Identifying a cis-element in PtoCP1 promoter for efficiently controlling constitutive gene expression in Populus tomentosa

Gene expression is regulated by transcription factors binding to in promoters. However, efficient for genetic engineering are rarely reported. In this study, we identified an 11 bp in the PtoCP1 promoter that drives strong constitutive gene expression in . A 2,270 bp promoter region upstream of the gene's translation start site was cloned and named ProPtoCP1. This promoter controls GUS reporter gene expression in the roots, leaves, and stems of seedlings. Based on the location and density of , the PtoCP1 promoter was divided into four fragments by 5'-end deletions. GUS staining and RT-qPCR revealed a key at -466 to -441 bp essential for gene expression. Further analysis showed that the MYB-TGACG is a positive regulator, whereas neither MYB nor TGACG alone drove gene expression. This study enhances our understanding of gene expression regulation by and provides a valuable tool for genetic engineering.