Heavy Metal Accumulation Potential and Tolerance in Tree and Grass Species

Abstract

Heavy metals (HM) are nondegradable, persistent, and toxic elements. Heavy metal contamination is a global concern and a major health hazard throughout the world. However, plants have evolved different mechanisms to combat these stresses and even have potential to accumulate them in large quantity. Natural flora has differential ability to metal tolerance with some plants showing induced tolerance at metal-enriched medium, whereas others find it difficult to sustain. Bioaccumulation potential of trees and grasses will be assessed based on peer-reviewed publications. Plants will be classified based on their accumulation potential of different heavy metals. Metal accumulation ability in plants and sources of heavy metals will be assessed for different regions of the world. Anthropogenic input of heavy metals from different sources significantly affects the biogeochemical cycling. Heavy metal depositions considerably affect the plant response. Heavy metal tolerance, uptake, and accumulation in different parts of the plant and possible metal-chelating compounds and their role in metal chelation in trees and grasses will be discussed. Morphological, physiological, biochemical, and molecular biomarkers of heavy metal tolerance or sensitivity among the trees and grasses will be correlated with bioaccumulation potential and heavy metal tolerance. This article will provide a broad overview of higher plant abilities and tolerance capabilities in heavy metal accumulation.