidopsis, apoplastic pH, cell growth, acid growth theory, cell wall, auxin, apoplastic pH measurement
|
|
| |
|
|
Mechanisms of establishment and maintenance of PIN polarity in Arabidopsis
Glanc, Matouš ; Friml, Jiří (advisor) ; Grebe, Markus (referee) ; Luschnig, Christian (referee)
Cell polarity is a key concept in plant biology. The subcellular localization of Pin- formed (PIN) auxin efflux carriers in the root of "#$%&'()*&* is remarkably asymmetrical, making PINs prominent markers to study cell polarity. In spite of its developmental importance and two decades of research, the molecular basis of PIN polarity remains largely unknown. In this thesis, I employed advanced transgenic and fluorescence microscopy approaches to gain insight into several aspects of PIN polarity regulation. I participated in establishing a novel genetically encoded inhibitor of endocytosis, an invaluable tool for the study of the importance of endocytosis for various cellular processes, including PIN polarity. I demonstrated that apical polarity of PIN2 needs to be re-established after cell division and that this process depends on endocytosis, '+!,(-( protein secretion and the action of WAG1 and related protein kinases, but not transcytosis, cell-cell signaling or intact cytoskeleton. Finally, I identified the previously unknown role of MAB4/MEL proteins in PIN polarity, which lies in the ability of MAB4/MELs to reduce PIN lateral diffusion and thus contribute to PIN polarity maintenance. My results, besides broadening current understanding of PIN polarity regulation, identify mechanisms that...
|
|
|
Mechanism of auxin transport across plasma membrane through PIN auxin efflux carriers
Lefnar, Radek ; Petrášek, Jan (advisor) ; Nodzynski, Tomasz (referee)
Phytohormone auxin and its directional distribution plays an essential role in the regulation of numerous processes during vegetative and reproductive plant development. Regulation of the expression, localization and activity of the PIN-FORMED (PIN) proteins is important for proper polar auxin transport in plant tissues. PIN proteins have been described as the major auxin efflux carriers regulating auxin's directional flow to build up gradients that provide information for the coordination of plant development. PIN protein structure topology prediction through bioinformatic analysis is still insufficient to understand their transport mechanism. Experimental analysis of PIN protein domains can provide valuable insight into understanding their role in mediating auxin transport. In this study, the C-terminal part of PINs have been modified by gradual trimming to determine the existence of relevant functional domains, which could be important for auxin transport. Seven modified PIN proteins from Arabidopsis thaliana and Nicotiana tabacum were prepared. Transiently transformed tobacco cell line Bright Yellow-2 (BY-2) was used to monitor differences in PIN transport activity. This approach allowed indirect monitoring of intracellular auxin levels using the DR5 reporter system. Transiently expressed...
|
|
|
The role of cytoskeleton in auxin transport
Kebrlová, Štěpánka ; Petrášek, Jan (advisor) ; Mašková, Petra (referee)
Auxins are a class of plant hormones (phytohormones) with their most frequently endogenously occurring representative indol-3-acetic acid (IAA). Because of their influence on division and elongation of cells, auxins play an important role in many developmental and physiological processes such as embryo development, vascular tissue patterning and tropisms. These effects are often mediated by polar auxin transport, which results in a wide variety of auxin concentrations in cells and entire tissues. Transport of auxin from cell to cell is partly mediated by diffusion, the prevalence of auxin transport is however mediated by auxin carriers located on plasma membrane (PM). Among such carriers belong AUX1/LAX (AUXIN RESISTANT 1/LIKE AUX1) transporter family, which helps with auxin influx and families of PIN-FORMED (PIN) and ABCB/PGP (ATP-binding cassette subfamily B/P-glycoprotein) transporters, which take part in auxin efflux. These proteins are in various degrees dependent on a system of membrane vesicles, trafficking along actin cytoskeleton, which ensures among others cycling of these vesicles among PM and endosomal cell space. Regulation of auxin transport is possible on multiple levels including influencing of gene expression for carrier proteins and regulation of their localization, activity and...
|
guest ::
