Broadening the epigenetic horizon of abiotic stress response in plants

Plants, unlike animals, cannot move from one place to another and have to face different climatic disturbances wherever they are growing. So, they have innumerable built-in mechanisms to adapt to various abiotic stressful conditions like drought, heat, cold, and salinity. The changing environmental conditions influence the expression patterns of genes. Epigenetics involves heritable changes in DNA bases or histone proteins, which ultimately create different conformational states of chromatin. The regulatory enzymes of epigenetic modifications are grouped as writers, readers and erasers, which add, recognize and remove the epigenetic marks, respectively. Here, we provide a comprehensive overview of the mechanism of DNA methylation by the RdDM pathway, its maintenance and removal, and different histone modification categories like acetylation, methylation, phosphorylation and ubiquitination. This review further discusses in detail the crucial role these modifications play in adapting to major abiotic stresses and how plants preserve these experiences as stress memory to respond to recurring stresses. It emphasizes the role of epigenetic modifications as a crucial mechanism for building plant’s tolerance and how it can be an important research priority to improve plant growth and development under abiotic stress conditions.