Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a key vegetable crop in Asia, but its commercial value is often reduced by premature flowering triggered by vernalization. The molecular mechanisms behind this process are not fully understood. MADS-box genes, as crucial transcriptional regulators, play vital roles in plant development, including flowering. In this study, 102 MADS-box genes were identified in Chinese cabbage through bioinformatics analyses, covering phylogeny, chromosomal localization, and gene structure. Real-time quantitative PCR and RNA-seq data analysis revealed that the expression level of AGL27 declined as vernalization time increased. To determine BrAGL27′s functions, we obtained BrAGL27-overexpressed (OE) Arabidopsis thaliana lines that showed significantly later flowering compared with the wild type (WT). The expression levels of flowering suppressor genes AtFLC and AtTEM1 were significantly high-regulated in the BrAGL27-OE lines compared to WT plants, while the expression levels of the floral genes AtSPL15, AtSOC1, AtFT, and AtAP3 were significantly lower in the BrAGL27-overexpressed lines than in the wild type. These findings enhance understanding of MADS-box genes in vernalization and flowering regulation, offering a basis for further research on bolting resistance and flowering control in Chinese cabbage.

Bolting and flowering time are critical agronomic traits affecting the commercial value and breeding efficiency of Chinese cabbage (Brassica rapa L. ssp. pekinensis). Although vernalization is a key environmental signal promoting flowering, its regulatory mechanisms remain poorly understood in this crop. Here, we identify the flowering repressor gene BrMAF5 and its antisense long non-coding RNA BrMAF5L as negative regulators of vernalization-induced flowering. During vernalization, transcript levels of both genes showed a decreasing trend as the vernalization period extended. Functional assays in Arabidopsis thaliana demonstrated that ectopic expression of BrMAF5 or BrMAF5L significantly delayed flowering, accompanied by increased expression of floral repressors (AtFLC, AtTEM1) and reduced expression of floral activators (AtFT, AtSOC1). Moreover, protein interaction analysis revealed that BrMAF5 associates with BrACP4 and BrRAB1A, linking it to fatty acid metabolism and membrane trafficking pathways. Collectively, our results reveal a novel regulatory module in vernalization-mediated flowering. These findings pave the way for developing bolting-resistant Brassicaceae crops by identifying promising molecular targets.