Senior Research Associate
222A Robert W. Holley Center for Agriculture and Health
Plant physiology of heavy metals and mineral nutrition
My research interests involve achieving a greater understanding of plant-metal interactions. Metals are critical factors in the normal functioning of plants but can also represent hazards to plants as well as to consumers of plants. My work has focused on the physiological processes underlying movement and retention of the potentially toxic heavy metal cadmium in durum wheat plants. Durum wheat has a tendency to accumulate cadmium in grain when it is grown in soils in which cadmium is a component. My research has revealed insights into factors that affect cadmium entry into and movement within the plant body. For example, zinc (which is chemically similar to cadmium) can compete with cadmium for entry into root cells and also can affect movement of cadmium in phloem. I have shown that an important step in reducing the amount of cadmium that accumulates in wheat grain is to inhibit movement of cadmium out of roots into shoots. This process is not controlled by sequestration of cadmium in root cell vacuoles as a complex with phytochelatins. However, it may be related to movement of cadmium out of root cells into the xylem, which constitutes the major pathway of movement from roots to shoots. Essential metals such as zinc and iron are important nutrients of plants, acting as components of enzymes and other cellular constituents. An important goal of plant nutrition research is to understand the basis of mineral nutrient acquisition and utilization. Studying the pathways of zinc and cadmium uptake and distribution has led to insights into similar processes for other metal micronutrients such as iron. I have recently become involved with an effort to understand the bioavailability of iron in maize and in human consumers of maize. There is a large inherent variation among maize varieties in the ability to store iron in grains. Studies with an in vitro human intestinal cell culture system have shown that there is a poor correlation between grain iron concentration and iron uptake into intestinal cells. It appears that some intrinsic factor(s) in the maize grain can either suppress or enhance iron uptake. Identifying and characterizing this factor is the primary goal for my research efforts.