Abstract: 【Objective】Identify SNPs and candidate genes that are significantly related to wheat grain quality traits, and reveal their genetic mechanism. 【Method】 In this study, 298 introduced varieties (lines), Xinjiang landrace (lines) and Xinjiang bred varieties (lines) were used for an association population. Seven grain quality traits, including protein content (PRC), wet gluten content (WGC), sedimentation value (SV), starch content (STC), grain hardness (GH), flour yield (FY) and test weight (TW), were measured under five environments. Based on phenotypes of seven quality traits and genotypes of 55K SNP markers in this population, the Q+K association mixed model was used for genome-wide association analysis to obtain significantly associated SNP loci.【Result】The coefficients of variation of the seven grain quality traits of introduced varieties (lines), landraces and bred varieties (lines) under different environments were 1.3%-13.4%, 1.1%-18.6% and 1.0%-13.9%, respectively. Among them, the protein content, wet gluten content and sedimentation value of introduced varieties (lines) have the highest coefficient of variation (CV); Xinjiang bred varieties (lines) have the largest CV of starch content, grain hardness and flour yield. Whereas, for other six grain quality traits, including protein content, wet gluten content, sedimentation value, starch content, grain hardness, and the coefficients of variation of Xinjiang landraces are all between those of the introduced varieties (lines) and Xinjiang bred varieties (lines). Population structure analysis showed that 298 wheat varieties (lines) can be divided into 3 subgroups. Subgroup 1 contains 128 (43.0%) the materials mainly from landrace (lines); Subgroup 2 has 24 (8.1%) materials, mainly including introduced varieties (lines) and landraces; Subgroup 3 contains 146 (48.9%) materials, mainly introduced varieties (lines). The linkage disequilibrium analysis showed that the LD attenuation distances of the A, B and D genomes and the whole genome respectively were 10, 10, 6 and 8 Mb, according to the LD attenuation distance of the whole genome, the loci in the 8 Mb interval after the physical map were identified as a candidate loci. A total of 85 loci were simultaneously detected in two or more environments, that were significantly associated with 7 wheat grain quality traits detected by GWAS, with a contribution rate of 3.7%-10.9%. Stable SNPs associated with multiple traits were detected on chromosomes 1B, 1D, 2D, 3A, 3D, 4A, 4B, 5A, 6A, 6D, 7A and 7D. Among them, AX-109452823-AX-110545157 on chromosome 7A is related to protein content, starch content, wet gluten content, sedimentation value, flour yield and grain hardness, and was detected across four environments. Candidate genes at stable loci associated with multiple traits were searched, and 10 candidate genes that might be related to wheat grain quality were screened. Among them, TraesCS4A01G299800 (cationic amino acid transporter), TraesCS7A01G059500 (tryptophan decarboxylase), TraesCS7A01G331200, TraesCS7D01G418700 (xyloglucan endoglucosylase/hydrolase) play important roles in regulating the amino acid content in wheat grains.【Conclusion】The 85 loci were simultaneously detected in two or more environments, and 10 candidate genes related to wheat grain quality traits were predicted.

Key words: wheat, quality traits, genome-wide association analysis, SNP, candidate genes