Breeding for micronutrients in staple food crops from a human nutrition perspective
TL;DR: The world's agricultural community should adopt plant breeding and other genetic technologies to improve human health, and the world's nutrition and health communities should support these efforts.
Abstract: Over three billion people are currently micronutrient (i.e. micronutrient elements and vitamins) malnourished, resulting in egregious societal costs including learning disabilities among children, increased morbidity and mortality rates, lower worker productivity, and high healthcare costs, all factors diminishing human potential, felicity, and national economic development. Nutritional deficiencies (e.g. iron, zinc, vitamin A) account for almost two-thirds of the childhood death worldwide. Most of those afflicted are dependent on staple crops for their sustenance. Importantly, these crops can be enriched (i.e. ‘biofortified’) with micronutrients using plant breeding and/ or transgenic strategies, because micronutrient enrichment traits exist within their genomes that can to used for substantially increasing micronutrient levels in these foods without negatively impacting crop productivity. Furthermore, ‘proof of concept’ studies have been published using transgenic approaches to biofortify staple crops (e.g. high b-carotene ‘golden rice’ grain, high ferritin-Fe rice grain, etc). In addition, micronutrient element enrichment of seeds can increase crop yields when sowed to micronutrient-poor soils, assuring their adoption by farmers. Bioavailability issues must be addressed when employing plant breeding and/or transgenic approaches to reduce micronutrient malnutrition. Enhancing substances (e.g. ascorbic acid, S-containing amino acids, etc) that promote micronutrient bioavailability or decreasing antinutrient substances (e.g. phytate, polyphenolics, etc) that inhibit micronutrient bioavailability, are both options that could be pursued, but the latter approach should be used with caution. The world’s agricultural community should adopt plant breeding and other genetic technologies to improve human health, and the world’s nutrition and health communities should support these efforts. Sustainable solutions to this enormous global problem of ‘hidden hunger’ will not come without employing agricultural approaches.
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TL;DR: Plant breeding strategy (e.g., genetic biofortification) appears to be a most sustainable and cost-effective approach useful in improving Zn concentrations in grain, and application of Zn fertilizers or Zn-enriched NPK fertilizers offers a rapid solution to the problem.
Abstract: Zinc deficiency is a well-documented problem in food crops, causing decreased crop yields and nutritional quality. Generally, the regions in the world with Zn-deficient soils are also characterized by widespread Zn deficiency in humans. Recent estimates indicate that nearly half of world population suffers from Zn deficiency. Cereal crops play an important role in satisfying daily calorie intake in developing world, but they are inherently very low in Zn concentrations in grain, particularly when grown on Zn-deficient soils. The reliance on cereal-based diets may induce Zn deficiency-related health problems in humans, such as impairments in physical development, immune system and brain function. Among the strategies being discussed as major solution to Zn deficiency, plant breeding strategy (e.g., genetic biofortification) appears to be a most sustainable and cost-effective approach useful in improving Zn concentrations in grain. The breeding approach is, however, a long-term process requiring a substantial effort and resources. A successful breeding program for biofortifying food crops with Zn is very much dependent on the size of plant-available Zn pools in soil. In most parts of the cereal-growing areas, soils have, however, a variety of chemical and physical problems that significantly reduce availability of Zn to plant roots. Hence, the genetic capacity of the newly developed (biofortified) cultivars to absorb sufficient amount of Zn from soil and accumulate it in the grain may not be expressed to the full extent. It is, therefore, essential to have a short-term approach to improve Zn concentration in cereal grains. Application of Zn fertilizers or Zn-enriched NPK fertilizers (e.g., agronomic biofortification) offers a rapid solution to the problem, and represents useful complementary approach to on-going breeding programs. There is increasing evidence showing that foliar or combined soil+foliar application of Zn fertilizers under field conditions are highly effective and very practical way to maximize uptake and accumulation of Zn in whole wheat grain, raising concentration up to 60 mg Zn kg−1. Zinc-enriched grains are also of great importance for crop productivity resulting in better seedling vigor, denser stands and higher stress tolerance on potentially Zn-deficient soils. Agronomic biofortification strategy appears to be essential in keeping sufficient amount of available Zn in soil solution and maintaining adequate Zn transport to the seeds during reproductive growth stage. Finally, agronomic biofortification is required for optimizing and ensuring the success of genetic biofortification of cereal grains with Zn. In case of greater bioavailability of the grain Zn derived from foliar applications than from soil, agronomic biofortification would be a very attractive and useful strategy in solving Zn deficiency-related health problems globally and effectively.
