Fe Bioavailability Research Articles

Enhancement of sorghum grain yield and nutrition: A role for arbuscular mycorrhizal fungi regardless of soil phosphorus availability

Societal Impact StatementSorghum is an important cereal crop that provides calories and nutrients for much of the world's population, and it is often grown with low fertiliser input. Optimising the yield, nutritive content and bioavailability of sorghum grain with minimal input is of importance for human nutrition, and arbuscular mycorrhizal (AM) fungi have previously shown potential to assist in this. Across sorghum genetic diversity, AM fungi improved the yield, nutrition and zinc and iron bioavailability of grain in a low phosphorus soil. Thus, food production systems that effectively manage AM fungi may improve consumer outcomes.Summary Sorghum is a C4 cereal crop that is an important source of calories and nutrition across the world, predominantly cultivated and consumed in low‐ and middle‐income countries. Sorghum can be highly colonised by arbuscular mycorrhizal (AM) fungi, and the plant‐fungal association can lead to improvements in biomass and nutrient uptake. High‐throughput phenotyping allows us to non‐destructively interrogate the ‘hidden’ effects of AM fungi on sorghum growth and phenology. Eight genetically diverse sorghum genotypes were grown in a soil amended with 2 or 20 mg P kg−1 and inoculated with an AM fungal culture of Rhizophagus irregularis. High‐throughput phenotyping uncovered the ‘hidden’ effects of AM fungi on growth and phenology, while grain biomass, nutrition, Zn and Fe bioavailability and root AM colonisation was determined after destructive harvest. Sorghum plants colonised by AM fungi generally performed better than non‐AM control plants, with greater yield, harvest indices, and grain P, Zn and Fe contents. During the early growth stages, AM colonisation led to temporary growth depressions. There were also AM fungal and P fertilisation effects on sorghum time‐of‐flowering. The sorghum genotype with the highest AM colonisation could barely produce grain when non‐inoculated. The two genotypes that failed to mature had very low AM colonisation. Generally, the genetically diverse sorghum genotypes were highly responsive to AM colonisation and produced more grain of greater nutritive quality when colonised, without adverse consequences for micronutrient bioavailability.

High iron content in river waters: environmental risks for aquatic biota and human health

This study assessed the concentrations of metals in the Dourados and Brilhante Rivers, investigated the influence of landscape features surrounding these rivers on water quality, and evaluated the risks associated with metal contamination for aquatic biota and human health. Sampling was conducted at eighteen sites distributed along the rivers in June 2016. The concentrations of metals (Cu, Zn, Mn, Fe, Cr, Al and Co) in the water were analyzed by inductively coupled plasma optical emission spectroscopy. All the samples possessed Fe concentrations above the threshold value for aquatic biota (0.3 mg L-1). Moreover, land use and land cover assessment of the study area revealed extensive agriculture activity, particularly in areas surrounding the Dourados River headwaters. Fe bioavailability for both rivers indicated risks for aquatic biota and human health. Overall, the elevated Fe content in these rivers was attributed to anthropogenic activity in the vicinity of these water bodies and the soil characteristics of the area. Considering the importance of river basins, it is necessary to implement public policies for their conservation, especially those related to the cultivation of forests of native species and sustainable agricultural practices, in addition to improving the effluent treatment infrastructure, which is essential to minimize the adverse effects of contamination by chemical elements in water bodies.
 Keywords: aquatic ecosystems, environmental contaminants, forest fragments.

