Cabbage (Brassica oleracea) is one of the most important vegetable crops worldwide. qRT-PCR is a sensitive technique for gene expression studies and choosing the appropriate reference gene is essential to obtain reliable results. In the present work, 22 candidate reference genes were evaluated under various experimental conditions, including NaCl, drought stress treatment, temperature treatments (cold and heat) and a set of hormones stress (6-BA, NAA, and ABA) treatments, across a range of tissue types and cultivars. Gene expression data taken from 45 cabbage samples was analyzed using two algorithms, geNorm and NormFinder. Suitable combinations of reference genes for qRT-PCR normalization should be applied according to different experimental conditions. In this study, the genes EF1a, GAPC2 and SAND were verified as the suitable reference genes across all tested samples. Additionally, each experimental condition had a unique set of reference genes best suited to samples within the particular condition. To validate the suitability of the candidate reference genes, the gene expression of WSD1, a gene that may be involved in biosynthesis pathway of wax esters in cabbage, was measured across all 45 samples and normalized using the three best reference gene candidates. WSD1 displayed variation in gene expression across different tissues and cultivars, and exhibited diverse up- or down- regulated expression patterns under various treatments, which indicate that BoWSD1 may play an important role in the response to abiotic stresses in cabbage. Our results provide the foundation for gene expression analysis in Brassica oleracea and other species of Brassica vegetables.

卷心菜（甘蓝）是世界上最重要的蔬菜作物之一。qRT-PCR是用于基因表达研究的敏感技术，选择合适的参考基因对于获得可靠的结果至关重要。在目前的工作中，在不同的实验条件下评估了22个候选参考基因，这些条件包括NaCl，干旱胁迫处理，温度处理（冷热）和一组激素胁迫（6-BA，NAA和ABA）处理。组织类型和品种的范围。使用geNorm和NormFinder这两种算法分析了从45个卷心菜样品中获得的基因表达数据。用于qRT-PCR标准化的参考基因的适当组合应根据不同的实验条件应用。在这项研究中，基因EF1a在所有测试样品中，GAPC2和SAND被确认为合适的参考基因。另外，每个实验条件都有一组最适合特定条件下样品的参考基因。为了验证候选参考基因的适用性，在全部45个样品中测量了WSD1的基因表达，该基因可能与白菜中蜡酯的生物合成途径有关，并使用三个最佳参考基因候选者对其进行了标准化。WSD1在不同组织和品种中的基因表达均表现出差异，并且在各种处理下均表现出多种上调或下调的表达模式，这表明BoWSD1可能在甘蓝对非生物胁迫的响应中起重要作用。我们的结果为甘蓝和其他芸苔属蔬菜中的基因表达分析提供了基础。