Genome-Wide Association Analysis and Candidate Gene Prediction of Wheat Grain Copper Concentration

Copper (Cu) is an essential micronutrient for almost all organisms; however, the genetic basis regarding copper accumulation remains unclear. In the present study, a genome-wide association study (GWAS) was performed on the Cu concentration in grains of 207 wheat accessions based on five multi-locus models (FASTmrMLM, ISIS EM-BLASSO, mrMLM, pKWmEB, pLARmEB). A total of 86 significant quantitative trait nucleotides (QTNs) were identified using five methods, with the mrMLM model detecting the fewest QTNs, only 12, while the other four models detected 21–40 QTNs. Thirty stable QTNs were detected in multiple environments or multiple models, mainly distributed on chromosomes 2A, 4B, 2B, and 5A, explaining 0.5–29.3% of the phenotypic variation. Finally, five potential candidate genes associated with Cu absorption and transport in the genomic regions near the reliable QTNs were screened out, including TraesCS2A02G505500 and TraesCS4B02G019300 (zinc transporters), TraesCS2B02G313200 (copper transporter), TraesCS3A02G042600 and TraesCS3B02G040900 (metal tolerance protein). These findings provide new insights into the genetic basis for Cu accumulation in wheat grains and demonstrate the role of the multi-locus GWAS (ML-GWAS) method.