COMPARATIVE RESPONSES OF TWO TRIGONELLA SPECIES TO SALINITY AND DROUGHT STRESSES IN VITRO

Effects of salinity and drought on growth, contents of proline, malondialdehyde (MDA), protein and activity of antioxidative enzymes were studied in two Trigonella species. Seeds and explants of T. foenum-graecum and T. aphanoneura were grown on Murashige and Skoog medium (MS) complemented with iso-osmotic concentrations of NaCl (0, 100, 150 mM) and mannitol (0, 180, 275 mM). Growth and relative water content (RWC) of seedlings and calli decreased by increasing of salinity and drought in both species. In contrast to that of calli, proline and protein contents increased in seedlings of both species under both stresses. The increase of proline content in seedlings of T. aphanoneura was higher than that of T. foenumgraecum under NaCl stress. MDA content in seedlings of T. aphanoneura was higher than that of T. foenum-graecum and increased in both species under salinity. Among antioxidative enzymes, catalase (CAT) activity increased continuously in seedlings of T. aphanoneura comparing to that of T. foenum-graecum. Similar increasing trends were obtained regarding CAT activities in calli of both species under both stresses. Increase in activities of SOD, CAT and POX was observed in calli of both species under stress. It seems that undifferentiated calli respond more regularly to both stresses. Finally, higher proline content and lower amount of MDA could be considered as criteria for higher tolerance of T. foenum-graecum seedlings against osmotic stresses.