E3 ubiquitin ligases as central hubs orchestrating plant cold stress responses

Abstract

Low temperature is a major environmental constraint limiting plant growth, development, productivity, and geographical distribution. To survive chilling and freezing conditions, plants have evolved sophisticated regulatory systems that perceive thermal changes and convert them into coordinated transcriptional, hormonal, post-translational, and metabolic responses. Among these mechanisms, the ubiquitin–proteasome system (UPS), particularly E3 ubiquitin ligases, has emerged as a central regulatory module in cold adaptation. By conferring substrate specificity, E3 ligases determine the timing, amplitude, and duration of stress signaling through selective ubiquitination of key regulatory proteins. Recent studies show that E3 ligases not only control the stability of core transcription factors in the ICE–CBF pathway, but also integrate phytohormone signaling, post-translational modification (PTM) crosstalk, and environmental cues such as light, circadian rhythms, and nutrient status. These functions are especially relevant in horticultural species, in which cold stress affects both field performance and postharvest quality. Here, we summarize recent advances in the roles of E3 ubiquitin ligases in plant cold stress responses, with emphasis on transcriptional regulation, hormone signaling, PTM crosstalk, and environmental cue integration. We also discuss emerging themes, including non-proteolytic ubiquitination, the spatiotemporal specificity of E3 networks in perennial woody plants, and AI-assisted engineering of E3 ligases for crop improvement. This review provides a framework for understanding ubiquitin-mediated cold adaptation and highlights new opportunities for breeding cold-tolerant horticultural crops.