---

The study aimed at examining the epigenetic and physiological mechanisms of Arabidopsis thaliana and Oryza sativa to cadmium (Cd) and lead (Pb) stress, an increasing issue of heavy metal pollution, and how plants can withstand them. The experiment investigated the changes in DNA methylation and histone modification and expression change of genes to metal stress. Data were obtained through bisulfite sequencing and the ChIP-qPCR test (chromatin immunoprecipitation with a QIAcube automated nucleic acid purification system and real-time PCR system), and the gene expression was observed through RT-qPCR. Physiological parameters such as biomass, chlorophyll content, electrolyte leakage, and metal accumulation were determined by spectrophotometry and atomic absorption spectroscopy. ANOVA and Pearson correlation coefficients were used as statistical methods to test significance and relationship. The results revealed that the exposure to Cd and Pb caused widespread reprogramming of the epigenome: in Arabidopsis, MET1 concentrations dropped by 45% during Cd stress, and ROS1 concentrations rose by 60%, leading to a 20% decrease in global methylation. Promoters of metal homeostasis genes were enriched with histone marks H3K4me3 and H3K27me3 and were associated with a two-to-threefold increase in the level of detoxification genes. Physiologically, there was a decrease in growth of up to 30% and 50 percent growth in root metallic content of treated plants. The findings indicate that epigenetic alterations are important in the mediation of the plant responses to heavy metal stress and could be used as biomar