Engineered Plants for Heavy Metals and Metalloids Tolerance

Abstract

Agricultural soils around the world are slightly to moderately polluted with heavy metals such as As, Cd, Hg, Cr, Cu, Pb, Ni, and Zn as a result of industrialization, widespread application of pesticides, fertilizers, and anthropogenic activities. Plants experience toxic effects of heavy metals in the form of oxidative stress, reduction in overall growth, and productivity. To minimize these toxic effects, plants have evolved an arsenal of mechanisms such as preventing uptake via roots or blocking transport to aboveground parts. If everything fails, the toxic metal inside the cell is dealt with using a range of detoxification and storage strategies including chelation with thiols and amino acids and subsequent sequestration into subcellular compartments. In this chapter, we have reviewed general strategies for heavy metal tolerance and detoxification by plants. Also plants engineered for heavy metal transport, oxidative stress tolerance pathways, and other mechanisms such as stress-associated protein have substantially advanced our understanding of heavy metal tolerance by plants. In future, as a result of ongoing climate change, frequent floods, storms, and more use of underground and recycled water from industrial and municipal wastes for crop irrigation can further increase the heavy metals in the agricultural soils. Therefore, to minimize the impact of heavy metals on global agricultural production, it will be of utmost importance to further our knowledge of heavy metal tolerance and detoxification by plants.