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Comparisons of recombination in elite and wide crosses of durum wheat



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Recombination rates along wheat chromosomes can vary significantly. Recombination hotspots are common in the telomeric regions of the wheat chromosomes while largely void in centromeric regions. This has consequences for plant breeders who ideally would like maximum recombination among all genes in order to maximize variability. Disturbances in meiosis can lead to changes in the rate and distribution of chiasmata within paired homologues. In this thesis, the influence of alien chromatin on recombination in two tetraploid wheat backgrounds was examined. The material was developed from Langdon triticale (AABBRR; Langdon X Rye-13) and alien addition line DGE-1 along with two tetraploid (AABB) durum wheats, Langdon and W9262-260D3. Three crosses were made in which the first cross was the normal durum wheat cross (Pop1; Langdon/W9262-260D3), the second was between the hexaploid triticale and durum wheat (Pop2; Langdon triticale/W9262-260D3) so that rye univalents would be present during the F1 meiosis. The third was between an addition line and durum wheat named as Pop3 (DGE-1/W9262-260D3). For each F2 population, the genetic mapping of extracted DNA samples was performed using genotypic data derived from the wheat 90K iSelect array and the recombination rates were estimated using MareyMap. The genetic maps from all of these crosses were compared with the map of the durum DH population (Kofa/W9262-260D3). Comparative analysis revealed the presence of alien chromatin both increased and suppressed recombination in the chromosomes. In Pop2 and Pop3, the telomeric regions showed maximum recombination in chromosomes 1A, 1B, 2A, 2B, 3A, 3B, 6A, 6B, and 7A. On the other hand, Pop2 showed suppressed recombination at some points in chromosome 2A, 2B, 3A, 5B, and 6A whereas in Pop3, in chromosomes 3A, 4B, 5A, and 7B, recombination was low at some points as compared to Pop1 and DH population. However, the maximum recombination occurred in the peri-centromeric and telomeric regions for both the populations with alien chromatin. Hence, the results showed the positive impact of alien chromatin on genetic recombination in the wheat homologous chromosomes and the presence of alien chromatin can be helpful in enhancing recombination rates in wheat which could be a useful breeding strategy.



Recombination, wheat



Master of Science (M.Sc.)


Plant Sciences


Plant Sciences


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