National Repository of Grey Literature 28 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Albino variants of orchids. Evolution towards mycoheterotrophic species?
Králová, Zuzana ; Figura, Tomáš (advisor) ; Vosolsobě, Stanislav (referee)
Albinism is a condition of a plant that is the result of a loss of a pigment, in most cases chlorophyll, either only partially or in its entirety. Full albinism is found in many plant species but leads to large amount of maladaptive features that are usually lethal in early stages of plant development. Some plant species are heterotrophic their whole lives and therefore incapable of photosynthesis. Those are for example parasitic plants of mycoheterotrophic plants that para- site on fungi. Mixotrophic orchids are capable of photosynthesis, but are dependend on fungal carbon. It is the case in mixotrophic plants that there are cases of full albinism in adult individ- uals that offset the loss of photosynthesis and its products by obtaining carbon from different sources - from fungi. This work summarizes ecophysiological and morphological specifica- tions of albino variants, mostly of mixotrophic orchids, because they are the focus of most research, and tries to answer the question whether the albino variants lead to emergence of a new mycoheterotrophic species. Key words: orchids, mixotrophy, mycoheterotrophy, evolution, albino variants, albinism.
Creating and testing bioluminescence sensors for cytokinins in Arabidopsis thaliana
Novotná, Lenka ; Petrášek, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Advances in microscopy and the sensitivity of novel biosensors have enabled the development of new methods for monitoring phytohormones with low invasiveness and relatively high resolution, providing greater insight into phytohormone function in plants. Genetically encoded indirect biosensors for cytokinins, one of the main plant hormones, are widely used for the tracking of dynamic changes in their levels during plant development and growth. The cytokinin-sensitive synthetic promoters used as cytokinin biosensors are being continuously improved, providing better insight into cytokinin function. However, the reporter systems used for the visualizations are either based on the enzymatic reaction producing colour or on the usage of fluorescence proteins. Luminescence-based biosensors are often used to visualize signaling outputs of plant hormones, but they are based on exogenous addition of luciferin substrate. Therefore, in this thesis, I have introduced a new technique for the generation of cytokinin signaling output sensors based on autonomous bioluminescence. This autonomous bioluminescence represents a non-invasive technique that depends on the expression of the whole autonomous bioluminescence system from fungi Neonothopanus nambi, in particular, the caffeic acid cycle with the fungal...
Mechanisms of physical dormancy and germination of orchid seeds
Jiroušková, Anna ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Orchid seeds are called dust seeds because of very reduced structure. A mature dust seed is composed of living embryo and two seed coats which are formed by dead cells. While the outer seed coat is distinctive, the inner seed coat (known as carapace) is very thin and tightly surrounds the embryo. Seed coat is hydrophobic and prevents water from entering embryo. To induce germination artificially, calcium hypochlorite or sodium hypochlorite solutions are often used. However, the effect of chemical scarification on seed coats is poorly understood. I focused on seeds of Epipactis helleborine and Dactylorhiza majalis and I analysed changes in seeds induced by calcium hypochlorite treatment using germination of seeds in vitro, permeability tests of seed coats and histochemical analyses of selected components of seed coats. The most prominent change observed was decrease of amount of lignin in the outer seed coat. This is likely related to increase in permeability of seeds and stimulation of in vitro germination rate in Dactylorhiza majalis which has only thin and less complex inner seed coat. However, this relationship was less evident in Epipactis helleborine, which has thicker and more complex inner seed coat which is more resistant to hypochlorite scarification. This could indicate existence of...
Land plant terrestrialization - New insights from genomes of charophyte algae
Horňák, Milan ; Pichrtová, Martina (advisor) ; Vosolsobě, Stanislav (referee)
The terrestrialization of land plants was an important event in the history of life on Earth. Genomic and transcriptomic studies published in the last decade shed light on many aspects of this process. This work presents an overview of the traits facilitating the conquest of land by land plants. It focuses on streptophyte algae to elucidate what properties relevant to life on land the ancestors of terrestrial plants possessed and in what form, primarily using recent genomic and transcriptomic data.
Reception of temperature on the cellular and molecular level
Albrechtová, Ema ; Vosolsobě, Stanislav (advisor) ; Pleskot, Roman (referee)
Temperature is a key factor modulating a wide range of processes in the plant cell. While the signaling pathways that triggered temperature changes are described, the way plants sense temperature is not well understood. Plants perceive temperature changes by a complex network of processes and response to temperature change is regulated by signals from different organelles and cellular complexity levels. The main mechanisms taking part in temperature perception in plants are changes in physical membrane properties, membrane proteins, changes in protein conformation, photoreceptors, and secondary structure of RNA and DNA. My thesis is focused on these main mechanisms by which plants sense temperature and their context in cellular metabolism and evolution.
