Location: Hard Winter Wheat Genetics Research
Project Number: 3020-21000-012-029-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2026
End Date: May 31, 2027
Objective:
The objective of this project is to characterize the dynamics of cadmium (Cd) and zinc (Zn) movement to wheat seeds during plant development, in order to understand how cadmium uptake interacts or interferes with zinc distribution within wheat plants. Our overall objective for this study is to determine how zinc alters cadmium transport, accumulation and bioavailability in wheat. Our central hypothesis is that cadmium transport, accumulation and bioavailability are influenced by zinc concentration in the soil and plant. The rationale for this project is that elucidation of the underlying differences in metal transport, sequestration and bioavailability will enable breeding of more nutritious and safer food crops. Cadmium is a naturally occurring toxic metal in North American agricultural soils that threatens human health by causing renal failure, bone disease and cancer. Cadmium in grain-based baby foods is a particular concern. Although decreasing cadmium in grains will lower dietary exposure, the problem is exacerbated by attempts to increase beneficial iron and zinc micronutrients in grain through breeding. Efforts aimed at addressing population-level micronutrient iron and zinc deficiency may inadvertently cause elevated toxic metals such as cadmium. There is a critical need to reduce cadmium accumulation in staple foods, such as wheat, while increasing nutrient density. A desirable solution to avoid metal toxicity would be to breed plants with selective uptake of beneficial micronutrients without the concomitant uptake of toxic heavy metals. The grain loading processes of cadmium are not well understood, and this understanding is imperative to simultaneously improve iron and zinc and limit cadmium through wheat variety development efforts.
Approach:
A high-cadmium cultivar (Wesley) and a low-cadmium cultivar (Panhandle) of hard red winter wheat will be grown in hydroponics either with or without Cd (1 uM, and 0 uM) and additionally with or without Zn fertilization (5 uM and 2 uM respectively). The plants will be harvested during vegetative growth, at anthesis, 2 weeks after anthesis (WAA), and 4WAA, to assess the dynamics of Cd and Zn accumulation in different tissues. The harvested plants will be separated into root, stem, lower leaves, flag leaf, rachis, spikelet and grain. We will have 6 replicates for each of treatment condition and the treatments will be assigned randomly to the pots. The tissues will be dried and digested using nitric acid/hydrogen peroxide using stepwise heating at 100, 125, 150, and 165 C to dryness, and then resuspended in 5 mL 2% nitric acid. Cd, Zn, and other mineral concentrations will be quantified using ICP-OES in the different tissues collected at different time points over the course of the life cycle.
The experiments will reveal mechanistic differences between the high and the low near-isogenic sibling-pair lines. Our expectation is that the partitioning experiments will help us identify the effect of Zn fertilization on translocation and accumulation of Cd from root to shoot to seed and the differences in high and low Cd lines. We will assess the difference in xylem loading and grain loading processes between the high and low-Cd lines.
The cooperator will grow, treat, and collect, and digest tissue samples that will be sent to an external cooperator for mineral quantification by ICP-OES. There will be a total of 1800 digested tissue samples. The cooperator will analyze and summarize the resulting data.