Micronutrient density in European elite wheat: Breeding opportunities for enhanced iron and zinc nutrition

Context The importance of staple crops as sources of micronutrients such as zinc (Zn), iron (Fe), and selenium (Se) is increasing in Europe due to dietary shifts towards plant-based foods. While wheat that is biofortified with these micronutrients may partially cover this micronutrient demand, it needs to be assured that such wheat does not contain elevated concentrations of the contaminant cadmium (Cd). Objective We aimed to assess the potential of European elite wheat germplasm for micronutrient biofortification by evaluating the genetic variation in grain concentrations of Zn, Fe, Se, Cd, and phytate, among other nutrients. Methods We analysed 103 European elite bread wheat cultivars ( Triticum aestivum ) grown in field experiments in Switzerland in 2015 and 2017 for trace elements, minerals, protein content, phytate, and yield components. Linear mixed models were applied to estimate across year-site heritabilities and genetic correlations. Results The heritabilities of the grain concentrations were highest for Fe (H 2 = 0.73), followed by phytate (0.65), Zn (0.59), Se (0.29), and Cd (0.22). The heritability of Fe was close to the heritability of the thousand kernel weight (0.83) which is a reference trait for a high heritability. Genetic correlations were strongest for Fe and Zn ( r = 0.88), Fe and phytate (0.80) and Fe and Cd (0.78), while this correlation was not significant for Zn and Cd. Multivariate analyses indicated that country-specific breeding programs influenced protein, sulfur, and phosphorus concentrations, but not trace element concentrations. Conclusion & implications The considerable genetic variation and corresponding heritabilities of Fe and Zn in European elite wheat germplasm suggests that breeding for increased micronutrient content could be feasible without extensive pre-breeding. Hence, biofortified elite cultivars could improve Fe and Zn nutrition in plant-based diets. However, Cd accumulation and the bioavailability of Fe and Zn would need to be evaluated in genetically biofortified elite wheat.