Grain mineral nutrient profiling and iron bioavailability of an ancient crop tef (Eragrostis tef)

Tef (Eragrostis tef) is an underutilized food crop rich in minerals, vitamins, and amino acids. However, mineral profiling of diverse tef accessions, and estimation of bioavailable iron from tef has been lacking. In this study, we analyzed the mineral content of 41 tef accessions along with major cereals. Our analysis revealed that tef seeds contain significantly more minerals than maize, rice, and the wheat varieties used in this study. A significant variation in mineral content was also observed across the tef accessions. We also performed a relative estimation of Fe bioavailability from selected tef accessions and reference crops using an established Caco-2 cell bioassay. This bioassay measures human intestinal cell Fe uptake via intracellular ferritin formation, a storage protein that is a validated marker of Fe uptake. Higher levels of Fe uptake were observed in the PI-494307, PI-494425, and PI-195937 accessions, than those recorded in cells fed wheat, rice, or tef accessions PI-329681, PI-494408 and PI-494293. There was no marked difference in phytic acid (PA) content between tef and wheat, while the PA level in rice was lower than tef and wheat. Enhanced Fe uptake evident in tef accession PI494425 could not be explained by seed Fe content. The Fe content of PI-494425 was lower than the other tef accessions, suggesting that other factors control the amount of bioavailable Fe from tef. Considerable variation in mineral content and bioavailable Fe between tef and other cereals indicate a potential for improving mineral nutrition from this vital food crop

Redefining Bean Iron Biofortification: A Review of the Evidence for Moving to a High Fe Bioavailability Approach

Iron biofortification of the common bean (Phaseolus vulgaris) commenced in earnest ~18 years ago. Based on knowledge at the time, the biofortification approach for beans was simply to breed for increased Fe concentration based on 3 major assumptions: (1) The average bean Fe concentration is ~50 μg/g; (2) Higher Fe concentration results in more bioavailable Fe delivered for absorption; (3) Breeding for high Fe concentration is a trait that can be achieved through traditional breeding and is sustainable once a high Fe bean sample is released to farmers. Current research indicates that the assumptions of the high Fe breeding approach are not met in countries of East Africa, a major focus area of bean Fe biofortification. Thus, there is a need to redefine bean Fe biofortification. For assumption 1, recent research indicates that the average bean Fe concentration in East Africa is 71 μg/g, thus about 20 μg/g higher than the assumed value. For assumption 2, recent studies demonstrate that for beans higher Fe concentration does not always equate to more Fe absorption. Finally, for assumption 3, studies show a strong environment and genotype by environment effect on Fe concentration, thus making it difficult to develop and sustain high Fe concentrations. This paper provides an examination of the available evidence related to the above assumptions, and offers an alternative approach utilizing tools that focus on Fe bioavailability to redefine Fe biofortification of the common bean.

Salp fecal pellets release more bioavailable iron to Southern Ocean phytoplankton than krill fecal pellets

Over the last decades, it has been reported that the habitat of the Southern Ocean (SO) key species Antarctic krill (Euphausia superba) has contracted to high latitudes, putatively due to reduced winter sea ice coverage, while salps as Salpa thompsoni have extended their dispersal to the former krill habitats. To date, the potential implications of this population shift on the biogeochemical cycling of the limiting micronutrient iron (Fe) and its bioavailability to SO phytoplankton has never been tested. Based on uptake of fecal pellet (FP)-released Fe by SO phytoplankton, this study highlights how efficiently krill and salps recycle Fe. To test this, we collected FPs of natural populations of salps and krill, added them to the same SO phytoplankton community, and measured the community's Fe uptake rates. Our results reveal that both FP additions yielded similar dissolved iron concentrations in the seawater. Per FP carbon added to the seawater, 4.8± 1.5 times more Fe was taken up by the same phytoplankton community from salp FP than from krill FP, suggesting that salp FP increased the Fe bioavailability, possibly through the release of ligands. With respect to the ongoing shift from krill to salps, the potential for carbon fixation of the Fe-limited SO could be strengthened in the future, representing a negative feedback to climate change.

