Abstract
BackgroundIron deficiency anemia is a global problem which often affects women and children of developing countries. Strategy I plants, such as common bean (Phaseolus vulgaris L.) take up iron through a process that involves an iron reduction mechanism in their roots; this reduction is required to convert ferric iron to ferrous iron. Root absorbed iron is critical for the iron nutrition of the plant, and for the delivery of iron to the shoot and ultimately the seeds. The objectives of this study were to determine the variability and inheritance for iron reductase activity in a range of genotypes and in a low × high seed iron cross (DOR364 × G19833), to identify quantitative trait loci (QTL) for this trait, and to assess possible associations with seed iron levels.ResultsThe experiments were carried out with hydroponically grown plants provided different amounts of iron varying between 0 and 20 μM Fe(III)-EDDHA. The parents, DOR364 and G19833, plus 13 other cultivated or wild beans, were found to differ in iron reductase activity. Based on these initial experiments, two growth conditions (iron limited and iron sufficient) were selected as treatments for evaluating the DOR364 × G19833 recombinant inbred lines. A single major QTL was found for iron reductase activity under iron-limited conditions (1 μM Fe) on linkage group b02 and another major QTL was found under iron sufficient conditions (15 μM Fe) on linkage group b11. Associations between the b11 QTL were found with several QTL for seed iron.ConclusionsGenes conditioning iron reductase activity in iron sufficient bean plants appear to be associated with genes contributing to seed iron accumulation. Markers for bean iron reductase (FRO) homologues were found with in silico mapping based on common bean synteny with soybean and Medicago truncatula on b06 and b07; however, neither locus aligned with the QTL for iron reductase activity. In summary, the QTL for iron reductase activity under iron limited conditions may be useful in environments where beans are grown in alkaline soils, while the QTL for iron reductase under sufficiency conditions may be useful for selecting for enhanced seed nutritional quality.
Highlights
Iron deficiency anemia is a global problem which often affects women and children of developing countries
Parental differences and germplasm diversity The parents of the DOR364 × G19833 mapping population based on a high seed iron × low seed iron cross as described by Blair et al [17] were evaluated in an initial randomized complete block experiment in the growth chamber with four replications to evaluate iron reductase activity across a range of iron concentrations that included 0, 1, 2, 5, 10 and 20 μM Fe(III)-EDDHA (Fe)
These differences were more evident in plants grown at low Fe concentrations than at high iron concentrations, such that G19833 had its highest iron reductase activity when grown at 0 μM Fe, while DOR364 exhibited very low iron reductase activity when grown at 0 or 1 μM Fe, but achieved higher rates when grown at 2 μM Fe
Summary
Iron deficiency anemia is a global problem which often affects women and children of developing countries. Iron deficiency anemia (IDA) is among the most common nutritional problems of human populations throughout the world, affecting more than 2 billion people to varying degrees [1]. Drawbacks are the taste of the liquid medicine, teeth staining and need for outreach and a delivery mechanism [4] Fortification is another approach for delivering iron to IDA susceptible populations that is best done with flours produced from cereals but tends to be costly and is not an option for whole grains, like legumes. An alternative to both of these is to increase the concentration of iron in diets through biofortification of staple foods [6]. Common bean, has been targeted in the worldwide effort on biofortification as a strategic crop for increasing dietary iron for human beings
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