The transcription factor PavERF28 promotes fruit softening by regulating cell wall degradation in sweet cherry...

Fruit softening is a critical determinant of shelf life and marketability in sweet cherry (Prunus avium L.). This process is predominantly driven by cell wall disassembly, which is tightly regulated by transcription factors. Despite evidence for ethylene's role in sweet cherry softening, how these signals are transduced to regulate the expression of cell wall-modifying genes is unclear. Here, we identified the ethylene-responsive transcription factor PavERF28 as a key regulator in this process. Overexpression of PavERF28 significantly upregulated the transcriptional levels of genes involved in pectin degradation (including genes encoding polygalacturonase, pectin methylesterase inhibitor, and pectate lyase), thus effectively enhancing fruit softening. Moreover, heterologous overexpression of PavERF28 in tomato confirmed its function in promoting fruit softening. At the molecular level, PavERF28 was shown to directly activate the expression of two polygalacturonase genes (PavPG1 and PavPL5) by binding to their promoters, which catalyze pectin depolymerization and thus drive softening. Collectively, our work provides an in-depth elucidation of the regulatory mechanism by which ERF family members control fruit softening in sweet cherry and offers potential targets for the manipulation of fruit ripening, especially softening.