Conserved Regions of Resistance Genes as a Source of Nucleotide Polymorphisms in Wheat Hexaploid Research - Cytology and Genetics
Abstract The study was performed to identify primer pairs to conserved regions of R resistance genes to powdery mildew and other wheat pathogens effective in detecting polymorphism in amplicon spectra between samples contrasting in powdery mildew resistance. The resistant samples were the amphidiploid Aurotica (AAВВTT genome) and wheat lines developed on its basis (AAВВВDD). Detection of polymorphic components of spectra will make it possible to use appropriate primer pairs to assess the prospects of modern varieties of common wheat to be a recipient of the resistance gene(s) that can be transferred from Aurotica to the genetic pool of common wheat through sexual hybridization. The research method is PCR on genomic DNA of the studied genotypes using primer pairs developed using nucleotide sequences in conserved regions of powdery mildew resistance genes as well as degenerate primers to conservative regions of different resistance genes for arbitrary pairing of them using the RGAP method. The use of the RGAP method was shown to provide more information about the polymorphism present in the studied genomes compared to the use of primers to conserved sequences of Pm genes. They can be used in combinations with other RGAP primers to increase the number of effective PCR markers of resistance genes.
Genetic Basis of Resistance to Wheat Yellow Rust - Cytology and Genetics
Abstract Yellow (stripe) rust, the agent of which is a biotrophic fungus, Puccinia striiformis West. f. sp. tritici (Pst), is one of the most harmful diseases of wheat. Creating resistant genotypes is considered an ecologically safe and economically profitable technology for plant protection. At present, there are over 80 known and officially recognized genes of resistance to stripe rust (Yr) as well as dozens of genes with temporary labeling. Some Yr genes were characterized, and the corresponding molecular markers to them were selected. An urgent direction of studies is the search for effective quantitative trait loci (QTL) to be used in breeding programs for resistance to yellow rust. In current views, the genetic resistance of wheat to yellow rust is divided into adult seedling resistance (ASR) and adult plant resistance (APR). Most identified genes of resistance to yellow rust are considered race-specific ASR-genes. At present, the unification and systematization of all races were performed using the global pathogen collections, which allowed for the practical application of approximately 20 identified genetic groups of Pst. Triticum aestivum L. is believed to be the source of most genes of resistance to yellow rust: more than 50 Yr genes originate from bread wheat. Relevant sources of resistance genes can also be found in wild and cultivated Triticum species and genetically related plants, including different species of goat grass. The localization of Yr genes of the chromosomes of genomes А, B, and D of T. aestivum L. demonstrated their highest number in genome В. The genotypes with a complex of genes, controlling resistance to several diseases, are considered especially valuable and widely used in breeding programs worldwide.
Markers Linked to Stem Rust Resistance Genes Sr39 and Sr40 for Selecting Wheat Breeding Lines - Cytology and Genetics
Abstract Introduction of genes conferring resistance to Puccinia graminis is considered as the best approach to protect common wheat against stem rust. To facilitate marker-assisted selection of common wheat breeding lines with the stem rust resistance genes Sr39 and Sr40, the testing of molecular markers for these genes was carried out. The markers used for the research were the following: BE500705, Xmag2090, Xmag464, Xcnl158, Xwmc25, Sr39#50, Sr39#22, BCD260, and Xwmc344. Among the simple sequence repeat markers, only Xmag2090, Xwmc25, and Xwmc344 proved to be polymorphic upon analysis of amplicons by polyacrylamide gel electrophoresis followed by silver staining. The markers Sr39#50 and Sr39#22 produced similar amplicons in the control lines RL5711 with Sr39 and RL6089 with Sr40, while amplified fragments were absent in the cultivars. Sr39#50 and Sr39#22 were used for marker-assisted selection of F2 lines from the cross Khutorianka × RL6089 (Sr40) and F4 lines from the cross Solomiia × RL5711 (Sr39). Using Sr39#50, the Sr40 resistance marker was found in 46% of the F2 offspring of the cross Khutorianka × RL6089. Among the F4 offspring of the cross Solomiia x RL5711, the frequency of genotypes with the combination of the Sr39#50 and Sr39#22 marker amplicons was only 11%. Additionally, 33% of the F4 lines showed the Sr39#22 amplicon of approximately 800 bp but lacked the Sr39#50 resistance markers. The reduced frequency of lines with the Sr39 and Sr40 genes may be due to the decreased survival of genotypes with the 2B chromosome introgression after fall planting. The winter wheat lines with the Sr39 or Sr40 gene may be used as the initial material in breeding programs.
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The community of microbes living in and on our bodies may be acting as a reservoir for antibiotic resistance, according to new research from the Earlham Institute and Quadram Institute in Norwich. The work is published in the journal Nature Communications.
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Phys.org