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Molecular Characterization and Genome-Wide Association Mapping For Root System Architecture and Quality Related Traits In Ethiopian Durum Wheat (Triticum Turgidum Ssp. Durum) With High Density Snp Markers

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dc.contributor.advisor Feyissa, Tileye (PhD)
dc.contributor.advisor Tuberosa, Roberto (Professor)
dc.contributor.author Alemu, Admas
dc.date.accessioned 2020-10-12T11:04:06Z
dc.date.available 2020-10-12T11:04:06Z
dc.date.issued 2019-12-12
dc.identifier.uri http://etd.aau.edu.et/handle/123456789/22679
dc.description.abstract Durum wheat is an allotetraploid wheat (2n = 4x = 28, AABB) commonly used for production of semolina (purified flour of durum wheat mainly used in making pasta and couscous) worldwide. Durum wheat is indigenous to Ethiopia and farmers have grown the crop since immemorial time, mostly under adverse environmental conditions and developed a broad gene pool adapted to various environmental conditions. Hence, dissecting and identifying the genetic basis of agronomically relevant traits have paramount importance to enhance the yield, improve the quality and reduce genetic vulnerability to various stresses. The present study aimed to assess the genetic diversity and map valuable QTLs for root system architecture, grain shape and color related traits through genome-wide association (GWAS) analysis. A total of 192 Ethiopian durum wheat comprising 167 landraces and 25 improved varieties were assembled for this study. High-density Infinium® iSelect® Illumina 90K wheat SNP array was used to genotype accessions and 15,338 polymorphic SNPs were generated that was used for genetic diversity analysis. After excluding markers with < 0.05 minor allele frequency and > 0.1 missing values per accession and followed by imputation, 10,789 SNP markers with known chromosome position were used for GWAS analysis of root system architecture, grain shape and color related traits. Linkage disequilibrium, population structure and kinship of the panel were also estimated based on LD-pruned SNP markers. Mean values of Nei‘s gene diversity (0.246) and polymorphic information content (0.203) specified the presence of rich genetic diversity within this collection. Varieties grouped in a distinct cluster separately from landraces in clustering analysis and landraces clustering was irrespective of their geographical origin, signifying the presence of higher admixture that could arise due to the existence of historical exchange of seeds through informal seed exchanging systems involving regional and countrywide farming communities. xvi Four major and 34 nominal QTLs were identified for ten RSA traits making one clear root growth angle cluster on the chromosome arm 6AL and 15 clusters for the rest of RSA traits across chromosomes. After mapping the identified QTLs on a high-density tetraploid consensus map along with previously reported RSA QTLs in durum and bread wheat, fourteen nominal QTLs were found to be novel. Two novel major QTLs along with 18 nominal QTLs were detected for kernel length, width and color-related traits. The current high-density SNP based genetic diversity and QTL mapping analysis proved the presence of rich genetic variation and source of novel alleles in Ethiopian durum wheat. Hence, sustainable utilization and conservation of this rich durum wheat genetic resource is incomparable to cope up the recurrent climate changes and biotic stresses. Identified QTLs and chromosome regions of RSA and quality-related traits could be used as a tool to employ marker-assisted selection aimed to enhance yield, yield stability and quality of durum wheat. Further investigations including validation, fine mapping and positional cloning of major and novel RSA and quality-related QTLs identified in the current study is highly recommended to employ MAS or genomic editing to enhance durum wheat breeding. en_US
dc.language.iso en en_US
dc.publisher Addis Ababa University en_US
dc.subject Ethiopian Durum Wheat en_US
dc.subject Gwas en_US
dc.subject Qtlome en_US
dc.subject Genetic Diversity en_US
dc.subject Snps en_US
dc.subject Rsa en_US
dc.subject Grain Color en_US
dc.subject Shape en_US
dc.title Molecular Characterization and Genome-Wide Association Mapping For Root System Architecture and Quality Related Traits In Ethiopian Durum Wheat (Triticum Turgidum Ssp. Durum) With High Density Snp Markers en_US
dc.type Thesis en_US

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