Development of Callus Cultures of Eggplant Solanum melongena L. Cultivars and Their Response to NaCl Stress | Получаване на калусни култури от сортове патладжан Solanum melongena L. и техния отговор на солеви стрес

Plant productivity is strongly influenced by abiotic stress conditions induced by salt. Knowledge of salt tolerance in vegetable plants is necessary to increase productivity and profitability of crops irrigated with saline wastewaters. Eggplant Solanum melongena L. is moderately sensitive to salinity. The objective of the present work was to investigate the response of some eggplant cultivars to increasing salinity during the callus induction. Calli were obtained from cotyledon and hypocotyl explants of Solanum melongena L. cvs China-A2, Larga Negra and Black Beauty. For callus induction Murashige and Skoog MS nutrient medium was supplemented with different concentrations of auxin and cytokinin combination. The best callusing was obtained from cotyledon and hypocotil explants cultured on MS medium containing 2.0 mg/l ?-naphthaleneacetic acid NAA + 0.5 mg/l kinetin Kin. NaCl was added into the callus induction media in concentration of 50 mM, 100 mM, 150 mM and 200 mM for simulation of salinity. Its effect on the process of callusogenesis was studied. Callus growth was not influenced by concentrations of 50 mM and was slightly at 100 mM NaCl. Medium concentration 150 mM inhibited the callus growth. Higher concentration of 200 mM NaCl was lethal for callus formation. Some biochemical indices were also used which characterize the callus tolerance to salt stress. Our results demonstrated increased peroxidase activity, higher accumulation of malondialdehyde MDA, hydrogen peroxide H2O2 and proline of eggplant calli treated with NaCl, compared with untreated control. In salted medium cv. Black Beauty produced smaller callus quantity and accumulated higher MDA, H2O2 and proline than cvs China-A2 and Larga Negra. The present results demonstrated that the response of cultured eggplant calli to salt stress was clearly genotype specific. Concentration of 100 mM NaCl could be appropriate in salt tolerance selection in vitro of this crop.