Agronomic biofortification in crops with Zn: the zinc-iron interaction dilemma

Summary

This narrative review examines the zinc-iron interaction dilemma in agronomic biofortification of staple cereals, particularly relevant to programmes in Sub-Saharan Africa, Middle East and South-East Asia. Whilst zinc biofortification addresses zinc deficiency in human populations, emerging evidence suggests it may trigger systemic plant responses that antagonistically reduce iron accumulation in grains—a significant concern given comparable nutritional importance of both minerals. The review synthesises mechanisms of interaction at multiple plant levels and proposes agronomic, genetic and integrated approaches to preserve iron whilst enhancing zinc content.

Regional applicability

This review focuses primarily on biofortification programmes in Sub-Saharan Africa, Middle East and South-East Asia, regions with high prevalence of micronutrient deficiencies. The findings have limited direct applicability to United Kingdom agriculture, where micronutrient deficiencies are less prevalent and staple crops are not typically subject to biofortification programmes; however, the mechanistic insights may inform future crop breeding or agronomic research addressing global food security.

Key measures

Zinc and iron content in grain and edible tissues; antagonistic and synergistic interactions between zinc and iron; micronutrient bioavailability

Outcomes reported

This review synthesises evidence on zinc-iron interactions in biofortified crops, examining potential antagonistic effects where zinc biofortification may reduce iron accumulation in edible tissues. The review identifies mechanisms of interaction across soil, roots, shoots, leaves and grains, and proposes agronomic, genetic and integrated interventions to optimise both micronutrients.

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