Genome editing for nutritional biofortification in maize: bridging molecular innovation and food security in the Global South

Abstract

Micronutrient deficiency is a prevalent challenge in Sub-Saharan Africa and other geographies of the Global South where populations rely on maize as the primary calorie source. Globally, the most widespread micronutrient deficiencies include iron, zinc, and vitamin A, which are inherently low in maize. Besides, maize grain protein percentage of the essential amino acids falls below the recommended daily allowance. Traditional plant breeding practices have enabled the generation of hybrid plant varieties with superior nutritional value, such as Quality Protein Maize (QPM). However, obtaining novel varieties from existing gene pools often results in linkage drag drawbacks, yield penalties, poor-quality kernels, and requires multiple backcrossing cycles. Thus, genome editing offers a precise strategy for enhancing nutritional value, without the associated trade-offs. CRISPR/Cas, base editors and prime editors reduce breeding timelines and enable precise targeting of nutrient-accumulation pathways. In this review, we explore how genome editing technology could serve as the next-generation approach for maize biofortification. The review outlines various ways CRISPR/Cas allow precise and targeted modification of genes responsible for micronutrient biosynthesis, transport, and storage. We describe the application of CRISPR in disrupting negative regulators of nutrient transport, up-regulating nutrient biosynthesis pathways, and knocking out anti-nutritional factor genes. We further highlight that CRISPR-enabled biofortification is not just a technological innovation but a public health intervention for mitigating nutrient deficiencies. However, fully unlocking the potential of gene-edited biofortified maize will require coordinated efforts in regulatory policy and alignment with farmer/consumer preference.