Roles of cardiac glycosides in improving growth and productivity of salt-stressed flax plants

Abstract

Abstract Secondary metabolites of several plants, including esculin and digitoxin, which are cardiac glycosides, were previously employed for their therapeutic effects. The current study aims to investigate the functions of the main Na+ /K + transport inhibitor digitoxin and the antioxidant esculin for enhancing flax plant growth and production under salinity. Exogenous treatment with digitoxin and esculin with 50 mg L− 1 and 100 mg L− 1 were used for this work. According to results of this work, foliar spraying of esculin or digitoxin increased salinity tolerance of flax plants. The efficiency of esculin and digitoxin to sustain ion homeostasis by inhibiting Na absorption and increasing potassium, calcium, and phosphorus in flax plants may be the reason for their protective actions towards salinity. Esculin and digitoxin in particular counteract oxidative stress via increasing the activity antioxidant enzymes including superoxide dismutase, catalase, and peroxidase and penyl alanine ammonia lyase and tyrosine ammonia lyase, leadig to a decrease in reactive oxygen species and lipid peroxidation levels and electrolyte leakage. As a consequence, esculin and digitoxin increased the amount of photosynthetic pigments consequently photosynthetic osmolytes and yield quantity and quality as shown by increases in all investigated yield criteria that were examined, especially those that improved the desired oil properties. In conclusion, this study concluded that digitoxin, as opposed to esculin, was more effective in inhibiting Na build up and increasing flax salinity tolerance. The exogenous treatment of digitoxin and esculin glycosides is a novel method for enhancing salinity stress tolerance in flax plants.