Abstract
The effect of different concentrations of NaCl (100, 150, and 200 mM) on cell membrane stability, photosynthetic pigment and
carbohydrate contents, antioxidant enzymes activities, glutathione contents, and lipid peroxidation (malondialdehyde content) in faba
bean (Vicia faba) leaves were investigated. In addition, the role of stigmasterol, a promising plant development regulatory substance
in increasing tolerance to salt stress was evaluated. The results revealed that salt-stressed bean plants treated with stigmasterol had an
increased membrane stability index, and photosynthetic pigment and carbohydrate contents compared with salt-stressed plants
untreated with stigmasterol. The level of antioxidant system components (catalase, ascorbic acid peroxidase, and reduced
glutathione) increased in response to stigmasterol treatment. Enhanced antioxidant activities helped to decrease oxidative damage
from salt and develop tolerance against salt stress in stigmasterol-treated faba bean plants. An increase in the degree of salt tolerance
induced by stigmasterol was indicated by the improvement of the membrane stability index, photosynthetic activity and consequently
the carbohydrate pool. The data provided evidence that stigmasterol treatment reduced the adverse effects of salt stress on faba bean
plants, and might play a key role in providing stress tolerance by stimulation of the antioxidant system as a stress protection
mechanism.