The issues of heavy metal adulteration are becoming common in world. Heavy metal toxicity cases are prevailing in mining industries, smelters, power plants based on coal burning, agriculture, etc. There are several heavy metals, such as Cd, Cu, Pb, Cr, Hg, Ar, etc. These heavy metals are major pollutants of environment, particularly in areas with increasing anthropogenic activities. The cumulation of heavy metal in soils is of great concern in agriculture because of the deleterious effects on food safety, crop growth and soil organisms’ health. Heavy metals affect several physiological and biochemical processes in plants. They diminish crop yield by bringing toxic effects to several physiological processes in plants such as, seed chlorophyll reduced by the production of reactive oxygen species, affecting the redox balance and instigating oxidative stress. Lead (Pb) is one of the looming heavy metal which is neither essential nor plays any part in the course of cell metabolism. Pb has toxic effects on plant which may include inhibition of photosynthesis, disruption of mineral nutrition and water balance, and disturbs membrane structure and permeability. Its phytotoxicity can also affect human health and can prove detrimental through food chain. However, in order to combat the effects generated by heavy metal stress particularly by Pb, several amelioratives can be used. Pb phytotoxicity can be ameliorated by the application of certain phytohormones which can be a part of signal transduction pathway, or they may trigger reactions and causative agents to respond to stress. Various signaling molecules such as NO, H2 S, CO, etc. enhance the activity of antioxidant enzymes, level of secondary metabolites and osmolytes, hence scavenge the oxidative stress due to generation of free radicals in response to heavy metal stress
Expression Patterns of Oxidative Stress-Related Genes of Cucurbita pepo and Relation to Cellular H2O2 under Short-Term Heavy Metal Stress