Alterations in the Intestinal Morphology, Gut Microbiota, and Trace Mineral Status Following Intraamniotic Administration (Gallus gallus) of Genistein

Abstract Objectives Assess the effects of intraamniotic genistein administration on brush border membrane (BBM) functionality, intestinal morphology, cecal microbiome and Fe status in-vivo (Gallus gallus). Methods Broiler chickens (Gallus gallus, n = 39) were injected in ovo (day 17 of embryonic incubation) with varying concentrations of 1 mL pure genistein in 18 Ω H2O. Two treatment groups (1.25, 2.5%), two controls (water and non-injected), and a positive control (5% inulin) were administered. Upon hatch, blood was taken for hemoglobin determination and chicks were then euthanized. Nutritional status was assessed using pectoral muscle glycogen storage and body weight analysis. Duodenal and cecal tissues were excised for BBM morphometric analysis, mRNA gene expression of relevant BBM Fe transporter proteins, and 16S rRNA gene sequencing was done to evaluate gut microbiota modulation in the intestinal cecum. Results Preliminary results reveal significant increase in body weight, decrease of cecum weight, and increase in villus surface area with the higher dose of genistein administration (P < 0.05) compared to controls. Blood hemoglobin was found to be increased in the genistein-treated groups when compared to the controls (P < 0.05). Additionally, genistein administration downregulated the expression of duodenal cytochrome B (DcytB) and divalent metal transporter 1 (DMT1) and upregulated the expression of ferroportin with a dose responsive effect, indicating improved Fe physiological status. Further, administration of genistein altered the composition and function of cecal microbiota. Conclusions Genistein is a compound present in multiple staple food crops, including soybeans and chickpeas, and may be extracted and potentially used to enhance dietary Fe bioavailability and improve Fe deficiency in vulnerable populations. Recent evidence suggests a physiological role for genistein administration in improving the functionality and development of the BBM, improving Fe status, affecting the intestinal microbiome, as well as improving physiological status. Funding Sources N/A.

Nicotianamine-Chelated Iron Positively Affects Iron Status, Intestinal Morphology and Microbial Populations In Vivo (Gallus Gallus)

Abstract Objectives Iron (Fe) fortification involves low dose delivery of bioavailable Fe fortificants to food products during manufacture (or point-of-use) and is an effective population-based strategy to combat human Fe deficiencies that affect over 2 billion people globally. Iron fortification of wheat flour is now mandatory in 75 countries worldwide, however, the tendency of Fe fortificants to oxidize and cause undesired organoleptic and sensory properties pose significant challenges. Nicotianamine (NA) is a natural chelator of Fe and zinc (Zn) in higher plants and NA-chelated Fe is highly bioavailable in vitro. In graminaceous plants NA serves as the biosynthetic precursor to 2′ -deoxymugineic acid (DMA), a related Fe chelator and enhancer of Fe bioavailability, and increased NA/DMA biosynthesis has proved an effective Fe biofortification strategy in several cereal crops. In this study we aimed to investigate the impact of NA-chelated Fe on Fe status and gastrointestinal health in vivo. Methods We utilized the versatile chicken (Gallus gallus) model to assess NA-chelated Fe when delivered to chickens through intraamniotic administration (short-term exposure) or over a period of six weeks as part of a biofortified wheat diet containing increased NA, Fe, Zn and DMA (long-term exposure). Results Following short-term exposure, chickens that received an NA-chelated Fe treatment demonstrated significantly increased blood serum Fe, intestinal goblet cell number, and abundance of Bifidobacterium relative to chickens that received control Fe treatments (either EDTA-chelated Fe or unchelated Fe). Following long-term exposure, chickens that consumed the biofortified diet had significantly increased liver Fe, liver and muscle glycogen, and intestinal goblet cell number, as well as significantly different microbial population diversities (including a greater abundance of Bifidobacterium and Lactobacillus) relative to chickens that consumed the control diet. Conclusions Taken together these results demonstrate numerous health benefits associated with NA-chelated Fe in a biofortified wheat diet and uncover novel impacts of NA-chelated Fe on gastrointestinal health and functionality. Funding Sources This work was supported by grants from the USDA-ARS and HarvestPlus.

