An overview of heavy metals toxicity in plants, tolerance mechanism, and alleviation through lysine-chelation with micro-nutrients—A novel approach

Plants must adapt themselves to the prevailing conditions for their survival, resulting in the acquisition of a wide range of metal tolerance mechanisms. Although many metal elements are essential for the growth of plants in low concentrations, their excessive amounts in soil above threshold values can result in toxicity. This detrimental effect varies with the nature of an element as well as plant species. However, their presence in excess is harmful to plants and other organisms and also to the environment. Therefore, remediation is necessary to alleviate the negative effects caused by the heavy metals incorporated into ecosystems. Research has been continuing to develop effective methods of remediation to treat contaminated lands. To date, many scientific approaches have been employed to remediate the heavy metal stress in plants, particularly by using exogenous applied amino acids. Amino acids play a very critical role in metal compartmentation, transport and tolerance in plants. Micronutrient chelated fertilizers complexed with lysine (lys) as amino acid have been reported to improve the growth and yield of crops. The use of amino-chelates rather than organic chelators and/fertilizers is a cheap, effective, and scientifically accepted technique to increase crop yield, photosynthesis, and nutritional status when plants grown in metal-contaminated sites. Also, amino-chelates are safe and give maximum efficiency, and eco-friendly (without any negative impact on the ecosystem). Many studies focus on heavy metals stress under the application of amino-chelates, but no literature review is available, focusing on amino-chelates role with micronutrients in plants under toxic metals polluted environment. Hence, this review highlights the toxicity of heavy metals in plants and their remediation/sustainability mechanism using micronutrient chelation with amino acids. Graphical abstract