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Mechanisms of self-incompatibility in angiosperms and how to break them
Velebová, Veronika ; Urfus, Tomáš (advisor) ; Slovák, Marek (referee)
Plants have developed a reproductive strategy known as allogamy that involves fertilization using pollen from a genetically distinct member of the same species. This approach is crucial to prevent inbreeding and promote outcrossing. The mechanism responsible for ensuring outcrossing and preventing self-fertilization is called self-incompatibility. Self-incompatibility can be categorized into two types - heteromorphic and homomorphic. The incompatible reaction can be determined by the haploid (n) genotype of the pollen (gametophytic self-incompatibility) or by the diploid (2n) genotype of the plant on which the pollen is produced (sporophytic self-incompatibility). Three systems have been described in detail for homomorphic incompatibility, differing in their operation at the molecular and physiological levels. However, there are other systems that have not yet been described. Although self-incompatibility is an effective mechanism, there are certain circumstances where this mechanism can become ineffective, leading to the self-fertilization of typically cross- pollinating plants. This phenomenon is called pseudo-compatibility. A specific example of the breakdown of self-incompatibility is the mentor effect. It is a phenomenon where foreign pollen induces self-fertilization in usually...
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The Origin and Function of Heterostyly in Angiosperms
Nainar, Adam ; Münzbergová, Zuzana (advisor) ; Slovák, Marek (referee)
This bachelor's theses focuses on the phenomenon of heterostyly, which is an extraordinary feature of several representatives of plants from Angiosperm group like primroses /Primula/, based on two or three simultaneously occuring forms of one species, and expresses itself by opposite height configuration of anthers and stigmas, and that supports a reciprocal pollination and decreases a risk of self-pollination. The introduction in the beginning of the theses compares heterostyly with another various adaptations, which Angiosperms use them to avoid self-pollination. Further, the theses is divided to topical chapters, such as occurence and types of heterostyly (distyly, tristyly), and there are also many mentions about history of research of this phenomenon and about possibilities, according to which the heterostyly could have been evolved. In the theses there are mentioned other supplementary features, such as pollen grain differences as well. Also, this theses dedicates to interactions between heterostylous plants and pollinators and even to a brief genetic basis of heterostyly, which is a very important topic for explaining all these features. In the conclusion, there is mentioned a project named "The chase for cowslips", which is mapping populations of primroses - cowslips /Primula veris/ in...
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