Genome Wide Identification and Characterization of <i>BrE2F</i> Family Gene of <i>Brassica rapa</i>

The <i>E2F</i> family gene is one of the most important G₁-S checkpoint regulatory transcription factors to monitor and regulate the accurate DNA replication and progression of the cell cycle in eukaryotes. Expression of this gene in multiple environmental factors has been reported in diversified plant species. However, characterization and investigation of the putative influential role of this family gene in <i>Brassica</i> species were not reported. In addition to expression profiling and mRNA target analysis, we have comprehensively identified and characterized 14 <i>Br</i>E2F/DP transcription factors from the data in available databases of <i>Brassica rapa</i> and compared them with five other species. Six pairs of segmentally duplicated <i>BrE2F/DP</i> paralogous genes were identified in this study, with Ka/Ks values of < 1.0. The findings indicated their evolution through segmental duplication across the chromosome after the <i>Brassica</i> splits from <i>Arabidopsis</i> and functional similarities with <i>Brassica oleracea</i> proteins. Most of the stress-responsive microRNA (miRNA) targeted <i>BrE2F/DP5</i>, <i>BrE2F/DP12</i>, BrE2F/DP1, and BrE2F/DP8. Cis-element composition and diversified functional expressions indicated their involvement in biological pathways for adaptation under multiple stress resistances, including cell cycle progression during growth and development. The findings provided comprehensive information on the multifunctional roles of the E2F/DP family in <i>Brassica</i> spp., importantly, biotic and abiotic stress resistance.