Micronutrient Biofortification in Wheat: QTLs, Candidate Genes and Molecular Mechanism

Micronutrient deficiency (hidden hunger) is one of the serious health problems globally, often due to diets dominated by staple foods. Genetic biofortification of a staple like wheat has surfaced as a promising, cost-efficient, and sustainable strategy. Significant genetic diversity exists in wheat and its wild relatives, but the nutritional profile in commercial wheat varieties has inadvertently declined over time, striving for better yield and disease resistance. Substantial efforts have been made to biofortify wheat using conventional and molecular breeding. QTL and genome-wide association studies were conducted, and some of the identified QTLs/marker-trait association (MTAs) for grain micronutrients like Fe have been exploited by MAS. The genetic mechanisms of micronutrient uptake, transport, and storage have also been investigated. Although wheat biofortified varieties are now commercially cultivated in selected regions worldwide, further improvements are needed. This review provides an overview of wheat biofortification, covering breeding efforts, nutritional evaluation methods, nutrient assimilation and bioavailability, and microbial involvement in wheat grain enrichment. Emerging technologies such as non-destructive hyperspectral imaging (HSI)/red, green, and blue (RGB) phenotyping; multi-omics integration; CRISPR-Cas9 alongside genomic selection; and microbial genetics hold promise for advancing biofortification.