1,743 citations
Cites background from "Breeding for micronutrients in stap..."
...Among micronutrients, Zn deficiency is occurring in both crops and humans (White and Zasoski 1999; Hotz and Brown 2004; Welch and Graham 2004)....
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...Besides having inherently low levels of Zn, wheat grain is also rich in substances limiting utilization (bioavailability) of Zn in the human digestive tract, such as polyphenols and phytic acid (Welch and Graham 2004)....
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...Besides having inherently low levels of Zn, wheat grain is also rich in substances limiting utilization (bioavailability) of Zn in the human digestive tract, such as polyphenols and phytic acid (Welch and Graham 2004)....
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TL;DR: The dominant fluxes of Zn in the soil-root-shoot continuum are described, including Zn inputs to soils, the plant availability of soluble Zn(2+) at the root surface, and plant uptake and accumulation of ZN.
Abstract: Zinc (Zn) is an essential component of thousands of proteins in plants, although it is toxic in excess. In this review, the dominant fluxes of Zn in the soil-root-shoot continuum are described, including Zn inputs to soils, the plant availability of soluble Zn(2+) at the root surface, and plant uptake and accumulation of Zn. Knowledge of these fluxes can inform agronomic and genetic strategies to address the widespread problem of Zn-limited crop growth. Substantial within-species genetic variation in Zn composition is being used to alleviate human dietary Zn deficiencies through biofortification. Intriguingly, a meta-analysis of data from an extensive literature survey indicates that a small proportion of the genetic variation in shoot Zn concentration can be attributed to evolutionary processes whose effects manifest above the family level. Remarkable insights into the evolutionary potential of plants to respond to elevated soil Zn have recently been made through detailed anatomical, physiological, chemical, genetic and molecular characterizations of the brassicaceous Zn hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri.
1,691 citations
TL;DR: In this paper, the authors review aspects of soil science, plant physiology and genetics underpinning crop bio-fortification 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).
Abstract: Summary
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, β-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.
1,677 citations
TL;DR: The positional cloning of Gpc-B1, a wheat quantitative trait locus associated with increased grain protein, zinc, and iron content, is reported here, and reduction in RNA levels of the multiple NAM homologs by RNA interference delayed senescence by more than 3 weeks and reduced wheat grain protein and zinc content.
Abstract: Enhancing the nutritional value of food crops is a means of improving human nutrition and health. We report here the positional cloning of Gpc-B1, a wheat quantitative trait locus associated with increased grain protein, zinc, and iron content. The ancestral wild wheat allele encodes a NAC transcription factor (NAM-B1) that accelerates senescence and increases nutrient remobilization from leaves to developing grains, whereas modern wheat varieties carry a nonfunctional NAM-B1 allele. Reduction in RNA levels of the multiple NAM homologs by RNA interference delayed senescence by more than 3 weeks and reduced wheat grain protein, zinc, and iron content by more than 30%.
1,377 citations
13 Jul 2011
1,119 citations
References
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Book•
01 Jan 1986
TL;DR: This chapter discusses the relationship between Mineral Nutrition and Plant Diseases and Pests, and the Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition.
