Genome-wide association study of seedling leaf rust resistance in European winter wheat cultivars

Leaf rust, caused by Puccinia triticina, is a major wheat disease that impacts yield and quality. This study aimed to identify genetic loci associated with seedling resistance to leaf rust in European winter wheat cultivars. A genome-wide association study was conducted on a panel of 181 wheat genotypes, including 143 modern cultivars and 38 lines with known leaf rust resistance genes. Pathogen evaluation involved 18 P. triticina isolates, which revealed diverse virulence levels and allowed resistant cultivars to be identified. The study identified 88 marker-trait associations clustered into 23 quantitative trait loci (QTL) across 13 chromosomes. Three QTL-QLr.ihar-1B.1, QLr.ihar-3D.1, and QLr.ihar-4 A.1-correspond to the major resistance genes Lr26, Lr24, and Lr28. Several QTL appear novel, with six (QLr.ihar-2B.2, QLr.ihar-3 A.1, QLr.ihar-3B.2, QLr.ihar-7 A.1, QLr.ihar-7D.1, and QLr.ihar-7D.2) explaining over 20% of phenotypic variance that could be considered for breeding purposes. Among 113 resistant cultivars, only 23 QTL were present in 51 genotypes, suggesting that resistance in the remaining 62 cultivars is under control of unidentified loci. The findings highlight the complex and diverse resistance patterns in European wheat, offering significant insights for breeding programs targeting enhanced leaf rust resistance.