Salicylic Acid Regulates Sugar Metabolism that Confers Freezing Tolerance in Magnolia wufengensis During Natural Cold Acclimation

To improving the understand of the accumulation pattern of soluble sugars in Magnolia wufengensis during natural cold acclimation, the dynamics of freezing tolerance, the content of various soluble sugars in the shoots of M. wufengensis seedlings treated with salicylic acid, and the correlation between them were analyzed from September 2017 to March 2018. Salicylic acid advanced the natural cold acclimation and ultimately enhanced mid-winter hardiness by promoting the accumulation of total soluble sugars. Improved freezing tolerance highly correlated with enhanced glucose, fructose, and raffinose accumulation. The enhanced accumulation of these sugars by elevated amylase, sucrose synthase, and sucrose-P-synthase activities may contribute to advanced natural cold acclimation.