PROJECT SUMMARY
Cadmium (Cd) is an important contaminant that threatens human health, as well as agricultural productivity
and biodiversity. In the United States, the largest source of Cd exposure in non-smoking adults and children is
through the diet. Although adverse effects on kidneys, bones and as a carcinogen are well documented, there
is emerging evidence that Cd has significant neurotoxicological effects at low doses especially in pediatric
population. Several studies have found most grain containing baby foods have an abundance of cadmium. Although
decreasing cadmium in grains will lower dietary exposure the problem is exacerbated by attempts to increase
iron and zinc micronutrients. Efforts aimed to address population-level micronutrient deficiency inadvertently
cause elevated toxic metals such as cadmium. A simple solution to avoid metal toxicity is to breed plants with
selective uptake of beneficial micronutrients without the concomitant uptake of toxic heavy metals. Since little
is known about the grain loading processes of cadmium, it is imperative to understand the dynamics of
cadmium movement to grains, and how cadmium uptake interacts or interferes with zinc distribution within
plants. Dietary exposure to cadmium depends not only on the concentration of cadmium in the food but also on
the bioavailable fraction of cadmium from the food. Previous studies have only examined bioavailability of
cadmium in foods, without assessing how micronutrients affect cadmium bioavailability. Therefore, our long-
term goal is to achieve biofortification of essential micronutrients such as zinc without the commensurate
increase in the concentration of contaminants such as cadmium. Our overall goal for this study is to determine
how zinc alters cadmium transport, accumulation and bioavailability in wheat. The specific aims proposed to
attain our overall goal are 1) To define translocation and accumulation of cadmium from root to shoot to seed
in wheat and 2) To determine the mechanism by which addition of zinc to the soil alters cadmium
bioavailability. We will determine the relationship between cadmium accumulation and bioaccessibility in
response to zinc treatment, for which data do not exist. This new knowledge will include genes that can be
studied in greater detail to characterize the localization and complexation of cadmium and zinc in the grains.
The proposed research will have a strong positive impact because we will generate knowledge needed
to enhance the nutritional quality of major cereal crops while limiting bioavailability of toxic metals
such as cadmium that threatens human health especially children.
