Location: Plant, Soil and Nutrition ResearchTitle: Metabolic engineering of bread wheat improves grain iron concentration and bioavailability
|BEASLEY, JESSE - University Of Melbourne|
|BONNEAU, JULIEN - University Of Melbourne|
|SANCHEZ-PALACIOUS, JOSE - University Of Melbourne|
|MORENO-MOYANO, LAURA - University Of Melbourne|
|CALLAHAN, DAMIEN - Deakin University|
|LOMBI, ENZO - University Of South Australia|
|JOHNSON, ALEXANDER - University Of Melbourne|
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2018
Publication Date: 1/8/2019
Citation: Beasley, J., Bonneau, J., Sanchez-Palacious, J., Moreno-Moyano, L., Callahan, D., Tako, E.N., Glahn, R.P., Lombi, E., Johnson, A. 2019. Metabolic engineering of bread wheat improves grain iron concentration and bioavailability. Plant Biotechnology Journal. 17(8):1514-1526. https://doi.org/10.1111/pbi.13074.
Interpretive Summary: Bread wheat (Triticum aestivum L.) is cultivated on more land than any other crop and produces a fifth of the calories consumed by humans; however, wheat grain contains low concentrations of bioavailable iron (Fe). As a result, many resource-poor populations worldwide who are highly dependent on wheat for food are deficient in Fe and thus susceptible to Fe-deficiency anemia. To address this problem, this study explored an approach to insert a gene that enhances the levels of two compounds, nicotianamine and 2'-deoxymugineic acid that occur naturally in grains. These compounds are known to mobilize more Fe into the edible portions of the wheat kernel. Therefore, this study was designed to measure if more Fe was indeed mobilized into the wheat kernel, and determine if this Fe was more available for absorption in the intestine. The results indicated that this approach enhanced the amount of Fe in the kernel, and that more Fe was available for absorption. This research is significant as it demonstrates an approach for development of wheat varieties that can enhance the nutritional quality of this crop in the food supply and alleviate a major nutritional deficiency.
Technical 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 grain is rich in starch yet contains low concentrations of bioavailable 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 nicotianamine synthase 2 (OsNAS2) gene in bread wheat to upregulate biosynthesis of two metabolites - nicotianamine (NA) and 2'-deoxymugineic acid (DMA) - that play key roles in metal transport and nutrition. The CE-OsNAS2 plants remobilized higher concentrations of Fe, Zn, NA and DMA to grain and synchrotron X-ray Fluorescence Microscopy elemental maps revealed enhanced localization of Fe and Zn to endosperm and crease tissues, respectively. Iron bioavailability, as measured in an established cell culture model, in white flour milled from field-grown CE-OsNAS2 grain was increased and positively correlated with NA and DMA concentration.