Exogenous Sucrose Protects Potato Seedlings Against Heat Stress by Enhancing the Antioxidant Defense System

To analyze the ability of exogenous sucrose application to moderate adverse effect of high-temperature stress on potato seedlings. Potato ( Solanum tuberosum L.) seedlings were pretreated with 100-mM sucrose solution for 24 h and then exposed to a heat stress treatment at 42 °C. Our results showed that exogenous sucrose enhanced the thermotolerance of potato seedlings and alleviated morphological injuries caused by heat stress. Sucrose pretreatment was found to efficiently inhibit heat stress-induced increases in electrolyte leakage in potato leaves and to reduce the accumulation of reactive oxygen species (ROS) such as superoxide radicals (O 2 •- ) and hydrogen peroxide (H 2 O 2 ) under heat stress. Sucrose treatment alone was found to significantly enhance peroxidase activity (POD), ascorbate peroxidase (APX), and endogenous sucrose content. Additionally, sucrose pretreatment was also found to help maintain higher activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), APX, and POD, and to increase the accumulation of endogenous sucrose and proline in leaves when potato seedlings were exposed to heat stress for 6 and 8 h. Our results show that sucrose can alleviate the detrimental effects of heat stress on potato seedlings by enhancing the antioxidant enzyme system and increasing sucrose and proline accumulation. Therefore, exogenous sucrose treatment may be a useful experimental tool to enable potato plants to tolerate heat that might otherwise cause plants to accumulate lethal levels of ROS.