ABSTRACT
Many of the heavy metals like zinc, cadmium, chromium, mercury, lead, arsenic and copper are tremendously turning into the major cause of abiotic stress in the plants. Though they also possess some of the positive aspects in the biological activity of plants and their scarcity can cause abnormalities in their metabolic pathways, their over-accumulation generates a much more toxic effect on the plants. They hamper the primary functions like photosynthesis, electron transport chain and seed germination. Their toxic effects can also cause deadly consequences in plants like mutation and even sabotages the balance between the macro and micronutrients in the plants. They are the sole reason for the oxidative stress produced in the plants due to the generation of the reactive oxygen species (ROS). This heavy-metal stress eventually ends up inducing some of the major alterations in the plants’ biochemical and physiological pathways. These adaptive or constitutive changes turn the plants to be stress tolerant. They employ many of the mechanisms and many transporter proteins and hormones and other secondary metabolites to inhibit the metals to get inside the cells. Complexes like GSH and superoxide dismutase also use their antioxidant properties to scavenge these ROS and eliminate those harmful free radicals. Finally, the ways of the alleviation come up with some treatments with some hormones and also use up their internal defence and mitigating strategies to pump out the heavy metals out of the leafy vegetables.
