Cytochemical localisation of adenosine triphosphatase activity in salt glands of Sporobolus virginicus (L.) Kunth

The ultracytochemical localisation of adenosine triphosphatase activity in the bicellular salt glands of the halophytic grass, Sporobolus virginicus ( L.) Kunth, was investigated using a modified lead precipitation technique. Electron dense lead deposits in the cells, following the lead phosphate pre cipitation, suggested the localisation of membrane proton pumps and/or memb rane associated soluble phosphatase. Staining was prominent in the plasma m embrane of the basal cell, especially in the suberised neck-like protrusion , and in the plasmodesmata. Staining was less prominent along the plasma me mbrane invaginations, at the common wall between basal and cap cells. and a long the partitioning membranes lining the channels within the basal cell. The plasma membrane of the cap cell exhibited weak staining. Control tissue , incubated in the absence of ATP, exhibited no staining. Evidence suggests that ion loading into the basal cell and unloading from the cap cell are a ctive processes.