Trans-2-hexenal activates PpWRKY75 to promote pathogenesis-related protein expression and enhance postharvest peach resistance against Rhizopus stolonifer

Peach fruit is highly susceptible to postharvest soft rot caused by Rhizopus stolonifer , resulting in substantial economic losses. This study investigated the efficacy and mechanism of trans-2-hexenal (E2H) in controlling postharvest soft rot in peach fruit. Exogenous E2H treatment significantly inhibited R . stolonifer infection in peach fruit, reducing both disease incidence and lesion diameter. RNA-Seq revealed that E2H-induced differentially expressed genes were mainly enriched in pathways associated with disease resistance and pathogenesis-related (PR) proteins. In E2H-treated peach fruit, the expression levels of PpWRKY75 , PpGLU1 , and PpPR10 were significantly upregulated. Subcellular localization and transactivation assays demonstrated that PpWRKY75 was localized in the nucleus and possessed transcriptional activation activity. Dual luciferase reporter (DLR) assay and electrophoretic mobility shift assay (EMSA) further confirmed that PpWRKY75 can activate transcription of PpGLU1 and PpPR10 by binding to their promoters. Consistently, transient overexpression of PpWRKY75 in peach fruit significantly inhibited lesion expansion, reduced disease incidence, and markedly increased the expression levels of the defense-related genes PpGLU1 and PpPR10 , thereby enhancing fruit disease resistance. Conversely, silencing PpWRKY75 in peach fruit weakened disease resistance. In addition, the transient expression analysis of PpGLU1 and PpPR10 indicated that they had the function of enhancing disease resistance. In summary, this study demonstrated that exogenous E2H activated PpWRKY75 expression, which in turn regulated the expression of PpGLU1 and PpPR10 , thereby enhancing peach fruit resistance against R. stolonifer . These findings provide novel insights into the regulatory mechanism underlying postharvest soft rot resistance in peach fruit.