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A possible role of proline in plant stress memory
Ušák, David ; Holá, Dana (advisor) ; Konrádová, Hana (referee)
The previous exposure to abiotic stress such as drought may prime plants, leading to their improved response upon later stress onset. This phenomenon, called plant stress memory, is linked to a plethora of mechanisms exerted on several levels. A complex analysis of proline metabolism in leaves and roots was performed to test the putative role of proline in such response to recurrent stress, represented by two periods of water deficit, interrupted by a period of rewatering during recovery. To provide a better understanding of intraspecific differences in drought stress memory response of plants and its inheritance, maize (Zea mays L.) parental genotypes with differing drought sensitivity and their F1 reciprocal hybrid offspring were chosen as the plant material. The water deficit had a more pronounced effect on proline metabolism in leaves than in roots. The proline content increased in response to drought, which was linked to a higher proline biosynthesis and a lower proline catabolism. Marked differences in proline metabolism among genotypes were observed, confirming the previous findings that recurrent drought response is not conserved even within the same species. However, contrary to the original assumptions on the role of proline in plant stress memory, the statistical analysis showed that...
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Self-regulating mechanisms of photosynthetic systems
Semerák, Matěj ; Mančal, Tomáš (advisor) ; Holá, Dana (referee)
Photosynthesis, a process utilising energy of arriving photons for driving electron transport chain creating transmembrane pH gradient, is a widespread way of subsistence in the nature. However, the intensity of sunlight can exceed the rate which the organisms are able to manage by their gadgetry. In this situation, essential protective mechanisms, safely draining the excess energy away, take a turn. Many theories about the principle and regulation of these functions have been developed and new still arise. It appears that the attention focuses mainly on the antenna complex LHCII. It is possible to state that with high probability, the protective processes are assured by several mechanisms, and quite a stable opinion prevails that crucial role in their activation is played by decreasing pH. That is logical since the more photons come, the more intensively the transport of protons across the membrane happens, thus ΔpH reflects the balance between ATP usage and the membrane apparatus illumination. Generally, the phenomenon is called NPQ (non-photochemical quenching), because it weakens the chlorophyll fluorescence. An important task is probably handled by carotenoids, mainly zeaxanthin, created by violaxanthin deepoxidase at low pH; it provides chlorophylls with energetical trap during excitation...
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Genetic variability in growth, reproductive and photosynthetic parameters of plants and its changes by exogenously applied steroids
Rothová, Olga ; Holá, Dana (advisor) ; Motyka, Václav (referee) ; Hradilík, Jan (referee)
While animal steroid hormones are very well known and have been studied for a long time, in plants no steroid substances were known until relatively recently. Only in the second half of the past century brassinosteroids were discovered; later on, their hormonal function in plants was confirmed. Still a lot of unknown remains as regards their function in plant cells. This paper presents in its first part the evidence that brassinosteroids control in maize (Zea mays L.) grown under field conditions not only its morphology and yield but also some developmental/reproduction characteristics like e.g. number of female inflorescences or speed of the development of male inflorescences. Particular response of a plant depends, however, on the type of applied brassinosteroid, its concentration, and last but not least also on a particular maize genotype and developmental stage of the plant during applicatin. Impact of brassinosteroids on primary photosynthetic processes in plants has not been proven under these conditions, neither on the activity of photosystem (PS) I nor on the Hill reaction. No statistically significant differences in the content of photosynthetic pigments have been found either. Another topic dealt with in this thesis is the possible protective influence of brassinosteroids on plants...
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Analysis of parameters presumably associated with drought-resistance in various sorghum genotypes
Panchártek, Daniel ; Holá, Dana (advisor) ; Hniličková, Helena (referee)
The aims of this work were 1) to assess whether sorghum (Sorghum bicolor (L.) Moench) genotypes originating from the India can be grown and analyzed in the climatic conditions of central Europe and 2) to find out the utilization potential of selected non- destructive and destructive methods based mostly on the chlorophyll a fluorescence measurements and the determination of photosynthetic pigments' content for the differentiation of sorghum genotypes based on their presumed drought tolerance. Field experiments made during 2 years compared 15 genotypes of this species (2 stay-green parental lines, 2 senescent parental lines and 11 introgression lines with stay-green loci), 2 of these genotypes were further analyzed in greenhouse conditions where the water deficit was induced by a cessation of watering for 12 days. The field-grown plants showed some differences between individual genotypes in all measured parameters; however, for the majority of the genotypes these differences were not statistically significant. The stay-green parental genotype B35 differred the most from the other ones in both field seasons, but the other stay-green genotypes usually did not differ from the senescent genotypes. No significant differences between both greenhouse-tested genotypes (presumably contrasting in their...
