24-Epibrassinolide regulates carbohydrate metabolism and increases polyamine content in cucumber exposed to Ca(NO3 )2 stress

Key message This study focuses on the impact of carbohydrate metabolism and endogenous polyamines levels in leaves of cucumber seedlings under salt stress by exogenous BRs.

The effects of 24-epibrassinolide (EBL) on carbohydrate metabolism and endogenous content of polyamines were investigated in cucumber seedlings (Cucumis sativus L. cv. Jinyou No. 4) exposed to salinity stress [80 mM Ca(NO₃)₂]. Spraying of exogenous EBL partially enhanced the enzyme activities of sucrose phosphate synthase, sucrose synthase and acid invertase; thus, raising the level of sucrose, fructose and total soluble sugars. The amylase activity was also increased by EBL, companied by the rising of sucrose level. These results indicated that EBL improved the carbohydrate metabolism of cucumber under Ca(NO₃)₂ stress. Moreover, EBL raised the levels of soluble conjugated and insoluble bound polyamines while lowered the free polyamines content, particularly putrescine. Our experiment demonstrated that exogenous EBL elevated stability of cellular membrane and positively improve the carbohydrate metabolism in cucumber growing under Ca(NO₃)₂ stress.