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Risk of hybridization of threatened P. fruticosa with cultivated Prunus species
Musilová, Lenka ; Vít, Petr (advisor) ; Zahradníček, Jaroslav (referee)
Many agriculturally important fruit trees occur in the genus Prunus, among other also Sour cherry (Prunus cerasus) and Sweet cherry (Prunus avium). P. cerasus is considered to be an allopolyploid hybrid originated by hybridization of Prunus fruticosa (2n = 4x = 32) and P. avium (2n = 2x = 16). The world production of sour cherry fruit (P. cerasus) in 2008 is estimated to be more than 1, 15 million tones. Prunus fruticosa is a steppe (forest steppe) relict species, severely endangered in the Czech Republic (C2). The main threat of P. fruticosa are both the direct and indirect human activities, causing, above all the loss of natural biotopes and hybridization with cultivated species that ran wild to the nature. P. fruticosa hybridizes all over its occurrence area with wild P. cerasus (Sour cherry; which is not primary species of the Czech Republic) and originates fertile hybrid Prunus × eminens. The results of existing studies indicate that the hybrids are more common in the central Europe and that the frequency of hybridization rises towards the west. Such phenomenon is related to human activities (cherries cultivation and landscape changes). Many authors consider hybridization to be the main cause of endangerment of this species and noticed that in many habitats the hybrids could totally replace...
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Optimization and application of in vitro techniques in selected members of the family Brassicaceae
Hilgert-Delgado, Alois Antonín ; Fernández Cusimamani, Eloy (advisor) ; Jana, Jana (referee)
This thesis is focused on the application and optimization of biotechnological methods within the family Brassicaceae. Most of this thesis is focused specifically the genus Brassica. The main objective of this dissertation thesis was to optimize and apply selected biotechnological methods in the resynthesis of oilseed rape (B. napus) from its baseline species (B. oleracea, CC and B. rapa, AA) and subsequently create valuable genetic plant materials.
The optimized procedure implemented in my work have exhibited better results of hybrid production (resynthesis) than in similar published experiments and provides a simplified and less laborious method via simple ovule culture and early hybrid verification.
The next accomplished step was to work with a wider range of materials using a broader source of different and contrasting genotypes from Brassica rapa (spring and winter oilseed and vegetable turnips) and B. oleracea (green and purple curly kales and cabbages) for new combinations and wider genetic diversity.
It was concluded that the optimized ovule culture protocol with early verification, developed in the framework of this thesis, is satisfactorily sufficient enough to be applicable in breeding programmes, aimed at diversity expansion of winter oilseed rape gene pool, as the resynthesized embryos were derived in most combinations.
New resynthesized verified lines were colchicine treated in order to obtain diploid regenerants and the fertile plants were self-pollinized and crossed with elite oilseed rape lines for further research and breeding.
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Interspecific sperm competition in sturgeon
ŠACHLOVÁ, Hana
Sturgeon species (order Acipenseriformes) are prone for interspecific hybridization. Anthropogenic activities in river basins influence sturgeon reproduction by destruction of their natural spawning grounds. Consequently, spawning areas, as well as the time of spawning of sturgeon species overlap and different sturgeon species reproduce concurrently. This increases the probability of meeting of heterospecific gametes and pre-zygotic postcopulatory reproductive barriers, comprising of sperm competition and cryptic female choice, may play an important role in preventing undesirable interspecific hybridization. The goal of this study was to evaluate the role of interspecific sperm competition and cryptic female choice during interspecific hybridization of sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser baerii). Reproductive characteristics (fertilization rate and hatching rate) were described in each of experimental and control groups showing similar values for competitive and non-competitive trials. Parentage assignment was performed in hatched larvae using combination of mitochondrial DNA and microsatellite DNA markers. Obtained results revealed higher fertilization success of sterlet spermatozoa, when these competed for fertilization with spermatozoa of Siberian sturgeon. Total reproductive success of starlet spermatozoa was 78.9 % and Siberian sturgeon 21.1 %. Contrary, when spermatozoa did not compete for fertilization, males of analysed species showed equal fertilization success. In the trials, where eggs of both studied species were mixed and fertilized by sperm from each species separately, eggs of any species did not show a tendency to bias fertilization by spermatozoa of conspecific males. Probably, there are no pre-zygotic postcopulatory reproductive barriers that prevent interspecific hybridization of sterlet and Siberian sturgeon at the gametic level.
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