Identification of loci for pre-harvest sprouting resistance in the highly dormant spring wheat RL4137

Key message Combination of RL4137 alleles at three QTLs on chromosomes 4A, 6B and 6D, and 'Roblin' allele at a novel QTL on chromosome 1D increases pre-harvest sprouting resistance in 'Roblin'/RL4137 doubled haploid population. Pre-harvest sprouting (PHS) significantly reduces wheat grain yield and quality. Therefore, identifying quantitative trait loci (QTL) for PHS resistance is key to facilitate marker-assisted breeding. To this end, we studied PHS in a population of 330 doubled haploid (DH) lines derived from 'Roblin'/RL4137. The parental and DH lines were examined for their PHS phenotype based on speed of germination index in five environments and genotyped using the wheat Infinium 90 K SNP array. A total of five QTLs were detected on linkage groups 1D, 4A.2, 6B.1, 6D and 7A over the five environments. The QTLQPhs.umb-4Aon linkage group 4A.2 was the most consistent across all environments and explained 40-50% of phenotypic variation. The QTL on 1D is a novel QTL and explained 1.99-2.33% of phenotypic variation. The QTLs on 6B.1 and 6D each explained 3.09-4.33% and 1.62-2.45% of phenotypic variation, respectively. A combination of four stable QTLs on linkage groups 1D, 4A.2, 6B.1 and 6D greatly increased PHS resistance. Allelic effects for the QTLsQPhs.umb-4A,QPhs.umb-6BandQPhs.umb-6Dwere contributed by RL4137, whereas 'Roblin' contributed the resistant allele forQPhs.umb-1D.QPhs.umb-4Awas required for strong dormancy in the 'Roblin'/RL4137 DH population, and the presence of QTLsQPhs.umb-1D,QPhs.umb-6BandQPhs.umb-6Dincrementally increased dormancy; DH lines carrying all four QTLs are considerably more dormant than those carrying onlyQPhs.umb-4Aor none of the four QTLs. Thus, the QTLs identified in this study have the potential to improve PHS resistance in spring wheat.