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Mechanisms that control physiological seed dormancy
Řezková, Natálie ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physiological dormancy is an important developmental trait ensuring that seed does not germinate when the environmental factors are appropriate only temporary. The transition from seed dormancy to germination is regulated by a large number of factors and the phytohormone abscisic acid (ABA) plays a crucial role. Enhanced response to ABA and its biosynthesis is a key mechanism in dormancy induction and maintenance. ABA interacts antagonistically with gibberellins (GAs). Therefore GA biosynthesis and ABA catabolism are positive germination regulators. However, other phytohormones are also involved in the regulation of dormancy and germination. The most studied is ethylene which supports germination similarly to GA. Numerous factors affect dormancy at molecular level, namely chromatin remodeling, gene products that function only in dormancy regulation [e.g. DELAY OF GERMINATION 1 (DOG1)] or gene products that mediate seed response to environmental factors. The dormancy, its induction, depth and release, is driven not only by environmental conditions affecting mature seeds, but also by conditions acting during seed maturation in a maternal plant when the primary dormancy is induced. Requirements for dormancy release and germination induction may vary considerably between species. The physiological...
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Dynamics of ALBA proteins in Arabidopsis thaliana evaluated by fluorescence microscopy
Popelářová, Anna ; Honys, David (advisor) ; Vosolsobě, Stanislav (referee)
ALBA proteins were discovered in Archaea more than 30 years ago. They were gradually identified to be well conserved in Eucaryotes as well. A functional dimeric form of these proteins with DNA and RNA-binding capability was claimed in both mentioned domains of organisms. However, their roles diversified during evolution and vary in between organisms. In Archaea, ALBAs are involved in the genome organization and RNA-protein interactions. In Eukaryotes, there are presented two different subfamilies of ALBA proteins - Rpp20 and Rpp25 subfamily. A sole protein from each subfamily was identified in some organisms though they were multiplied in plants, respectively. These proteins can interact with each other and participate in ontogenetic development and stress responses. According to several studies, ALBA proteins were found to be involved in DNA stability maintenance or pre-rRNA splicing in the nucleus of Arabidopsis thaliana. However, they have been shown to play a role in the cellular metabolism and stress responses in cytoplasm. Six ALBA proteins were identified in the genome of A. thaliana, three from each subfamily. In this study, all heterodimeric protein- protein interactions were investigated by the bimolecular fluorescence complementation (BiFC) assay which revealed positive results in...
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Connection between Unfolded Protein Response (UPR) and plant immunity
Kapr, Jan ; Burketová, Lenka (advisor) ; Vosolsobě, Stanislav (referee)
This bachelor thesis is concerned with the specific pathway in a response to endoplasmic reticulum stress in plant cells - the Unfolded Protein Response (UPR) and its role in plant immunity signalling. The work summarizes the main recent knowledges of molecular components of plant immunity and response to plant pathogens, focusing on important molecules that are also connected to UPR. The role of salicylic acid as a molecule on a crossroad between UPR signalling pathways and local and systemic resistence, is highlighted in this work. Recently, the phospholipids have also been shown to be important component of signaling pathways in response to biotic stress in plants and their role is also mentioned.
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The mechanisms of pollen incompatibility in the Brassicaceae family
Šesták, Petr ; Fíla, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Sporophytic incompatibility (SI) represents one of the systems by which angiosperms prevent pollination by their own pollen or by the pollen from a genetically related plant. It is mostly studied in the Brassicaceae family, mainly due to its agricultural importance. Another reason is that the model plant Arabidopsis thaliana belongs to this family. In the last three decades, advances in molecular biological methods enabled the characterization of a large part of the signalling cascade that leads to the rejection of incompatible pollen. Then, the functions of various cellular components (e.g. cytoskeleton, exocyst or proteasome) involved in the incompatible response to pollination are studied mainly by live cell microscopy. Last but not least, the function of SI under various abiotic stresses was described to reveal their influence on SI mechanisms. The aim of this bachelor thesis is to summarize the new discoveries characterizing the molecular mechanisms of SI in the Brassicaceae family, to describe the processes leading to the germination of compatible pollen grain and to characterize the newly described proteins involved in cellular signalling leading to the rejection of incompatible pollen.
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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
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Evolution of physiological adaptations of plants during dry land colonization.
