An R1R2R3 MYB Transcription Factor, MnMYB3R1, Regulates the Polyphenol Oxidase Gene in Mulberry ( Morus notabilis )

The aim of this study was to determine how the mulberry ( ) polyphenol oxidase 1 gene ( ) is regulated during plant stress responses by exploring the interaction between its promoter region and regulatory transcription factors. First, we analyzed the -acting elements in the promoter. Then, we used the promoter region [(1268 bp, including an MYB3R-binding -element (MSA)] as a probe to capture proteins in DNA pull-down assays. These analyses revealed that the MYB3R1 transcription factor in (encoded by ) binds to the promoter region. We further explored the interaction between the promoter and MYB3R1 with the dual luciferase reporter, yeast one-hybrid, and chromatin immunoprecipitation assays. These analyses verified that MnMYB3R1 binds to the MSA in the promoter region. The overexpression of in tobacco upregulated the expression of the tobacco gene. This observation as well as the quantitative real-time PCR results implied that and are involved in the abscisic acid-responsive stress response pathway.