Identification and characterization of stripe rust, leaf rust, leaf spot, and common bunt resistance in spring wheat

Hundreds of quantitative trait loci (QTLs) have been reported in diverse types of hexaploid wheat (Triticum aestivum L.) populations, but direct comparisons of QTLs in different studies and populations are still challenging due to the lack of physical positions for most QTLs. Here, we used the International Wheat Genome Sequencing Consortium (IWGSC) RefSeq v2.0 physical map of all markers to map QTLs associated with leaf spot (Ls), leaf rust (Lr), stripe rust (Yr), and common bunt (Cbt) resistance in two recombinant inbred line populations. QTL mapping was conducted using the IWGSC physical map of 3158 and 5732 markers and disease severity data of Peace/Carberry and Attila/CDC Go populations evaluated in three to eight environments. We uncovered a total of 82 QTLs associated with Yr (36), Ls (18), Lr (15), and Cbt (13) resistance in the individual and overall means of all combined environments. Among them, 29 were associated with all combined environments, which accounted for 0.5%-20.9% individually and 12.4%-41.2% of the total disease severity per trait. Three (QLr.dms-2D.2, QLs.dms-5B, and QYr.dms-5B.2) of the 29 QTLs were common in both populations. Fourteen out of the 29 QTLs were stable as they were identified both in the overall means and most of the individual environments. Ten chromosome arms harbored a cluster of QTLs associated with resistance to two to four diseases. This methodology would serve as one of the resources to compare QTLs identified in different populations and studies based on the improved physical information of all markers instead of population-specific and consensus linkage maps.