Iron Chelator Transmetalative Approach to Inhibit Human Ribonucleotide Reductase.

Efforts directed at curtailing the bioavailability of intracellular iron could lead to the development of broad-spectrum anticancer drugs given the metal’s role in cancer proliferation and metastasis. Human ribonucleotide reductase (RNR), the key enzyme responsible for synthesizing the building blocks of DNA replication and repair, depends on Fe binding at its R2 subunit to activate the catalytic R1 subunit. This work explores an intracellular iron chelator transmetalative approach to inhibit RNR using the titanium(IV) chemical transferrin mimetic (cTfm) compounds Ti(HBED) and Ti(Deferasirox)2. Whole-cell EPR studies reveal that the compounds can effectively attenuate RNR activity though seemingly causing different changes to the labile iron pool that may account for differences in their potency against cells. Studies of Ti(IV) interactions with the adenosine nucleotide family at pH 7.4 reveal strong metal binding and extensive phosphate hydrolysis, which suggest the capacity of the metal to disturb the nucleotide substrate pool of the RNR enzyme. By decreasing intracellular Fe bioavailability and altering the nucleotide substrate pool, the Ti cTfm compounds could inhibit the activity of the R1 and R2 subunits of RNR. The compounds arrest the cell cycle in the S phase, indicating suppressed DNA replication, and induce apoptotic cell death. Cotreatment cell viability studies with cisplatin and Ti(Deferasirox)2 reveal a promising synergism between the compounds that is likely owed to their distinct but complementary effect on DNA replication.

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

BackgroundAnemia 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.ResultsTo 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.ConclusionsThis 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.

Interactions between Fe and light strongly affect phytoplankton communities in a eutrophic lake

The global increase in occurrence of harmful algae blooms in lakes has gained widespread attention. Although N and P are the main factors for primary productivity in lake ecosystems, dissolved iron (Fe) plays a crucial role as an essential micronutrient for phytoplankton growth. The interaction between Fe and light in phytoplankton growth is reasonably well studied in marine ecosystems, but there is a lack of understanding of this interaction in lakes. We conducted both a field study and an incubation experiment to identify the role of Fe and light in modulating phytoplankton growth and species composition in a eutrophic lake, Lake Xingkai, Northeast China. We found that the interactions between Fe bioavailability and light intensity impact phytoplankton community structure and Fe uptake. Phytoplankton composition and abundance varied greatly in response to elevated light and Fe. Bacillariophyta are favored under light-Fe co-limitation, while the dominant taxa changed from Bacillariophyta to Cyanophyta and Chlorophyta under elevated Fe and light conditions. We unveil the competitive advantage of a common bloom-forming and N2-fixing algae Anabaena azotica relative to other species under high light and high Fe conditions. Our findings expand the knowledge of Fe-light interactions on phytoplankton growth and provide fresh insight into phytoplankton community responses to variation in light and Fe in eutrophic lakes. This information is important for efficient eutrophication control and lake management.

Content of minerals and antinutritional factors in moin-moin (steamed cowpea food)

Moin-moin (steamed cowpea food; MM) is one of the most popular local dishes in Bahia-Brazil. The present study was carried out to improve the knowledge of type of cowpea used in the preparation of moin-moin and its influence on mineral content and antinutritional factors. MM samples were collected from 30 out of the sales points located in the city of Salvador-Bahia. The mineral contents of MM showed a wide variation: K: 917.4 ± 166.2 mg 100 g-1 DM, P: 400.0 ± 59.8 mg 100 g-1 DM, Mg: 97.9 ± 16.4 mg 100 g-1 DM, Ca: 94.0 ± 70.4 mg 100 g-1 DM, Fe: 57.3 ± 16.9 µg g-1 DM, Zn: 22.4 ± 4.2 µg g-1 DM, Cu: 6.3 ± 3.3 µg g-1 DM, Mn: 6.0 ± 2.8 µg g-1 DM and V: 4.3 ± 2.0 µg g-1 DM. AF in MM were: 0.60 ± 0.77 µmol g-1 DM (InsP4); 1.34 ± 1.07 µmol g-1 DM (InsP5); 4.77 ± 3.53 µmol g-1 DM (InsP6); 1.69 ± 0.03 mg eq. CE g-1 DM (tannins); 6.37 ± 0.12 mg g-1 DM (polyphenols). Fe bioavailability might be negatively affected. Information on cowpea cultivars used for MM preparation was obtained from a structured questionnaire. ‘Olho de Pombo’ showed the highest concentrations for AF and minerals. MM was identified as a good source of minerals. Key words: Antinutritional factors, cowpea (Vigna unguiculata), crude palm oil, minerals, moin-moin.

