|
|
Analysis of Gretchen Hagen 3 gene family in tobacco BY-2 cell culture
Helusová, Lenka ; Müller, Karel (advisor) ; Pěnčík, Aleš (referee)
Auxin conjugation is one of the crucial metabolic processes regulating auxin activity in plant cells. Gretchen Hagen 3 (GH3) is a family of acyl amido synthetases that conjugates auxin with amino acids and belongs amongst important enzymes involved in auxin conjugation. Due to the existence of more sensitive methods to detect auxin metabolites and the current study of abiotic stress effects, research on GH3 enzymes is intensified these days. These enzymes are best known in thale cress (Arabidopsis thaliana), soya bean (Glycine max), rice (Oryza sativa). These models don't allow to study their activities in a biochemical way. Therefore, the aim of this work was to monitor the auxin metabolism in the established model tobacco BY-2 cell lines (Nicotiana tabacum). The NtGH3.1 and NtGH3.6 genes, which were shown to have a variability in their expression regulation by auxin, were targeted and mutated using tne CRISPR/Cas9 method. Mutations in the derived lines were detected by sequencing. In the derived lines, auxin metabolic profililing was analysed by LC/MS. Metabolic profiling showed a correlation between the NtGH3.6d form and the specific production of the metabolite oxIAA- Gln (N-(2-onindole-3-acetyl)-glutamine). The study of an eventual substitution of individual GH3 gene forms in mutant lines...
|
|
|
Rodina auxinových přenašečů PIN: funkční a evoluční pohled
Skůpa, Petr ; Zažímalová, Eva (advisor) ; Hejátko, Jan (referee) ; Opatrný, Zdeněk (referee)
Growth and development of plant body is dependent on correct and effective integration of information about current deployment of its body parts, as well as on perception and transduction of inputs from environment. Multiple developmental processes within plant body are determined by specific and tightly controlled distribution of molecule with unique signaling mission within plant development - auxin. Spatial distribution of auxin is co-determined by plethora of tightly controlled processes, and the polar auxin transport plays unique role among them. PIN proteins are the plant-specific family of secondary transporters driving movement of auxin across membranes. With their frequent asymmetrical localization within cells, specific expression patterns in developing tissues and their reactiveness to external cues they secure unique, dynamic and asymmetric distribution of auxin within the plant body. This dissertation thesis is focused on characterization of the role different PIN proteins play in determining cellular auxin homeostasis and consequent formation of auxin gradients. Controlled overexpression of PIN proteins in tobacco cells showed, that PIN4 and to some extent also PIN6, function as the direct auxin efflux carriers. In the cellular auxin transport they play the role analogous to other...
|
|
|
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 homeostasis mechanisms
Skokan, Roman ; Petrášek, Jan (advisor) ; Buschmann, Henrik (referee) ; Holzinger, Andreas (referee)
The evolution of auxin homeostasis mechanisms Ph.D. thesis Roman Skokan, 2021 Abstract The streptophyte lineage consists of land plants (embryophytes) and several groups of primarily freshwater green algae called charophytes. While the phytohormone auxin is a conserved regulator of land plant development, little has been known of the possible origins of auxin response mechanisms in charophytes. We found that one of these mechanisms, the cellular auxin efflux via the PIN family of transport proteins, is most likely a deeply conserved feature in streptophytes. Additionally, we investigated the state of conservation in the green lineage (Viridiplantae) of the gene families known to be involved in auxin transport in land plants. We revealed that some families are deeply conserved outside land plants, but not others. We also helped uncover a unique radiation within the PIN family in Charophyceae. Striving to uncover the native significance of auxin transport in charophytes, we discovered a growth response to exogenously-applied auxin in Closterium, though the effort to produce stable mutant lines in the native PIN homolog is still underway. Altogether, we brought important insights into the evolution of auxin transport and response in the streptophyte lineage, though many questions still remain.
|
|
|
The role of auxin in streptophyte algae
Schmidt, Vojtěch ; Petrášek, Jan (advisor) ; Pleskot, Roman (referee)
The phytohormone auxin is an important morphogen with an essential role in the development of land plants, where mechanisms of its action are well described. However, its role in green algae is poorly understood. Land plants are part of the phylum Streptophyta together with six closely related groups of predominantly freshwater green algae (charophytes). So far, the knowledge about the evolutionary origins of auxin action mechanism is mainly based on genomic information, and much less on experimental findings. In this work, the presence of auxin, its precursor, and catabolism products were shown in representative species of charophytes with varying levels measured compounds both produced endogenously and into the culture media. Thus, we gained a comprehensive insight into the possible strategies of auxin homeostasis across the non-land plant streptophytes. Also, an effect of exogenous auxin on the cell morphology and culture growth of the desmid Closterium was investigated. Image analysis of IAA-treated cells revealed a rather pleiotropic effect on cell morphology. The culture growth was inhibited by IAA. Additionally, IAA induced malformations in cell shape, and the extent of this phenomenon across individual cultures was dependent on the culture growth status. Lastly, we optimized the method of...
|
|
|
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.
|
|
|
Plant hormones homeostasis: auxin and cytokinin crosstalk
Doležálková, Lucie ; Zažímalová, Eva (advisor) ; Dračínská, Helena (referee)
5 AbstractAbstractAbstractAbstract It has been since 19th century when the phytohormones and their crosstalk became one of the central themes in plant biology. Due to advances in molecular biology there is number of metabolic pathways linked to certain groups of plant hormones revealed by now, nevertheless much remains to be determined about their cooperation. The aim of this thesis is to evaluate the effect of exogenous cytokinin application on oat leaf segments (Avena sativa) - both specifically towards other phytohormones levels and generally in physiological context (in relation to their senescence). Our results confirmed increased auxin levels due to exogenous application of selected cytokinins and identified biological activity of trans-zeatin-9-glucoside (previously considered as irreversibly deactivated cytokinin type substance) in respective plant model. (In Czech) Key words: phytohormones, auxin, cytokinin, Avena sativa, senescence assay
|
|
|
Rodina auxinových přenašečů PIN: funkční a evoluční pohled
Skůpa, Petr ; Zažímalová, Eva (advisor) ; Hejátko, Jan (referee) ; Opatrný, Zdeněk (referee)
Growth and development of plant body is dependent on correct and effective integration of information about current deployment of its body parts, as well as on perception and transduction of inputs from environment. Multiple developmental processes within plant body are determined by specific and tightly controlled distribution of molecule with unique signaling mission within plant development - auxin. Spatial distribution of auxin is co-determined by plethora of tightly controlled processes, and the polar auxin transport plays unique role among them. PIN proteins are the plant-specific family of secondary transporters driving movement of auxin across membranes. With their frequent asymmetrical localization within cells, specific expression patterns in developing tissues and their reactiveness to external cues they secure unique, dynamic and asymmetric distribution of auxin within the plant body. This dissertation thesis is focused on characterization of the role different PIN proteins play in determining cellular auxin homeostasis and consequent formation of auxin gradients. Controlled overexpression of PIN proteins in tobacco cells showed, that PIN4 and to some extent also PIN6, function as the direct auxin efflux carriers. In the cellular auxin transport they play the role analogous to other...
|
guest ::
