Grain unloading of arsenic species in rice

Anne Marie Carey, Kirk G. Scheckel, Enzo Lombi, Matt Newville, Yongseong Choi, Gareth J. Norton, John M. Charnock, Joerg Feldmann, Adam H. Price, Andrew A. Meharg

Research output: Contribution to journalArticle

155 Citations (Scopus)

Abstract

Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dimethylarsinic acid (DMA). To investigate how As species are unloaded into grain rice, panicles were excised during grain filling and hydroponically pulsed with arsenite, arsenate, glutathione-complexed As, or DMA. Total As concentrations in flag leaf, grain, and husk, were quantified by inductively coupled plasma mass spectroscopy and As speciation in the fresh grain was determined by x-ray absorption near-edge spectroscopy. The roles of phloem and xylem transport were investigated by applying a ± stem-girdling treatment to a second set of panicles, limiting phloem transport to the grain in panicles pulsed with arsenite or DMA. The results demonstrate that DMA is translocated to the rice grain with over an order magnitude greater efficiency than inorganic species and is more mobile than arsenite in both the phloem and the xylem. Phloem transport accounted for 90% of arsenite, and 55% of DMA, transport to the grain. Synchrotron x-ray fluorescence mapping and fluorescence microtomography revealed marked differences in the pattern of As unloading into the grain between DMA and arsenite-challenged grain. Arsenite was retained in the ovular vascular trace and DMA dispersed throughout the external grain parts and into the endosperm. This study also demonstrates that DMA speciation is altered in planta, potentially through complexation with thiols. © 2009 American Society of Plant Biologists.

Original languageEnglish
Pages (from-to)309-319
Number of pages11
JournalPlant Physiology
Volume152
Issue number1
Early online date30 Oct 2009
DOIs
Publication statusPublished - Jan 2010

Keywords

  • oryza-sativa L.
  • helianthus-annuus
  • dietary exposure
  • paddy rice
  • accumulation
  • plants
  • translocation
  • speciation
  • wheat
  • contamination

ASJC Scopus subject areas

  • Plant Science
  • Genetics
  • Physiology

Cite this

Carey, A. M., Scheckel, K. G., Lombi, E., Newville, M., Choi, Y., Norton, G. J., ... Meharg, A. A. (2010). Grain unloading of arsenic species in rice. Plant Physiology, 152(1), 309-319. https://doi.org/10.1104/pp.109.146126

Grain unloading of arsenic species in rice. / Carey, Anne Marie; Scheckel, Kirk G.; Lombi, Enzo; Newville, Matt; Choi, Yongseong; Norton, Gareth J.; Charnock, John M.; Feldmann, Joerg; Price, Adam H.; Meharg, Andrew A.

In: Plant Physiology, Vol. 152, No. 1, 01.2010, p. 309-319.

Research output: Contribution to journalArticle

Carey, AM, Scheckel, KG, Lombi, E, Newville, M, Choi, Y, Norton, GJ, Charnock, JM, Feldmann, J, Price, AH & Meharg, AA 2010, 'Grain unloading of arsenic species in rice', Plant Physiology, vol. 152, no. 1, pp. 309-319. https://doi.org/10.1104/pp.109.146126
Carey AM, Scheckel KG, Lombi E, Newville M, Choi Y, Norton GJ et al. Grain unloading of arsenic species in rice. Plant Physiology. 2010 Jan;152(1):309-319. https://doi.org/10.1104/pp.109.146126
Carey, Anne Marie ; Scheckel, Kirk G. ; Lombi, Enzo ; Newville, Matt ; Choi, Yongseong ; Norton, Gareth J. ; Charnock, John M. ; Feldmann, Joerg ; Price, Adam H. ; Meharg, Andrew A. / Grain unloading of arsenic species in rice. In: Plant Physiology. 2010 ; Vol. 152, No. 1. pp. 309-319.
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