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Characterization of factors participating in regulation of intracellular dynamics of auxin carriers
Lacek, Jozef ; Zažímalová, Eva (advisor) ; Ibl, Verena (referee) ; Nodzynski, Tomasz (referee)
Plants are known to adjust the orientation of their organs, shoot and root, to ensure maximal energy generation and nutrient uptake, but also to avoid toxic growth conditions. Directional growth regulation depends on asymmetric plant organ growth and it is crucial to ensure plant survival. It is orchestrated on cellular level in concert with exogenous and intrinsic signals. Even though tropistic growth responses of plants were described by Darwin on macroscopic level already in 1880, now it is necessary to understand molecular mechanisms that underpin efficient modulation of directional plant growth. During my studies I focused on factors that modulate directional root growth regulation. The root is a complex, three-dimensional object, which continuously modifies its shape and growth path. Since the root needs to expand its surface to supply the plant with nutrients and water, it is important to understand how roots cope with changing growth conditions while exploring the soil. If the root cannot manage to grow through soil efficiently, mechanical impedance and lack of resources will also restrict shoot growth as well. Manifold signaling pathways coordinate the complex processes that underpin efficient root growth, including those modulated by phytohormones, sugars, flavonoids and other...
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Totální syntéza [15N4] cytokininů a jejich využití
BUČEK, Jan
Cytokinins (CKs) and their metabolites and derivatives are essential for cell division, plant growth regulation and development. They are typically found at minute concentrations in plant tissues containing very complicated biological matrices. Therefore, defined standards labelled with stable isotopes are required for precise metabolic profiling and quantification of CKs, as well as in vivo elucidation of CK biosynthesis in various plant species. In this work, eleven [15N]-labelled C6-purine derivatives were prepared, among them five aromatic (4, 5, 6, 7, 8) and three isoprenoid (9, 10, 11) CKs. Compared to current methods, optimized syntheses of 6-amino-9H-[15N5]-purine (adenine, 1) and 6-chloro-9H-[15N4]-purine (6-chloropurine, 3) were performed to achieve more effective, selective and generally easier approaches. The chemical identity and purity of prepared compounds were confirmed by physico-chemical analyses (TLC; HRMS; HPLC-MS; 1H, 13C, 15N NMR). The presented approach is applicable for the synthesis of any other desired [15N4]-labelled C6-substituted purine derivatives.
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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
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