Nickel and Cadmium Toxicity in Plants

Abstract

Nickel (Ni) and Cadmium (Cd) considered as an essential nutrient where plants cannot complete their life cycle in its absence and cannot be substituted with any other element. Ni was first established as an essential nutrient for the completion of the life cycle and it was reported that Ni deficiency decreases the capacity of plants to develop viable seeds because of hindrance of embryo growth. The uptake of Ni in plants is mainly carried out through the root system via passive diffusion and active transport. The ratio of uptake between active and passive transport varies with the species. It has been reported that plant species and cultivars significantly differ in the uptake of Cd and its subsequent translocation from roots into shoots. Higher Cd accumulation in roots than leaves suggest that Cd transport to the xylem is restricted and Cd is not readily translocated in the phloem. Also, Cd accumulation in root and leaf also depends on binding to the extracellular matrix due to which a significant inhibition of root elongation may be observed. In a study, it was reported that Cd was translocated from lower leaves to upper leaves, and then from upper leaves to culms and ears. Lower leaves accumulated highest Cd content during the early growth stages. However, heavy metals accumulating in the food chain pose risk for health of living being as well as cytotoxicity in plants

Assessment of Heavy Metals Concentration in Mangroves Leaves of the Red Sea Coast of Yemen

“…The common indicators of nickel phytotoxicity to plants include inhibition of germination, leaf spotting, chlorosis, abnormal flower shape, reduced growth of roots and shoots, deformation of plant parts, poor branching and decreased yield [51]. Ni also affects various physiological and biochemical processes in higher plants [52]. Plants could take up nickel through the roots by both passive diffusion and active transport mechanisms [53].…”

Nickel and ozone stresses induce differential growth, antioxidant activity and mRNA transcription in Oryza sativa cultivars

“…Ni 2+ treatment caused an increase in the efflux of K + and Ca 2+ from the roots and shoots of both rice cultivars. Such damage could result from various mechanisms including the oxidation by reactive oxygen species or the changes in cell permeability that increased nonselective conductance and inhibition of the H + -ATPase activity of the plasma membrane fraction in rice (Sharma and Dhiman 2013).…”

Impact of nickel on grapevine (Vitis vinifera L.) root plasma membrane, ROS generation, and cell viability

“…Ouzounidou et al (2006) working with wheat plants reported, that long exposure with 1 mM Ni 2+ reduced iron content leading to iron and manganese defi ciency. Additionally, excess Ni 2+ also can retard shoot and root growth, impair plant metabolism, inhibit photosynthesis and transpiration, and cause ultrastructural modifi cations, which are well documented in the review by Sharma and Dhiman (2013).…”

“…In addition, Ni 2+ is a constituent of several metalloenzymes such as urease (Brown et al 1987). On the other hand excess of Ni 2+ in the medium alters various physiological processes, resulting in detrimental effects on plants and causing diverse toxicity symptoms (Sharma and Dhiman 2013). Among these, iron defi ciency that leads to chlorosis and foliar necrosis and inhibition of nutrient absorption by roots have been widely found in different plant species (Pandey andSharma 2002, Chen et al 2009).…”