PpERF27-PpCBF2/4 Module Integrates Low-Temperature and Ethylene Signals to Activate Abscisic Acid and DAM Pathways to...

Perennial deciduous plants withstand prolonged low temperatures by entering bud endodormancy, a developmental state tightly regulated by phytohormones and dormancy-associated MADS-box (DAM) genes. Although abscisic acid (ABA) is well-established as a key regulator of bud endodormancy, the role of endogenous ethylene (ET) in low-temperature-mediated endodormancy regulation remains largely unclear. In this study, we showed that short-term low temperature increased endogenous ET levels in peach buds, thereby inducing the expression of PpERF27. Functional analyses revealed that overexpression of PpERF27 increased ABA accumulation in peach buds, whereas virus-induced gene silencing of PpERF27 reduced ABA levels and promoted endodormancy release. PpERF27 directly activated the transcription of PpDAM5 and the ABA biosynthetic genes PpNCED2 and PpNCED3, thereby promoting bud endodormancy. Moreover, PpERF27 interacted with the C-repeat binding factors PpCBF2 and PpCBF4, further enhancing the transcriptional activation of PpDAM5, PpNCED2 and PpNCED3, which increased ABA accumulation and delayed bud endodormancy release. After long-term exposure to low temperatures, ET levels decreased and the expression of PpCBF2 and PpCBF4 was downregulated in peach buds. This reduction weakened ABA biosynthesis and DAM gene expression, consequently accelerating bud endodormancy release. Together, this study provides novel insights into how perennial deciduous plants integrate low-temperature and ET signals to regulate bud endodormancy and highlights the PpERF27-PpCBF2/4 module as a potential molecular target for improving endodormancy regulation in peach and other perennial fruit trees.