Salt Stress-Induced Responses in Cucumber Callus

Growth, nutrient acquision, osmotic potential, proline accumulation and protein content of cucumber callus were studied under the influence of sodium chloride salt stress. Friable callus were transferred to Murashige and Skoog (MS) solid media containing 2 mg. L -1 BA and 0.2 mg L -1 NAA. Salinity was induced by incorporating different concentrations [0.0, 25, 50, 75, and 100 mM] of sodium chloride (NaCl) to the medium. Callus growth and viability was negatively affected by salinity, where fresh and dry weight and TTC- reduction capacity declined significantly with elevated NaCl levels. NaCl-induced salinity reduced (more negative) callus cell sap osmotic potential. Total protein content declined significantly with increasing the concentration of NaCl, while more proline accumulated. Thus it is tempting to speculate that proline accumulation was due to breakdown of existing proteins rather than new synthesis. Sodium and Cl contents were increased by salinity, while the uptake of K, Ca and P were significantly reduced.