title: Sulfur mediated reduction of arsenic toxicity involves efficient thiol metabolism and the antioxidant defense system in rice.
abstract: Arsenic (As) contamination is a global issue, with South Asia and South East Asia being worst affected. Rice is major crop in these regions and can potentially pose serious health risks due to its known As accumulation potential. Sulfur (S) is an essential macronutrient and a vital element to combat As toxicity. The aim of this study was to investigate the role of S with regards to As toxicity in rice under different S regimes. To achieve this aim, plants were stressed with AsIII and AsV under three different S conditions (low sulfur (0.5mM), normal sulfur (3.5mM) and high sulfur (5.0mM)). High S treatment resulted in increased root As accumulation, likely due to As complexation through enhanced synthesis of thiolic ligands, such as non-protein thiols and phytochelatins, which restricted As translocation to the shoots. Enzymes of S assimilatory pathways and downstream thiolic metabolites were up-regulated with increased S supplementation; however, to maintain optimum concentrations of S, transcript levels of sulfate transporters were down-regulated at high S concentration. Oxidative stress generated due to As was counterbalanced in the high S treatment by reducing hydrogen peroxide concentration and enhancing antioxidant enzyme activities. The high S concentration resulted in reduced transcript levels of Lsi2 (a known transporter of As). This reduction in Lsi2 expression level is a probable reason for low shoot As accumulation, which has potential implications in reducing the risk of As in the food chain.
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Garima
authors.initials: G
authors.lastname: Dixit
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Amit Pal
authors.initials: AP
authors.lastname: Singh
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Pradyumna Kumar
authors.initials: PK
authors.lastname: Singh
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Smita
authors.initials: S
authors.lastname: Kumar
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Dwivedi
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Prabodh Kumar
authors.initials: PK
authors.lastname: Trivedi
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India.
authors.forename: Vivek
authors.initials: V
authors.lastname: Pandey
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen AB24 3UU, UK.
authors.forename: Gareth John
authors.initials: GJ
authors.lastname: Norton
authors.affiliation: Stockbridge School of Agriculture, Paige Laboratory Room 318 (Office) and Room 320 (Lab), 161Holdsworth Way, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Om Parkash
authors.initials: OP
authors.lastname: Dhankher
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, Uttar Pradesh, India. Electronic address: tripathi_rd@rediffmail.com.
authors.forename: Rudra Deo
authors.initials: RD
authors.lastname: Tripathi
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001151:Arsenic / Q000633:toxicity*; D018533:Biomass; D002352:Carrier Proteins / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D012275:Oryza / Q000201:enzymology / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D054811:Phytochelatins; D018517:Plant Roots / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013455:Sulfur / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D002352:Carrier Proteins; D013438:Sulfhydryl Compounds; D013455:Sulfur; D054811:Phytochelatins; D006861:Hydrogen Peroxide; D005978:Glutathione; D001151:Arsenic
keywords: Antioxidant enzymes; Arsenic; Rice; Sulfate and arsenic transporters; Sulfur; Thiol metabolism