One of the most important events that have impact on plant growth, development, and productivity is the distribution of photosynthetic products, usually sugar molecules, throughout the organs of the plant. The distribution depends on regulating sugar transport across the plasma membrane of plant cells. It has been speculated that this process involves carrier molecules, however, very little is known about the carrier molecules themselves. Recently, Drs. Grimes and Hitz and their collaborators have identified and cloned a plasma membrane protein that appears to possess all the right characteristics to be a sucrose transporter. In this project, Drs. Grimes and Hitz will further characterize the nature and role of this protein, called 62 SBP, using various approaches including membrane physiology, protein analysis, genetic engineering and immunology. They will also collaborate with a group in Germany who has identified another membrane protein that appears to play a role in sucrose transport. It is generally believed that sucrose transport system is complex, consisting of several components. Therefore, this collaboration is likely to enhance the opportunity to advance our understanding of the sucrose transport process in higher plants. The primary experimental system for this project is soybean cotyledon as virtually all of the cells in the soybean cotyledon are actively transporting sucrose. Successful completion of this project will provide a tool to further studies of the mechanisms by which plants distribute their photosynthetic products, which will ultimately contribute to our understanding of the mechanisms of growth and development in plants.
