National Repository of Grey Literature 19 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Oxidative stress level as a marker of stress memory in selected genotypes of potato Solanum tuberosum ssp. tuberosum and ssp. andigena
Lotová, Gabriela ; Mašková, Petra (advisor) ; Lhotáková, Zuzana (referee)
Plants are exposed to the stress of the environment throughout their entire live. They therefore had to develop sophisticated mechanisms to avoid or tolerate stress. In some plants, repeated exposure to stress increases tolerance, which is known as stress memory. The aim of this study is to assess stress memory in terms of oxidative stress level. Content of malondialdehyde (MDA), reactive oxygen species (ROS) and the electrolyte leakage were chosen as markers of oxidative stress. Fresh weight, plant height and water content were also evaluated. The level of oxidative stress was assessed in several genotypes of Solanum tuberosum subspecies, Andigena and Tuberosum. In vitro culture did not work well for the evaluation of stress memory, ex vitro partially did. The content of MDA in 66B was significantly lower than in cv. Lada (Tuberosum) in root (in vitro) and shoot (ex vitro) in control groups as well as during water shortage. Treatment of acclimation-inducing cold before the stress-inducing cold had a variable effect on growth and electrolyte leakage according to the culture conditions. In vitro, the effect on electrolyte leakage in roots of cv. Lada was positive, in leaves of 66B (Andigena) it was negative. In ex vitro, a positive effect was found on electrolyte leakage in 66B leaves, but at the...
Arsenic toxicity and hyperaccumulation in plants and their potentail use in phytoremediation
Gímeš, Lukáš ; Mašková, Petra (advisor) ; Podlipná, Radka (referee)
Arsenic is classified as a heavy metalloid. Small amounts of arsenic can be found in the environment naturally, but human activity constantly increases the amount of arsenic in the soil. Increasing arsenic contamination of the soil causes serious health problems for both animals and humans. Due to its toxicity, it can also cause considerable problems for plants. Arsenic negatively affects a number of processes in the body of plants, such as oxidative stress or the metabolism of important macromolecules. Photosynthesis is a physiological process that is the most affected by arsenic toxicity. Closely related to photosynthesis are the growth properties of plants. Negative effects that arsenic has on many biochemical, physiological and morphological processes in the plant body, we must understand the uptake, translocation and detoxification of arsenic in the plant body. Arsenic hyperaccumulators are plants that can accumulate orders of magnitude higher concentrations of As and better manage the phytotoxicity of this contaminant than non-hyperaccumulating plants. Hyperaccumulation of heavy metals is associated with changes in the physiological properties of plants. A common characteristic of hyperaccumulators is that they can accumulate the higher concentrations of metals they in the aboveground parts...
The effect of temperature in interaction with other factors of climatic change on selected physiological parameters and yield of C3 and C4 crops
Jiras, Tomáš ; Albrechtová, Jana (advisor) ; Mašková, Petra (referee)
The current climate change mainly involves global warming of the Earth, and anthropogenic activity is predominantly identified as the dominant cause. As a result of the ongoing climate change, there are ever-expanding areas with rainfall deficits, extreme weather patterns including heat waves, etc. Plants must be acclimated or adapted to worsening environmental conditions in the short term as a result of the climate change. Stress load significantly changes plant physiological parameters, even lethally. Plants respond to stress by acclimation responses and adaptations induced by changes in gene expressions on metabolic, physiological or structural levels, by phenotype modification, and other changes. The threat also affects agricultural plant production, which is obliged to ensure food security of the ever-increasing human population. The climate change is expected to reduce crop yields. The aim of this Thesis is to summarize knowledge about changes in crop physiology and agricultural production due to stress factors of the climate change, especially temperature, with emphasis on differences between C3 and C4 plants. Most of the work deals with C3 cereals: wheat, barley, rice and C4: corn, sorghum. Different responses of these crops are discussed, such as change in phenology, water use, CO2...
Modulation of BELL transcription factors balance as a tool for tuberisation strengthening in selected potato cultivars
Zounková, Andrea ; Mašková, Petra (advisor) ; Fischer, Lukáš (referee)
Potato (Solanum tuberosum) is the third most important crop in terms of human consumption. Hence understanding regulatory mechanisms controlling tuber initiation is significant not only from a theoretical but also practical point of view. Tuberization of S. tuberosum is a complex morphogenic process regulated by both, environmental conditions and inner plant status. Environmental conditions regulating the onset of tuberization have been known for a long time, but the molecular basis of tuber initiation has only recently been discovered, in particular using wild subspecies S. tuberosum subsp. andigena. BELL transcription factors are among the important components of the regulatory signalling network. The aim of this study was to modulate balance between the BELL transcription factors that induce and repress tuberization towards strengthening of tuber induction using two cultivars of Solanum tuberosum subsp. tuberosum, cv. Kamýk, resp. cv. Korela. To achieve this, transgenic lines carrying construct containing a part of coding sequence StBEL11, resp. StBEL29 in antisense orientation (AS) under control of constitutive promoters and lines carrying complete sequences of StBEL5 and StPTB6 genes under control of their native promoters were derived. We used the StBEL11 and StBEL29 AS constructs with the aim to...
