PIF3 is a negative regulator of the CBF pathway and freezing tolerance in Arabidopsis ($)

Light and temperature are two major factors affecting plants’ growth. Jiang et al. discovered a circuit (EBF1/2-PIF3-CBF) that integrates light and freezing tolerance by integrating EBF1/2 (EIN3-BINDING F-BOX 1/2), PIF3 (PHYTOCHROME-INTERACTING FACTOR 3) and CBF (C-REPEAT BINDING FACTOR). In light, temperate growth conditions, PIF3 directly represses  CBF expression.  PIF3 is subjected to ubiquitination and degradation through EBF1/2. Under cold stress, EBF1/2 are degraded, and PIF3 becomes more stable, moderating CBF expression, independent of light. This network is part of the balancing act plants have to achieve in ever-changing environmental conditions. PNAS 10.1073/pnas.1706226114 (Contributed by Arif)