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

Peach (Prunus persica) production and the northward expansion of its cultivation boundaries are severely constrained by recurrent extreme climatic events. Based on time-series transcriptomic analysis of two independent parallel treatments (cold stress and ABA application) and qRT-PCR validation, multiple candidate transcription factor genes co-responsive to both cold stress and ABA were identified (PpERF48, PpERF017, PpMYB6, PpWRKY46, PpWRKY40, and PpbHLH35). Among these, PpMYB6 was further characterized through bioinformatic analysis, and transgenic peach callus and Arabidopsis thaliana lines overexpressing PpMYB6 were generated, revealing its dual role in modulating plant growth and conferring low-temperature stress tolerance. Yeast one-hybrid and dual-luciferase reporter assays confirmed that PpMYB6 directly binds to and activates the PpCBF2 promoter. Yeast two-hybrid library screening identified DWARF8 as a candidate interacting protein, pointing to a working hypothesis by which PpMYB6 may negatively regulate vegetative growth via the gibberellin pathway. Together, this study characterizes a novel molecular module associated with cold tolerance and growth balance in peach, providing a promising candidate gene for molecular breeding of cold-resistant cultivars and rootstocks.