This compartment includes not only
the large vacuole but also the Golgi apparatus and intermediary
vesicles, in which the toxic effects of increased sodium accumulation
may occur at specific sub-compartments and not necessarily
in the large central vacuole. It has been speculated that the
potassium dependency of some membrane assembly and secretory
functions may provide targets for sodium toxicity in the vacuole
compartment [17]. In addition, the results of this study show that
expression of nhaA results in salt sensitivity in rice, which is similar
to those effects described in yeast. A strategy to target a
heterologous sodium transporter only to the plasma membrane
could potentially lead to the compartmentalization of sodium
solely into the vacuole in a salt sensitive crop such as rice.