Unveiling the Mechanisms of DNA Damage Response and Epigenetic Modifications of Chromatin in Response to Cadmium-Mediated Phytotoxicity

Rapid industrialization and urbanization during the last decade have resulted in increasing concentrations of heavy metals in soil and water. In developing countries increased industrialization, agricultural activities, transportation, and mining along with natural processes like volcanic eruptions, are mainly responsible for heavy-metal accumulation in the ecosystem. The consumption of crops from heavy metal-contaminated agricultural fields poses a potential threat to both animals and humans. Being sessile in nature, plants develop several physiological, biochemical and molecular strategies that ultimately generate resistance in plants against heavy metals via sequestration, transportation, chelation, and exclusion mechanisms. Cadmium (Cd) is found widely in soil and is severely toxic for plants, causing oxidative damage in plant cells because of its heavy metal characteristics. Cadmium reduces seed germination, seedling growth, and plant biomass via altering photosynthetic activity, relative water content, transpiration rate, and stomatal conductance. Moreover, the Cd-induced oxidative stress can induce damage at the genomic level via inducing DNA replication stress, DNA double-strand breaks, and alterations in chromatin structure. This chapter considers the recent progress in understanding the mechanism of plant cellular responses to cadmium toxicity which seems to be composed of a series of interlinked biochemical reactions via the generation of ROS and DNA damage-induced replication stress, ultimately activating cell cycle control pathways, DNA repair systems, and epigenetic adaptations.