9522043 Wang This project proposes to apply a new technology, designated "optical trapping," to study the initial events in a soybean root cell upon binding of symbiotic bacteria, Bradyrhizobium japonicum. The "optical trap" employs a focused beam of laser light to trap a micron-sized particle(s) within the focal plane. The use of the optical trap will allow B. japonicum cells to be moved to the surface of a soybean cell to study the effects of their adhesion on a single soybean cell in a defined region of the root, and with a clear definition of the time of binding. Time-dependent changes in membrane potential, pH, calcium fluxes, and cytoskeletal organization will be monitored. The B. japonicum - soybean cell interaction is an example of the binding of a biologically significant ligand (the B. japonicum cell) to a target (soybean cell), and a systematic description of the structural and physiological dynamics of the plant cell upon ligand binding in this system may offer insights on the analysis of other receptor-ligand and/or cell adhesion systems. ***
