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

Plant growth regulators are significant chemical compounds which are synthesized inside the plant cells and play vital role in plant growth and development. Such compounds are usually active at very low concentrations. These plant growth regulators act as a signalling molecule, which influences the growth of plants. Throughout the previous year’s remarkable investigation have been done for understanding the synthesis of auxin and its effect on various physiological progressions. Auxin is a plant hormone that is involved in various physiological activities, including basic cellular processes such as cell enlargement, regulation of the cell cycle and distinction progress. Plants and several other microorganisms together produce auxin in order to carry out their cell cycle. The chemically synthesized auxins like NAA (naphthalene acetic acid) and IBA (Indole- butyric acid), also take part in various cellular processes. Against various types of biotic and abiotic stress conditions, these plant hormones significantly contribute in promoting acclimatization and adaptation in combination with other phytohormones. The present review highlights some of the important features of auxin role in regulation of plant growth either alone or in crosstalk with other plant hormones.