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.
My teaching
responsibilities include a basic course in Plant Anatomy for graduate
and upper-division undergraduate students, and a graduate level seminar
course on special topics in Plant Cell Biology. In Plant Anatomy students
learn about the structure and organization of cells and tissues in the
plant body during primary and secondary growth. Lectures and lab exercises
relate the structure of plants to physiology, development, and evolution.
In the seminar course, current literature relating to plant cell biology
and development is discussed.
Faculty