PpWRKY53 transcriptionally activating <i>PpPGIP1</i> contributes to agaro-oligosaccharides–induced disease resistance in peach fruit

Abstract The polygalacturonase -inhibiting protein (PGIP) family member PpPGIP1 in peaches responds to Monilinia fructicola infection and positively regulates disease resistance. However, the molecular mechanism still needs to be further explored. In this study, we identified PpWRKY53, a member of the pathogen resistance-associated WRKY family. Its expression was upregulated in response to both M. fructicola infection and agaro-oligosaccharides treatment. Pearson correlation analysis indicated that PpWRKY53 and PpPGIP1 had a positive correlation. Subcellular localization analysis showed that PpWRKY53 is a nuclear localization protein. Yeast one-hybrid and electrophoretic mobility shift assays demonstrated that PpWRKY53 bound directly to the W-box element within the PpPGIP1 promoter. The dual-luciferase reporter system further revealed that PpWRKY53 positively activated PpPGIP1 expression. Furthermore, transient overexpression of PpWRKY53 in peach fruit upregulated the expression of PpPGIP1, while silencing PpWRKY53 downregulated the expression of PpPGIP1. In summary, PpWRKY53 transcriptionally activating PpPGIP1 contributes to agaro-oligosaccharides–induced disease resistance in peach fruit.