QTL Mapping for Grain Zinc and Iron Concentrations in Bread Wheat

Deficiency of micronutrient elements, such as zinc (Zn) and iron (Fe), is called hidden hunger, and bio-fortification is the most effective way to overcome the problem. In this study, a high-density Affymetrix 50K single-nucleotide polymorphism (SNP) array was used to map quantitative trait loci (QTL) for grain Zn (GZn) and grain Fe (GFe) concentrations in 254 recombinant inbred lines (RILs) from a cross Jingdong 8/Bainong AK58 in nine environments. There was a wide range of variation in GZn and GFe concentrations among the RILs, with the largest effect contributed by the line x environment interaction, followed by line and environmental effects. The broad sense heritabilities of GZn and GFe were 0.36 +/- 0.03 and 0.39 +/- 0.03, respectively. Seven QTL for GZn on chromosomes 1DS, 2AS, 3BS, 4DS, 6AS, 6DL, and 7BL accounted for 2.2-25.1% of the phenotypic variances, and four QTL for GFe on chromosomes 3BL, 4DS, 6AS, and 7BL explained 2.3-30.4% of the phenotypic variances. QTL on chromosomes 4DS, 6AS, and 7BL might have pleiotropic effects on both GZn and GFe that were validated on a germplasm panel. Closely linked SNP markers were converted to high-throughput KASP markers, providing valuable tools for selection of improved Zn and Fe bio-fortification in breeding.

Automated summary

This study identified multiple QTL for grain zinc (GZn) and grain iron (GFe) concentrations in wheat, highlighting the significant effects of line x environment interaction on the variation. The high heritabilities of GZn and GFe suggest the potential for genetic improvement through bio-fortification breeding. Conversion of SNP markers to high-throughput KASP markers provides valuable tools for marker-assisted selection in breeding programs.