Growth and Physiological Responses of Catharanthus roseus (L.) Shoot Cultures to Salinity Stress

In vitro shoots of the Catharanthus roseus L. CVS. Rosea (pink flowered) and Alba (white flowered) were subjected to salinity stresses using different NaCl levels (0 to 100 mM) in a shoot proliferating medium composed of the Murashige and Skoog (MS) basal medium supplemented with 2 mu g alycine, 1 me L-1 kinetin and 30 g L-1 sucrose. The cultivar Rosea was the more tolerant cultivar. As the level of NaCl increased, there were corresponding linear increases in the levels of total phenol, proline and sugar, while the leaf chlorophyll content showed a marked decline. The foliar mineral contents showed distinct patterns between the salinity tolerant and susceptible cultivars. The level of Na+ increased in the foliar tissue with increases in NaCl, while K+ showed a slow decrease. The trends of lipid per oxidation and antioxidative enzymes activity are completely disparate. The foliar malondialdehyde (MDA) content was lowered (2-2.5 fold) and antioxidative enzymes activity (superoxide dismutase, catalase and peroxidase) were significantly higher in the tolerant cultivar than that of salinity susceptible foliar tissue. Increased antioxidative enzymes activity in Rosea cultivar can contribute to reduce the damaging effects of salinity stress via preventing oxidative injury of membrane. The results of this study on shoot cultures suggest that C. roseus (L.) cv. Rosea may be considered as stress tolerant, candidate cultivar for future breeding and cultivated at commercial level to meet the ever increasing demand of medicine., as well as the pharmaceutical industries of northern India.