A mapping review to identify breeder‐friendly quantitative trait loci/gene clusters for wheat biofortification

Abstract

Genetic biofortification of wheat grain to increase iron (Fe) and zinc (Zn) content is a cost‐effective method to reduce mineral deficiency in human diets. Breeding for increased Fe and Zn can benefit from marker‐assisted selection for high‐confidence quantitative trait loci (QTLs) or genes affecting the traits. We conducted a mapping review for loci associated with Fe and/or Zn mineral content of wheat grain/plant and identified congruency in the findings from 51 publications across QTL mapping studies, genome‐wide association studies, and transcriptomic studies of characterized genes affecting Fe and Zn uptake and transport. The information extracted was overlaid on a consensus map of linkage and physical positions based on the 90K Illumina single nucleotide polymorphism chip for wheat. We used a novel graphical method called Interval‐MAST (markers around segregating traits), which allows us to incorporate a larger volume of information than the commonly used meta‐analysis algorithms. We identified 22 marker clusters for increased Fe and/or Zn concentration in grain, with chromosomes 7A and 7B harboring the highest concentration of clusters. Our findings further supported the importance of the previously reported meta‐QTL on chromosome 2B, with the associated marker “barc159.” The remaining 21 marker clusters were likely novel key genomic regions highlighted through this mapping study. Finally, gene ontology (GO) enrichment of the candidate genes retrieved within those marker clusters revealed the GO term GO:0010043, associated with the biological process of response to zinc as a set of genes directly related to biofortification.