ABSTRACT
The exposure of heavy metals to plants is a general phenomenon due to their environmental pervasiveness. The unifying aspect of toxicity and carcinogenicity determination for all these metals is excessive ROS (reactive oxygen species) generation, which causes oxidative stress. ROS are the main source of the signaling battery in plants’ unified signaling events. The interplay between ROS and major signaling components (calcium-signaling steers, mitogen-activated kinases and hormonal signaling) activates remote signaling pathways to translate metal-induced oxidative stress into highly specific cellular signals. ROS induced oxidative damage through lipid peroxidation, biological macromolecule deterioration, membrane dismantling, leakage of ions and cleavage of DNA-strands, and ultimately leads to the death of plants. As a result, it is suggested that the toxic effects of heavy metals are partially due to metal-induced oxidative stress in the cells. This chapter presents a complete account of current developments in the research on heavy metal poisoning especially the role of oxidative stress/free radicals in the toxic manifestation.
