Stigmasterol alleviates the impacts of drought in flax and improves oil yield via modulating efficient antioxidant and ROS homeostasis

The present study aimed at alleviating the impacts of drought on flax growth, antioxidants and ROS homeostasis by stigmasterol. Seeds were soaked in water or stigmasterol and sown in plastic pots. On the 24th day after sowing (DAS), water regime was applied and samples were harvested up to the 56th DAS for measuring growth parameters, free radicles, antioxidants, and POD and Rubisco quantification. At seed maturity, yield analysis measurements (capsules, seeds, oil yield and fatty acid composition) were performed. Drought provoked significant decreases in growth parameters, ascorbic acid and glutathione but elevated lipid peroxidation and H2O2 concurrently with significant inhibition in the activities of catalase, guiacol peroxidase, ascorbic peroxidase and glutathione reductase as well as activity and quantification of peroxidase and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). Yield analysis demonstrated decreases in capsule and seed numbers, the oil and fatty acid contents and the fatty acid composition. Nevertheless, stigmasterol mitigated the drastic effects of drought on growth parameters, antioxidants and Rubisco and rendered the contents of lipid peroxides and H2O2 comparable to control. In the meantime, oil yield and fatty acid composition were improved in synchronization with the efficiency of antioxidants and ROS homeostasis. These findings conclude that drought resulted in a state of stress in flax; however, stigmasterol alleviated these drastic impacts and improved oil yield and fatty acid composition via modulating efficient antioxidant capacity and ROS homeostasis.