Arsenic shoot-grain relationships in field grown rice cultivars.
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.
Norton
Gareth J
GJ
Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, U.K. g.norton@abdn.ac.uk
Islam
M Rafiqul
MR
Duan
Guilan
G
Lei
Ming
M
Zhu
Yongguan
Y
Deacon
Claire M
CM
Moran
Annette C
AC
Islam
Shofiqul
S
Zhao
Fang-Jie
FJ
Stroud
Jacqueline L
JL
McGrath
Steve P
SP
Feldmann
Joerg
J
Price
Adam H
AH
Meharg
Andrew A
AA
D001151:Arsenic / Q000633:toxicity*; D012275:Oryza / Q000187:drug effects* / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D012825:Silicon / Q000378:metabolism
D010758:Phosphorus; D001151:Arsenic; D012825:Silicon