It may be said that LAECV contains mitostatic and metaphase arresting components that are able to induce significant metaphase arrest in root apical meristems and also in mouse bone marrow cells.

Plants, being sessile in nature, are constantly exposed to various environmental stresses, such as solar UV radiations, soil salinity, drought and desiccation, rehydration, low and high temperatures and other vast array of air and soil borne chemicals, industrial waste products, metals and metalloids. These agents, either directly or indirectly via the induction of oxidative stress and overproduction of reactive oxygen species (ROS), frequently perturb the chemical or physical structures of DNA and induce both cytotoxic or genotoxic stresses. Such condition, in turn, leads to genome instability and thus eventually severely affecting plant health and crop yield. With the growing industrialization process and non-judicious use of chemical fertilizers, the heavy metal mediated chemical toxicity has become one of the major environmental threats for the plants around the globe. The heavy metal ions cause damage to the structural, enzymatic and non-enzymatic components of plant cell, often resulting in loss of cell viability, thus negatively impacting plant growth and development. Plants have also evolved with an extensive and highly efficient mechanism to respond and adapt under such heavy metal toxicity mediated stress conditions. In addition to morpho-anatomical, hormonal and biochemical responses, at the molecular level, plants respond to heavy metal stress induced oxidative and genotoxic damage via the rapid change in the expression of the responsive genes at the transcriptional level. Various families of transcription factors play crucial role in triggering such responses. Apart from transcriptional response, epigenetic modifications have also been found to be essential for maintenance of plant genome stability under genotoxic stress. This review represents a comprehensive survey of recent advances in our understanding of plant responses to heavy metal mediated toxicity in general with particular emphasis on the transcriptional and epigenetic responses and highlights the importance of understanding the potential targets in the associated pathways for improved stress tolerance in crops.

In this study, variations in physicochemical parameters and heavy metal contamination in water-sediments of a natural stream in the Durgapur industrial zone have been investigated. pH, COD, Cl − , CN − and heavy metals, viz. Pb, Hg and Fe concentrations in channel water, are higher than Indian standards. Metal concentrations in sediments are many folds higher than background value, where Pb, Cd, Hg and Cr contents exceed the sediment quality guidelines. Contamination factor (C f) value of channel water follows the order of Hg > Pb > Fe > Cr > Cd > Cu > Ni, whereas enrichment factor and geoaccumulation index (I geo) values in channel sediments are in the order of Hg > Cr > Ni > Pb > Cd > Fe > Cu. The assessment of contamination index (C d), modified contamination index (mC d) and pollution load index indicates that channel water and sediment samples in the study area are strongly contaminated by heavy metals. Sediment samples based on PELQ and ERMQ are highly toxic, with high degree of potential ecological risk at all the monitored stations. Multivariate analysis infers that heavy metals in channel water and sediments are majorly sourced from industrial discharge.

The presence of residual dyesin textile effluent is not desired as they are very toxic to the ecosystem components and carcinogenic in nature. The removal of reactive azo dye Remazol Brilliant Orange 3RID (RBO3RID) and anthraquinone dye Reactive Blue MR (RBMR) by nanoscale zero-valent iron (NZVI) particles was investigated in this study. The dyes were degraded up to 97%by NZVI particles under different experimental conditions likeNZVI dosages (0.15-0.3 g/L), initial dye concentrations (100-500 mg/L), and pH values (2-12). NZVIwas found to work the best in the pH range of 8-12 which is the typical range of pH in textile wastewater. One gram of NZVI could remove up to 2757mg of RBO3RID dye and 2207 mg of RBMR dye, and more than 80% dye removal was achieved within the first 15 minutes of reaction. FT-IR analyses showed the end products after the degradation are amines.

A facile one-pot hydrothermal synthesis of hollow ball-like ZnS nanostructures is reported using cysteamine, an ecofriendly sulfur source. Following similar protocol, a heterostructure of RGO-ZnS nanocomposite have been synthesized. The as-synthesized samples are structurally and optically characterized using different techniques. The photocatalytic activity of RGO-ZnS has been found to be ∼9% higher than that of ball-like ZnS nanostructures at a dose of 0.4 g/L. This result is attributed to the improved charge transport by hindering charge recombination of photoinduced excitons. One of the significant findings of this work is that the model anionic dye degraded better under alkaline condition with ZnS whereas the trend is reversed for RGO-ZnS composite. The removal efficiency of both the systems is allied with structural, morphological, and optical properties to understand the underlying mechanism of synthesis as well as photocatalysis process.