Abstract:Role of abscisic acid(ABA) in the induction of freezing tolerance in Acacia mearnsii suspension-cultured cells was studied, which mainly concerned the concentration of exogenous ABA added into medium, the time course for the induction of freezing tolerance,induction of increase in soluble proteins and inhibitory effects of cycloheximide on development of freezing tolerance.The results indicated that Acacia mearnsii suspension-cultured cells could be hardened for 8 days at 25℃ by adding ABA into MS medium. Cells treated with ABA (10mg/L) attained a survival of 83.6% at-6℃, while the survival of the nonhardened(control) was 0.In comparision,the cells treated with ABA increased 5.5 fold more soluble proteins.The biosynthesis of soluble proteins was inhibited by cyclohexomide,and the development of freezing tolerance induced by cold acclimation and ABA was simultaneously prevented.