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Evolution of the genus Arabidopsis in its centre of diversity
Šrámková, Gabriela
A prerequisite for addressing general questions concerning the evolution of intraspecific variability in space and time is the knowledge of the distribution of variability within the species' range. The development of molecular methods has been a major step forward, allowing various evolutionary questions to be addressed using natural populations of model species and their close relatives. Although wild relatives of Arabidopsis thaliana have long been in the focus of plant evolutionary biologists and molecular geneticists, the patterns of genetic diversity and phenotypic variation in their natural populations are often overlooked. The present work focuses on some of the most studied model species in the Brassicaceae family, Arabidopsis halleri and the complex of A. arenosa, whose members are widely used to study ecology, physiology and evolution as well as the molecular basis of phytoremediation and parallel adaptation. The study aimed to determine intraspecific variation at the ploidy level, to reveal phylogenetic relationships and the spatial distribution of genetic diversity across the range, and to propose a new taxonomic concept based on the detected intraspecific genotypic and phenotypic variation. In order to accomplish this goal, we used DNA flow cytometry, several molecular methods (AFLP,...
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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 the genus Arabidopsis in its centre of diversity
Šrámková, Gabriela ; Marhold, Karol (advisor) ; Greimler, Josef (referee) ; Mártonfi, Pavol (referee)
A prerequisite for addressing general questions concerning the evolution of intraspecific variability in space and time is the knowledge of the distribution of variability within the species' range. The development of molecular methods has been a major step forward, allowing various evolutionary questions to be addressed using natural populations of model species and their close relatives. Although wild relatives of Arabidopsis thaliana have long been in the focus of plant evolutionary biologists and molecular geneticists, the patterns of genetic diversity and phenotypic variation in their natural populations are often overlooked. The present work focuses on some of the most studied model species in the Brassicaceae family, Arabidopsis halleri and the complex of A. arenosa, whose members are widely used to study ecology, physiology and evolution as well as the molecular basis of phytoremediation and parallel adaptation. The study aimed to determine intraspecific variation at the ploidy level, to reveal phylogenetic relationships and the spatial distribution of genetic diversity across the range, and to propose a new taxonomic concept based on the detected intraspecific genotypic and phenotypic variation. In order to accomplish this goal, we used DNA flow cytometry, several molecular methods (AFLP,...
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The role of phenotypic plasticity in parallel altitudinal differentiation in Arabidopsis arenosa
Požárová, Doubravka ; Kolář, Filip (advisor) ; Klimeš, Adam (referee)
Plants adjust to challenging environments by genetically fixed changes and phenotypically plastic response. Alpine environments pose multiple challenges to plant life including cold, high irradiance and short vegetative period. To survive such specific conditions, plants often significantly alter their morphology. In my thesis I studied to which extent specific traits of alpine ecotypes repeatedly appear among independently formed alpine populations and to which extent these changes represent fixed genotypic differentiation vs phenotypic plasticity. To address these questions I performed an experiment in which Arabidopsis arenosa plants from sixteen populations belonging to two ecotypes (alpine and foothill) were grown in conditions resembling alpine vs foothill conditions. Specifically, I modified levels of irradiance and temperature and complemented alpine-like and foothill-like treatment by additional two extreme treatments to reach full-factorial design. I used discriminant and classificatory analysis to examine the overall morphological differentiation characterised by set of twenty measured traits. Then I examined variation in each trait by statistical Bayesian model that I designed for this purpose. I found out that although ecotypes are predominantly differentiated by fixed morphological...
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Local adaptation of natural population of Arabidopsis arenosa to serpentine soil
Lamotte, Timothée ; Kolář, Filip (advisor) ; Chrtek, Jindřich (referee)
Arabidopsis arenosa represents a promising model for studying the mechanisms underlying the adaptation to serpentine soil. Genetic basis of serpentine adaptation is still poorly known and A. arenosa possesses many advantages as a tool to complete that knowledge. The first step of this study was to reveal the presence of a local adaptation to serpentine soil in a population of A. arenosa. To do so, I used the data from a reciprocal transplant experiment realized between a Czech pair of serpentine - non-serpentine populations and I explored the phenotypes associated with the adaptation. Subsequently, I produced the F2 hybrids coming from crosses between serpentine - non-serpentine parents and I studied the expression of fitness traits in F2 plants growing in serpentine in order to estimate the number of loci underlying the adaptation which I compared with other studies. I confirmed the presence of a local adaptation, with the population of serpentine origin performing better than the non-serpentine population in the serpentine substrate of origin, associated with accumulation of heavy metals in the leaves. Analyses of the soil composition revealed differences in heavy metals and nutrients contents, Ca/Mg ratio and pH between the two localities. Those results fitted with the function of the candidate...
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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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Molecular evolution of meiosis in diploids and tetraploids of Arabidopsis arenosa
Holcová, Magdalena ; Schmickl, Roswitha Elisabeth (advisor) ; Mozgová, Iva (referee)
Meiosis is functionally conserved across eukaryotes, thus not expected to vary considerably among different species, and even less so among lineages within a species. However, recent studies showed that this is not necessarily the case in Arabidopsis arenosa. Genome scanning identified an excess differentiation in meiosis genes between A. arenosa diploids and tetraploids, interpreted as meiosis adaptation to the whole genome duplication in tetraploids and differentiation was also found between two diploid lineages. Thus, I present a population-based analysis of positive selection acting on meiosis proteins across multiple lineages of A. arenosa. I showed that meiosis proteins were under positive selection in all diploid lineages, mainly in the Pannonian and South-eastern Carpathian lineage. The evidence for positive selection in diploid lineages suggested differential pathways of meiosis adaptations in the species, probably reflecting the necessity to adapt to local environments, among all to temperature. The highest enrichment of amino acid substitutions (AASs) under positive selection was identified in tetraploids, in consistence with previous genome-scan results. As several interacting meiosis proteins were under positive selection in the same A. arenosa lineage, I hypothesize that the close...
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Autopolyploids: particularly hopeful monsters
Holcová, Magdalena ; Schmickl, Roswitha Elisabeth (advisor) ; Mráz, Patrik (referee)
Autopolyploidy, genome duplication per se, is a severe mutation which presents both great challenge and great opportunity for the species which has undergone it. First, a whole series of initial challenges has to be overcome, e.g., establishment within diploid parental population, proper functioning of the cell with doubled genetic information and restoration of proper mitosis and meiosis. The population genetic changes can become beneficial afterwards as the two times higher effective population size and polysomic inheritance increase heterozygosity and genetic variability within the new polyploid lineage. It also reduces negative impacts of genetic drift and inbreeding depression. In evolutionary context, having two genomes allows selection to be more relaxed, thus genes can quickly diversify into alleles with new function or sub-function. To better understand the molecular mechanisms of selection on a population level, I choose example of meiosis genes evolution in a polyploid Arabidopsis arenosa (Brassicaceae) species complex. This only diploid-autotetraploid member of the plant leading model genus Arabidopsis provides an ideal system for addressing general questions on the triggers and consequences of genome duplication in plants. In contrast to other members of the genus, A. arenosa remained...
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