The Central Role of Epigenetic Regulation in Establishing Stress Memory in Plants

Abstract

Plants, as sessile organisms, have evolved sophisticated mechanisms to cope with environmental stresses through a phenomenon known as stress memory. This adaptive strategy enables plants to respond more efficiently to recurring stress events by retaining information from previous exposures. Epigenetic regulation plays a central role in establishing and maintaining stress memory through dynamic modifications of chromatin structure, DNA methylation, and histone modifications. These molecular changes allow plants to "remember" stress experiences without altering their DNA sequence, providing a flexible yet heritable mechanism for stress adaptation. This review examines the fundamental epigenetic mechanisms underlying stress memory formation, including DNA methylation patterns, histone post-translational modifications, chromatin remodelling, and the involvement of non-coding RNAs. We discuss the molecular basis of somatic, intergenerational, and transgenerational stress memory, with particular emphasis on responses to temperature extremes, drought, and pathogen attacks. Furthermore, we explore the temporal dynamics of memory formation and erasure, highlighting the balance between maintaining adaptive responses and avoiding maladaptive persistence of stress-induced changes. Understanding these epigenetic mechanisms has significant implications for crop improvement strategies, particularly in developing climate-resilient varieties capable of withstanding increasingly unpredictable environmental conditions. Recent advances in epigenome editing technologies offer promising avenues for engineering stress-tolerant crops through targeted manipulation of epigenetic marks. This review synthesises current knowledge on epigenetic stress memory and identifies key questions for future research in this rapidly evolving field.