Genetically modified plants for improved trace element nutrition

Dietary Zn deficiency, the current situation and potential solutions

Zinc (Zn) deficiency is a worldwide problem, and this review presents an overview of the magnitude of Zn deficiency with a particular emphasis on present global challenges, current recommendations for Zn intake, and factors that affect dietary requirements. The challenges of monitoring Zn status are clarified together with the discussion of relevant Zn bioaccessibility and bioavailability issues. Modern lifestyle factors that may exacerbate Zn deficiency and new strategies of reducing its effects are presented. Biofortification, as a potentially useful strategy for improving Zn status in sensitive populations, is discussed. The review proposes potential actions that could deliver promising results both in terms of monitoring dietary and physiological Zn status as well as in alleviating dietary Zn deficiency in affected populations.

A comprehensive review on infant formula: nutritional and functional constituents, recent trends in processing and its impact on infants' gut microbiota

Human milk is considered the most valuable form of nutrition for infants for their growth, development and function. So far, there are still some cases where feeding human milk is not feasible. As a result, the market for infant formula is widely increasing, and formula feeding become an alternative or substitute for breastfeeding. The nutritional value of the formula can be improved by adding functional bioactive compounds like probiotics, prebiotics, human milk oligosaccharides, vitamins, minerals, taurine, inositol, osteopontin, lactoferrin, gangliosides, carnitine etc. For processing of infant formula, diverse thermal and non-thermal technologies have been employed. Infant formula can be either in powdered form, which requires reconstitution with water or in ready-to-feed liquid form, among which powder form is readily available, shelf-stable and vastly marketed. Infants' gut microbiota is a complex ecosystem and the nutrient composition of infant formula is recognized to have a lasting effect on it. Likewise, the gut microbiota establishment closely parallels with host immune development and growth. Therefore, it must be contemplated as an important factor for consideration while developing formulas. In this review, we have focused on the formulation and manufacturing of safe and nutritious infant formula equivalent to human milk or aligning with the infant's needs and its ultimate impact on infants' gut microbiota.

Soil Threshold Values for Zn Based on Soil-Rice System and Health Risk Assessment in a Typical Carbonate Area of Guangxi

Zinc (Zn) is enriched in carbonate area related to geological genesis. To ensure safety of rice, soil threshold values of Zn in soil-rice systems were assessed based on analysis of soil-rice Zn concentration in relation to human health risk. Models for the prediction of Zn concentration of early-season and late-season rice grain were accurately established on the basis of significant partial correlations between log₁₀ (BAFs) and log₁₀ (soil properties). The rice threshold value ranged from 10.67 to 37.90 mg/kg, which might not suitable for male and urban residents. The soil safety threshold of early-season rice and late-season rice in carbonate area ranged from 148-200 mg/kg, 119-200 mg/kg with pH below 6.5, 148-250 mg/kg, 119-250 mg/kg with pH ranging from 6.5 to 7.5; 148-300 mg/kg, 119-300 mg/kg with pH above 7.5, respectively.

Analytical assessment of maize kernels for Fe, Zn, and β-carotene dense cultivars with low phytate contents

The present paper reports that significant genetic variability was evident in Fe, Zn, β-carotene, and phytic acid (phytate, PA) contents in a set of 39 diverse maize genotypes collected from maize breeding programme of hill agriculture, India. The Fe, Zn, β-carotene, and PA concentrations were found to be in the range 19.31–50.64 mg kg−1, 12.60–37.18 mg kg−1, 0.17–8.27 µg g−1, and 6.59–7.13 g kg−1, respectively. The genotypes V335, V420, V393, V416, V414, V372, and V351 were identified to have higher concentration of β-carotene, Fe, and Zn but lower amount of PA. Possible availability of the minerals Fe and Zn was determined using molar ratio between PA as inhibitor and β-carotene as promoter for their absorption. The micronutrient molar ratio showed that Fe and Zn traits could be dependent of each other. Low R2 value revealed relation between β-carotene and kernel colour. The selected genotypes could be considered as potential sources of favourable genes for further breeding programs to develop micronutrient enriched maize cultivars.

