Study of the involvement of osmotic adjustment and H+-ATPase activity in the resistance of Catharanthus roseus suspension cells to salt stress

Abstract

The salt-induced H+-ATPase activity and osmotic adjustment responses of Catharanthus roseus (L.) G. Don suspension cultures were studied. Cells were treated with 0, 50 or 100mM NaCl for 7days or were maintained for 8 months with 50 mM NaCl (50T cells). Growth, osmotic potential (Ψπ), ions content, soluble sugars, proline and total amino acids were determined in the sap of control and salt-treated cells. Salinity reduced cell growth and Ψπ. The higher decrease in the Ψπ in salt-treated cells was due to higher accumulation of Na+ and Cl−. The levels of organic solutes, such as soluble sugars, free proline and total amino acids, increased with salt treatment. These results suggest that salt-tolerant cells are able to osmotically adjust. Salinity treatments stimulated H+-ATPase activity. Immunodetection of the enzyme showed that the increased activity was due to an increased amount of protein in the plasmalemma. The induction by NaCl, especially at 100 mM NaCl and for 50T cells, could account for the K+ and Cl− uptake but not for higher or lower tolerance.