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Title: Arsenic in rice : the role of phosphate in sensitivity and the genetics behind shoot arsenic
Author: Lou-Hing, Daniel Edward
ISNI:       0000 0004 2709 7703
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2010
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Rice consumption is responsible for the largest dietary contribution of inorganic arsenic. In addition to the direct human health impact of arsenic, arsenic toxicity impacts on rice yield. Thus two issues must be addressed: rice sensitivity to arsenic and the contribution of rice towards dietary arsenic. The grass Holcus lanatus achieves arsenate tolerance through the constitutive down regulation of phosphate transporters, which facilitate arsenate uptake. To gain a better understanding of mechanisms underlying arsenic sensitivity in rice and determine if phosphate uptake was responsible for differential arsenic sensitivity between two rice cultivars (Azucena and Bala) an experiment was undertaken examining the role of phosphate in rice arsenic sensitivity. Although high phosphate treatments were found to provide protection against both arsenate and arsenite toxicity and the two cultivars were found to respond differently to phosphate induced protection, the mechanism underlying reduced arsenic sensitivity did not appear to be controlled through a reduced phosphate uptake system. Attempts to link lab-based arsenic sensitivity of various rice cultivars to published biomass and tissue arsenic concentrations of rice grown in the field is presented. No consistent trend was identified across field sites although two negative correlations at two different sites were found (grain arsenic concentrations and shoot dry weight plotted against arsenate sensitivity). These data demonstrated the importance environment influence on traits examined. These correlations suggest that breeding for more arsenic resistant rice strains may increase plant yield but inadvertently lead to an increase in grain arsenic. Finally, QTL mapping and genome-wide association mapping were used to identify genomic regions and candidates genes responsible for variations in shoot arsenic concentrations in rice. The purpose of which was to offer a better understanding of the mechanisms responsible for this variation. Unfortunately the QTLs revealed were not reproduced in the association mapping study. A list of potential positional candidate genes are summarised and functional candidates identified and discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Rice ; Arsenic ; Rice in human nutrition