Genome-wide identification and comparative analysis of Dof gene family in Brassica napus

Abstract

DOF, DNA binding with one finger proteins are plant-specific transcription factors shown to play roles in diverse plant functions. However, a--little is known about DOF protein repertoire of the allopolyploid crop, Brassica napus. Here, we report genome-wide identification and systematic analysis of the Dof transcription factor family in this important oilseed crop. We identified 117 Brassica napus Dof genes (BnaDofs). So far, this is the largest number of Dof genes reported in a single eudicot species. Based on phylogenetic analysis, BnaDofs were classified into nine groups (A, B1, B2. C1, C2.1, C2.2, C3, D1, D2). Most members belonging to a particular group displayed conserved gene structural organisation and similar protein motifs distribution. Chromosomal localisation analysis highlighted the uneven distribution of BnaDofs across all chromosomes. Evolutionary analysis exemplified that the divergence of Brassica genus from Arabidopsis, the whole genome triplication event, and the hybridisation of B. oleracea and B. rapa to form B. napus, followed by gene loss and rearrangements, led to the expansion and divergence of Dof TF gene family in B. napus. Functional annotation of BnaDof proteins, cis-element analysis of their promoters suggested potential roles in organ development, the transition from vegetative to the reproductive stage, light responsiveness, phytohormone responsiveness as well as abiotic stress responses. Furthermore, the transcriptomic analysis highlighted the preferential tissue-specific expression patters of BnaDofs and their role in response to various abiotic stress. Overall, this study provides a comprehensive understanding of the molecular structure, evolution, and potential functional roles of Dof genes in plant development and abiotic stress response.