Genome-Wide Association Study and Candidate Gene Prediction of Copper Content in Wheat Grain

Copper is an essential trace element in humans, and copper deficiency can compromise health. Wheat is a major staple crop worldwide, and biofortification of wheat grain with copper is a cost-effective strategy to help alleviate dietary copper deficiency. However, the genetic basis of grain copper content in wheat remains poorly understood. Here, grain copper content was evaluated in 225 wheat accessions, and a genome-wide association study (GWAS) was performed using the Wheat 660 K SNP array. In total, 146 significant SNPs were identified, mainly on chromosomes 2A, 3A, 3B, and 4A. Haplotype analysis indicated that GCuC_2A_Hap, GCuC_4A.1_Hap, and GCuC_4A.2_Hap are key loci associated with grain copper content and show a significant pyramiding effect. Based on bioinformatics and haplotype analysis, TraesCS2A02G549200, TraesCS2A02G550300, TraesCS2A02G550800, TraesCS4A02G305300, and TraesCS4A02G305400 were proposed as candidate genes regulating grain copper content. These results clarify the genetic architecture of grain copper content in wheat and provide a valuable foundation for developing germplasm with elevated grain copper content for wheat quality improvement breeding.