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Antioxidant enzymes response to abiotic stress. Impact of decreased cytokinin level.
Lubovská, Zuzana ; Wilhelmová, Naďa (advisor) ; Prášil, Ilja (referee) ; Kočová, Marie (referee)
Charles University in Prague, Faculty of Science Department of Experimetnal Plant Biology Ph.D. study program: Plant physiology and anatomy Abstract Antioxidant enzymes response to abiotic stress. Impact of decreased cytokinin level. Zuzana Lubovská Supervisor: RNDr. Naďa Wilhelmová, CSc. Supervisor-consultant: RNDr. Helena Štorchová, CSc. Praha, 2015 The response of the antioxidant enzyme system to drought, heat and a combination of these stresses was followed in tobacco plants overexpressing cytokinin oxidase/dehydrogenase1 (CKX1) under the root-specific WRKY6 promoter (W6:CKX1 plants) and under the constitutive 35S promoter (35S:CKX1 plants) and in the corresponding wild type (WT). CKX1 over-producing lines developed a bigger root system, which contributed to their stress tolerance. The high stress tolerance of 35S:CKX1 plants was also associated with a dwarf shoot phenotype and changed leaf morphology. The genes for chloroplastic antioxidant enzymes, stroma ascorbate peroxidase (sAPX), thylakoid ascorbate peroxidase (tAPX) and chloroplastic superoxide dismutase (FeSOD), which are responsible for scavenging of reactive oxygen species produced via electron transfer during photosynthesis, were all strongly transcribed in control conditions. All the tested stresses down-regulated expression of these genes...
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Cytokinins and plant senescence
Pokorná, Monika ; Lipavská, Helena (advisor) ; Kutík, Jaromír (referee)
Senescence is a natural process, which is a part of plant developmental programme. However, the onset of senescence can be greatly influenced by external conditions. An important part of plant senescence is a senescence of leaves manifested by chloroplasts breakdown. That is connected to mobilization of nitrogen contained in proteins, which provide their function. However, the correct timing of natural senescence is substantive for the plant. The initiation as well as the process of natural senescence is influenced by several factors. Senescence is in varying degrees controlled by phytohormones, regulation factors and it is also driven by epigeneticall processes. Leaf senescence can be caused by several exogenous (light conditions, temperature, water and mineral availability, pathogen attack) and internal (carbohydrate levels, hormones, age, developmental stage) conditions. As well as many other developmental stages, senescence is greatly regulated by phytohormones. Ethylene, abscisic acid, salicyl acid and methyljasmonate support leaf aging, on contrary cytokinins delay senescence associated processes. Studying of cytokinin with chlorophyll analysis is an important part of every study of senescence. This work summarizes literature information of regulation of senescence with an accent on the role...
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Vliv modulace hladin cytokininů na fenom a proteom rostlin
Koukalová, Vladěna
Negative effects of biotic and abiotic stressors of the environment are limiting factors for agricultural production. To minimize the effect of these factors, molecular genetics focuses on preparing the new genetically modified organisms with higher tolerance to stress. However, recent legislation strongly limits the use of GMO and thus new approaches focused on similar outcomes are followed. One of these approaches is developing of new pharmaceuticals with positive effects on plant tolerance to environmental stressors. This thesis is focused on the characterization of such substance called INCYDE. INCYDE inhibits degradation of plant hormons cytokinins, which are known to have positive effects on delaying senescence and tolerance to extreme drought conditions. In the classical bioassay based on inhibition of the main root growth, INCYDE was shown to be active as one of the most active cytokinin trans-zeatin. Analysis of the lines with modified canonical cytokinin signalling pathway showed INCYDE and trans-zeatin to act by same signalling components. Despite the fact of similar effects on morphological alterations, proteom analysis revealed differences in the effect of INCYDE and trans-zeatin on protein abundance. Differences on the proteom level will be analyzed in following study.
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Proteom rostlin v reakci na abiotický stres
Čotková, Veronika
Plants as a sessile organisms have evolved complex mechanisms to cope with unfavorable environmental conditions. This diploma thesis summarizes current state of knowledge and focuses on light, temperature and phytohormones in plant abiotic stress responses. The practical part is devoted to proteomics and completes and extends the project started during my Bachelor program. Transgenic Arabidopsis seedlings carrying inducible barley cytokinin oxidase/dehydrogenase (CaMV35S> GR> HvCKX2) were profiled to elucidate proteome-wide responses to down-regulation of cytokinin levels under heat stress at standard (80 umol.m-2.s-1) and low light intensity (20 umol.m-2.s-1). In total, 2-DE analysis and mass spectrometry analysis revealed 63 differentially abundant proteins involved in diverse metabolic processes. These data provide evidence of a link between temperature, light and cytokinin signaling in Arabidopsis and will be used in the modeling of cytokinin-light-temperature interactions.