Dual-Fortified Lentil Products-A Sustainable New Approach to Provide Additional Bioavailable Iron and Zinc in Humans.

ABSTRACTBackgroundIron (Fe) and zinc (Zn) deficiencies are global health problems affecting 20% and 33% of the world's population, respectively. Lentil (Lens culinaris Medik.), part of the staple food supply in many countries, can be a potential vehicle for Fe and Zn fortification.ObjectiveWe developed a dual-fortification protocol to fortify 3 milled lentil product types (LPTs) [red-football (RF), red-split (RS), and yellow-split (YS)], with NaFeEDTA and ZnSO4.H2O to increase the bioavailable content of Fe and Zn.MethodsAppropriate Fe and Zn doses were determined to fortify lentils based on RDAs. Relative Fe bioavailability (RFeB%) and phytic acid (PA) content were assessed using an in vitro Caco-2 cell bioassay and PA analysis, respectively. One-factor ANOVA determined the differences in colorimetric score; concentrations of Fe, Zn, and PA; and RFeB% among samples. The least significant difference was calculated with significance level set at P < 0.05.ResultsFe and Zn concentration and RFeB% increased and PA concentration decreased significantly in dual-fortified lentils. Dual-fortified lentil samples had higher RFeB% compared with Fe-fortified (single) samples in all 3 LPTs, whereas RFeB% decreased in Zn-fortified (single) RF and YS samples by 43.4% and 36%, respectively. The RF, RS, and YS samples, fortified with 16 mg Fe and 8 mg Zn/100 g of lentils, provided 27 mg Fe and 14 mg Zn, 28 mg Fe and 13.4 mg Zn, and 29.9 mg Fe and 12.1 mg Zn, respectively. RFeB% of RF, RS, and YS lentil samples increased by 91–307%, 114–522%, and 122–520%, respectively. Again, PA concentrations of RF, RS, and YS lentils were reduced by 0.63–0.53, 0.83–0.71, and 0.96–0.79 mg/g, respectively.ConclusionsDual-fortified lentil consumption can cost-effectively provide a significant part of the daily bioavailable Fe and Zn requirements of people with these 2 globally important micronutrient deficiencies.

Iron- and Zinc-Fortified Lentil (Lens culinaris Medik.) Demonstrate Enhanced and Stable Iron Bioavailability After Storage

