Effect of Relatively High Concentrations of Mannitol and Sodium Chloride on Regeneration and Gene Expression of Stress Tolerant (alhagi Graecorum) and Stress Sensitive (lycopersicon Esculentum L.) Plant Species

Regeneration and gene expression of salt/drought stress tolerant Alhagi graecrum and stress sensitive Lycopersicon esculentum under different concentrations of NaCl and mannitol were studied. Mannitol and NaCl applied at concentrations of 86, 172, 256 and 43, 86, 172 mM, respectively, in a shoot regeneration medium, caused similar water potentials. In L. esculentum, regeneration was influenced negatively by NaCl. Indirect regeneration pathway was chosen for it is more sensitive to stress than that of the direct one. Growth adaptation of calli under salt the stress by gradual increase in NaCl concentration improves the regeneration capacity of stress tolerant species under high concentration of NaCl. Under stress conditions, water content in calli decreased. The decrease in stress sensitive species was higher than that of the stress tolerant species. Free amino acids and proline contents as well as relative peroxidase activity increased under stress conditions. These values in stress tolerant species were higher than those of stress sensitive species. Studying native PAGE indicated that protein expression in stress tolerant plant species was more stable than that of stress sensitive plant species. In addition, while SDS PAGE profile under salt stress was the same as the profile under drought stress in A. graecorum, expression of different polypeptides were detected in L. esculentum. In A. graecorum, glutamate oxaloacetate transaminase showed extra isoenzyme forms under stress condition although malate dehyderogenase expressed extra bands in L.