PpERF/ABR1 functions as an activator to regulate PpPG expression resulting in fruit softening during storage in peach (Prunus persica)

Fruit softening is a complex process that accelerates postharvest spoilage and shortens the shelf life of fruit. The precise mechanisms underlying fruit softening remain elusive, especially in terms of genetic function. Here, we analyzed in deep the RNA-Seq data of ‘Hongli’ (readily softens after harvest) and ‘Baili’ (slowly softens after harvest) peach fruit. We identified polygalacturonase (PpPG) gene in the ‘plum3’ module as a potential fruit softening biomarker in peach through weighted gene co-expression network analysis (WGCNA). Through transcription factor-target gene regulatory network analysis and molecular approaches, we identified an ethylene response factor (ERF) transcript factor, PpERF/ABR1, as a transcriptional activator that binds directly to the promoter of PpPG. Moreover, transient overexpression of PpERF/ABR1 also enhanced PpPG expression, thereby resulting in fruit softening. These results provide a theoretical basis for the molecular mechanism of ERF in the transcription regulation of cell wall-related genes during fruit softening.