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Actinobacteral communities in agricultural soils at sites with occurence of potato common scab.
Daniel, Ondřej ; Kopecký, Jan (advisor) ; Lichá, Irena (referee)
The diploma thesis is focussed on understanding relationships between soil chemical characteristics, actinobacterial communities of agricultural field soils and occurrence of potato common scab, a disease caused by members of the genus Streptomyces. The aim of monitoring study, on thirty-three sites covering main potato- growing regions in the Czech Republic, was to find relationships suitable for prediction of common scab severity. The second part of the thesis compared actinobacterial communities and incidence of Streptomyces harboring a pathogenic determinant, gene txtA (gene of biosynthetic pathway of phytotoxin thaxtomin A), in soils differing in occurrence of common scab. In the screening study, analysis of terminal restriction fragment length polymorphism (T-RFLP) was employed to compare composition of soil actinobacterial communities. Real-time PCR was used to quantify total actinobacteria and streptomycetes harboring txtA gene in soils differing in scab incidence. The screening study revealed negative correlations between the scab severity and (i) available phosphorus in soil and (ii) diversity of actinobaterial community. The results were used to design a model for scab prediction. A qPCR analysis showed difference in numbers of total actinobacteria and the strains harboring txtA gene in...
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Secondary metabolite production in actinomycetes causing and suppressing common scab of potatoes
Komžák, Ondřej ; Bosáková, Zuzana (advisor) ; Slaninová Kyselková, Martina (referee)
This diploma thesis focused on screening for bacterial pathogens and antagonists suppressing common scab mainly caused by Streptomyces scabiei. Common scab affects some agricultural crops causing significant economical losses. Bacterial strains, mostly streptomycetes, were isolated from potato rhizosphere because they belong to most important producents of secondary metabolites and the causative agents of the disease are also members of this genus. The isolated bacteria were characterised by PCR amplification and sequencing of 16S rRNA gene to reveal their phylogenetic relationships. The ability of isolated strains to suppress growth of Streptomyces scabiei was tested by a simple co-cultivation experiment. The strains were tested by PCR for presence of specific genes for biosynthesis of thaxtomin A, a common virulence factor found in all described pathogens causing symptoms of this disease on the surface of affected tubers. Genes for synthesis of thaxtomin belong to pathogenicity island. Standard of phytotoxin thaxtomin A was used to optimize its analysis by mass spectroscopy for further in vivo and in vitro experiments. Phylogenetic analysis of strains harboring one of the genes necessary for thaxtomin A biosynthesis supported the hypothesis of sharing the pathogenicity island by horizontal gene...
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The influece of soil conditions by the occurrence of common scab of potato tubers
PETRŮ, Ondřej
The aim of the thesis was focused on assessing the significance of the impact of habitat on the occurrence of the common scab of potatoes. In this context, following factors were evaluated: degree and extent of infestation tubers with common scab, effect of the habitat, impact of the variety, vintage influence, the influence of fertilization with nitrogen and sulfur influence seed treatment, starch content, tuber yield, the proportion of tubers over 40 mm. The review of literature of thesis includes chapters regarding the origin of potato, potato and morphological characteristics of its growth, consumer potatoes and factors that affect the quality and yield. It mentions measures against diseases and pests. The last section is devoted to common scab of potato. The practical part deals with evaluating the impact of habitat on the incidence of common scab of potatoes. The attempt was based on the habitat with the occurrence of common scab and habitats without occurrence of common scab in Vyklantice. The results were processed in program Statistica, version 12.0. (StatSoft) function of multifactor and one-way analysis of variance (ANOVA). At the habitat with higher pH and KVK higher incidence of common scab was recorded. It confirmed the impact of resistance of variety on the incidence of common scab. It was not confirmed statistically significant dependence on fertilizer nitrogen fertilizer LAV and seed treatment tubers with Trichoderma strains. It confirmed a statistically significant dependence on the incidence of common scab on fertilization with SulfoGranulat.
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Common scab important problem at growing of potato
Diviš, J. ; Krištůfek, Václav
Potato varieties with high susceptibility (Agria) and low susceptibility (Kariera) to common scab were grown on both the sites with a low occurrence and with a strong occurrence of common scab. The degree of common scab was evaluated by using the scale of Wenzel and Demel (1967). The obtained results confirmed tne significant position of the variety as the indirect measure of common scab protection. It is possible to use both varieties Agria and Kariera for indication of common scab occurrence at field conditions.
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