Pb is not biologically essential and manifests toxicity even at low concentrations 3. It seriously affects the plant metabolism, induces reduction in growth, deforms cell structures, impairs ion homeostasis, and chlorophyll synthesis, produces ROS that attacks biomolecules 2. Reduction in root length, shoot biomass, increased concentration of MDA, and H 2O 2 in Arabidopsis halleri and A. It interferes with the photosynthetic machinery, PSI, and PSII 4.Īlterations in chloroplast ultrastructure were observed Cd exposure caused impaired root elongation, mitotic process, and chromosomal aberrations in root tips of pea plant reduces activity of nitrate reductase in shoots Cd indirectly produces ROS by preventing electron transport in the chloroplast and mitochondria 5. Zn being related to DNA and RNA stabilization, excess Zn can be genotoxic Ĭhanges in plant soluble sugars and leaf reflectance in Lycopersicon esculentum, 2.Ĭd stress reduces the root length, specific root length, surface area, and number of root tips in plants stunted growth is observed 3. Shoot biomass reduced, in Arabidopsis halleri, Chlorophyll content slightly decreased, Zn accumulation was more in A. Zn affected plant growth, impaired uptake, and distribution of mineral nutrients, affected metabolism, and antioxidative defense system 6. Replace cations from the allosteric sites of enzymes like RuBISCO impairs CO 2 fixation 5. Inhibits photosynthesis, interferes with the translocation, and absorption of Fe, and Mg in chloroplast induces ROS generation leading to oxidative stress disrupts membrane integrity 4. Reduction in root and shoot length necrosis, and rolling of leaf margins 3. lycopersicum Ĭhlorosis of young leaves Cu and Fe deficiency 2. Inhibits light reaction of photosynthesis leaves were bleached and wilted, chlorophyll a/chlorophyll b ratio slightly decreased, reduced fresh weight in Crassula helmsii 5.Ĭu happened to decrease fresh weight, number of leaves, and roots, shoot length, interfered with protein synthesis, photosynthesis, enzymatic activity, and altered membrane permeability in Solanum nigrum and S.
Generates harmful reactive oxygen species (such as H 2O 2, Veinal chlorosis of leaf with development of brown spots, reduced leaf in Raphanus sativus 2. Manifestation of toxicity of HMs in plants
Table 6.1 depicts the manifestation of toxicity induced by copper, zinc, cadmium, and lead to different plant species. Nonessential heavy metals like Cd, Pb, Hg, Cr, and Al are not required by plants, even in trace amounts, for any of the metabolic processes. Essential elements are often required in trace amounts in the level of 10–15 ppm and are known as micronutrients. There are numerous essential heavy metals like Cu, Fe, Mn, Co, Zn, and Ni required by plants as they form cofactors that are structurally and functionally vital for enzymes and other proteins. Essential HMs are those required by living organisms for carrying out the fundamental processes like growth, metabolism, and development of different organs. The HMs can be broadly classified into two categories: essential and nonessential heavy metals. Heavy metals (HMs) are defined as those elements having an atomic number greater than 20 and atomic density above 5 g cm − 3 and must exhibit the properties of metal.
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