Genome wide linkage mapping for black point resistance in a recombinant inbred line population of Zhongmai 578 and Jimai 22

Black point, a black discoloration of the grain embryo, downgrades the grain quality and commodity grade. Identification of the underlying genetic loci can facilitate the improvement of black point resistance in wheat. Here, 262 recombinant inbred lines (RILs) from the cross of Zhongmai 578/Jimai 22 were evaluated for black point reaction in five environments. A high-density genetic linkage map of the RIL population was constructed with the wheat 50K single nucleotide polymorphism (SNP) array. Six stable QTLs for black point resistance, QBp.caas-2A, QBp.caas-2B1, QBp.caas-2B2, QBp.caas-2D, QBp.caas-3A and QBp.caas-5B were detected, explaining 2.1-28.8% of the phenotypic variances. The resistance alleles of QBp.caas-2B1 and QBp.caas-2B2 were contributed by Zhongmai 578 while the others were from Jimai 22. QBp.caas-2B2, QBp.caas-2D and QBp.caas-3A are overlapped with previously reported loci, whereas QBp.caas-2A, QBp.caas-2B1 and QBp.caas-5B are likely to be new. Five KASP markers, Kasp_2A_BP, Kasp_2B1_BP, Kasp_2B2_BP, Kasp_3A_BP and Kasp_5B_BP were validated in a natural population of 165 cultivars. The findings provide useful QTL and molecular markers for improvement of black point in wheat resistance in marker-assisted breeding.