Localization of iron in rice grain using synchrotron X-ray fluorescence microscopy and high resolution secondary ion mass spectrometry

Bianca Kyriacou, Katie Moore, David Paterson, Martin de Jonge, Daryl Howard, James Stangoulis, Mark Tester, Enzo Lombi, Alexander Johnson

    Research output: Contribution to journalArticle

    46 Citations (Scopus)

    Abstract

    Cereal crops accumulate low levels of iron (Fe) of which only a small fraction (5-10%) is bioavailable in human diets. Extensive co-localization of Fe in outer grain tissues with phytic acid, a strong chelator of metal ions, results in the formation of insoluble complexes that cannot be digested by humans. Here we describe the use of synchrotron X-ray fluorescence microscopy (XFM) and high resolution secondary ion mass spectrometry (NanoSIMS) to map the distribution of Fe, zinc (Zn), phosphorus (P) and other elements in the aleurone and subaleurone layers of mature grain from wild-type and an Fe-enriched line of rice (Oryza sativa L.). The results obtained from both XFM and NanoSIMS indicated that most Fe was co-localized with P (indicative of phytic acid) in the aleurone layer but that a small amount of Fe, often present as "hotspots", extended further into the subaleurone and outer endosperm in a pattern that was not co-localized with P. We hypothesize that Fe in subaleurone and outer endosperm layers of rice grain could be bound to low molecular weight chelators such as nicotianamine and/or deoxymugineic acid.

    Original languageEnglish
    Pages (from-to)173-180
    Number of pages8
    JournalJournal of Cereal Science
    Volume59
    Issue number2
    DOIs
    Publication statusPublished - 2014

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