Identification and validation of novel loci associated with wheat quality through a genome-wide association study

Understanding the genetic basis of quality-related traits contributes to the improvement of grain protein concentration (GPC), grain starch concentration (GSC), and wet gluten concentration (WGC) in wheat. In this study, a genome-wide association study (GWAS) based on a mixed linear model (MLM) was performed on 236 wheat accessions, including 160 cultivars and 76 landraces, using a 55K single nucleotide polymorphism (SNP) array in multiple environments. A total of 12 stable QTL/SNPs that control different quality traits in this populations in at least two environments under stripe rust stress were identified. Among these 12, three, seven and two QTLs associated with GPC, GSC and WGC were characterized, respectively, and they were located on chromosomes (chr) 1B, 1D, 2A, 2B, 2D, 3B, 3D, 5D, and 7D with the phenotypic variation explained (PVE) ranging from 4.2 to 10.7%. Compared with the previously reported QTLs/genes, five QTLs (QGsc.sicau-1BL, QGsc.sicau-1DS, QGsc.sicau-2DL.1, QGsc.sicau-2DL.2, and QWgc.sicau-5DL) were potentially novel. KASP markers for the SNPs AX-108770574 and AX-108791420 on chr5D associated with wet gluten concentration were successfully developed. The phenotypes of the cultivars containing the A-allele in AX-108770574 and the T-allele in AX-108791420 were extremely significantly (P<0.01) higher than those of the landraces containing the G- or C-allele with respect to the wet gluten concentration in each of the environments. The KASP markers developed and validated in this study could be utilized in molecular breeding aimed at improving the quality of wheat.