Brassinosteroids (BR) are multifunctional plant hormones that can regulate growth and development and respond to abiotic stresses. In this study, we investigated the effect of one of brassinosteroids – 24- epibrassinolide (EBL) in alleviating of cold tolerance in winter turnip rape. The results showed that EBL pretreatment could reduce the degree of membrane damage by lipid peroxidation, alleviate ROS burst, improve the osmotic potential, stomatal conductance, photosynthetic efficiency, and antioxidant capacity of winter turnip rape under cold treatment. Compared with EBL + 4 °C treatment, EBL + LaCl₃ + 4 °C and EBL + EGTA + 4 °C treatments can significantly increase the degree of membrane lipid damage, reactive oxygen species (ROS) content, decrease the osmotic adjustment and antioxidation ability, reduce photosynthetic efficiency and stomatal conductance in winter turnip rape. RNA-Seq analysis showed that there were 116 differentially expressed genes (DEGs) in EL (EBL + 4 °C) vs. L (4 °C), including 70 up-regulated genes and 46 down-regulated genes. These DEGs play a critical role in regulating various physiological processes in plants, such as photosynthesis, osmotic regulation of biofilm systems, Ca²⁺ signal transduction, redox reactions. We selected the 10 DEGs for further qRT-PCR verification and the results were correlated with the results of RNA-sEq. In conclusion, our research demonstrates that BRs play an important role in enhancing cold tolerance of winter turnip rape. Moreover, additionally LaCl₃ and EGTA effects was studied and discussed together with EBL, the results show that Ca²⁺ signalling is involved in BRs-induced cold tolerance.

油菜素类固醇 (BR) 是一种多功能植物激素，可以调节生长发育并应对非生物胁迫。在这项研究中，我们研究了油菜素类固醇之一 - 24-表油菜素内酯 (EBL) 在减轻冬季萝卜油菜耐寒性方面的作用。结果表明，EBL预处理可以降低脂质过氧化对膜的损伤程度，减轻ROS的爆发，提高冷处理下冬萝卜油菜的渗透势、气孔导度、光合效率和抗氧化能力。与 EBL + 4 °C 处理相比，EBL + LaCl ₃ + 4 ℃和EBL + EGTA + 4 ℃处理可显着增加冬萝卜油菜膜脂损伤程度、活性氧（ROS）含量，降低渗透调节和抗氧化能力，降低光合效率和气孔导度。RNA-Seq分析显示EL（EBL + 4°C）和L（4°C）有116个差异表达基因（DEGs），包括70个上调基因和46个下调基因。这些 DEGs 在调节植物的各种生理过程中起着关键作用，例如光合作用、生物膜系统的渗透调节、Ca ²⁺信号转导，氧化还原反应。我们选择了 10 个 DEG 进行进一步的 qRT-PCR 验证，结果与 RNA-sEq 的结果相关。总之，我们的研究表明，BRs 在提高冬季萝卜油菜的耐寒性方面发挥着重要作用。此外，还与 EBL 一起研究和讨论了LaCl ₃和 EGTA 效应，结果表明 Ca ²⁺信号参与了 BRs 诱导的耐寒性。