Vernalization plays a crucial role in the flowering and yield of Chinese cabbage, a process intricately influenced by long non-coding RNAs (lncRNAs). Our research focused on lncFLC1, lncFLC2a, and lncFLC2b, which emerged as key players in this process. These lncRNAs exhibited an inverse expression pattern to the flowering repressor genes FLOWERING LOCUS C 1 (BrFLC1) and FLOWERING LOCUS C 2 (BrFLC2) during vernalization, suggesting a complex regulatory mechanism. Notably, their expression in the shoot apex and leaves was confirmed through in fluorescent in situ hybridization (FISH). Furthermore, when these lncRNAs were overexpressed in Arabidopsis, a noticeable acceleration in flowering was observed, unveiling functional similarities to Arabidopsis’s COLD ASSISTED INTRONIC NONCODING RNA (COOLAIR). This resemblance suggests a potentially conserved regulatory mechanism across species. This study not only enhances our understanding of lncRNAs in flowering regulation, but also opens up new possibilities for their application in agricultural practices.

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.

Among the Brassica species in China, including Chinese cabbage, pak-choi, caixin, zicaitai, and wucai, Brassica rapa plays an important role in vegetable production. Purple resources from the species itself are scarce. It is worth noting that the tissue positions expressing a purple phenotype vary greatly between purple pak-choi and zicaitai. In this study, the genetic patterns of the purple phenotype were analyzed in purple pak-choi and zicaitai, and the F₁ showed purple leaves and green stems, which indicated that purple traits in the leaves and stem were inherited independently. In conjunction with field identification, RNA-seq was used to sequence the transcriptomes of the purple expression sites of purple pak-choi, zicaitai, and their F₁. The high expression of the regulatory genes Dark_pur and BrTT8 affected the purple color of pak-choi and caused the high expression of structural genes of the anthocyanin metabolism pathway and the accumulation of anthocyanins in leaves. The regulatory genes BrPAP₂ and BrTT8 affected the purple color of zicaitai stems, were significantly upregulated, and caused high expression of related structural genes, leading to the accumulation of anthocyanins in the stem epidermis. This suggested that BrPAP₂ and Dark_pur were both R2R3-MYB transcription factors, which were tissue-specific for the regulation of purple color traits in B. rapa. They also had a gene epistatic effect, which influenced the expression of purple traits in the F₁. The gene MYBL2 was highly expressed in all purple tissue sites. The present study on the regulatory genes of the purple phenotype of zicaitai and purple pak-choi provides a theoretical basis for revealing the influence of purple traits on B. rapa leaves and stems, and it may lay the foundation for the selection and breeding of purple vegetables of B. rapa.