Growth inhibition and cold-acclimation strategies help plants withstand cold stress, which adversely affects growth and survival. PHYTOCHROME B (phyB) regulates plant growth through perceiving both light and ambient temperature signals. However, the mechanism by which phyB mediates the plant response to cold stress remains elusive. Here, we show that the key transcription factors mediating cold acclimation, C-REPEAT BINDING FACTORs (CBFs), interact with PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) under cold stress, thus attenuating the mutually assured destruction of PIF3–phyB. Cold-stabilized phyB acts downstream of CBFs to positively regulate freezing tolerance by modulating the expression of stress-responsive and growth-related genes. Consistent with this, phyB mutants exhibited a freezing-sensitive phenotype, whereas phyB-overexpression transgenic plants displayed enhanced freezing tolerance. Further analysis showed that the PIF1, PIF4, and PIF5 proteins, all of which negatively regulate plant freezing tolerance, were destabilized by cold stress in a phytochrome-dependent manner. Collectively, our study reveals that CBFs–PIF3–phyB serves as an important regulatory module for modulating plant response to cold stress.

生长抑制和冷驯化策略可帮助植物承受冷胁迫，这会对生长和存活产生不利影响。PHYTOCHROME B（phyB）通过感知光和环境温度信号来调节植物的生长。但是，phyB介导植物对冷胁迫的反应的机制仍然不清楚。在这里，我们显示了介导冷驯化的关键转录因子C-重复结合因子（CBFs）在低温胁迫下与植物染色体相互作用因子3（PIF3）相互作用，从而减弱了相互保证的PIF3-phyB破坏。冷稳定的phyB通过调节应激反应和生长相关基因的表达，在CBF的下游起作用，以积极调节抗冻性。与此一致，phyB突变体表现出冷冻敏感的表型，而phyB过表达的转基因植物表现出增强的冷冻耐受性。进一步的分析表明，PIF1，PIF4和PIF5蛋白均负性调节植物的耐寒性，并且受冷胁迫以植物色素依赖性方式失稳。总体而言，我们的研究表明CBFs–PIF3–phyB是调节植物对冷胁迫反应的重要调控模块。