Biotechnological Approaches for Generating Zinc-Enriched Crops to Combat Malnutrition

The past twenty years have seen the application of biotechnology to generate nutritionally improved food crops. Biofortified rice, cassava, maize, sorghum and other staple crops biofortified with essential micronutrients have great potential to benefit the world’s poor, in terms of both health and economics. This paper describes the use of genetic modification to generate crops that are biofortified with zinc. Examples of zinc-enhanced crops which have been developed using biotechnological approaches will be discussed, and new approaches for research and development will be outlined. The impact of these biofortified crops on human health and well-being will be examined. This paper will conclude with a discussion of the obstacles that must be overcome to enable zinc-fortified crops to be accessible for the world’s malnourished.

Genetic Engineering: A Possible Strategy for Protein-Energy Malnutrition Regulation

Protein-energy malnutrition (PEM) has adversely affected the generations of developing countries. It is a syndrome that in severity causes death. PEM generally affects infants of 1-5 age group. This manifestation is maintained till adulthood in the form of poor brain and body development. The developing nations are continuously making an effort to curb PEM. However, it is still a prime concern as it was in its early years of occurrence. Transgenic crops with high protein and enhanced nutrient content have been successfully developed. Present article reviews the studies documenting genetic engineering-mediated improvement in the pulses, cereals, legumes, fruits and other crop plants in terms of nutritional value, stress tolerance, longevity and productivity. Such genetically engineered crops can be used as a possible remedial tool to eradicate PEM.

Plant ferritin--a source of iron to prevent its deficiency

Iron deficiency anemia affects a significant part of the human population. Due to the unique properties of plant ferritin, food enrichment with ferritin iron seems to be a promising strategy to prevent this malnutrition problem. This protein captures huge amounts of iron ions inside the apoferritin shell and isolates them from the environment. Thus, this iron form does not induce oxidative change in food and reduces the risk of gastric problems in consumers. Bioavailability of ferritin in human and animal studies is high and the mechanism of absorption via endocytosis has been confirmed in cultured cells. Legume seeds are a traditional source of plant ferritin. However, even if the percentage of ferritin iron in these seeds is high, its concentration is not sufficient for food fortification. Thus, edible plants have been biofortified in iron for many years. Plants overexpressing ferritin may find applications in the development of bioactive food. A crucial achievement would be to develop technologies warranting stability of ferritin in food and the digestive tract.

Metabolomics of genetically modified crops

Metabolomic-based approaches are increasingly applied to analyse genetically modified organisms (GMOs) making it possible to obtain broader and deeper information on the composition of GMOs compared to that obtained from traditional analytical approaches. The combination in metabolomics of advanced analytical methods and bioinformatics tools provides wide chemical compositional data that contributes to corroborate (or not) the substantial equivalence and occurrence of unintended changes resulting from genetic transformation. This review provides insight into recent progress in metabolomics studies on transgenic crops focusing mainly in papers published in the last decade.

Influence of human lactoferrin expression on iron homeostasis, flavonoids, and antioxidants in transgenic tobacco

This study was aimed at to check the influence of human lactoferrin (hLF) expression on iron homeostasis, flavonoids, and antioxidants in transgenic tobacco. Transgenic tobacco expressing hLF cDNA under the control of a CaMV 35S promoter was produced. The iron content as well as chlorophyll content of transgenic tobacco was lower compared to mock and untransformed wild plants. Interestingly, hLF transgenic tobacco showed higher level of transcript expression for genes related to iron content regulation like iron transporter and metal transporter. While expression of genes related to iron storage such as ferritin 1 and ferritin 2 was downregulated. The transcript expression of genes encoding antioxidant enzymes such as glutathione reductase, glutathione-S-transferase, ascorbate peroxidase, and catalase was downregulated in hLF transgenic tobacco compared to controls. Further, the transcript expression of two important genes encoding dihydroflavonol reductase (DFR) and phenylalanine ammonia lyase regulatory enzymes of flavonoid biosynthesis pathway was analyzed. The expression of DFR was found to be downregulated, while PAL expression was upregulated in hLF transgenic tobacco compared to mock and untransformed wild plant. Total phenolics, flavonoids, and proanthocyanidins contents were found to be higher in hLF transgenic tobacco than the mock and untransformed wild plant. Results suggest that hLF expression in transgenic tobacco leads to iron deficiency, downregulation of antioxidant enzymes, and increase in total flavonoids.

