Freezing stress poses a threat to plant survival and crop production; therefore, understanding the molecular basis of freezing tolerance and broader cold hardiness is essential for developing cold-hardy crop varieties. This review summarizes molecular responses to freezing, proposes a causal framework from perception to signaling, phenotypes, and applications, and compiles genetic evidence for early signals (Ca 2+ , ROS, kinases). We outline the ICE–CBF–COR transcriptional network and its multi-layered regulation, and integrate protective metabolic modules (osmotic adjustment, antioxidant defense, membrane lipid remodeling, protective proteins). Phytohormones and epigenetic and non-coding RNA regulation are also discussed, with an emphasis on cold-stress memory. Finally, we discuss strategies to improve freezing tolerance and cold hardiness through natural variation, genome editing, and cold-inducible expression systems, thereby informing molecular breeding and rigorous phenotyping.
Wei et al. (Thu,) studied this question.