Recent studies have shown that the R2 R3-MYB transcription factor Md MYB73 is involved in salt stress response in apple. However,no research was done whether Md MYB73 mediated cold tolerance in apple or not. In this study,we found that the expression of Md MYB73 was obviously induced by cold stress. Functional analysis showed that Md MYB73 significantly increased cold tolerance in transgenic apple calli and Arabidopsis. Quantitative real-time PCR(q RT-PCR) assay indicated that the expression levels of cold-responsive genes including Md CBF2,Md CBF3,Md CBF4,and Md CBF5 were obviously enhanced in Md MYB73 transgenic calli,suggesting that Md MYB73 increased cold tolerance via C-repeat binding factor(CBF) cold response pathway. Finally,we found that soluble sugar,which provides an osmoticum for cells,was increased in Md MYB73 transgenic calli compared to that in the wild type control. These findings provide a new insights into how Md MYB73 is involved in cold stress response. In this study, we found that the expression of Md MYB73 is involved in salt stress response in apple. However, no research was done whether Md MYB73 mediated cold tolerance in apple or not. Md MYB73 was obviously induced by cold stress. Functional analysis showed that Md MYB73 significantly increased cold tolerance in transgenic apple calli and Arabidopsis. Quantitative real-time PCR (q RT-PCR) assay indicated that the expression levels of cold-responsive genes including Md These found that soluble sugar, CBF2, Md CBF3, Md CBF4, and Md CBF5 were significantly enhanced in Md MYB73 transgenic calli, suggesting that Md MYB73 increased cold tolerance via C-repeat binding factor (CBF) cold response pathway. an osmoticum for cells, was increased in Md MYB73 transgenic calli compared to that in the wild type control. These findings provide a new insights into how Md MYB73 is involved in cold stress response.