Study on iron availability from prepared soybean sprouts using an iron-deficient rat model

During soya seeds germination in FeSO(4) solutions their phytoferritin content is multiplied. Prepared soybean sprouts have been proposed as a safe and easily available source of iron supplementation. The preparation was compared with FeSO(4) and ferritin isolates, using rats with induced iron deficiency anaemia. After the end of the 2-week supplementation experiment, it was observed that no statistically significant differences in haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration existed between those animals supplemented with sprouts enriched in ferritin, ferritin isolate and FeSO(4) and healthy animals forming the control group. Moreover, the examined preparation had a beneficial influence on the recreation of ferritin reserves in both the liver and the blood serum, and also did not induce negative alterations in general growth parameters of animals. Use of an easily obtainable ferritin iron source may be a profitable alternative in supplementation due to its wide availability and food preservative properties.

Root-specific reduction of cytokinin causes enhanced root growth, drought tolerance, and leaf mineral enrichment in Arabidopsis and tobacco

Optimizing root system architecture can overcome yield limitations in crop plants caused by water or nutrient shortages. Classic breeding approaches are difficult because the trait is governed by many genes and is difficult to score. We generated transgenic Arabidopsis thaliana and tobacco (Nicotiana tabacum) plants with enhanced root-specific degradation of the hormone cytokinin, a negative regulator of root growth. These transgenic plants form a larger root system, whereas growth and development of the shoot are similar. Elongation of the primary root, root branching, and root biomass formation were increased by up to 60% in transgenic lines, increasing the root-to-shoot ratio. We thus demonstrated that a single dominant gene could regulate a complex trait, root growth. Moreover, we showed that cytokinin regulates root growth in a largely organ-autonomous fashion that is consistent with its dual role as a hormone with both paracrine and long-distance activities. Transgenic plants had a higher survival rate after severe drought treatment. The accumulation of several elements, including S, P, Mn, Mg, Zn, as well as Cd from a contaminated soil, was significantly increased in shoots. Under conditions of sulfur or magnesium deficiency, leaf chlorophyll content was less affected in transgenic plants, demonstrating the physiological relevance of shoot element accumulation. Our approach might contribute to improve drought tolerance, nutrient efficiency, and nutrient content of crop plants.

Substitutions of 2S and 7U chromosomes of Aegilops kotschyi in wheat enhance grain iron and zinc concentration

Biofortification through genetic manipulation is the best approach for improving micronutrient content of the staple food crops to alleviate hidden hunger, namely, the deficiency of Fe and Zn affecting more than two billion people worldwide. An interspecific hybridization was made between T. aestivum line Chinese Spring (CS) and Aegilops kotschyi accession 3790 selected for high grain iron and zinc concentration. The CS x Ae. kotschyi F(1) hybrid with low chromosome pairing was highly male and female sterile. This was backcrossed with wheat cultivars to get seed set. The selfed BC(1)F(1) and BC(2)F(1) plants with high grain iron and zinc concentration were selected in subsequent generations. The selected derivatives showed 60-136% enhanced grain iron and zinc concentration and 50-120% increased iron and zinc content per seed as compared to the recipient wheat cultivars. Thirteen cytologically stable, fertile and agronomically superior plants with high grain iron and zinc concentrations were selected for molecular characterization. The application of anchored wheat SSR markers, transferable to Ae. kotschyi, to the high grain iron and zinc containing derivatives indicated introgression of group 2 and group 7 chromosomes of Ae. kotschyi. GISH and FISH analysis of some derivatives confirmed the substitution of chromosomes 2S and 7U for their homoeologues of the A genome, suggesting that some of the genes controlling high grain micronutrient content in the Ae. kotschyi accession are on these chromosomes.