Tuber induction in spontaneously tuberizing potato line: the role of saccharides and mobile transcripts
Stupecká, Lenka ; Mašková, Petra (advisor) ; Fischer, Lukáš (referee)
Potato is one of the most important agricultural crops and there is an attempt to increase and improve yields of tubers, among other things, by elucidation of the mechanisms that regulate the process of tuber induction. Potato tuberization is a morphogenetic process in which the tubers are formed from the underground parts of the stem - stolons. The correct timing of this process is controlled by a complex regulatory network and influenced by many internal and external factors. Under favourable conditions, an inductive signal is generated in the leaves and it is transported to the stolon by a "phloem information superhighway" driven by carbohydrates flow. The signal triggers cell division, expansion, and changes in the cell growth orientation in the stolon. The development of tubers is influenced by number of biochemical and morphological processes driven by a regulatory network of genes that are expressed in different parts of plants. This work was focused on Solanum tuberosum, Lada cultivar and its derived D69 mutant line with lacking isoform of manganese-stabilizing protein (MSP), which is so far the only dissimilarity identified under all tested conditions. I aimed to map the processes related to the production of carbohydrates in leaves (photosynthetic characteristics - rate of photosynthesis...
Regulation of floral initiation in woody perennials
Čermák, Vladimír ; Mašková, Petra (advisor) ; Čermák, Vojtěch (referee)
Floral initiation is an important process for temperate woody perennials that affects the subsequent development of the flower. Although this process is well known in annual plants such as Arabidopsis thaliana, not much research has been done in woody plants. This review summarizes the knowledge about mechanisms of flowering induction in woody perennials, compared to the findings in model plants, especially A. thaliana, including factors involved in the regulation of the flowering process. In particular, FT-like genes and TFL1-like genes, which play an important role in the regulation of flowering induction, are discussed in detail. In temperate woody plants the dormancy period follows the floral induction before the floral development. Periodic regulation of this stage is controlled endogenously and, in addition to other factors, it is affected by expression of DAM genes. The genetic mechanisms regulating endodormancy release in woody perennials are similar to vernalization in herbs. Better understanding of processes such as the floral induction and endodormancy release can help us to develop cultivars with a modified flowering time.
Functions of RAB GTPases and SNARE proteins in post-Golgi trafficking pathways in response to abiotic stress in plants
Moulík, Michal ; Hála, Michal (advisor) ; Mašková, Petra (referee)
Plants as sessile organisms are strongly affected by abiotic and biotic stress factors. Thus, they have developed an array of morfological, biochemical and physiological adaptations to reduce the negative effects of these factors. The membrane trafficking, among others, plays very important role in adaptation to abiotic stress. In my bachelor thesis I have focused on two important protein families involved in this trafficking, namely on RAB GTPases and SNARE proteins. In the first part, the phenomenon of stress is characterized and the strategies how plants cope with the effect of stressors are described, especially the production of reactive oxygen species (ROS) and autophagy. Following chapter deals with an introduction to the membrane trafficking in plants. In the rest of the thesis, I characterize RAB GTPases and SNARE proteins and provide contemporary insight in the mechanism of their function. The aim of the key parts of these chapters is to summarize current knowledge of RAB GTPases' and SNARE proteins' functions in post-Golgi trafficking pathways during response to abiotic stressors or secondary oxidative stress. Key words: plants, abiotic stress, membrane trafficking, secretion, endocytosis, vacuole, RAB GTPases, SNARE proteins
Cell cycle regulation in plants: the role of CDK activatory dephosphorylation at entry into mitosis
Mašková, Petra ; Macháčková, Ivana (advisor) ; Havel, Ladislav (referee) ; Vaňková, Radomíra (referee)
t I I I I I I I I I I I I I I Summary of PhD. thesis Cel1 division representsone of fundamentalattributesof all living creatuÍes.Basic molecular mechanisms operating during cell proliferation seem to be evolutionary conservedamongeukaryotes.The cell cycle is dividedin four subsequentphases;themost regulatoryeventsareconcentratedin Gr/S andGzlM checkpoints. The key regulatory proteins, cyclin-dependentkinases (CDKs), govern the progress throughthe whole cell cycle. Their function is strictly dependenton catalytic cyclin subunits.The correspondingcyclin partnerbinding CDK determinesthe time window of the specific CDlVcyclin complex actionin individual cell cycle phase.To becomefully active, the complex requiresfurtherposttranslationalmodificationincluding activatory phosphorylationanddephosphorylationof theCDK on specificaminoacidresidues. Plant cell cycle, besideswell-conservedmechanismscoÍlmonto all eukaryotes,exhibits other specific mechanismsresultingfrom plant survival strategy.The Gr/S transitionis stronglyaffectedby extemalandinternalsignals,mainlyphytohormonesandmetabolites, reflectingthe elementaryconditionssuitablefor accomplishmentof the whole cell cycle. The centralmoleculerespondingto thesesignalsat Gr/S is D cyclin, whoseexpressionis regulatedby cýokinin and sucrose(Riou-Khamlichi et aI.,...
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...
Mutations in brassinosteroid biosynthetic genes and their effects on plant phenotype
Frimlová, Klára ; Rothová, Olga (advisor) ; Mašková, Petra (referee)
Brassinosteroids are important group of phytohormones, whose presence affects anatomy, morphology and development of plants. They occur in all vegetative and mainly generative organs. Brassinosteroids are biosynthesized via two main paths named early C-6 oxidation pathway and late C- 6 oxidation pathway. Brassinosteroid biosynthesis is catalyzed by enzymes from the group of cytochrome P450. Gene mutations - which affect brassinosteroid biosynthesis - have been studied especially in Arabidopsis thaliana L., Pisum sativum L., Solanum lycopersicum L. and Oryza sativa L. Mutations lead to changes in the composition and amount of brassinosteroids in plants. The reduced content of brassinosteroids is manifested by typical phenotype that includes reduced growth, reduced size of plant organs, and dark green leaves in mutant plants. The mutant phenotype can be reversed by exogenous application of brassinosteroids, which is nevertheless dependent on the concentration of the brassinosteroids used. Higher concentrations of brassinosteroids cause mostly inhibition of root elongation. Keywords: brassinosteroids, biosynthesis, mutant, phenotype

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