Investigation and genome-wide association study of grain copper content in Chinese common wheat

Copper is a necessary trace mineral for the human body, and its deficiency threatens human health. Here, a panel of 243 Chinese wheat cultivars from five replications was used to measure the grain copper content (GCC) by atomic absorption spectrometry. Phenotypic analysis results revealed that the averaged GCC of surveyed cultivars ranged from 6.81 to 11.36 mg/kg with an average of 9.23 mg/kg. A genome-wide association study (GWAS) indicated that a total of 489 single-nucleotide polymorphisms (SNPs) were significant, explaining 10.1%-32.6% of the phenotypic variation and were mainly distributed on chromosomes 2A and 5A. Further analysis indicated that GCC_Hap_2A1, GCC_Hap_3B1, and GCC_Hap_5A1 may be important genetic loci that regulate GCC in wheat. Linkage mapping using a bi-parental population detected four QTLs on 1D, 6A, 6B, and 7D, explaining 8.66%, 7.55%, 8.21%, and 4.71% of the phenotypic variation, respectively. Additionally, two of the significant SNPs were located on 1D, as detected by GWAS, and were within the interval of QGCC.hau-1D, suggesting that this locus plays an important role in regulating wheat GCC. This study dissected the genetic mechanism of GCC in wheat and provides useful information for the utilization of high-GCC wheat germplasm by marker-assisted selection in wheat quality breeding.