Genetic and Physiological Analysis of Iron Biofortification in Maize Kernels

Abstract

BackgroundMaize is a major cereal crop widely consumed in developing countries, which have a high prevalence of iron (Fe) deficiency anemia. The major cause of Fe deficiency in these countries is inadequate intake of bioavailable Fe, where poverty is a major factor. Therefore, biofortification of maize by increasing Fe concentration and or bioavailability has great potential to alleviate this deficiency. Maize is also a model system for genomic research and thus allows the opportunity for gene discovery. Here we describe an integrated genetic and physiological analysis of Fe nutrition in maize kernels, to identify loci that influence grain Fe concentration and bioavailability.MethodologyQuantitative trait locus (QTL) analysis was used to dissect grain Fe concentration (FeGC) and Fe bioavailability (FeGB) from the Intermated B73 × Mo17 (IBM) recombinant inbred (RI) population. FeGC was determined by ion coupled argon plasma emission spectroscopy (ICP). FeGB was determined by an in vitro digestion/Caco-2 cell line bioassay.ConclusionsThree modest QTL for FeGC were detected, in spite of high heritability. This suggests that FeGC is controlled by many small QTL, which may make it a challenging trait to improve by marker assisted breeding. Ten QTL for FeGB were identified and explained 54% of the variance observed in samples from a single year/location. Three of the largest FeGB QTL were isolated in sister derived lines and their effect was observed in three subsequent seasons in New York. Single season evaluations were also made at six other sites around North America, suggesting the enhancement of FeGB was not specific to our farm site. FeGB was not correlated with FeGC or phytic acid, suggesting that novel regulators of Fe nutrition are responsible for the differences observed. Our results indicate that iron biofortification of maize grain is achievable using specialized phenotyping tools and conventional plant breeding techniques.

Biofortification of Wheat with Iron

“…Moreover, recombinant hybrid line formed from crossing of two distantly related lines may help in mapping and identifying of quantitative and single trait loci like in Medicago [80] and wheat [81]. Different crops such as maize and rice line with novel traits have been screened on the basis of Fe uptake and its biobioavailability analysis [82].…”

Comprehensive phenotypic analysis and quantitative trait locus identification for grain mineral concentration, content, and yield in maize (Zea mays L.)

“…Several QTL studies have been conducted in maize for grain mineral concentration (Garcia-Oliveira et al 2009;Zhou et al 2010;Lung'aho et al 2011;Qin et al 2012;Šimic et al 2012;Baxter et al 2013Baxter et al , 2014. Stable or consistent QTL across different environments could only be identified in some of these above studies.…”

Genetic Variation for Biofortifying The Maize Grain

“…In some cases, environment affects both the traits simultaneously in the same direction or sometimes in different directions (Yücel et al, 2009). Several studies have reported significant positive correlation between Fe and Zn contents in maize and other crops (Baxter et al, 2013;Chakraborti et al, 2009;Lungaho et al, 2011;Baloch et al, 2014). This could be possibly due to linkage between the genes affecting the accumulations or pleotropic effects of the genes governing the accumulation of micronutrients and the existence of one or more common genetic-physiological mechanisms involved in mineral absorption or uptake by the root system, translocation and redistribution within the plant tissues, remobilization to the grain, or accumulation in the developing grain (Çakmak, 2008;Peleg et al, 2008;Chatvaz et al, 2010).…”