Červenka, Ondřej ; Žárský, Viktor (advisor) ; Vosolsobě, Stanislav (referee)
Terrestrialization, the transition of plants from water to land and the subsequent colonization of these new habitats, took place approximately 480 million years ago. This event caused significant changes in the planet's surface and enabled the formation of modern terrestrial ecosystems. It is associated with a number of morphological, anatomical and physiological adaptations, without which terrestrial plants would not be able to control newly inhabited habitats. The aim of this thesis is to summarize current knowledge about the possible ancestor of land plants, based on fossil remains and phylogenetic studies. The chapter dealing with macrofossils highlights the importance of the Scottish locality near the village of Rhynie and the description of the oldest vascular land plant Cooksonia barrandei. Attention is also paid to the alternation of generations within the life cycle, including a brief excursion into the history of the study and a description of the metagenesi sof rhyniophytes. Molecular aspects of this issue are also described, especially the emphasis on the role of biopolymers and phytohormones.
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Physical dormancy of seeds
Jiroušková, Anna ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physical dormancy of seeds is a widespread adaptation, allowing plant seeds to time the germination to a suitable season. Seeds with physical dormancy possess hard seed coats, which are impermeable to water and sometimes also to gases. This allows seeds to create a long-term seed bank and to wait for favourable conditions even for years. There are two main mechanisms, which break physical dormancy and enable water to enter the seed. The seed coat can be disrupted through the whole surface, or in one specialized place only. The disruption through the whole surface is common in the seeds dispersed by endozoochory. In this case, the long-distance seed dispersal brings an important advantage. In physically dormant seeds, which are dispersed by other ways, a complicated structure called water gap is usually present in the seed coat. Water gap responds to exogenous signals and controls when the water enters the seed. In such a case, physical dormancy can be broken as a response to annual or diurnal temperature fluctuations, which times germination into a proper time of the year. Another species germinate in response to high temperatures during a fire. This ensures, that seedlings emerge in suitable conditions with a high level of available nutrients, low competition and that they can restore the damaged...
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Evolutionary-developmental study of membrane proteins
Vosolsobě, Stanislav ; Schwarzerová, Kateřina (advisor) ; Baluška, František (referee) ; Štorchová, Helena (referee)
Evolutionary-developmental study of membrane proteins Mgr. Stanislav Vosolsobě Abstract Using a plethora of experimental approaches for phylogenetical and functional study on several membrane signalling proteins, I brought new evidences supporting a hypothesis that the molecular evolution of protein families is a highly dynamic, not conservative, process. In DREPP family of calcium-binding peripherally-associated plasma-membrane proteins I found a broad flexibility in protein-membrane binding manners coupled with a many independent duplication of this Euphyllophyta-clade specific plant gene. In three families of auxin transporting proteins, PIN-FORMED, LAX and PILS, I showed that emergences of these proteins are uncorrelated and placed on different levels of the plant kingdom phylogenetic tree. However these proteins ensure very fundamental plant morphogenetic processes, like cell differentiation, organ formation or tropisms, with strong effects of their deleterious mutations, I found many gene radiations and losses on a all taxonomic levels in these families, evidencing that key and shared physiological processes may be realised by genes touched by a recently undergoing evolution. Evolutionary-developmental synthesis of a functional and phylogenetic data must be done with caution due to high risk of...
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Mechanisms that control physiological seed dormancy
Řezková, Natálie ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physiological dormancy is an important developmental trait ensuring that seed does not germinate when the environmental factors are appropriate only temporary. The transition from seed dormancy to germination is regulated by a large number of factors and the phytohormone abscisic acid (ABA) plays a crucial role. Enhanced response to ABA and its biosynthesis is a key mechanism in dormancy induction and maintenance. ABA interacts antagonistically with gibberellins (GAs). Therefore GA biosynthesis and ABA catabolism are positive germination regulators. However, other phytohormones are also involved in the regulation of dormancy and germination. The most studied is ethylene which supports germination similarly to GA. Numerous factors affect dormancy at molecular level, namely chromatin remodeling, gene products that function only in dormancy regulation [e.g. DELAY OF GERMINATION 1 (DOG1)] or gene products that mediate seed response to environmental factors. The dormancy, its induction, depth and release, is driven not only by environmental conditions affecting mature seeds, but also by conditions acting during seed maturation in a maternal plant when the primary dormancy is induced. Requirements for dormancy release and germination induction may vary considerably between species. The physiological...
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