Abstract: Nutritional Physiology: Introduction, Definition, and Classification of Mineral Nutrients. Ion Uptake Mechanisms of Individual Cells and Roots: Short Distance Transport. Long-Distance Transport in the Xylem and Phloem and its Regulation. Uptake and Release of Mineral Elements by Leaves and Other Aerial Plant Parts. Yield and the Source-Sink Relationships. Mineral Nutrition and Yield Response. Nitrogen Fixation. Functions of Mineral Nutrients: Macronutrients. Function of Mineral Nutrients: Micronutrients. Beneficial Mineral Elements. Relationship between Mineral Nutrition and Plant Diseases and Pests. Diagnosis of Deficiency and Toxicity of Mineral Nutrients. Plant-Soil Relationships: Nutrient Availability in Soils. Effect of Internal and External Factors on Root Growth and Development. The Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition. Adaptation of Plants to Adverse Chemical Soil Conditions. References. Subject Index.
18,276 citations
"Breeding for micronutrients in stap..." refers background in this paper
...For an indepth discussion of these topics the reader is referred to the following references (Graham et al., 2001; Graham and Welch, 1996; Marschner, 1995; Welch, 1986, 1995, 1999; Yang and RoÈmheld, 1999)....
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Book•
01 Jan 1986
TL;DR: In this article, the authors discuss the relationship between mineral nutrition and plant diseases and pests, and diagnose deficiency and toxicity of mineral nutrients in leaves and other aerial parts of a plant.
Abstract: Nutritional Physiology: Introduction, Definition, and Classification of Mineral Nutrients. Ion Uptake Mechanisms of Individual Cells and Roots: Short Distance Transport. Long-Distance Transport in the Xylem and Phloem and its Regulation. Uptake and Release of Mineral Elements by Leaves and Other Aerial Plant Parts. Yield and the Source-Sink Relationships. Mineral Nutrition and Yield Response. Nitrogen Fixation. Functions of Mineral Nutrients: Macronutrients. Function of Mineral Nutrients: Micronutrients. Beneficial Mineral Elements. Relationship between Mineral Nutrition and Plant Diseases and Pests. Diagnosis of Deficiency and Toxicity of Mineral Nutrients. Plant-Soil Relationships: Nutrient Availability in Soils. Effect of Internal and External Factors on Root Growth and Development. The Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition. Adaptation of Plants to Adverse Chemical Soil Conditions. References. Subject Index.
16,025 citations
3,701 citations
TL;DR: Research into the functional benefits of carotenoids should consider the fact that the bioavailability of beta-carotene in particular is one order of magnitude higher when provided as a pure compound added to foods than when it is present naturally in foods.
Abstract: Carotenoids are thought to contribute to the beneficial effects of increased vegetable consumption. Various dietary factors have an effect on the bioavailability of carotenoids. The type of food matrix in which carotenoids are located is a major factor. The bioavailability of beta-carotene from vegetables in particular has been shown to be low (14% from mixed vegetables) compared with that of purified beta-carotene added to a simple matrix (e.g., salad dressing), whereas for lutein, the difference is much smaller (relative bioavailability of 67% from mixed vegetables). Processing, such as mechanical homogenization or heat treatment, has the potential to enhance the bioavailability of carotenoids from vegetables (from 18% to a sixfold increase). The amount of dietary fat required to ensure carotenoid absorption seems low (approximately 3-5 g per meal), although it depends on the physicochemical characteristics of the carotenoids ingested. Unabsorbable, fat-soluble compounds reduce carotenoid absorption, and interaction among carotenoids may also result in a reduced carotenoid bioavailability. Research into the functional benefits of carotenoids should consider the fact that the bioavailability of beta-carotene in particular is one order of magnitude higher when provided as a pure compound added to foods than when it is present naturally in foods.
700 citations
"Breeding for micronutrients in stap..." refers background in this paper
...The bioavailability of micronutrients in plant foods can be greatly affected by the composition of the diet used to test the bioavailability (House, 1999; van het Hof et al., 2000; Wienk et al., 1999)....
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