Identification and Validation of a New Source of Low Grain Cadmium Accumulation in Durum Wheat

Cadmium (Cd) is a heavy metal that has no known biological function and is toxic for many living organisms. The maximum level of Cd concentration allowed in the international market for wheat grain is 0.2 mg kg^-1 Because phenotyping for Cd uptake is expensive and time consuming, molecular markers associated with genes conferring low Cd uptake would expedite selection and lead to the development of durum cultivars with reduced Cd concentrations. Here, we identified single nucleotide polymorphisms (SNPs) associated with a novel low Cd uptake locus in the durum experimental line D041735, which has hexaploid common wheat in its pedigree. Genetic analysis revealed a single major QTL for Cd uptake on chromosome arm 5BL within a 0.3 cM interval flanked by SNP markers. Analysis of the intervening sequence revealed a gene with homology to an aluminum-induced protein as a candidate gene. Validation and allelism tests revealed that the low Cd uptake gene identified in this study is different from the closely linked Cdu1-B gene, which also resides on 5BL. This study therefore showed that the durum experimental line D041735 contains a novel low Cd uptake gene that was likely acquired from hexaploid wheat.