This award will support collaborative research between Dr. Paul Hasegawa, Department of Horticulture, Purdue University, and Drs. T. J. Flowers and A. R. Yeo, School of Biological Sciences, University of Sussex, England. The objective of the proposed project is to study the response of the plasma membrane and tonoplast ATPase to salt stress. Salinity is a major factor limiting agricultural production, since it reduces yields in land under cultivation. Salt tolerance in plants involves the integration of mechanisms at all levels of cytological and anatomical organization. Mechanisms of critical importance are those which function to regulate the rate of ion accumulation and mediate the effects of high ion accumulation, yet promote sufficient solute uptake for osmotic adjustment necessary for growth in the new osmotic environment. It is reasonable to envisage that the plasma membrane and the tonoplast have central roles in regulated solute accumulation and compartmentation. However, experimental results have not defined the physi- ological or biochemical roles of the plasma membrane and tonoplast in plasma membrane. This project will focus on the plasma membrane and tonoplast H+ - translocating ATPases because of their central roles in the generation of the H+ electrochemical gradient across the respective membranes, which mediates facilitated transmembrane solute import into the cell. The objective of this project is to provide evidence regarding the significance of these H+ - pumps in the regulation of solute import into the plant during regimes of salt imposition. This project will benefit from the complementary expertise of the US and British investigators in molecular biology and physiology of salt stress. The results of this research may have important economic implications for agriculture.