What factors underlie gene reuse in adaptation?
Poštulková, Alžběta ; Bohutínská, Magdalena (advisor) ; Vosolsobě, Stanislav (referee)
Is the fate of a mutation predictable? The repeatability of evolution may indicate its predictability. If some change has emerged multiple times in the past, it may also occur in the future. Convergent evolution provides a natural model of repeated evolution and suggests the presence of certain constraints. Examination of the genetic processes, that have led to convergent adaptive traits, can contribute to the knowledge of the predictability of evolution. The aim of my work is to summarize the available knowledge about factors affecting gene reuse in adaptation. My work shows that the repeatability of evolution is biased by the genome characteristics, the population characteristics and also the trait encoding complexity. The likelihood of genomic region reuse increases with the amount of emerging mutations affecting the phenotype. Regarding the pleiotropic constraints of gene reuse, the most suitable is a mutation in the cis-regulatory region of the gene on the periphery of the functional pathway. Of the population traits, the greater effective size of the population, the higher standing genetic variation and the lower divergence between populations raise the chance of gene reuse. Despite the dependence of evolution on random processes, there are many factors that direct it and make it more...
The role of atmospheric precipitation in anther dehiscence
Kampová, Anna ; Vosolsobě, Stanislav (advisor) ; Valuchová, Soňa (referee)
Anther dehiscence is an important process taking place at the end of the plant life cycle. This process consists of various follow-up steps which result in anther opening and pollen grains exposure. Good timing of the anther dehiscence must be synchronized with pollen grains maturation and flower opening. Atmospheric precipitation is a high-risk factor for the anther dehiscence. Male fitness of plants can be reduced when anthers open during poor weather conditions. The aim of this study was to investigate the effect of atmospheric precipitation, rain and dew, on Arabidopsis arenosa anther dehiscence. We observed that rain and dew led to a postponed final stage of the anther dehiscence. This caused delayed pollen release. The effect of aqueous and nonaqueous environment on the anther dehiscence was also tested. Experiments with transformation of A. arenosa using Agrobacterium tumefaciens were performed. Key words: anther dehiscence, flower opening, rain, dew, Arabidopsis arenosa, Agrobacterium tumefaciens, transformation
Mechanoreception in plants
Martinek, Jan ; Vosolsobě, Stanislav (advisor) ; Kulich, Ivan (referee)
Because of their sessile nature, plants are unable to change their location and thus they are forced to adapt as much as possible to the environment they grow in. Plants evolved the ability to sense many environmental cues, which enables them to perceive the conditions in their surroundings. One class of these stimuli are mechanical forces - from wind sways to contact with obstacles, herbivores or other plants - other mechanical stimuli are e.g. gravity or sound waves. Carnivorous or climbing plants have structures specialised for perception and rapid response to mechanical stimuli. Intriguingly, there is a less spectacular but maybe even more interesting and important response to mechanical perturbation in non-specialized plants. This thesis tries to summarize ubiquity of mechanoperception in plant kingdom and its adaptive importance for the plant life - from activation of traps, to morphological adaptation for growth at windy sites, tendril coiling in climbing plants and root navigation through obstacles in soil. In the following part, the thesis summarizes the recent knowledge of molecular processes accompanied with mechanoreception, signal transduction and integration, and response to mechanostimulation. In the last part I proppose a scheme of mechanosensing workflow from initial mechanical...
The effect of desiccation on streptophyte algae - mechanisms of stress resistance
Pošmourný, Martin ; Pichrtová, Martina (advisor) ; Vosolsobě, Stanislav (referee)
In this thesis I dealt streptophyta algae resistance against desiccation. Even though the area previously devoted only a few people. Considerable amount of work in recent years has been published on the subject. They were found interesting information and discovered new facts. Research continues on and on, and it would be useful to look at what was observed. I believe that understanding this phenomenon is the key to understanding some of the events in the evolution of nature and realizing how tough life can be on the very border of its possible occurrence. I tried to sort out the current knowledge about the mechanisms of stress resistance streptophyta algae and hope that I obtained an overview will help me understand better this issues. So far, it has been observed several approaches to defend against drying. Preventing drying, adaptation to water shortage and tolerance to desiccation. Among the preventive methods of defense include creating clusters of cells, multi-layered mats or secretion mucilage. As an adaptation to the lack of water algae evolved more complex answers in the form of changes in ultrastructure, or regulation of physiological processes. Klebsormidium is capable of half an hour to start the production of significant quantities callose and incorporate it into the cell wall. This...

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