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

Abstract

Background Anemia is thought to affect up to 1.6 billion people worldwide. One of the major contributors to low iron (Fe) absorption is a higher proportion of cereals compared to meats and pulse crops in people’s 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 vehicle for bringing more bioavailable Fe into the diet. Results 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 UK wheat polymorphism, was grown over two seasons in the UK. The population was phenotyped for both Fe concentration and Fe bioavailability using an established Caco-2 cell bioassay. It was found that increasing Fe concentrations in the grains was not correlated with higher Fe bioavailability and that the underlying genetic regions controlling grain Fe concentrations do not co-localise with increased Fe absorption. Furthermore, we show that phytate concentrations do not correlate with Fe bioavailability 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. Conclusions This suggests that breeders will have to select not only for Fe concentrations directly in grains, but also increased bioavailability. However the use of numerous controls and replicated trials limits the practicality of adoption of screening by Caco-2 cells by many breeders.

Trade-offs in the genetic control of functional and nutritional quality traits in UK winter wheat

“…Additional small genetic effects may explain the remaining heritability but were not detected using the statistical power available in this study. Wright et al ( 2021 ) investigated similar traits in the same population with a similar number of lines and found that the probability of detecting small effect QTL (explaining <10% of the variation) was very low, unless the trait heritability was very high. We acknowledge that low heritability of some traits and testing in only two trial years may limit the extent to which results can be interpreted.…”

Nutritional and genetic variation in a core set of Ethiopian Tef (Eragrostis tef) varieties

“…While future research is required to determine whether elevated levels of phenolics that stimulate and inhibit Fe uptake in the human gut can help alleviate the anaemia seen in Ethiopian children [ 67 ], the significance of the SNP in the tef F3’H gene Et_s3159-0.29-1.mrna1, which explains a large proportion of the variation in kaempferol glycoside and quercetin glycoside levels, suggest this might be a breeding target to improve Fe bioavailability in tef, as kaempferol glycoside is known to promote Fe absorption while quercetin glycoside inhibits Fe absorption in cell assays [ 60 ]. In addition, phenolic compounds have also been found to influence other agronomic traits, including tolerance to both biotic and abiotic stress [ 16 , 60 , 61 , 68 ].…”

“…Recent advancements in our understanding of the genetics of tef include a fairly complete genome assembly, the release of gene models, as well as a number of RNASeq datasets which are all publicly available [ 11 ] . These allow for translation of knowledge on grain fortification from other species, supporting more rapid advancements in efforts to improve the nutritional potential of tef [ 12 – 16 ].…”

Biofortification to avoid malnutrition in humans in a changing climate: Enhancing micronutrient bioavailability in seed, tuber, and storage roots

“…Yet, increasing Fe content in wheat seeds seems to not correlate with higher Fe bioavailability and the underlying genetic regions controlling Fe content not found, yet, to colocalize with increased Fe absorption. In addition, phytate content also does not correlate with Fe bioavailability, leading to the conclusion that phytate binding may be insufficient to explain the lack of correlation between Fe bioavailability and Fe content ( Wright et al., 2021 ). All these observations give hope that Fe content and bioavailability are independent and feasible to integrate the two traits simultaneously.…”