The Relationship between Cadmium Toxicity and the Modulation of Epigenetic Traits in Plants

Abstract

Elevated concentrations of heavy metals such as cadmium (Cd) have a negative impact on staple crop production due to their ability to elicit cytotoxic and genotoxic effects on plants. In order to understand the relationship between Cd stress and plants in an effort to improve Cd tolerance, studies have identified genetic mechanisms which could be important for conferring stress tolerance. In recent years epigenetic studies have garnered much attention and hold great potential in both improving the understanding of Cd stress in plants as well as revealing candidate mechanisms for future work. This review describes some of the main epigenetic mechanisms involved in Cd stress responses. We summarize recent literature and data pertaining to chromatin remodeling, DNA methylation, histone acetylation and miRNAs in order to understand the role these epigenetic traits play in cadmium tolerance. The review aims to provide the framework for future studies where these epigenetic traits may be used in plant breeding and molecular studies in order to improve Cd tolerance.

Effects of Cadmium on Root Morpho-Physiology of Durum Wheat

“…Most studies on Cd toxicity described nuclear changes such as chromatin condensation and DNA fragmentation since Cd exposure, among the proposed mechanisms, causes DNA strand breakage and inhibition of DNA repair (Niekerk et al, 2021). Among these toxic effects, condensed chromatin is reported to reduce gene expression since when chromatin is more condensed, it is harder for transcription factors and DNA binding protein to access DNA (Niekerk et al, 2021). So, according to the reported data, the wheat cultivar Iride trapped Cd in root avoiding translocation in the aboveground portions of the plant.…”

“…For a number of HMs, including Cd and Zn, increased vacuolation is reported as a mechanism that cells induce to prevent the free circulation of HM ions in the cytosol ( Hall, 2002 ; Liu and Kottke, 2004 ). Most studies on Cd toxicity described nuclear changes such as chromatin condensation and DNA fragmentation since Cd exposure, among the proposed mechanisms, causes DNA strand breakage and inhibition of DNA repair ( Niekerk et al, 2021 ). Among these toxic effects, condensed chromatin is reported to reduce gene expression since when chromatin is more condensed, it is harder for transcription factors and DNA binding protein to access DNA ( Niekerk et al, 2021 ).…”

Cadmium toxicity in medicinal plants: An overview of the tolerance strategies, biotechnological and omics approaches to alleviate metal stress

“…Epigenetic pathways like DNA methylation and histone modifications have become a significant, intricate aspect in how plants react to heavy metal stressors. However, only a small amount of research has emphasized how epigenetic pathways can enhance plant performance when exposed to Cd stress ( Niekerk et al., 2021 ). When heavy metals burden plants, a key gene regulatory mechanism for plants to respond to stress and minimize toxicity is the change in methylation status in the promoter region ( Chakrabarti and Mukherjee, 2021 ).…”

DNA methylation is enhanced during Cd hyperaccumulation in Noccaea caerulescens ecotype Ganges

“…These processes are dependent on the expression of specific genes and thus are controlled by genetic programming. Apart from transcriptional responses, epigenetic modifications are also essential for maintenance of plant genome stability under genotoxic metal stress (Dutta et al 2018;Niekerk et al 2021).…”