Epigenetic Adaptation as a Possible Component of Plant Breeding

Epigenetic regulation provides a mechanistic interface between genotype and environment and is increasingly considered a complementary component of plant breeding during climate- and policy-driven transitions toward low-input agriculture. This review summarizes major epigenetic mechanisms in plants, including DNA methylation through RNA-directed DNA methylation (RdDM), maintenance and demethylation pathways, and histone modifications, and evaluates their relevance to heritable phenotypic variation and crop improvement. We discuss the extent and context dependence of epigenetic inheritance, distinguishing intergenerational from transgenerational effects, and highlight approaches for identifying functional epialleles, including epigenetic quantitative trait locus (epiQTL) mapping and epigenome-wide association studies (EWASs). We then synthesize evidence linking epigenetic reprogramming to adaptation to water deficit, salinity, heat, and nutrient limitation, emphasizing the potential and limitations of epigenetic memory for breeding. Finally, we review agronomic and biotechnological approaches for inducing or engineering epigenetic variation, including grafting and mobile RNAs, chemical priming, in vitro propagation, exogenous RNA-triggered RdDM (exo-RdDM), and biopriming. We conclude by outlining the principal challenges for integration into breeding pipelines, particularly the stability, predictability, heritability, and causal attribution of epigenetic variants across environments and generations.