Effect of salicylic acid on freezing injury in peach floral organs and the expressions of CBF genes

We used flowering branches at the budding stage of two peach cultivars Xiahui 6 and Xiacui with different cold resistance to explore the effect of exogenous salicylic acid (SA) on the freezing injury of peach floral organs and the molecular mechanism. Using water application as the negative control, the effects of spraying with SA at concentrations of 20 or 100 mg dm-3 on stigma receptivity, frost damage characteristics of floral organs, and the expressions of C-repeat-binding factor (PpCBF) gene family members were investigated at 0 °C. No significant frost damage was observed on petals in all treatments. No frost damage was seen in the ovary and style under 20 mg dm-3 SA treatment, but damage was substantial at the other two treatments. Cultivar Xiahui 6 was more susceptible to freezing than cv. Xiacui. The expression peaks of PpCBFs in the SA-pretreated floral organs occurred at 3 or 6 h after low temperature treatment, and peak time was closely related to peach cultivar, organ, and SA concentration. This indicates that appropriate concentration of exogenous SA may alleviate freezing damage to floral organs and enhance cold resistance by the regulated expression pattern of PpCBF.