Lentil (Lens culinaris Medik.) is a quick-cooking, rapidly expanding protein-rich crop with high iron (Fe) and zinc (Zn), but low bioavailability due to the presence of phytate, similar to other grains. Lentils dual fortified with Fe and Zn can significantly improve the bioavailable Fe and Zn content. Three milled lentil product types (LPTs) were fortified with Fe using NaFeEDTA [ethylenediaminetetraacetic acid iron (III) sodium salt] (Fe fortified) or Zn from ZnSO4·H2O (Zn fortified), or both (dual fortified). Fe, Zn, phytic acid (PA) concentration, and relative Fe bioavailability (RFeB%) were assessed for samples from two fortified batches (initial and for 1 year stored). Fe, Zn, and RFeB% increased significantly in two batches of samples from the three LPTs, and decreased by 5–15% after 1 year of storage. PA concentration decreased from 8 to 15% after fortification of all samples from two batches of the three LPTs but showed different patterns of influence after storage. Dual-fortified lentil fortified with 24 mg Fe and 12 mg Zn 100 g−1 lentil had the highest amount of Fe and Zn, and the lowest PA concentration, and RFeB% was increased from 91.3 to 519.5%. Significant (p ≤ 0.01) Pearson correlations were observed between Fe concentration vs. PA:Fe molar ratio (MR), Fe concentration vs. RFeB%, RFeB% vs. PA:Fe MR, and Zn concentration vs. PA:Zn MR in all samples from two batches of the three LPTs. In conclusion, dual-fortified lentil can contribute significant bioavailable Fe and Zn to populations at risk of Fe and Zn deficiency.

PAP/SAL1 retrograde signaling pathway modulates iron deficiency response in alkaline soils

Iron (Fe) is an essential micronutrient for plants and is present abundantly in the Earth's crust. However, Fe bioavailability in alkaline soils is low due to the decreased solubility of the ferric ions. Previously, we have demonstrated the relationship between the PAP/SAL1 retrograde signaling pathway, the activity of Strategy I Fe uptake genes (FIT, FRO2, IRT1), and ethylene signaling. In this work, we have characterized mutant lines that are deficient in this retrograde signaling pathway and their ability to grow in alkaline soils. This adverse growth condition caused less impact on mutant plants, which showed less reduced rosette area, and higher carotenoid, chlorophyll and Fe content than wild-type plants. Several genes involved in the biosynthesis and excretion of secondary metabolites derived from the phenylpropanoid pathway, which improve Fe uptake, were elevated in mutant plants. Finally, we observed an increase in excreted fluorescent phenolic compounds in mutant lines compared to wild-type plants. In this way, PAP/SAL1 mutants showed alterations in the biosynthesis of metabolites that mobilize Fe, which ultimately improved these plants ability to grow in alkaline soils. Results agree with the existence of a link between the PAP/SAL1 retrograde signaling pathway and the regulation of Fe deficiency responses in Arabidopsis.

Exopolymeric Substances Control Microbial Community Structure and Function by Contributing to both C and Fe Nutrition in Fe-Limited Southern Ocean Provinces.

Organic ligands such as exopolymeric substances (EPS) are known to form complexes with iron (Fe) and modulate phytoplankton growth. However, the effect of organic ligands on bacterial and viral communities remains largely unknown. Here, we assessed how Fe associated with organic ligands influences phytoplankton, microbial, and viral abundances and their diversity in the Southern Ocean. While the particulate organic carbon (POC) was modulated by Fe chemistry and bioavailability in the Drake Passage, the abundance and diversity of microbes and viruses were not governed by Fe bioavailability. Only following amendments with bacterial EPS did bacterial abundances increase, while phenotypic alpha diversity of bacterial and viral communities decreased. The latter was accompanied by significantly enhanced POC, pointing toward the relief of C limitation or other drivers of the microbial loop. Based on the literature and our findings, we propose a conceptual framework by which EPS may affect phytoplankton, bacteria, and viruses. Given the importance of the Southern Ocean for Earth’s climate as well as the prevalence of viruses and their increasingly recognized impact on marine biogeochemistry and C cycling; the role of microbe–virus interactions on primary productivity in the Southern Ocean needs urgent attention.

Effect of Rice GDP-L-Galactose Phosphorylase Constitutive Overexpression on Ascorbate Concentration, Stress Tolerance, and Iron Bioavailability in Rice.

