Abstract
DNA-binding with One Finger (DOF) transcription factors play crucial roles in modulating plant growth, development, and environmental stress responses. However, the DOF family in flowering Chinese cabbage (Brassica campestris) remains poorly characterized. Here, 67 BcDOF genes were identified in B. campestris, distributed nonuniformly across ten chromosomes and classified into nine subfamilies. Structural analyses revealed that all BcDOF proteins harbor a conserved zinc-finger DOF (zf-DOF) domain, with members within individual subfamilies generally sharing similar motif architectures and exon-intron structures. Evolutionary analyses indicated that whole-genome triplication and segmental duplication were the major drivers of BcDOF family expansion, while purifying selection contributed to the evolutionary conservation of duplicated gene pairs. Promoter analysis revealed abundant cis-acting elements related to hormone signaling and abiotic stress responses. Quantitative real-time PCR (qRT-PCR) further demonstrated that many BcDOF genes responded to heat and drought stresses. Among them, BcDOF56 was markedly induced by both heat and drought and localized to the nucleus. Heterologous overexpression of BcDOF56 in Arabidopsis significantly improved heat and drought tolerance, as indicated by reduced malondialdehyde (MDA) accumulation and elevated superoxide dismutase (SOD) activity relative to wild-type (WT) plants. Collectively, these findings advance our understanding of the evolutionary and functional divergence of the BcDOF family and highlight BcDOF56 as a potential target for improving abiotic stress tolerance in B. campestris.