Role of zinc in alleviating heavy metal stress

Heavy metals pollution is continuously increasing and posing threats to our environment. This heavy metals' presence in soils accumulates in plants which become part of food supply. Heavy metals at their higher concentrations negatively affect plant growth parameters. Zn is one of the essential micronutrient which takes part in plant physiological functions and showed beneficial effects in plant growth, development processes and yield. Zn plays important role in cellular functions in all living organisms. Nevertheless, heavy metal concentrations are increasing in our agricultural soils through different anthropogenic activities which need to be discussed. Considering present scenario, this review was conducted to illustrate the promotive and beneficial role of Zn in alleviating heavy metals stress in various plants. It was observed that Zn not only ameliorate different metals' toxic levels but also improve plant growth attributes by inhibiting heavy metals uptake in plant parts. Heavy metals induced oxidative stress and decline plant growth, biomass, chlorophyll contents, photosynthetic traits and many metabolic functions. Zn combat heavy metals toxicity by generating antioxidant defence system against oxidative damage and improved plant growth parameters by alleviating metals toxicity in different plants. However, Zn inadequate availability declined crop yield. Additionally, Zn deficiency disturbs plant growth and leaf chlorosis. Various techniques in the form of bio-fortification have been used to overcome Zn deficiency.