Major QTLs resistant to Bipolaris sorokiniana black point identified by GWAS with an incomplete diallel cross population in wheat

Abstract Black point is a major wheat grain disease caused by complex pathogens, of which Bipolaris sorokiniana is dominant. Analysis of effective resistance genes/quantitative trait loci (QTLs) is an essential prerequisite for breeding by marker-assisted selection (MAS). In this study, we aimed to identify the QTLs resistant to black point caused by B. sorokiniana in 10 wheat genotypes by performing a genome-wide association study with an incomplete diallel cross population. Twenty-three major QTLs resistance to B. sorokiniana black point were identified, which could explain more than 11% of the phenotypic variations (QTLs). They were located on 1B, 1D, 2B (2), 2D, 3A (2), 3B (2), 3D, 4A, 5A (2), 5B (2), 6B (3), 6D, 7A (2), and 7D (2), respectively. The average number of major QTLs in the 10 resistant lines was 20.2, whereas that in the susceptible lines was 9.8. All the major QTLs in the parents were detected in the F1 hybrids. Three PCR markers were developed for detecting two QTLs using two recombinant inbred line populations. These PCR markers linked to black point resistance and accessions with a larger number of resistance alleles can be used to improve wheat resistance by QTL pyramiding via marker-assisted selection.