Chromium-Induced Oxidative Stress and Adaptive Response by Plants: A Physicochemical Review

Abstract

The ever-growing anthropogenic need for development by industrialization is causing severe environmental pollution. Chromium is mainly found in nature in 2 stable forms where Cr6+ is more toxic and mutagenic than Cr3+. Cr is generally known to induce the production of reactive oxygen species (ROS), which in turn affects various metabolic and physiological processes such as alteration in enzymatic antioxidant system, induction of lipid peroxidation and cell membrane damage, ultrastructural changes in cellular and sub-cellular level, alteration in cellular organelles including plastid and mitochondria and causing DNA damage and genotoxicity. Several studies have been conducted in the recent past regarding, genetic and transcriptional regulations for conferring tolerance to stress. However, plants in response to such damaging stress can generate their defense mechanism which helps them alleviate the stress. Among such defense mechanisms important are restriction uptake, intracellular sequestration, complexation, and chelation as well as induction of the antioxidant system. However, it has been seen that exogenous application of various organic acids, amino acids, and nitrous oxide derivatives has facilitated plant growth as well as helped strengthen its defense mechanism against chromium toxicity. We have, therefore, focused on the interaction of chromium with plants emphasizing photosynthetic metabolism, oxidative stress, plant signaling responses, and genotoxic responses of plants towards chromium toxicity explaining various adaptive responses of plants to cope with the chromium stress.