Genome-Wide Association Study Reveals the Genetic Architecture for Calcium Accumulation in Grains of Hexaploid Wheat (Triticum Aestivum L.)

Background: Hexaploid wheat ( Triticum aestivum L. ) is a leading cereal crop worldwide. Understanding the mechanism of calcium (Ca) accumulation in wheat is important to reduce the risk of human micronutrient deficiencies. However, the mechanisms of Ca accumulation in wheat grain are only partly understood. Results: : Here, we performed a genome-wide association study to identify the genetic basis of Ca accumulation in wheat grain using an association population consisting of 207 varieties, with phenotypic data from three locations and the combined locations. In total, 18 non-redundant quantitative trait loci (QTLs) associated with Ca concentration were identified that explained, on average, 9.61%–26.93% of the phenotypic variation. Cultivars containing more superior alleles and fewer inferior alleles had increased grain Ca concentrations. Notably, six non-redundant loci were identified in at least two environments, indicating their stability across different environments. Searches of public databases revealed six putative candidate genes linked to Ca accumulation. Among them, two subunits of V-type Proton ATPase ( TraesCS4A01G428900 and TraesCS3B01G241000 ) are encoded by genes associated with stable genetic loci on chromosomes 4A (AX-108912427) and 3B (AX-110922471), respectively, and they are typical generators of a proton gradient that might be involved in Ca homeostasis in wheat grain. Conclusion: This study could increases our understanding of the genetic architecture of grain Ca accumulation in wheat, and we plan to develop the identified superior alleles into molecular markers for wheat Ca biofortification pyramid breeding in the future.