Figure 7.

The los2 Arabidopsis Enolase Mutant Shows a Salinity-Dependent Reduction in Enolase Abundance at the Tonoplast and a Salinity-Dependent Reduction in Aldolase Stimulation of V-ATPase Hydrolytic Activity and Is Salt Sensitive.

(A) Immunodetection of enolase, aldolase, and VHA subunits in tonoplast (left) and enolase and aldolase in total protein fractions (right), isolated from wild-type (Col-0) and los2 Arabidopsis plants grown in the absence (C) or presence (S) of 75 mM NaCl for 4 d as indicated. Blots are representative of three independent experiments.

(B) V-ATPase hydrolytic activity in the presence or absence of 0.03 units of aldolase was estimated by spectrophotometric measurement of inorganic phosphate release as described in Methods. Activity was measured in tonoplast vesicles (15 ug protein) isolated from wild-type (Col-0) or los2 plants grown in the absence (black bars) or presence (thatched bars) of 75 mM NaCl for 4 d. Data represent means ± se of three replicate experiments.

(C) Response of wild-type (Col-0) and los2 plants to salinity. Plants were grown in the absence (top) or presence (bottom) of 75 mM NaCl for 4 d. Visual phenotype of leaves is shown with noticeable wilting and chlorotic lesions on the mutant plant.