Harnessing the interplay between metal toxicity and DNA methylation in plants.

Abstract

Research into how plants adapt to stress through genetic and epigenetic mechanisms is a rapidly evolving field, with epigenetic flexibility serving as a critical factor for survival in heavily contaminated, high-metal environments. Cutting-edge technologies, specifically Whole Genome Bisulfite Sequencing (WGBS) and Reduced Representation Bisulfite Sequencing (RRBS), have revolutionized this area by moving beyond broad, genome-wide surveys to pinpoint specific, gene-level alterations induced by metal stress. These high-throughput methods have fundamentally transformed the landscape of environmental plant research. Critical analysis of the literature revealed that exposure to metal stressors triggers rapid, time-dependent shifts in plant DNA methylation, often occurring within minutes. These epigenetic responses are highly contingent on species and genetic background, and the specific metal stressor involved, facilitating site-specific gene regulation without altering the underlying DNA sequence. This flexibility allows plants to modulate gene expression primarily through hypermethylation (70%) rather than hypomethylation (30%) to maintain homeostasis and develop heritable stress memory. These modifications predominantly target genes associated with metal transport (60%), such as HMA, ZIP, and ABC transporters, followed by sequestration (20%) and other metabolic functions (20%). Ultimately, harnessing these epigenetic mechanisms offers a pathway to developing crop cultivars that not only exhibit enhanced tolerance and productivity in contaminated environments but also restrict the accumulation of toxic metals in edible tissues, thereby improving food safety and supporting sustainable agriculture on Bednarekmarginal lands. Despite major analytical breakthroughs, the precise role of DNA methylation in regulating gene responses to metal toxicity remains a critical, unresolved challenge in research. This review provides an overview of DNA methylation mechanisms and outlines the plant genes that are modified in response to metal exposure.