Effects of salt treatment and osmotic stress on V-ATPase and V- XXXX in leaves of the halophyte Suaeda salsa.

@entity4338 @entity1219 @entity13977 @entity969 @entity970
The Chenopodiaceae Suaeda salsa L. was grown under different salt concentrations and under osmotic stress. The fresh weight was markedly stimulated by 0.1 M @entity1219 , 0.4 M @entity1219 and 0.1 M @entity4338 and reduced by osmotic stress ( @entity970 iso-osmotic to 0.1 M @entity1219 ). Treatment with 0.4 M @entity4338 severely damaged the plants. Membrane vesicle fractions containing tonoplast vesicles were isolated by @entity969 gradient from leaves of the S. salsa plants and modulations of V-ATPase and V- @entity13977 depending on the growth conditions were determined. Western blot analysis revealed that V-ATPase of S. salsa consists of at least nine subunits (apparent molecular masses 66, 55, 52, 48, 36, 35, 29, 18, and 16 kDa). This polypeptide pattern did not depend on culture conditions. V- @entity13977 is composed of a single polypeptide (69 kDa). An additional polypeptide (54 kDa) was detected in the fractions of @entity1219 -, @entity4338 - and @entity970 -treated plants. It turned out that the main strategy of salt-tolerance of S. salsa seems to be an up-regulation of V-ATPase activity, which is required to energize the tonoplast for ion uptake into the vacuole, while V- @entity13977 plays only a minor role. The increase in V-ATPase activity is not obtained by structural changes of the enzyme, but by an increase in V-ATPase protein amount.
