Abstract: Ultrastructural localization of ATPase activity in cells of leaf Chlorenchyma of Aloe vera L. under NaCl stress with or without Si addition were investigated by electron-microscopy-cytochemical technique. The results showed that ATPase activities, indicated by the status of cerium phosphate (CePO₄) precipitated products, were mainly localized in primary pit field and tonoplast of chlorenchyma cells of aloe seedlings irrigated with Hoagland's solution, next was in plasma membrane. Treated with 100 mmol·L^-1 NaCl without added Si for 30 d, ATPase activities in primary pit field, plasma membrane and tonoplast of the cells were all significantly decreased. Nevertheless, irrigated with 100 mmol·L^-1 NaCl with 2.0 mmol·L^-1 added Si, ATPase activities in these apartments of the cell were significantly enhanced, particularly in tonoplast and primary pit field. Based on results in this study and our previous findings, we believe that differences of ATPase activity in cells of aloe leaf Chlorenchyma reflect the differences of physiological status and function of aloe leaves, regulating and/or enhancing ATPase activity is an important cyto-physiological mechanism of Si-alleviated effect on salt injury to aloe.

Key words: Aloe vera L., salt stress, silicon, leaf chlorenchyma cell, ATPase activity, ultrastructural localization