title: Arsenic shoot-grain relationships in field grown rice cultivars.
abstract: Arsenic (As) accumulation in rice grains is a risk to human health. The mechanism of transfer of As from the shoot into the grain during grain filling is unknown at present. In this study As speciation in the shoot and grains at maturity were examined, and the relationships between phosphorus (P) and As, and silicon (Si) and As were established in a wide range of cultivars grown in As contaminated field trials in Bangladesh and China. No correlations were observed between shoot and grain speciation, with the inorganic form comprising 93.0-97.0% of As in the shoot and 63.0-83.7% in the grains. The percentage of dimethylarsinic acid (DMA) was between 1.4 and 6.6% in the shoot and 14.6 and 37.0% in the grains; however, the concentrations were comparable, ranging from 0.07 to 0.26 mg kg(-1) in the shoots and 0.03 to 0.25 mg kg(-1) in the grains. A positive correlation was observed between shoot As and shoot Si, however, no correlation was observed between shoot Si and grain As. A significant negative correlation was observed between shoot P and grain As concentrations. These results suggest that the translocation of As into the grain from the shoots is potentially using P rather than Si transport mechanisms. The findings also indicate that inorganic As and DMA translocation to the grain differ considerably.
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, U.K. g.norton@abdn.ac.uk
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Norton
authors.forename: M Rafiqul
authors.initials: MR
authors.lastname: Islam
authors.forename: Guilan
authors.initials: G
authors.lastname: Duan
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
authors.forename: Yongguan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Claire M
authors.initials: CM
authors.lastname: Deacon
authors.forename: Annette C
authors.initials: AC
authors.lastname: Moran
authors.forename: Shofiqul
authors.initials: S
authors.lastname: Islam
authors.forename: Fang-Jie
authors.initials: FJ
authors.lastname: Zhao
authors.forename: Jacqueline L
authors.initials: JL
authors.lastname: Stroud
authors.forename: Steve P
authors.initials: SP
authors.lastname: McGrath
authors.forename: Joerg
authors.initials: J
authors.lastname: Feldmann
authors.forename: Adam H
authors.initials: AH
authors.lastname: Price
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Meharg
mesh_terms: D001151:Arsenic / Q000633:toxicity*; D012275:Oryza / Q000187:drug effects* / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D012825:Silicon / Q000378:metabolism
chemical_list: D010758:Phosphorus; D001151:Arsenic; D012825:Silicon