Response of Plants towards Heavy Metal Toxicity: An overview of Avoidance, Tolerance and Uptake Mechanism

Heavy metal contamination of soils is one of the serious environmental concerns due to metal’s persistent nature and their biomagnification potential. The high concentrations of both essential and non-essential heavy metals affect the plant growth adversely and even lead to death in extreme conditions.  Plants adopt various cellular mechanisms to minimize the metal toxicity. On exposure to heavy metals plant initially try to prevent entry of metal in to root cells by implementing avoidance strategy. When heavy metals manage to enter the root cells, they are detoxified intra-cellularly through processes like cell wall binding, organic acids, chelation, sequestration etc. Excess of heavy metal also activate oxidative stress defense mechanisms and the synthesis of stress-related proteins in plants. This inherent ability of plants to tolerate and accumulate toxic contaminants can be explored to treat the metal contaminated areas efficiently. The present review paper covers an overview of plant responses towards heavy metal toxicity and mechanisms of metal uptake, translocation and accumulation.