Biofortification of crops with seven mineral elements often lacking in human diets--iron, zinc, copper, calcium, magnesium, selenium and iodine

The diets of over two-thirds of the world's population lack one or more essential mineral elements. This can be remedied through dietary diversification, mineral supplementation, food fortification, or increasing the concentrations and/or bioavailability of mineral elements in produce (biofortification). This article reviews aspects of soil science, plant physiology and genetics underpinning crop biofortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se). Two complementary approaches have been successfully adopted to increase the concentrations of bioavailable mineral elements in food crops. First, agronomic approaches optimizing the application of mineral fertilizers and/or improving the solubilization and mobilization of mineral elements in the soil have been implemented. Secondly, crops have been developed with: increased abilities to acquire mineral elements and accumulate them in edible tissues; increased concentrations of 'promoter' substances, such as ascorbate, beta-carotene and cysteine-rich polypeptides which stimulate the absorption of essential mineral elements by the gut; and reduced concentrations of 'antinutrients', such as oxalate, polyphenolics or phytate, which interfere with their absorption. These approaches are addressing mineral malnutrition in humans globally.

Phytic acid prevents oxidative stress in seeds: evidence from a maize (Zea mays L.) low phytic acid mutant

A maize mutant defective in the synthesis of phytic acid during seed maturation was used as a tool to study the consequences of the lack of this important reserve substance on seed survival. Data on germinability, free iron level, free radical relative abundance, protein carbonylation level, damage to DNA, degree of lipid peroxidation, alpha- and gamma-tocopherol amount and antioxidant capacity were recorded on seeds of maize B73 and of an isogenic low phytic acid mutant (lpa1-241), either unaged or incubated for 7 d in accelerated ageing conditions (46 degrees C and 100% relative humidity). The lpa1-241 mutant, compared to wild type (wt), showed a lower germination capacity, which decreased further after accelerated ageing. Whole lpa1-241 mutant kernels contained about 50% more free or weakly bound iron than wt ones and showed a higher content of free radicals, mainly concentrated in embryos; in addition, upon accelerated ageing, lpa1-241 seed proteins were more carbonylated and DNA was more damaged, whereas lipids did not appear to be more peroxidated, but the gamma-tocopherol content was decreased by about 50%. These findings can be interpreted in terms of previously reported but never proven antioxidant activity of phytic acid through iron complexation. Therefore, a novel role in plant seed physiology can be assigned to phytic acid, that is, protection against oxidative stress during the seed's life span. As in maize kernels the greater part of phytic acid (and thus of metal ions) is concentrated in the embryo, its antioxidant action may be of particular relevance in this crop.

Levels of inorganic constituents in raw nuts and seeds on the Swedish market

The levels of approximately 70 elements were determined in different culinary nuts (hazelnuts, walnuts, almonds, bitter almonds, pecans, cashews, Brazil nuts, pistachios, pine nuts, peanuts and coconuts) and seeds (pumpkin and sunflower) available on the Swedish market. The study was limited to raw, virtually unprocessed nuts and seeds (both shelled and unshelled) excluding mixed, roasted or salted products. In total, 44 products from different suppliers were analyzed, with the number of samples per nut/seed variety reflecting the availability of unprocessed products in retail outlets, varying from two for bitter almonds and pistachios to six for hazelnuts and walnuts. This selection includes samples from at least 11 different countries of origin. The optimized analytical procedure consists of microwave-assisted sample digestion using a HNO3/HF mixture, followed by multi-elemental analysis by double focusing, sector field inductively coupled plasma mass spectrometry. The analyses were accompanied by rigorous quality control measures including thorough control of potential sample contamination at all analytical stages, participation in inter-laboratory performance assessment schemes, and the analysis of certified reference materials of plant origin. Concentrations thus obtained were compared with data from product labels (where available), food composition tables and other relevant surveys, demonstrating, depending on the elements in question, close agreement as well as considerable differences.

Nutritional iron deficiency

Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming monotonous plant-based diets. The high prevalence of iron deficiency in the developing world has substantial health and economic costs, including poor pregnancy outcome, impaired school performance, and decreased productivity. Recent studies have reported how the body regulates iron absorption and metabolism in response to changing iron status by upregulation or downregulation of key intestinal and hepatic proteins. Targeted iron supplementation, iron fortification of foods, or both, can control iron deficiency in populations. Although technical challenges limit the amount of bioavailable iron compounds that can be used in food fortification, studies show that iron fortification can be an effective strategy against nutritional iron deficiency. Specific laboratory measures of iron status should be used to assess the need for fortification and to monitor these interventions. Selective plant breeding and genetic engineering are promising new approaches to improve dietary iron nutritional quality.

