Effect Of Ca～(2+) And NaCl Treatment On Tonoplast V-ATPase And Ca～(2+)-ATPase Activities In Seedlings Of Suaeda Salsa Han Ning(College Of Life Science, Shandong Normal University)

Calcium is one of the three major nutrient elements in plants, which plays an important role in alleviation of salt toxicity. Disturbance of the cell Ca2+ homeostasis may be the primary response to a variety of salt treatments. In present study salt dilution halophyte S. salsa treated with Ca"+ and Na+ was used to examine some physiological parameters and activites of tonoplast H+-ATPase and Ca2+-ATPase and Western blotting results of H+-ATPase was analysed. The results were shown as follows:1. Effect of Ca2+ and Na+ treatment on growth of S. salsa seedlingsEffect of salinity on the growth of S. salsa seedlings depended on Ca2" concentration in the root medium. The fresh and dry weight of shoots, roots and the whole plants were increased by increasing Ca2+ concentration in the external medium. Except for Ca2+ deficiency in root medium, the dry weight of shoots, roots and the whole plants was greatly increased by NaCl.The root/shoot ratio of 5. salsa was distinctively different from that of nonhalophytes under NaCl treatments. On the base of fresh weight, the root/shoot ratio was decreased rather than increased by NaCl treatments. Whatsmore the root/shoot ratio was decreased with the increasing of Na+ concentration at any Ca2+ concentration in the root medium. There was no difference in root/shoot ratio between control and NaCl treated plants on base of dry weight.2. Effect of Ca2+ and Na+ treatment on the concentrations of K+, Na+ and Ca2+ in leaf cell sap of 5. salsaIn cell sap of the leaves K+ and Ca2+ concentrations were gradually decreased with the increasing of NaCl concentration .On the contrary, the Na+ concentration was increased with the increasing of NaCl concentration. When plants were exposed to 0 mmol/L Ca2+ the concentrations of K+ and Ca2+ were dropped abruptly (P<0.05) but Na+ was increased accordingly.3. Effect of Ca2* and Na+ treatment on plasmalemma permeability and proline content in S. salsa seedlingsWhether Ca2+ was present or absent in the root medium, plasmalemma permeability did not change significantly under control. But plasmalemma permeability wasincreased with increasing concentration of NaCl. As a osmotic regulation solute, the proline content was increased with increasing NaCl and Ca + concentrations, which is useful in reducing the osmotic potential of cytoplasm balancing the decrement of osmotic potential in vacuole. 4. Effect of Ca2+ and Na+ treatment on the activities of V-ATPase and V-Ca2+~ATPaseThe activity of V-ATPase from S. salsa was markedly affected by Ca2+ and NaCl treatments. The activity of V-ATPase in the leaves was stimulated by Na+ when the plants were grown in high Ca2+ concentration (20 mmol/L). When the plants were grown under the deficiency of Ca2+, the activity of V-ATPase was not affected by NaCl treatmentsTo the activity of V-Ca2+-ATPase, whether Ca2+ was present or absent in the root medium, the activity of V-Ca'+-ATPase did not changed with increasing NaCl concentration. Under 20 mmol/L Ca2+ concentration condition, the level of activity of Ca2+-ATPase higher than that of Ca2+ deficiency .5.Effect of Ca2+ and Na+ treatment on the expression of subunit of V-ATPase in tonoplast vesicles prepared from leaves of S. salsaThe Western-blotting analysis of V-ATPase in tonoplast vesicles prepared from the leaves of 5. salsa showed that under the condition of non-salinity the subunits of A., B, D and c of V-ATPase were highly expressed. But the subunit expression had no difference under the NaCl treatment when Ca2+ was absent and increased with increasing concentration NaCl when Ca2+ was present.In conclusion, 5. salsa, a salt-dilution type halophyte, need Ca2+ for salt-tolerant or else the growth will markedly be decreased under the high salinity. And on the other hand, activites of V-ATPase and V-Ca +-ATPase in tonoplast are also influnced by Ca2+ and NaCl concentration in the root medium, which suggests Ca2+ nutrition also plays an important role in the salt tolerance of the halophytes.