ABA-Responsive Peach PpMYB6 Enhances Freezing Tolerance and Restricts Plant Growth: PpCBF2 as a Direct Transcriptional Target

Low-temperature stress limits peach (Prunus persica) cultivation and productivity. Although exogenous abscisic acid (ABA) enhances cold tolerance in peach, its underlying molecular regulatory mechanism remains unclear. Here, time-course RNA-seq analysis (0, 1, 2, and 4 h) under 0 °C cold stress and ABA treatments identified 2,659 cold-responsive and 3,664 ABA-responsive differentially expressed genes (DEGs), with 1,105 DEGs co-responsive to both treatments. Functional enrichment revealed significant crosstalk with distinct temporal dynamics across key pathways, including flavonoid and phenylpropanoid biosynthesis, hormone signal transduction, and transcriptional regulation. qRT-PCR validated the cold-induced upregulation of six co-responsive transcription factors (PpERF48, PpERF017, PpMYB6, PpWRKY46, PpWRKY40, and PpbHLH35). Functional characterization demonstrated that overexpressing PpMYB6 in peach calli enhanced cold tolerance at -5 °C while repressing callus growth, exemplifying a growth–defense trade-off. Yeast two-hybrid screening identified 24 candidate interacting proteins of PpMYB6, including NCED1, PpSRC2, and DWARF8, elucidating a potential mechanism balancing cold resistance and growth. Overall, this study clarifies an ABA-mediated molecular network and provides valuable targets for breeding cold-tolerant peach cultivars.