Salinity-induced modulation of growth and antioxidant activity in the callus cultures of miswak (Salvadora persica)

Miswak (Salvadora persica Linn.) is a medium-sized tree, desert facultative halophytic plant. Besides edible fruits and non-edible seed oil, the plant contains several bioactive compounds like alkaloids, tannins, saponins and sterols related to food and cosmetic industries. In the present study, physiological responses and antioxidant potential under salinity stress were investigated in callus cultures of S. persica to evaluate its use as a source of antioxidant. The callus cultures were grown on MS medium supplemented with 0.5 mg/l each of 2,4,5-T and BAP, which could be established successfully by regular subcultures of slow growing callus on this medium for several months. Increased dry weight, soluble proteins, proline, soluble carbohydrates and CAT activity were recorded under NaCl stress in comparison to control cultures. The DPPH and FRAP antioxidant activities were gradually elevated in NaCl-treated callus, whereas SOD quenching was recorded maximum at 200 mM. A significant correlation between antioxidant capacity and phenol content was observed, indicating that phenolic compounds are the major contributors to the antioxidant potential in S. persica. These findings suggest that increased salinity stress caused elevated antioxidant potentials and the plants grown in such conditions may serve as potential source of antioxidant.