DNA Methylation-Mediated Regulation of Plant Adaptation to Abiotic Stress

Climate change is intensifying environmental stresses, including drought, high temperature, and salinity, posing increasing challenges to plant growth and development. In addition to genetic variation, DNA methylation is an important epigenetic mechanism that regulates gene expression without altering the underlying DNA sequence through the addition of methyl groups to the fifth carbon of cytosine. Genome-wide dynamic changes in DNA methylation and demethylation at CG, CHG, and CHH sites contribute to the regulation of stress-responsive transcriptional networks, thereby shaping plant phenotypes and facilitating the establishment of stress memory. In recent years, advances in methylome profiling and molecular validation have shifted research from describing DNA methylation changes to elucidating their regulatory mechanisms. In this review, we summarize the molecular mechanisms underlying the establishment, maintenance, and removal of DNA methylation, with a particular focus on its dynamic changes and regulatory roles in plant responses to cold, heat, drought, and salt stresses. It also compares the characteristics of DNA methylation responses across different types of stress and discusses their potential molecular mechanisms. Overall, DNA methylation represents an important regulatory layer in plant responses to abiotic challenges, and its dynamic changes are closely associated with plant adaptation, providing new insights into the mechanisms underlying stress adaptation.