In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea

Wang, Peng, Menzies, Neal W., Lombi, Enzo, McKenna, Brigid A., de Jonge, Martin D., Paterson, David J., Howard, Daryl L., Glover, Chris J., James, Simon, Kappen, Peter, Johannessen, Bernt and Kopittke, Peter M. (2013) In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea. Plant Physiology, 163 1: 407-418. doi:10.1104/pp.113.222299

Author Wang, Peng
Menzies, Neal W.
Lombi, Enzo
McKenna, Brigid A.
de Jonge, Martin D.
Paterson, David J.
Howard, Daryl L.
Glover, Chris J.
James, Simon
Kappen, Peter
Johannessen, Bernt
Kopittke, Peter M.
Title In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea
Journal name Plant Physiology   Check publisher's open access policy
ISSN 0032-0889
Publication date 2013-09-01
Year available 2013
Sub-type Article (original research)
DOI 10.1104/pp.113.222299
Volume 163
Issue 1
Start page 407
End page 418
Total pages 12
Place of publication Rockville, MD United States
Publisher American Society of Plant Biologists
Language eng
Formatted abstract
The speciation and spatial distribution of selenium (Se) in hydrated plant tissues is not well understood. Using synchrotronbased x-ray absorption spectroscopy and x-ray fluorescence microscopy (two-dimensional scanning [and associated mathematical model] and computed tomography), the speciation and distribution of toxic Se were examined within hydrated roots of cowpea (Vigna unguiculata) exposed to either 20 μM selenite or selenate. Based upon bulk solution concentrations, selenate was 9-fold more toxic to the roots than selenite, most likely due to increased accumulation of organoselenium (e.g. selenomethionine) in selenate-treated roots. Specifically, uptake of selenate (probably by sulfate transporters) occurred at a much higher rate than for selenite (apparently by both passive diffusion and phosphate transporters), with bulk root tissue Se concentrations approximately 18-fold higher in the selenate treatment. Although the proportion of Se converted to organic forms was higher for selenite (100%) than for selenate (26%), the absolute concentration of organoselenium was actually approximately 5-fold higher for selenate-treated roots. In addition, the longitudinal and radial distribution of Se in roots differed markedly: the highest tissue concentrations were in the endodermis and cortex approximately 4 mm or more behind the apex when exposed to selenate but in the meristem (approximately 1 mm from the apex) when exposed to selenite. The examination of the distribution and speciation of Se in hydrated roots provides valuable data in understanding Se uptake, transport, and toxicity.
Keyword Quantitative Pixe Microanalysis
Silicon Influx Transporter
Australian Synchrotron
Nuclear Microprobe
Higher Plants
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 6 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 7 times in Scopus Article | Citations
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Created: Sun, 22 Sep 2013, 03:18:20 EST by Peng Wang on behalf of School of Agriculture and Food Sciences