Genome-wide identification and comparative analysis of diacylglycerol kinase (DGK) gene family and their expression profiling in Brassica napus under abiotic stress

Diacylglycerol kinases (DGKs) are signaling enzymes that play pivotal roles in response to abiotic and biotic stresses by phosphorylating diacylglycerol (DAG) to form phosphatidic acid (PA). However, no comprehensive analysis of the DGK gene family had previously been reported in B. napus and its diploid progenitors (B. rapa and B. oleracea). In present study, we identified 21, 10, and 11 DGK genes from B. napus, B. rapa, and B. oleracea, respectively, which all contained conserved catalytic domain and were further divided into three clusters. Molecular evolutionary analysis showed that speciation and whole-genome triplication (WGT) was critical for the divergence of duplicated DGK genes. RNA-seq transcriptome data revealed that, with the exception of BnaDGK4 and BnaDGK6, BnaDGK genes have divergent expression patterns in most tissues. Furthermore, some DGK genes were upregulated or downregulated in response to hormone treatment and metal ion (arsenic and cadmium) stress. Quantitative real-time PCR analysis revealed that different BnaDGK genes contribute to seed oil content. Together, our results indicate that DGK genes have diverse roles in plant growth and development, hormone response, and metal ion stress, and in determining seed oil content, and lay a foundation for further elucidating the roles of DGKs in Brassica species.