title: Mechanisms of silicon-mediated alleviation of heavy metal toxicity in plants: A review.
abstract: In present era, heavy metal pollution is rapidly increasing which present many environmental problems. These heavy metals are mainly accumulated in soil and are transferred to food chain through plants grown on these soils. Silicon (Si) is the second most abundant element in the soil. It has been widely reported that Si can stimulate plant growth and alleviate various biotic and abiotic stresses, including heavy metal stress. Research to date has explored a number of mechanisms through which Si can alleviate heavy metal toxicity in plants at both plant and soil levels. Here we reviewed the mechanisms through which Si can alleviate heavy metal toxicity in plants. The key mechanisms evoked include reducing active heavy metal ions in growth media, reduced metal uptake and root-to-shoot translocation, chelation and stimulation of antioxidant systems in plants, complexation and co-precipitation of toxic metals with Si in different plant parts, compartmentation and structural alterations in plants and regulation of the expression of metal transport genes. However, these mechanisms might be associated with plant species, genotypes, metal elements, growth conditions, duration of the stress imposed and so on. Further research orientation is also discussed.
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Adrees
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Shafaqat
authors.initials: S
authors.lastname: Ali
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan. Electronic address: mrazi1532@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rizwan
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Zia-Ur-Rehman
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ibrahim
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Farhat
authors.initials: F
authors.lastname: Abbas
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Mujahid
authors.initials: M
authors.lastname: Farid
authors.affiliation: Department of Soil Sciences, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Muhammad Farooq
authors.initials: MF
authors.lastname: Qayyum
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Muhammad Kashif
authors.initials: MK
authors.lastname: Irshad
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D004787:Environmental Pollution / Q000009:adverse effects; D007477:Ions / Q000378:metabolism; D019216:Metals, Heavy / Q000633:toxicity*; D018384:Oxidative Stress / Q000502:physiology; D063245:Plant Development / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D012825:Silicon / Q000378:metabolism*; D012989:Soil Pollutants / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D007477:Ions; D019216:Metals, Heavy; D012989:Soil Pollutants; D012825:Silicon
keywords: Abiotic stress; Genotypes; Heavy metal; Plant; Silicon; Tolerance