Quantitative trait loci mapping reveals the complexity of adult plant resistance to leaf rust in spring wheat ‘Copio’

Abstract The spring wheat ( Triticum aestivum L.) line ‘Copio’ has exhibited high level of adult plant resistance (APR) to the leaf rust Puccinia triticina ) pathogen in Mexico during field evaluations. To elucidate genetic basis Copio, 176 F 4 ‐derived 6 ‐recombinant inbred lines (RILs) from a cross ‘Apav’ and Copio were phenotyped for two seasons United States Mexico. A total 762 genotyping‐by‐sequencing (GBS) single nucleotide polymorphic (SNP) markers used develop linkage maps. Composite interval mapping identified seven quantitative trait loci (QTL), all contributed by Copio. Three QTL on chromosome arms 1BL QLr.umn‐1B ), 2AS QLr.umn‐2A 3BS QLr.umn‐3B consistently expressed across four environments. represents Lr46 , which is pleiotropic APR gene, while colocated Lr37 gene 2NS/2AS translocation fragment. 3BS, mapped Sr2/Yr30/Lr27 genomic region, more likely be unique locus conferring races because phenotyping environments had Lr27 virulent pathotypes. Moreover, functionality complimented Lr31 4BS, lacking both parents. Marker haplotypes RILs carrying combination alleles at three loci. This reduced coefficient infection up 52 36% Mexican U.S. environments, respectively. study reports complex mechanism its importance as potential source pyramiding through recombination breeding.