Genotypic Differences in Concentration and Bioavailability of Kernel‐Iron in Tropical Maize Varieties Grown Under Field Conditions

Abstract

Iron deficiency is estimated to affect over one‐half the world population. Improving the nutritional quality of staple food crops through breeding for high bioavailable iron represents a sustainable and cost effective approach to alleviating iron malnutrition. Forty‐nine late maturing tropical elite maize varieties were grown in a lattice design with two replications in three locations representing three agroecologies in West and Central Africa to identify varieties with high levels of kernel‐Fe. Bioavailable iron was assessed for some varieties selected for high Fe concentration in kernel and improved agronomic traits using an in vitro digestion/Caco‐2 cell model. Significant differences in kernel‐Fe and ‐zinc concentration were observed among varieties (P < 0.001). Kernel‐Fe levels ranged from 16.8 to 24.4 mg kg⁻¹, while kernel‐Zn levels ranged from 16.5 to 24.6 mg kg⁻¹. Environment did not have a significant effect on kernel‐iron and ‐zinc levels, but genotype by environment (G × E) interaction was highly significant. The genetic component accounted for 12% of the total variation in kernel‐Fe and 29% for kernel‐Zn levels. Kernel‐Fe was positively correlated with kernel‐Zn (R ² = 0.51, P < 0.0001). Significant differences in iron bioavailability were detected among selected Fe‐rich varieties grown at one location. Mean bioavailable Fe ranged between 30% below to 88% above the reference control variety. The results indicate that genetic differences exist in kernel‐Fe and ‐Zn concentrations and Fe bioavailability. These differences may be useful in biofortification intervention programs, but additional research is needed to determine the efficacy of iron‐rich maize varieties in alleviating iron deficiency in humans.

^#This research was supported by USDA-ARS/USAID and IITA.

Keywords:

• Caco‐2
• Grain‐iron and ‐zinc concentrations
• Iron bioavailability
• Tropical maize
• West and Central Africa

Acknowledgments

The authors wish to thank Gary Wortley and Borys Polon for their technical assistance and Dr. Leon Kochian, Leader, USPSNL for his constant encouragement.

Notes

^#This research was supported by USDA-ARS/USAID and IITA.

^aMention of trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the United State Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.