Reactive oxygen species (ROS) are produced as a normal product of plant cellular metabolism. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, they are well-described second messengers in a variety of cellular processes, including conferment of tolerance to various environmental stresses. Whether ROS would serve as signaling molecules or could cause oxidative damage to the tissues depends on the delicate equilibrium between ROS production, and their scavenging. Efficient scavenging of ROS produced during various environmental stresses requires the action of several nonenzymatic as well as enzymatic antioxidants present in the tissues. In this paper, we describe the generation, sites of production and role of ROS as messenger molecules as well as inducers of oxidative damage. Further, the antioxidative defense mechanisms operating in the cells for scavenging of ROS overproduced under various stressful conditions of the environment have been discussed in detail.

https://downloads.hindawi.com/archive/2012/217037.pdf

Reactive Oxygen Species, Oxidative Damage, and Antioxidative Defense Mechanism in Plants under Stressful Conditions

Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil. This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.

Heavy metals, occurrence and toxicity for plants: a review

Phytoremediation of heavy metals—Concepts and applications

Response to cadmium in higher plants

Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

https://portlandpress.com/biochemsoctrans/article-pdf/28/5/A468/834146/bst028a468a.pdf

Cadmium induced suppression in the activities of key metabolic enzymes and synthesis of stress specific proteins in growing rice (Oryza sativa L.) seedlings

Towards Water Security through Sustainable Management of Water Resources

Developing novel drug molecules against HIV is a scientific quest necessitated by development of drug resistance against used drugs. We report comparative results of molecular dynamics simulation s...

Evaluation of binding of potential ADMET/tox screened saquinavir analogues for inhibition of HIV-protease via molecular dynamics and binding free energy calculations.

Molluscs as a Tool for River Health Assessment: A Case Study of River Ganga at Varanasi

The Zinc transporter (ZnT superfamily) facilitates Zn-transport into intracellular vesicles in life forms. Existing database has been enriched with the identification of new Zn-transporters important for therapeutic and intra-channel metal binding capacity. The present work uses a consensus sequence approach to identify extra-membrane metal-binding motif in Zn transporter protein family. Molecular phylogeny among members of ZnT superfamily proteins was analyzed. In all 166 representative sequences covering all known members of ZnT protein subfamilies (subgroups Znt1-Znt10) from bacteria, archaea and eukarya were selected and used to obtain ten consensus sequences, each representing a specific ZnT subgroup (1-10). Using bioinformatics tools a phylogenetic tree was constructed to explore the evolutionary link between the various ZnT subgroup considering members from lower and higher life forms. The unrooted phylogenetic tree obtained by Clustal W and NJ method revealed the existence of three clearly separated clades, which were segregated early in the evolution of this superfamily. Consensus sequence analysis using Weblogo revealed motifs of (HX)n type that evolved to bind the Zn ions effectively, enabling Zn transport. No significant similarity among members of Znt1 and Znt10 or Znt2 and Znt10 suggest that gene duplication event in the ZnT superfamily gene probably occurred in the later phase of evolution when individual specificities of the distinguished ZnT subgroups were already formed.

Kavita Shah

Papers

Cadmium induced suppression in the activities of key metabolic enzymes and synthesis of stress specific proteins in growing rice (Oryza sativa L.) seedlings

Towards Water Security through Sustainable Management of Water Resources

Evaluation of binding of potential ADMET/tox screened saquinavir analogues for inhibition of HIV-protease via molecular dynamics and binding free energy calculations.

Molluscs as a Tool for River Health Assessment: A Case Study of River Ganga at Varanasi

PHYLOGENETIC RELATIONSHIPS IN ZnT SUPERFAMILY OF ZINC ION TRANSPORTERS IN SILICO