Adverse effect of heavy metal toxicity in plants' metabolic systems and biotechnological approaches for its tolerance mechanism

Abstract

Contamination of soil through heavy metals like As, Hg, Cd, Cr, Pb, etc. cause different environmental hazards, soil pollutions, and destruction of ecosystems integrity. Heavy metal exposure to plants causes severe oxidative stress due to production of free radical which leads to changes in morpho-physiological, biochemical, cellular, and tissue level gene integrity in entire plants. In these adverse conditions, crop plants develop several complex physiological, biochemical, and molecular adaptive mechanisms for better stability, tolerance, and survival. Plant scientists have used conventional breeding techniques for development of agriculturally important heavy metal stress tolerant cultivars which are time consuming and labor intensive. Recent advances in various branches of biological sciences such as hormonal interactions, microbiological engineering, transcriptomics, proteomics, metabolomics, and ionomics have dominantly supported the identification and characterization of genes, transcription factors, and stress tolerance proteins involved in heavy metal detoxifications, which apparently helps in developing metal stress tolerant crop cultivars. This book chapter summarizes several tolerance mechanisms of plants under heavy metal toxicity, the knowledge of recent advances on the role of hormones, microbes, genetic engineering, metabolomics, ionomics (trace elements), proteomics (stress related proteins), and various signal transduction pathways in relation to various heavy metals.