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ABSTRACT Yellow rust caused by Puccinia striiformis f. sp. tritici (Pst) is a major threat to bread wheat production in Ethiopia, causing severe yield and quality losses. The emergence of new virulent races necessitates the identification of durable resistance sources and associated genomic regions for wheat improvement. This study aimed to characterise the genetic diversity of 184 bread wheat lines obtained from CIMMYT, ICARDA and EIAR/KARC nurseries and to identify genomic regions associated with stripe rust resistance. Multi‐environment field trials were conducted across three Ethiopian wheat‐growing locations (KARC, Meraro and SARC) over two years. Disease resistance and agronomic traits, including Area Under Disease Progress Curve (AUDPC), Average Coefficient of Infection (ACI), Head Infection (HI), Plant Height (PH), Grain Yield (GY) and Thousand Kernel Weight (TKW) were evaluated. Phenotypic analysis revealed substantial variation among genotypes, while GY and TKW showed strong environmental influence. Genotyping using DArTseq technology generated 39,375 high‐quality Single Nucleotide Polymorphism (SNP) markers for genetic diversity and genome‐wide association studies (GWAS). Principal/Component Analysis (PCA) demonstrated clear genetic variation among the wheat lines, with the first two components explaining 27.8% of the total variation and clustering genotypes into three distinct groups. GWAS using Mixed Linear Models (MLM) identified highly significant loci associated with stripe rust resistance on chromosomes 6B (709.5 Mb, p = 1.61 × 10 −10 , 29.58% variance explained), 5D (426.6 Mb, p = 7.25 × 10 −10 , 24.47%) and 5A (670.8 Mb, p = 2.21 × 10 −10 , 19.76%). Additional moderate effect loci were observed on chromosomes 3A, 1D, 7A and 6B, indicating the resistance is controlled by both major‐ and minor‐effect quantitative loci (QTL). To biologically validate the GWAS signals, candidate genes within linkage disequilibrium intervals were functionally characterised using protein sequence‐based analysis. Conserved motifs analysis identified proteins containing kinase‐associated and leucine‐rich repeat (LRR) domains involved in plant immune signalling and pathogen recognition. Several large multidomain proteins characteristic of receptor‐like kinases (RLKs) and nucleotide‐binding leucine‐rich repeat (NLR) resistance proteins were prioritised as strong candidate genes. Overall, this integrative approach identified novel genomic regions and putative resistance‐associated genes that can support marker‐assisted breeding for developing durable stripe rust‐resistant and high‐yielding wheat varieties adapted to Ethiopia and similar agro‐ecological regions.
Regasa et al. (Wed,) studied this question.