Effects of Exogenous Salicylic Acid on Antioxidant Enzymes and CBF Transcription Factor in Apricot(Prunus armeniaca L.) Flowers under Chilling Stress

In order to explore the mechanism of exogenous salicylic acid(SA) induced chilling resistance of apricot flowers, the twigs with flower-buds of apricot plant(Prunus armeniaca L. cv. ‘Luotuohuang') were selected as experimental materials. The levels of MDA, antioxidant enzymes and the expression of CBF gene were investigated in apricot fl owers during –2 ℃ chilling stress with pretreated with H 2 O, 0.1 mmol·L-1 SA and SA inhibitors(ABT and PAC), respectively. The results showed that pretreatments with H 2 O, ABT and PAC decreased the activities of superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT), and increased the MDA content during chilling stress. In contrast, 0.1 mmol·L-1 SA pretreatment enabled apricot flowers to maintain higher activities of these three enzymes and a lower level of MDA to weaken oxidative injury induced by chilling temperature. The real-time RT-PCR analysis indicated that the expression of CBF gene could be induced by SA and the level of CBF was much higher than that in pretreatments with H 2 O, ABT and PAC, especially under chilling stress for 3 h. However, the CBF expression induced by SA was weakened with the chilling time prolonging. Taken together, it was considered that the suitable exogenous SA(0.1 mmol·L-1) enhanced chilling tolerance in apricot flower maybe through induction of CBF transcription factor and activations of antioxidative capacity, such as, POD, POD and CAT.