Genome-wide identification of U-box gene family and expression analysis under abiotic stresses in Salvia miltiorrhiza

Plant U-box (PUB) E3 ubiquitin ligases play important roles in hormone signaling pathways and in response to different abiotic stresses, but little is known about U-box genes in Danshen (root of Salvia miltiorrhiza Bunge). Here, we identified and characterized 70 SmPUB genes based on its genome sequence. Phylogenetic analysis of U-box genes from S. miltiorrhiza and Arabidopsis suggested that they can be clustered into seven subgroups (I-VII). Typical U-box domains were found in all identified SmPUB genes through the analysis of conserved motifs. Moreover, qRT-PCR was applied to analyze the relative expression levels of U-box genes in S. miltiorrhiza roots and leaves under PEG-induced water deficit and salt stresses. Results revealed that the SmPUB genes exhibited stronger response to drought than to salt stress. To the best of our knowledge, this report is the first to perform genome-wide identification and analysis of the U-box gene family in S. miltiorrhiza, and the results provide valuable information for better understanding of the function of U-box in S. miltiorrhiza.