Mechanism Of Salt Accumulation Into The Vacuole In Arabidopsis Cell Under High Salt Condition : Possible Role Of Vesicle Transport.

Abstract

High salinity restricts the growth of most higher plants. Vacuolar compartmentation constitutes a major cellular strategy for salt tolerance. During salt accumulation, we have previously observed a rapid increase of vacuolar volume without an increase in cell size in barley and Arabidopsis root cells and mangrove suspension cultured cells.
In the present study, we analyzed the behavior of membrane vesicles and vacuoles in Arabidopsis under high salt condition. Upon treatment with NaCl, a rapid increase in the vacuolar volume in Arabidopsis root cells and suspension cultured cells was observed. Experiments involving GFP-AtVam3 suspension cultured cells revealed an active movement of small vesicles around the main vacuole due to salt treatment. Furthermore, using the fluorescence Na+ indicator (Sodium Green), Na+ accumulation in the vesicles and vacuole was apparent. The immunostaining of suspension cultured cells with antibodies against AtNHX1 showed the vesicle-like fluorescence in the cytoplasm under salt treatment. Data support the involvement of vesicle transport in vacuolar Na+ accumulation.