ABSTRACT
Heavy metal pollution caused by both natural and anthropogenic activities pose serious environmental threats in present times. When their levels exceed the threshold limit, heavy metals interact with various important cellular biomolecules, which leads to excessive generation of reactive oxygen species (ROS) that bring about severe morphological and physiological alterations in plants. Under such conditions, plants are equipped with a repertoire of machineries to cope up with heavy metal toxicity. As oxidative stress becomes more pronounced within the cells, there occurs activation of stress-induced signal transduction pathways which ultimately initiate production of stress-related proteins to counter or neutralize stress injury. The key mechanism include chelating the metals by synthesizing amino acids, organic acids, phytochelatins (PCs) and metallothioneins (MTs), which altogether strengthen the detoxification capacity of intracellular antioxidant enzymes. This chapter addresses the toxicity induced by different heavy metals in plants and also discusses several physiological and molecular strategies adopted by the plants for metal detoxification and developing tolerance to various metals/metalloids.
