Genome-Wide Characterization of Nuclear Factor Y (NF-Y) Transcription Factors Gene Family in Cabbage (Brassica oleracea var. capitata L.) Uncovers Their Critical Roles in Salt Stress Tolerance

Nuclear Factor Y (NF-Y) transcription factors play pivotal roles in plant adaptation to abiotic stress, yet their genomic landscape and functional mechanisms in cabbage (<i>Brassica oleracea</i> var. <i>capitata</i> L.) remain underexplored. Here, we performed a genome-wide identification of the NF-Ys in cabbage, identifying 53 BoNF-Ys classified into three subfamilies: 20 BoNF-YAs, 22 BoNF-YBs, and 11 BoNF-YCs. Phylogenetic clustering revealed evolutionary conservation with their Arabidopsis orthologs. Domain analysis revealed that all BoNF-YA members contain the CBF_NF-YA domain, while all BoNF-YB and BoNF-YC members possess the CBFD_NFYB_HMF conserved domain. The BoNF-Y genes were named according to their chromosomal locations. Bioinformatic analysis showed that BoNF-Y proteins range in size from 131 to 642 amino acids, with molecular weights of 14.82-73.18 kDa, theoretical pI values of 4.57-9.96, instability indices between 33.02 and 73.48, aliphatic indices of 45.3-86.26, and grand average of hydropathicity (GRAVY) values ranging from -1.139 to -0.367. Promoter cis-element profiling uncovered stress- and hormone-responsive motifs, including abscisic acid-responsive elements (ABREs), TC-rich repeats, and ethylene-responsive elements (EREs). RNA sequencing (RNA-seq) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) conducted under salt stress (256 mM) identified three salt-responsive candidate genes (BoNF-YA14, BoNF-YB9, and BoNF-YC8). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses highlighted significantly expressed genes' roles in MAPK signaling, proline metabolism, and phytohormone transduction pathways. This study conducted a comprehensive survey of the BoNF-Y gene family in cabbage. It could serve as a theoretical foundation for further functional identification and utilization of BoNF-Y family members and their role in the interaction between cabbage and salt stress.