Salicylic acid alleviates cold-induced photosynthesis inhibition and oxidative stress in Jasminum sambac

Salicylic acid (SA) is a signal molecule that mediates many biotic and abiotic stress-induced physiological responses in plants. In the current study the protective effects of SA on cold stress-caused oxidative damage and photosynthesis inhibition in jasmine plants (Jasminum sambac) were examined. Jasmine seedlings were pretreated with 100 μM SA for 3 days and then subjected to cold stress (4 °C) for 15 days. The amounts of superoxide radicals (O2-) and hydrogen peroxide (H2O2) significantly increased in leaves of plants exposed to cold stress and resulted in oxidative damage, indicated by an increase in malondialdehyde accumulation and membrane leakage. The total chlorophyll content, stomatal conductance (gs), photochemical efficiency (Fv/Fm), and net photosynthesis rate (Pn) were significantly reduced in response to the cold treatment. However, plants pretreated with exogenous SA (100 μM) exhibited significantly higher photosynthesis-related parameters and antioxidant enzyme activities (peroxidase and catalase) and lower reactive oxygen species levels compared with the cold control. It was therefore concluded that SA could alleviate the cold treatment-caused oxidative stress and photosynthesis decline by enhancing the activities of antioxidant enzymes in leaves of jasmine.