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Ovlivnění odpovědi rostlin na teplotní stres modulovanými hladinami cytokininů - fenomická a protemická analýza
Vícha, Daniel
Cytokinins are important group of phytohormones regulating many physiological processes ranging from cell division to programmed cell death. This thesis is focused on effects of cytokinin levels in response to heat stress in Arabidopsis thaliana. Analysis of transgenic plants with regulated expression of ipt and HvCKX showed that cytokinins and their optimal levels play important role in the morphological alterations induced by heat stress. Seedlings with increased and decreased levels of cytokinins exhibit inhibition of petioles growth, decreased length of blades of true leaves and reduced leaf area. To obtain insights into molecular events underlying early response to heat stress LC-MS analysis of whole proteom was performed. Analysis revealed 57 differentialy regulated proteins in response to heat stress in Columbia ecotype. On the cellular level, most of the proteins were located in cytosol (47 %) nebo plastids (32 %). Coparative analysis between wild-type seedlings and seedlings with decreased level of cytokinins confirmed 31 proteinInfluencing plant responses to temperature stress modulating cytokinin levels - fenomic and proteomic analysiss regulated by cytokinins in response to heat stress. Among these proteins, desarurase 7 and Tudor SN1 protein were previously found as important factors in response to heat stress.
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Vliv aplikace cytokininů na výnos a kvalitu máku
Tajšl, Pavel
In this thesis the effect of foliar application of cytokinin to yield and qualitative parameters of poppy was observed. For the experimental part, two one-year experiments were conducted - small-plot experiment and pot experiment. Small-plot experiment had been designed in four variants: control, application of cytokinin in stage of beginning of upgrowth (BBCH 30) and stage before flowering (BBCH 61). Cytokininins were applicated in ratio of 2,75 g/ha. The inorganic plant analysis conducted after an application of cytokinins in BBCH 30 is due to their effect on the increase in dry matter to the impact of the increase in consumption of nutrients by plants. Cytokinins affected the branching poppy, which led to an increase in the number of capsules in the first variant (BBCH 30) of 11.5%, for the second variant (BBCH 61) of 46.2%. That resulted in increase of yield of 1.7, respectively 4.9 %, but not significantly. Yield closely correlated with the number of capsules, but not significantly Pot experiment in Mitscherlich's doses was designed in four variants: 1. control without application of cytokinins, 2. and 3. variant with application in stage BBCH 35, respectively BBCH 61 and 4. with double treatment (BBCH 35 + BBCH 61). The ration corresponded to 2.75 g cytokinin / ha in the 2. and 3. variants and 5.5 g / ha with split application in variant 4. It was observed the significant influence of cytokinins on yield of seed. While at variant with uniform doses of cytokinin seed production increased by 0.7 %, respectively 4.4 %, double application significantly reduced the yield by more than 50%. The HTS, the number and size of poppies contributed to yield. There was no observed effect of the application of cytokinins on the oil content in the poppy seeds.
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Inhibice regenerace prýtů na explantátech petunie (Petunia x hybrida) in vitro způsobená fluoranthenem
Czyžová, Kateřina
The aim of thesis was to study the effect of fluoranthene (FLT) on growth and biochemical processes of plant Petunia (Petunia hybrida cv. Lady blue) in in vitro conditions. In this experiment were used segments of the middle parts of the leaves, shoots from organogenesis in vitro and apical meristem of stem with four to five leaves from long-term in vitro culture. It was observed if fluoranthene influence organogenesis of shoots in vitro, contents of chlorophyll a and b, content of cytokinins and rating of shoots (from organogenesis in vitro) and apical meristem of stem with four to five leaves. It was used culture MS medium containing benzylaminopurin (1.5 mg/l), 1-naphtylacetic acid (0.18 mg/l) and fluoranthene (1 mg/l) or without fluoranthene (control). In the case of organogenesis in vitro, the experiment was performed at 4 different variations of media with subculturing to other media in triplicate. Variations of the media were chosen to allow period of cultivation with fluoranthene, which affects growth and biochemical processes. MS medium containing indol-3-butyric acid (0.5 mg/l) and FLT in different concentrations (0.1, 1, 3 a 5 mg/l) was used for monitoring rooting. The results showed that fluoranthen is able to affect organogenesis of shoots formed on the segments of leaves. There was lower frequency compared to the control organogenesis. It was found that fluoranthene more affects beginning of cultivation compared to later exposure of fluoranthene during cultivation. It was found the highest uptake of benzyladenine and its riboside from the culture medium. Fluoranthene affected significantly content of dihydrozeatin. Zeatin and its riboside were recorded in a minimal amount. Fluoranthene caused lower content of chlorophylls a and b in explantats. In the case of chlorophyll a were no significant differences between influence by fluoranthene at the beginning of the cultivation or during of cultivation. It was noted that fluoranthene influence the morphology of the roots subcultured shoots from organogenesis in vitro. Plant roots exhibited less branching and roots were shorter in culture medium containing higher content of fluoranthene (3 and 5 mg/l).
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