Ascorbate (vitamin C) is an essential multifunctional molecule for both plants and mammals. In plants, ascorbate is the most abundant water-soluble antioxidant that supports stress tolerance. In humans, ascorbate is an essential micronutrient and promotes iron (Fe) absorption in the gut. Engineering crops with increased ascorbate levels have the potential to improve both crop stress tolerance and human health. Here, rice (Oryza sativa L.) plants were engineered to constitutively overexpress the rice GDP-L-galactose phosphorylase coding sequence (35S-OsGGP), which encodes the rate-limiting enzymatic step of the L-galactose pathway. Ascorbate concentrations were negligible in both null segregant (NS) and 35S-OsGGP brown rice (BR, unpolished grain), but significantly increased in 35S-OsGGP germinated brown rice (GBR) relative to NS. Foliar ascorbate concentrations were significantly increased in 35S-OsGGP plants in the vegetative growth phase relative to NS, but significantly reduced at the reproductive growth phase and were associated with reduced OsGGP transcript levels. The 35S-OsGGP plants did not display altered salt tolerance at the vegetative growth phase despite having elevated ascorbate concentrations. Ascorbate concentrations were positively correlated with ferritin concentrations in Caco-2 cells – an accurate predictor of Fe bioavailability in human digestion – exposed to in vitro digests of NS and 35S-OsGGP BR and GBR samples.

The Coumarins: Secondary Metabolites Playing a Primary Role in Plant Nutrition and Health.

Although abundant in soils, iron (Fe) is poorly bioavailable for plants. Improving Fe uptake in crops, enabling them to grow in Fe-depleted soils, has become a major focal interest. The secretion of Fe-mobilizing coumarins by plant roots recently emerged as an important factor allowing nongrass species to cope with low Fe bioavailability. The main molecular actors involved in the biosynthesis and secretion of coumarins have been identified, but the precise regulatory mechanisms that tune their production remain poorly understood. Here, we review the recent progress in coumarin synthesis and transport in plants and future research directions to gain knowledge of these mechanisms, which will offer novel opportunities for improving plant growth and health and for generating Fe-fortified crops.

Iron Concentrations in Biofortified Beans and Nonbiofortified Marketplace Varieties in East Africa Are Similar

The predominant bean iron (Fe) biofortification approach is to breed for high Fe concentration and assumes the average Fe concentration is 50μg/g. This approach also assumes that a 40μg/g increase is sustainable and Fe bioavailability will not decrease to negate the increase in Fe. The overall objective was to determine if bean Fe biofortification via breeding for high Fe is producing beans with higher Fe concentration relative to nonbiofortified lines found in the East Africa marketplace. Seventy-six marketplace samples (East Africa Marketplace Collection; EAMC), and 154 genotypes known to be representative of the marketplace were collected from breeders in the Pan-Africa Bean Research Alliance (designated the East Africa Breeder Collection; EABC). Within the EAMC and EABC were 18 and 35 samples, respectively, that were released as biofortified lines. All samples were measured for Fe concentration. The Caco-2 cell bioassay assessed Fe bioavailability of the EAMC. Biofortified versus nonbiofortified samples were compared by the appropriate t-test or ANOVA. The Fe concentration of the 58 nonbiofortified EAMC lines was (mean±SD [range]) 71±9μg/g (52-93μg/g) which did not differ significantly from the 18 biofortified EAMC varieties (71±11μg/g [55-94μg/g]). The Fe concentration of the 119 nonbiofortified EABC varieties was 66±7μg/g (51-90μg/g) which was significantly different (P < 0.0001) from the 35 EABC biofortified lines (73±9μg/g [60-91μg/g]). However, the EABC biofortified lines were not different from the nonbiofortified EAMC samples. In the Caco-2 cell bioassay, biofortified EAMC varieties did not deliver more Fe compared with nonbiofortified EAMC varieties. The assumptions of the high Fe bean biofortification approach are not met in the East African marketplace. Iron concentration and bioavailability measurement indicate the biofortified bean varieties are providing no additional dietary Fe.

Low Phytate Peas (Pisum sativum L.) Improve Iron Status, Gut Microbiome, and Brush Border Membrane Functionality In Vivo (Gallus gallus).

