Genomic survey of bZIP transcription factor genes related to tanshinone biosynthesis in Salvia miltiorrhiza

Abstract

Tanshinones are a class of bioactive components in the traditional Chinese medicine <i>Salvia miltiorrhiza</i>, and their biosynthesis and regulation have been widely studied. Current studies show that basic leucine zipper (bZIP) proteins regulate plant secondary metabolism, growth and developmental processes. However, the bZIP transcription factors involved in tanshinone biosynthesis are unknown. Here, we conducted the first genome-wide survey of the bZIP gene family and analyzed the phylogeny, gene structure, additional conserved motifs and alternative splicing events in <i>S. miltiorrhiza.</i> A total of 70 SmbZIP transcription factors were identified and categorized into 11 subgroups based on their phylogenetic relationships with those in <i>Arabidopsis</i>. Moreover, seventeen <i>SmbZIP</i> genes underwent alternative splicing events. According to the transcriptomic data, the <i>SmbZIP</i> genes that were highly expressed in the Danshen root and periderm were selected. Based on the prediction of bZIP binding sites in the promoters and the co-expression analysis and co-induction patterns in response to Ag⁺ treatment <i>via</i> quantitative real-time polymerase chain reaction (qRT-PCR), we concluded that <i>SmbZIP7</i> and <i>SmbZIP20</i> potentially participate in the regulation of tanshinone biosynthesis. These results provide a foundation for further functional characterization of the candidate <i>SmbZIP</i> genes, which have the potential to increase tanshinone production.