Genome-Wide Identification of BrassinaZole Resistant (BZR) Gene Family in Brassica rapa ssp. pekinensis and Its Expression Pattern During Flowering Process

The BrassinaZole Resistant (BZR) gene family mediates the signal transduction of brassinolide, which is vital in regulating vegetative and reproductive growth of plants. In this research, a comprehensive analysis of all candidate BrBZR genes in Chinese cabbage (Brassica rapa ssp. pekinensis) was conducted using bioinformatics methods, including protein physicochemical properties, evolutionary relationship, gene structure, and conserved domains. Additionally, these candidate genes’ expression patterns during flowering development were analyzed utilizing transcriptome data, and key genes that regulate flowering of Chinese cabbage were screened. In the results, 14 BrBZR genes were identified, with coding sequence (CDS) lengths of 460–1162 bp, and encoding proteins of 152–386 amino acids. The majority of BrBZRs had a highly conserved motif 1 as well as numerous regulatory elements associated with hormone and abiotic stress responses. Transcriptome sequencing showed that 12 BrBZRs were expressed during the flowering development, among which BrBES1.1 and BrBES1.2 were highly expressed, with FPKM ranges of 61.78–99.91 and 43.71–76.69, respectively. Their expression was upregulated during vernalization and flower bud differentiation, suggesting that they may play a key role in regulating the flowering process of Chinese cabbage. Overall, our study provides comprehensive insights into the BrBZR gene family, and has important implications for the further elucidation of the mechanisms that regulate flower development in Chinese cabbage and potentially other related Brassica species.