Journal of Plant Process and Function

Drought stress is one of the limiting factors for plant growth and yield all over the world. Stevia rebaudiana from semi-humid area of Paraguay contains steviol glycosides with pharmacological properties. In the present study, the callus obtained from Stevia rebaudiana were treated with different treatments of poly ethylene glycol, paclobutrazol and gibberellin under in vitro culture and then some growth and physiological parameters were studied. The results showed that poly ethylene glycol decreased the fresh mass, dry mass, water content and relative growth rate of calluses, while paclobutrazol and gibberellin reduced the negative effects of drought stress on callus growth. Drought stress had a negative effect on membrane lipids and caused lipid peroxidation with a significant increase in malondialdehyde content. The paclobutrazol and gibberellin treatments reduced the lipid peroxidation induced by drought stress. The water soluble carbohydrates and reducing sugars contents significantly decreased in response to drought stress, while gibberellin and paclobutrazol treatments prevented the negative effects of drought stress on carbohydrates and their reduction. The carbohydrates play an important role in osmotic adjustment and stabilization of cellular structures. The Stevia calluses enhanced the antioxidant of phenols and α-tocopherol in response to poly ethylene glycol, gibberellin and paclobutrazol which reduce the adverse effects of drought-induced oxidative stress. According to the obtained results, the calluses obtained from Stevia is sensitive to drought stress and paclobutrazol and gibberellin treatments alleviated the negative effects of water deficient on them.