Genomic identification and expression analysis of the BBX transcription factor gene family inPetunia hybrida

The B-box proteins (BBXs) are a class of zinc finger transcription factors containing one or two B-BOX domains that play important roles in plant growth, development and stress response. The petunia (Petunia hybrida) is a model ornamental plant, and its draft genome has been published. However, no systematic study of theBBXgene family inPetuniahas been reported. In this study, a total of 28 BBX members from thePetuniagenome were identified. We performed analyses of their phylogenetic relationships, structures, conserved motifs, promoter regions, and expression patterns. Based on the phylogenetic relationship, the PhBBXs were divided into six groups. Analysis of the gene structures and conserved motifs further confirmed the closer relationships in each group. Based on the RNA-seq data, the transcript abundance ofPhBBXsin different tissues were divided into two major groups. The analysis ofcis-elements showed that many stress responsive elements appeared in the promoter region of mostPhBBXgenes. The stress response patterns ofPhBBXswere detected under drought, salinity, cold and heat treatments. Based on the RNA-seq data, we found that 3 genes responded to drought, 8 genes responded to salt, 18 genes responded to cold, and 15 genes responded to heat. In conclusion, this study may facilitate further functional studies of BBXs inPetunia.