Epigenetic regulation under light and temperature fluctuations: chromatin remodeling and transcriptional memory in...

Light and temperature are key environmental signals that regulate plant growth, development, and stress responses. To adapt to their fluctuating nature, plants employ epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and non-coding RNAs that reshape chromatin structure without altering DNA sequence. These processes convert transient environmental inputs into molecular memory, enabling rapid and reversible gene activation upon re-exposure. This review summarizes how photoreceptors (PHY, CRY, UVR8) and thermal sensors (H2A.Z, ELF3) coordinate with chromatin modifiers to regulate transcriptional states. Activating marks such as H3K4me3 and H3K27ac, along with poised RNA polymerase II, sustain transcriptional readiness, while demethylases and histone chaperones reset chromatin to restore stability after stress. Understanding this chromatin-based regulation provides a foundation for epigenetic crop improvement, offering new strategies to enhance plant resilience under increasing climatic variability.