2.
Mineral element composition in grain of awned and awnletted wheat (Triticum aestivum L.) cultivars tissue-specific iron speciation and phytate and non-phytate ligand ratioPaula Pongrac,
Iztok Arčon,
Hiram Castillo Michel,
Katarina Vogel-Mikuš, 2020, original scientific article
Abstract: In wheat (Triticum aestivum L.), the awns—the bristle-like structures extending from
lemmas—are photosynthetically active. Compared to awned cultivars, awnletted cultivars produce
more grains per unit area and per spike, resulting in significant reduction in grain size, but their
mineral element composition remains unstudied. Nine awned and 11 awnletted cultivars were
grown simultaneously in the field. With no difference in 1000-grain weight, a larger calcium and
manganese—but smaller iron (Fe) concentrations—were found in whole grain of awned than in
awnletted cultivars. Micro X-ray absorption near edge structure analysis of different tissues of
frozen-hydrated grain cross-sections revealed that differences in total Fe concentration were not
accompanied by differences in Fe speciation (64% of Fe existed as ferric and 36% as ferrous species) or
Fe ligands (53% were phytate and 47% were non-phytate ligands). In contrast, there was a distinct
tissue-specificity with pericarp containing the largest proportion (86%) of ferric species and nucellar
projection (49%) the smallest. Phytate ligand was predominant in aleurone, scutellum and embryo
(72%, 70%, and 56%, respectively), while nucellar projection and pericarp contained only non-phytate
ligands. Assuming Fe bioavailability depends on Fe ligands, we conclude that Fe bioavailability from
wheat grain is tissue specific.
Keywords: biofortification, phytate, iron, awn, X-ray fluorescence, X-ray absorption spectrometry, phosphorus, sulphur, nicotianamine
Published in RUNG: 16.01.2020; Views: 3672; Downloads: 0
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