Recent advances in rice biotechnology--towards genetically superior transgenic rice

Rice biotechnology has made rapid advances since the first transgenic rice plants were produced 15 years ago. Over the past decade, this progress has resulted in the development of high frequency, routine and reproducible genetic transformation protocols for rice. This technology has been applied to produce rice plants that withstand several abiotic stresses, as well as to gain tolerance against various pests and diseases. In addition, quality improving and increased nutritional value traits have also been introduced into rice. Most of these gains were not possible through conventional breeding technologies. Transgenic rice system has been used to understand the process of transformation itself, the integration pattern of transgene as well as to modulate gene expression. Field trials of transgenic rice, especially insect-resistant rice, have recently been performed and several other studies that are prerequisite for safe release of transgenic crops have been initiated. New molecular improvisations such as inducible expression of transgene and selectable marker-free technology will help in producing superior transgenic product. It is also a step towards alleviating public concerns relating to issues of transgenic technology and to gain regulatory approval. Knowledge gained from rice can also be applied to improve other cereals. The completion of the rice genome sequencing together with a rich collection of full-length cDNA resources has opened up a plethora of opportunities, paving the way to integrate data from the large-scale projects to solve specific biological problems.

Public health nutrition and genetics: implications for nutrition policy and promotion

The unravelling of the human genome has the potential to radically extend many of the strategies used in public health nutrition to improve health and to increase food availability, accessibility and utilization. The present paper divides nutrigenomics into two broad but differing areas in asking about possible public health applications: (1) the increasing mismatch between population growth and global food security, on top of the already approximately 800 million of the world population who are food insecure; (2) possible responses to the rising prevalence of non-communicable diseases as the Western diet becomes increasingly inappropriate to the needs of those consuming it. It is clear that complex interactions of multiple polymorphisms play a role in how individuals and sub-populations respond to dietary interventions. All these applications present public health and ethical challenges, particularly in ensuring that any benefits that do come from nutrigenomics are not restricted to the wealthy minority of only the affluent nations. The present paper concludes that the public health applications of nutrigenomics are probably at least a decade away, especially for developing countries. Clinical applications are likely to be more immediate, probably resulting in 'designer diets' for individuals with particular polymorphisms, but unless governments take on the role of ensuring some extent of equity in access, any benefits are most likely to go to those who can afford the screening, tests and treatment. At the same time, greatly increased international efforts are needed towards the continuing, and in some cases worsening, global malnutrition, as genetic manipulation of crops is unlikely to provide more than part of the solution.

BIOACTIVE COMPOUNDS IN NUTRITION AND HEALTH-RESEARCH METHODOLOGIES FOR ESTABLISHING BIOLOGICAL FUNCTION: The Antioxidant and Anti-inflammatory Effects of Flavonoids on Atherosclerosis

Identifying bioactive compounds and establishing their health effects are active areas of scientific inquiry. There are exciting prospects that select bioactive compounds will reduce the risk of many diseases, including chronic diseases such as cardiovascular disease. Recent findings have established that cardiovascular disease is a disease of inflammation, and consequently is amenable to intervention via molecules that have anti-inflammatory effects. In addition, research demonstrating adverse effects of oxidants on atherogenesis raises the possibility that antioxidants can confer cardioprotective effects. This review provides an overview of research approaches that can be used to unravel the biology and health effects of bioactive compounds. Because of the number of bioactive compounds and the diversity of likely biological effects, numerous and diverse experimental approaches must be taken to increase our understanding of the biology of bioactive compounds. Recognizing the complexity of this biology, sophisticated experimental designs and analytical methodologies must be employed to advance the field. The discovery of novel health effects of bioactive compounds will provide the scientific basis for future efforts to use biotechnology to modify/fortify foods and food components as a means to improve public health.

The nutritional fortification of cereals

The low micronutrient content of cereals requires the fortification of food and biofortification of plants. Many laboratories are currently pursuing biofortification using breeding and genetic modification, but progress is challenged by technical hurdles and our understanding of physiological processes. Recent studies have largely been confined to the improvement of levels of iron, zinc, some vitamins and a variety of essential amino acids. Progress has been made in the accumulation of iron, zinc, and vitamins A and E in genetically modified plants. For future success in this area, many more studies will be required on the physiology of ion uptake and on the transport of vitamin precursors.