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Cis and trans elements in plant response to drought (with a particular focus on photosynthetic genes)
Panchártek, Daniel ; Holá, Dana (advisor) ; Feketová, Zuzana (referee)
Abiotic stresses, such as drought, high salinity and cold can strongly affect plant development and growth. Cis and trans elements are one of the options how plants regulate their own metabolism in those cases. That's the way how the expression of many target genes is induced. The products of these genes function not only in stress tolerance but also in general stress response. Many transcription factors and regulatory proteins (trans elements) are involved in these adaptions; those often interact with specific sequences in gene promoters (cis elements). Recenly, a progress has been made in analyzing the signal paths and complex cascades of gene expression regulation, although a little is still known about this regulation during drought conditions. Some of these target genes code products participating in photosyntesis and the regulation of their expression can significantly affect this process. This essay briefly describes main cis and trans elements of plant response to drought (with a particular focus on the regulation of photosyntetic genes). Keywords: drought, gene expression, cis-element, transcription factor, abcisic acid, photosyntesis, promoter.
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Molecular cytogenetic analysis of marker chromosomes and related abnormalities
Semanko, Adam ; Kočárek, Eduard (advisor) ; Holá, Dana (referee)
The primary focus of this diploma thesis is on marker chromosomes and phenotypically similar human karyotype polymorphisms, variants of short acrocentric arms in particular. The first half provides a very useful review of literature concerning different aspects of both sSMC and human polymorphisms such as their origin, inheritance, associated phenotype, formation and molecular cytogenetic methods that are applied in the process of identification of these aberrations. The methodical emphasis is on FISH and its modifications (e.g. M-FISH, acro M FISH, cen M-FISH) as well as on the CGH methods. The main objective was to test the above-mentioned methods and state their limitations and applications. Thus, in the other half we provide evaluations of commonly used methods and introduce new strategies that could be implemented to make the identification of these additional chromosomes or satellite translocations more effective. All the conclusions are based on the analysis of 7 patients with sSMC and 4 patients with variants involving acrocentric NOR regions. The results of our thorough research into their karyotypes have been compared with similar findings in the literature. Last but not least, we tried to establish a link between observed abnormalities and the type of a chromosomal aberration at hand.
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Non-coding RNA in hepresvirus infection
Pelák, Ondřej ; Drda Morávková, Alena (advisor) ; Holá, Dana (referee)
MiRNAs are endogenous short RNAs that are well conserved in eukaryotic organisms and are thought to be a vital and evolutionarily ancient component of genetic regulation. Their key role is in post-transcriptional regulation of gene expression. Some viruses were able to utilize the capabilities of these tiny RNAs to regulate their own gen expression or to regulate host gene expression in use of avoidance from immunity answers to their presence. Among these viruses belongs also the Herpesviridae family. Members of this family are using miRNA in various ways, from regulation of their own gene expression to targeting host mRNA, which prevents translation of factors related to immune answers. This work is intent on biogenesis of miRNA, its mechanism, function and manner in which it is used by representatives from Herpesviridae family.
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Different response of maize inbred and hybrid genotypes to drought: analysis of leaf proteome and photosynthetic processes
Benešová, Monika ; Holá, Dana (advisor) ; Prášil, Ilja (referee) ; Pospíšilová, Jana (referee)
Drought is one of the most important stress factors affecting plants. Increasing drought resistance via plant breeding is currently the main approach for improvement of plant productivity and reduction of water usage. Plant breeders and scientists search for reliable and easy methods of the determination of drought sensitivity in different genotypes. A precise knowledge about processes underlying plant stress response and defence against limited water availability is necessary for this. The aim of this study was a detailed analysis of photosynthetic processes and changes in leaf proteome (again aimed especially at proteins involved in photosynthesis) during drought stress. This analysis was a part of a complex project focused on the possible causes of genetic variability and drought resistance in agronomically important crops. Another goal was to analyse whether the measurement of selected photosynthetic parameters can be used for the determination of drought sensitivity per se and/or for the prediction of the response of hybrids based on known behaviour of their parents. Young plants of maize inbred lines and their hybrids were used as a model for this analysis, which was made under conditions of moderate and more severe drought. Two inbred lines which were (together with their F1 hybrids) used...
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Epigenetic regulation of DQB1 gene in patients with type 1 diabetes mellitus
Gécová, Dominika ; Kotrbová - Kozak, Anna Katarzyna (advisor) ; Holá, Dana (referee)
Background: Type 1 diabetes mellitus is a multifactorial disease caused by beta cell destruction of Langerhans pancreatic islets. From the genetic aspect the main predisposition lays on HLA class II genes (40 - 50%), molecules of which present exogenous peptides to CD4+ T lymphocytes. Enviromental factors play a crucial role in the etiopathogenesis of T1DM. Through epigenetic regulation (e.g. DNA methylation) the genetic and enviromental factors communicate. The level of methylation in the regulatory regions can significantly affect expression of these genes. Aims: The aim of the diploma thesis was to define methylation profile of HLA DQB1 alleles in type 1 diabetes mellitus patients and determine their expression. Methods: The genotyping of HLA class II genes (HLA-DRB1, HLA-DQA1, HLA-DQB1) was performed using sequence specific primers. DNA was treated with sodium bisulfite, regulatory region of HLA DQB1 was amplified and cloned into E.coli, strain DH5α/XL1-Blue. Positive clones were sent for sequencing and results analyzed. RNA was transcribed to cDNA by reverse transcription and the level of expression was analyzed by quantitative PCR. Results: Statistically significant differences were found in total methylation of DQB1*0201 and *0302 alleles in the B section of DQB1 gene. Difference in...
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