Understanding Genetic and Molecular Bases of Fe and Zn Accumulation Towards Development of Micronutrient-Enriched Maize

Abstract

Micronutrient malnutrition is a global problem afflicting billions of people worldwide. The effects are more prevalent in developing countries where people rely upon cereal-based diets that are inherently deficient in micronutrients. Micronutrients are required in less quantity but play critical role in the growth and development of humans. Since human body cannot synthesize micronutrients, they must be made available through diet. Among micronutrients, deficiency of iron (Fe) and zinc (Zn) has profound effects and require urgent attention. Development of micronutrient-rich staple plant foods through plant breeding, a process referred to as “biofortification,” holds promise for sustainable food-based solutions to combat micronutrient deficiency. Maize is the third most important crop of the world, serving as staple food to billions of people in sub-Saharan Africa, Latin America and Asia. The development of Fe- and Zn-rich maize cultivar(s) would therefore have positive effects on health and well-being of humans. Wide variability has been reported for Fe and Zn in maize, which can be explored for genetic improvement of the trait. Genetics of Fe and Zn has been well elucidated, and genes/QTLs governing high Fe and Zn accumulation in maize have been identified. Moreover, by targeting the genes involved in Fe and Zn uptake, transportation and translocation, concentration of the same can be increased in the maize endosperm. Further, manipulating genes for promoter and antinutritional factors, bioavailability of Fe and Zn can be enhanced. Quality protein maize (QPM) genotype reported to have higher concentration of Fe and Zn provides opportunity to develop multinutrient-rich maize through a systematic breeding approach. We discussed here available genetic variation for Fe and Zn and their interactions with environments, relationship among micronutrients and grain yield, summary of research efforts with specific emphasis on mechanism of uptake and translocation, genetic and molecular basis of Fe and Zn accumulation, and the strategies that can be explored to breed for high Fe and Zn maize.