Histone methylation in plant responses to abiotic stresses

Abiotic stresses, including drought, salinity, temperature fluctuations, and nutrient deficiencies, challenge plant growth and productivity, requiring adaptive mechanisms for survival. Histone modifications, especially histone methylation, participate in gene expression regulation in response to these stresses. Notably, bivalent H3K4me3-H3K27me3 modifications play a central role in fine-tuning stress-responsive genes, allowing plants to adapt to environmental changes. Recent studies have highlighted the dynamic switching of these bivalent chromatin marks at specific loci during stress, facilitating plant acclimatization to adverse environments. This review focuses on the four major histone H3 methylation modifications-H3K4, H3K9, H3K27, and H3K36-examining the roles of the associated methyltransferases and demethylases in mediating histone methylation dynamics. We synthesize recent findings on how these modifications regulate plant responses to various abiotic stresses, such as drought, salinity, heat, light stress, heavy metal exposure, and nutrient stress. By exploring these molecular mechanisms, we aim to deepen our understanding of how histone methylation shapes plant stress responses at both transcriptional and epigenetic levels. Furthermore, we also discuss the functional interaction of histone methylation with histone acetylation. These insights are critical for advancing breeding strategies aimed at improving plant tolerance to environmental stressors, ensuring food security, and supporting sustainable agricultural practices amid climate change.