Genetic analysis of end-use quality traits in wheat

Wheat (Triticum aestivum L.) is a major cereal food crop in the world. End-use quality improvement is a major objective in wheat breeding programs. 'Tiger' is a hard white winter wheat cultivar with excellent bread baking qualities. The objective of this study was to identify the genetic loci underlying the quality traits in Tiger. A doubled-haploid (DH) population derived from a cross between Tiger and 'Danby' was grown in two environments. A total of 17 quality traits together with grain yield (GY) and stripe rust (Puccinia striiformis f. sp. Tritici) were evaluated. The population was genotyped using single nucleotide polymorphism (SNP) markers generated through genotyping-by-sequencing (GBS). A linkage map was constructed with 1,507 GBS-SNP markers that distributed over all 21 chromosomes. Most traits in this study showed normal or approximately normal distributions. Composite interval mapping analysis revealed a total of 72 quantitative trait loci (QTL), 67 for quality traits that were dispersed on all chromosomes except 3D, 5D, 6A, and 7A. Among the 67 QTL, some were novel QTL that have not been reported previously. Although many QTL were only significant in one environment, six genomic regions on chromosomes 1B, 1D, 2D, 5BL, 6B, and 6DL harbored major QTL for several important quality traits including kernel hardness (KH), grain and flour protein content (GPC, FPC), flour yield (FY), mix time (MT), mixing tolerance (MTOL), loaf volume (LV), and loaf volume regression (LVReg). At these major loci, Danby contributed favorable alleles for KH, GPC and FPC, while Tiger contributed favorable alleles for the other traits. The findings in this study will be useful for the genetic improvement of bread-making quality in wheat.