Genome-Wide Analysis and Exploration of WRKY Transcription Factor Family Involved in the Regulation of Shoot Branching in Petunia

The WRKY transcription factors (TFs) participate in various physiological, growth and developmental processes of plants. In our study, a total of 79 WRKY family members were identified and classified into three groups (Group I, Group IIa–e, and Group III) based on phylogenetic and conservative domain analyses. Conserved motif analysis showed that seven WRKYGQK domains changed. The promoter sequence analysis suggested that there were multiple stress- and hormone-related cis-regulatory elements in the promoter regions of PhWRKY genes. Expression patterns of PhWRKYs based on RNA-seq data revealed their diverse expression profiles in five tissues and under different treatments. Subcellular localization analysis showed that PhWRKY71 was located in the nucleus. In addition, overexpression of PhWRKY71 caused a significant increase in branch number. This indicated that PhWRKY71 played a critical role in regulating the shoot branching of Petunia hybrida. The above results lay the foundation for further revealing the functions of PhWRKY genes.