My research interests center around specialization of cells for calcium oxalate crystallization in plants. In my laboratory we intergrate a diversity of approaches, including biochemical and molecular techniques, immunological approaches, and light and electron microscopy to study plant cell structure in relation to calcium nutrition and sequestration.

During plant growth and development certain cells become specialized to serve as calcium sinks. Within the vacuoles of these cells calcium is precipitated as crystalline calcium oxalate. We believe these specialized cells are important in regulating excess environmental calcium by removing it from active plant metabolism. Crystals and crystal-forming cells occur in specific anatomical and developmental patterns, indicating that their development is biologically controlled, analagous to the formation of bones, teeth, and shells in other organisms. We are particularly interested in understanding what regulates differentiation of plant cells to accumulate and sequester calcium, in determining mechanisms that control calcium oxalate crystallization within the cell, and in defining the importance of these specialized cells in plant development and physiology.

We are presently studying specialized crystal-forming cells in grape, which produce calcium oxalate crystals with a needle-like morphology unique to plants. We developed a method to isolate crystals along with their associated intravacuolar organic matrix from grape leaves, allowing us to characterize the structural and biochemical features of the matrix. In addition, we have produced immunological probes which we can use to isolate and characterize specific proteins in the matrix and clones for the genes encoding those proteins. Our goal in these studies is to define the role of specific matrix components in crystal initiation and growth within the plant vacuole. In other research we are working with a cell culture system to determine factors that will induce calcium oxalate formation, as well as with model whole plant systems to examine calcium distribution in relation to external calcium supply.