Mercury toxicity: Plant response and tolerance

The presence of high levels of Hg (mercury) in the soil has been considered one of the major global environmental problems. Hg contamination mainly occurs through a number of anthropogenic activities, and mining plays a vital role in them. Hg presents in the soil medium as either bounded with minerals or as an adsorbent in soil solution, and their forms also regulate their toxicity in the organisms. Plants show a number of responses, including morphological, anatomical, photosynthetic, enzymatic and cellular levels when exposed to Hg. A number of physiological changes occurred in the plant body, including redox balance, ROS (reactive oxygen species) production, chelation, antioxidative tolerance, and miRNA-mediated tolerance to cope with Hg toxicity. The phytoremediation of Hg has not been successful due to a lack of finding Hg hyperaccumulator plant species. Hg contamination in Asia has received attention as a high level of methyl mercury uptake in the rice, and it has become the prenominal pathway for Hg exposure in the local populations. The Hg uptake in the plants demands further research as long-term consumption below than threshold level of methylmercury could be harmful to the human central nervous system.