Epigenetics in forest trees- key driver to phenotypic plasticity and adaptation under stress

Forest trees are complex, long-lived organisms that have evolved to survive in their natural climates. Because of their sedentary nature, they are constantly exposed to a range of external stimuli, which might cause quick alterations in their physiological and defensive processes. Given the vital ecological role forests play in maintaining environmental equilibrium and delivering essential ecosystem services, it is critical to understand the plasticity mechanism that allow forest trees to adapt to climate change. Throughout their lives, forest trees have developed a variety of adaptation mechanisms to deal with changing environmental conditions. Among them, epigenetic changes are important regulators of plant development, growth and stress responses. The major epigenetic processes include DNA methylation, histone modifications and small RNA based chemical alterations. These mechanisms enable fast and reversible changes in gene expression by changing chromatin structure without affecting the underlying DNA sequence, allowing trees to adapt quickly to environmental signals. Importantly, some of these epigenetic alterations can be sustained over time or even passed down between generations, allowing for long-term adaptation. In this review, we highlight recent advancements in tree epigenomics, examine the epigenetic processes governing tree responses to environmental stimuli, and address their broader implications and future perspective. CLINICAL TRIAL NUMBER: Not applicable.