Metal Induced Genotoxicity and Oxidative Stress in Plants, Assessment Methods, and Role of Various Factors in Genotoxicity Regulation

Abstract

Genotoxicity in a broader term includes all the adverse effects on genome and can be explained as the capability of chemical agents to damage genetic material like DNA or some cellular components involved in cell cycle and cell division like spindle apparatus, DNA polymerases, and DNA repair systems. Chemicals, physical agents, metal elements, free radicals, etc. are known to have mutagenic or genotoxic effects on organisms and popularly known as genotoxins. Plants are continuously exposed to numerous biotic and abiotic stresses such as radiations (UV light, infrared, etc.), salinity, drought, flood, nutrient imbalance, soil and airborne plant pathogens, etc. These factors either directly impede plant growth or indirectly through oxidative stress and overproduction of ROS, causing DNA damage which ultimately leads to genomic instability. Heavy metal plays an important role in different stages of a plant life cycle, their presence in more than required quantity may result in cytotoxicity or genotoxicity. Heavy metals can cause oxidative damage to the macromolecules and photosynthetic apparatus present in a cell resulting in physiological and/or biochemical irregularities with lower membrane stability and photosynthesis, nutrient imbalance, suppression or inhibition of cell division, DNA replication, and gene expression. Although plants have evolved sophisticated and complex regulatory mechanisms to adapt under heavy metal stress, but under extreme conditions, it may affect plant health severely leading to cell death. Plants respond to heavy metal stress-mediated toxicity through complex interlinked mechanisms and these metals induce the changes through direct and indirect interactions with genetic material.