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CBF transcription factors (TFs) are key regulators of plant stress tolerance and play an integral role in plant tolerance to adverse growth environments. However, in the current research situation, there are few reports on the response of the CBF gene to Begonia stress. Therefore, this experiment investigated a novel CBF TF gene, named <i>MbCBF2</i>, which was isolated from <i>M. baccata</i> seedlings. According to the subcellular localization results, the MbCBF2 protein was located in the nucleus. In addition, the expression level of <i>MbCBF2</i> was higher in new leaves and roots under low-temperature and high-salt induction. After the introduction of <i>MbCBF2</i> into <i>Arabidopsis thaliana</i>, the adaptability of transgenic <i>A</i><i>. thaliana</i> to cold and high-salt environments was significantly enhanced. In addition, the high expression of <i>MbCBF2</i> can also change many physiological indicators in transgenic <i>A</i><i>. thaliana</i>, such as increased chlorophyll and proline content, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity, and reduced malondialdehyde (MDA) content. Therefore, it can be seen from the above results that <i>MbCBF2</i> can positively regulate the response of <i>A</i><i>. thaliana</i> to low-temperature and osmotic stress. In addition, <i>MbCBF2</i> can also regulate the expression of its downstream genes in transgenic lines. It can not only positively regulate the expression of the downstream key genes <i>AtCOR15a</i>, <i>AtERD10</i>, <i>AtRD29a/b</i> and <i>AtCOR6.6/47</i>, related to cold stress at low temperatures, but can also positively regulate the expression of the downstream key genes <i>AtNCED3</i>, <i>AtCAT1</i>, <i>AtP5CS</i>, <i>AtPIF1/4</i> and <i>AtSnRK2.4</i>, related to salt stress. That is, the overexpression of the <i>MbCBF2</i> gene further improved the adaptability and tolerance of transgenic plants to low-temperature and high-salt environments.