Genetic control of iron bioavailability is independent from iron concentration in a diverse winter wheat mapping population

Authors: WRIGHT, TALLY - National Institute Of Agricultural Botany (NIAB); GARDNER, KEITH - National Institute Of Agricultural Botany (NIAB); Glahn, Raymond; MILNER, MATTHEW - National Institute Of Agricultural Botany (NIAB)

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2021
Publication Date: 5/11/2021
Citation: Wright, T.I., Gardner, K., Glahn, R.P., Milner, M.J. 2021. Genetic control of iron bioavailability is independent from iron concentration in a diverse winter wheat mapping population. Biomed Central (BMC) Plant Biology. 21:212-225. https://doi.org/10.1186/s12870-021-02996-6.
DOI: https://doi.org/10.1186/s12870-021-02996-6

Interpretive Summary: Anemia is thought to affect up to 1.6 billion people worldwide. One of the major contributors to low iron (Fe) absorption from a person’s diet is a high proportion of a cereals in the diet, rather than animal-based diets. This has now become a problem in both the developed and developing world, as a result of both modern food choice and food availability. Bread wheat accounts for 20% of the calories consumed by humans and is an important source of protein, vitamins and minerals meaning it could be a major route for bringing increased Fe into the diet. To investigate whether breeding for higher concentrations of Fe in wheat grains could help increase Fe absorption, a population of wheat varieties were generated that encompassed more than 80% of variability in wheat varieties within the United Kingdom. The population was assessed for both Fe concentration and Fe bioavailability. It was found that increasing Fe levels in the grains were not correlated with higher Fe absorption and that the underlying genetic regions controlling grain Fe levels do not co-localise with increased Fe absorption. This suggests that breeders will have to select not only for Fe levels directly in grains, but also increased bioavailability.

Technical Abstract: Anemia is thought to affect up to 1.6 billion people worldwide. One of the major contributors to low iron (Fe) absorption from a person’s diet is a high proportion of a cereals in the diet, rather than animal-based diets. This has now become a problem in both the developed and developing world, as a result of both modern food choice and food availability. Bread wheat accounts for 20% of the calories consumed by humans and is an important source of protein, vitamins and minerals meaning it could be a major route for bringing increased Fe into the diet. To investigate whether breeding for higher concentrations of Fe in wheat grains could help increase Fe absorption, a multiparent advanced generation intercross (MAGIC) population encompassing more than 80% of the UK wheat polymorphism was grown over two seasons in the UK. The population was phenotyped for both Fe concentration and Fe bioavailability using caco-2 cells. It was found that increasing Fe levels in the grains were not correlated with higher Fe absorption and that the underlying genetic regions controlling grain Fe levels do not co-localise with increased Fe absorption. This suggests that breeders will have to select not only for Fe levels directly in grains, but also increased bioavailability. Furthermore, we show that phytate levels do not correlate with Fe absorption in our wheat population and thus phytate-binding is insufficient to explain the lack of correlation between Fe bioavailability and Fe concentrations in the wheat grain. Finally, we observed no (Fe bioavailability) or low (Fe concentration) correlation between years for these traits, confirming that both are under strong environmental influence.