Genome-wide analysis of the BES1 transcription factor family in Chinese cabbage (Brassica rapa ssp. pekinensis)

The BES1 transcription factor family is one of the most important families involved in growth and development, hormone responses, and abiotic or biotic stress responses in plants. Completion of the sequencing of the Brassica rapa genome enabled us to undertake a genome-wide identification and functional study of the gene families related to the morphological diversity and agronomic traits of Brassica crops. Therefore, systematic analysis of the BES1 gene family in Chinese cabbage has profound significance. In this study, 15 BrBES1 genes were identified in Chinese cabbage, which could be classified into two groups according to their gene structural characteristics and motif compositions obtained. Fifteen BrBES1 genes mapped on chromosomes were further assigned to three subgenomes and eight ancestral karyotypes. Distribution mapping shows that BES1 proteins are non-randomly localized in eight chromosomes. Fourteen orthologous gene pairs are shared by Chinese cabbage and Arabidopsis. The expansion of BES1 genes in Chinese cabbage results from genome triplication. Quantitative RT-PCR analysis showed that expressions of BrBES1 genes varied widely under different abiotic stress treatments for different times. Numerous stress–responsive candidate genes were obtained. Our systematic analyses provided insights into the characterization of the BES1 genes in Chinese cabbage and basis for further functional studies of such genes.