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Plant Biotechnol J. 2019 Aug;17(8):1514-1526. doi: 10.1111/pbi.13074. Epub 2019 Jan 25.

Metabolic engineering of bread wheat improves grain iron concentration and bioavailability.

Author information

1
School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia.
2
School of Life and Environmental Sciences, Deakin University, Burwood, VIC, Australia.
3
Robert W. Holley Center for Agriculture and Health, USDA-ARS, Ithaca, NY, USA.
4
Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia.

Abstract

Bread wheat (Triticum aestivum L.) is cultivated on more land than any other crop and produces a fifth of the calories consumed by humans. Wheat endosperm is rich in starch yet contains low concentrations of dietary iron (Fe) and zinc (Zn). Biofortification is a micronutrient intervention aimed at increasing the density and bioavailability of essential vitamins and minerals in staple crops; Fe biofortification of wheat has proved challenging. In this study we employed constitutive expression (CE) of the rice (Oryza sativa L.) nicotianamine synthase 2 (OsNAS2) gene in bread wheat to up-regulate biosynthesis of two low molecular weight metal chelators - nicotianamine (NA) and 2'-deoxymugineic acid (DMA) - that play key roles in metal transport and nutrition. The CE-OsNAS2 plants accumulated higher concentrations of grain Fe, Zn, NA and DMA and synchrotron X-ray fluorescence microscopy (XFM) revealed enhanced localization of Fe and Zn in endosperm and crease tissues, respectively. Iron bioavailability was increased in white flour milled from field-grown CE-OsNAS2 grain and positively correlated with NA and DMA concentrations.

KEYWORDS:

2′-deoxymugineic acid; Caco-2; X-ray fluorescence microscopy; Zinc; biofortification; nicotianamine

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