The inclusion of pulses in traditional wheat-based food products is increasing as the food industry and consumers are recognizing the nutritional benefits due to the high protein, antioxidant activity, and good source of dietary fiber of pulses. Iron deficiency is a significant global health challenge, affecting approximately 30% of the world’s population. Dietary iron deficiency is the foremost cause of anemia, a condition that harms cognitive development and increases maternal and infant mortality. This study intended to demonstrate the potential efficacy of low-phytate biofortified pea varieties on dietary iron (Fe) bioavailability, as well as on intestinal microbiome, energetic status, and brush border membrane (BBM) functionality in vivo (Gallus gallus). We hypothesized that the low-phytate biofortified peas would significantly improve Fe bioavailability, BBM functionality, and the prevalence of beneficial bacterial populations. A six-week efficacy feeding (n = 12) was conducted to compare four low-phytate biofortified pea diets with control pea diet (CDC Bronco), as well as a no-pea diet. During the feeding trial, hemoglobin (Hb), body-Hb Fe, feed intake, and body weight were monitored. Upon the completion of the study, hepatic Fe and ferritin, pectoral glycogen, duodenal gene expression, and cecum bacterial population analyses were conducted. The results indicated that certain low-phytate pea varieties provided greater Fe bioavailability and moderately improved Fe status, while they also had significant effects on gut microbiota and duodenal brush border membrane functionality. Our findings provide further evidence that the low-phytate pea varieties appear to improve Fe physiological status and gut microbiota in vivo, and they highlight the likelihood that this strategy can further improve the efficacy and safety of the crop biofortification and mineral bioavailability approach.

Iron Biofortification of the Common Bean: Assessment of Bean Iron Concentration and Iron Bioavailability from Markets and Breeder Collections in East Africa

Abstract Objectives To assess the practicality and assumptions of the high Fe concentration approach for bean Fe biofortification in east Africa. Methods A collection of 76 marketplace samples (East Africa Marketplace Collection; EAMC) were assembled, consisting of multiple color classes from locations in Uganda, Rwanda, Democratic Republic of Congo, Burundi, Ethiopia, Kenya and Tanzania. In addition, because market samples can be a mixture of seed varieties within a market class, 170 samples from the Africa CIAT Collection were also assembled that represent beans of common markets in the region. Iron concentration was measured via inductively coupled plasma emission spectroscopy (ICP-ES) and Fe bioavailability via an established Caco-2 cell bioassay. Using these measures, the following assumptions of high Fe bean Fe biofortification approach were assessed: 1) the average Fe concentration in beans currently consumed in east Africa is approximately 50 μg/g (dry weight), 2) a 40 μg/g increase (target value 90 μg/g) can be sustained through traditional breeding, and 3) iron bioavailability from the biofortified bean will not decrease substantially to negate the increase in Fe concentration. Results The average EAMC bean Fe concentration was 72 μg/g, ranging from 52–93 μg/g, with a couple of outlying varieties at 105 μg/g (MAC9) and 129 μg/g (MAC49). The Africa CIAT collection averaged 67.5 μg/g with a range of 51–90 μg/g. The 18 biofortified varieties within the EAMC averaged 73 μg/g (range of 55–94 μg/g), which is essentially equal to the overall mean (70 μg/g) and range (54–93 μg/g) of the non-biofortified bean varieties in the EAMC. Using a Caco-2 cell bioassay to measure Fe bioavailability of the EAMC, the biofortified varieties did not deliver any additional Fe relative to non-biofortified varieties. Conclusions The results indicate that the assumptions of the high Fe bean breeding approach are not met in the typical east African market place. Furthermore, based on the Fe content and bioavailability data collected from this study, the biofortified bean varieties from these markets are providing no additional dietary Fe. An alternative approach for bean Fe biofortification, such as enhanced Fe bioavailability should be pursued. Funding Sources USDA.