| Abstract
| - A “whole-body” radioassay procedure was used to assess retention and absorption by rats of Zn inmature kernels of whole grain wheat harvested from 28 genotypes (Triticum spp.) grown in nutrientsolution supplied with 2 μM ZnSO4 radiolabeled with 65Zn. Grain-Zn concentration differed amonggenotypes and ranged from 33 to 149 μg g-1 of dry weight (DW); similarly, grain-Fe concentrationvaried ∼4-fold, from 80 to 368 μg g-1 of DW. Concentrations of Zn and Fe in the grain were positivelycorrelated. Therefore, selecting genotypes high in grain-Zn also tends to increase grain-Feconcentration. Concentrations of myo-inositolhexaphosphate (phytate) in the wheat grain varied from8.6 to 26.1 μmol g-1 of DW. Grain intrinsically labeled with 65Zn was incorporated into test meals fedto Zn-depleted rats. All rats readily ate the test meals, so that Zn intake varied directly with grain-Znconcentration. As determined by the percentage of 65Zn absorbed from the test meal, the bioavailabilityto rats of Zn in the wheat genotypes ranged from about 60 to 82%. The amount of bioavailable Zn(micrograms) in the grain was positively correlated to the amount of Zn accumulated in the grain.There was a significant negative correlation between grain-phytate levels and percentage of Znabsorbed from the wheat grain, but the effect was not large. These results demonstrate thatconcentrations of Zn in whole-wheat grain, as well as amounts of bioavailable Zn in the grain, can beincreased significantly by using traditional plant-breeding programs to select genotypes with highgrain-Zn levels. Increasing the amount of Zn in wheat grain through plant-breeding contrivances maycontribute significantly to improving the Zn status of individuals dependent on whole grain wheat asa staple food. Keywords: Zinc; bioavailability; biofortification; grain; plant breeding; rats; phytate, micronutrientmalnutrition
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