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Wairich A, Ricachenevsky FK, Lee S. A tale of two metals: Biofortification of rice grains with iron and zinc. FRONTIERS IN PLANT SCIENCE 2022; 13:944624. [PMID: 36420033 PMCID: PMC9677123 DOI: 10.3389/fpls.2022.944624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Iron (Fe) and zinc (Zn) are essential micronutrients needed by virtually all living organisms, including plants and humans, for proper growth and development. Due to its capacity to easily exchange electrons, Fe is important for electron transport in mitochondria and chloroplasts. Fe is also necessary for chlorophyll synthesis. Zn is a cofactor for several proteins, including Zn-finger transcription factors and redox metabolism enzymes such as copper/Zn superoxide dismutases. In humans, Fe participates in oxygen transport, electron transport, and cell division whereas Zn is involved in nucleic acid metabolism, apoptosis, immunity, and reproduction. Rice (Oryza sativa L.) is one of the major staple food crops, feeding over half of the world's population. However, Fe and Zn concentrations are low in rice grains, especially in the endosperm, which is consumed as white rice. Populations relying heavily on rice and other cereals are prone to Fe and Zn deficiency. One of the most cost-effective solutions to this problem is biofortification, which increases the nutritional value of crops, mainly in their edible organs, without yield reductions. In recent years, several approaches were applied to enhance the accumulation of Fe and Zn in rice seeds, especially in the endosperm. Here, we summarize these attempts involving transgenics and mutant lines, which resulted in Fe and/or Zn biofortification in rice grains. We review rice plant manipulations using ferritin genes, metal transporters, changes in the nicotianamine/phytosiderophore pathway (including biosynthetic genes and transporters), regulators of Fe deficiency responses, and other mutants/overexpressing lines used in gene characterization that resulted in Fe/Zn concentration changes in seeds. This review also discusses research gaps and proposes possible future directions that could be important to increase the concentration and bioavailability of Fe and Zn in rice seeds without the accumulation of deleterious elements. We also emphasize the need for a better understanding of metal homeostasis in rice, the importance of evaluating yield components of plants containing transgenes/mutations under field conditions, and the potential of identifying genes that can be manipulated by gene editing and other nontransgenic approaches.
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Affiliation(s)
- Andriele Wairich
- Graduate Program in Molecular and Cellular Biology, Biotechnology Center, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Felipe K. Ricachenevsky
- Graduate Program in Molecular and Cellular Biology, Biotechnology Center, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
- Department of Botany, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Sichul Lee
- Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, South Korea
- Department of Agricultural Biotechnology, National Institute of Agricultural Science, Jeonju, South Korea
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Shi X, Shen J, Niu B, Lam SK, Zong Y, Zhang D, Hao X, Li P. An optimistic future of C 4 crop broomcorn millet ( Panicum miliaceum L.) for food security under increasing atmospheric CO 2 concentrations. PeerJ 2022; 10:e14024. [PMID: 36097526 PMCID: PMC9463996 DOI: 10.7717/peerj.14024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/16/2022] [Indexed: 01/19/2023] Open
Abstract
Broomcorn millet, a C4 cereal, has better tolerance to environmental stresses. Although elevated atmospheric CO2 concentration has led to grain nutrition reduction in most staple crops, studies evaluating its effects on broomcorn millet are still scarce. The yield, nutritional quality and metabolites of broomcorn millet were investigated under ambient CO2 (aCO2, 400 µmol mol-1) and elevated CO2 (eCO2, aCO2+ 200 µmol mol-1) for three years using open-top chambers (OTC). The results showed that the yield of broomcorn millet was markedly increased under eCO2 compared with aCO2. On average, eCO2 significantly increased the concentration of Mg (27.3%), Mn (14.6%), and B (21.2%) over three years, whereas it did not affect the concentration of P, K, Fe, Ca, Cu or Zn. Protein content was significantly decreased, whereas starch and oil concentrations were not changed by eCO2. With the greater increase in grain yield, eCO2 induced increase in the grain accumulations of P (23.87%), K (29.5%), Mn (40.08%), Ca (22.58%), Mg (51.31%), Zn (40.95%), B (48.54%), starch (16.96%) and oil (28.37%) on average for three years. Flavonoids such as kaempferol, apigenin, eriodictyol, luteolin, and chrysoeriol were accumulated under eCO2. The reduction in L-glutamine and L-lysine metabolites, which were the most representative amino acid in grain proteins, led to a reduction of protein concentration under eCO2. Broomcorn millet has more desirable nutritional traits for combating hidden hunger. This may potentially be useful for breeding more nutritious plants in the era of climate change.
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Affiliation(s)
- Xinrui Shi
- Shanxi Agricultural University, Taigu, China
| | - Jie Shen
- Changzhi University, Changzhi, China
| | - Bingjie Niu
- Shanxi Agricultural University, Taigu, China
| | - Shu Kee Lam
- University of Melbourne, Melbourne, Australia
| | | | | | - Xingyu Hao
- Shanxi Agricultural University, Taigu, China,Ministerial and Provincial Co-Innovation Centre for Endemic Crops Production with High-quality and Effciency in Loess Plateau, Taigu, China
| | - Ping Li
- Shanxi Agricultural University, Taigu, China,Ministerial and Provincial Co-Innovation Centre for Endemic Crops Production with High-quality and Effciency in Loess Plateau, Taigu, China
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Semba RD, Askari S, Gibson S, Bloem MW, Kraemer K. The Potential Impact of Climate Change on the Micronutrient-Rich Food Supply. Adv Nutr 2021; 13:80-100. [PMID: 34607354 PMCID: PMC8803495 DOI: 10.1093/advances/nmab104] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/27/2021] [Accepted: 08/25/2021] [Indexed: 11/13/2022] Open
Abstract
Micronutrient deficiencies are a major cause of morbidity and mortality in low- and middle-income countries worldwide. Climate change, characterized by increasing global surface temperatures and alterations in rainfall, has the capacity to affect the quality and accessibility of micronutrient-rich foods. The goals of this review are to summarize the potential effects of climate change and its consequences on agricultural yield and micronutrient quality, primarily zinc, iron, and vitamin A, of plant foods and upon the availability of animal foods, to discuss the implications for micronutrient deficiencies in the future, and to present possible mitigation and adaptive strategies. In general, the combination of increasing atmospheric carbon dioxide and rising temperature is predicted to reduce the overall yield of major staple crops, fruits, vegetables, and nuts, more than altering their micronutrient content. Crop yield is also reduced by elevated ground-level ozone and increased extreme weather events. Pollinator loss is expected to reduce the yield of many pollinator-dependent crops such as fruits, vegetables, and nuts. Sea-level rise resulting from melting of ice sheets and glaciers is predicted to result in coastal inundation, salt intrusion, and loss of coral reefs and mangrove forests, with an adverse impact upon coastal rice production and coastal fisheries. Global ocean fisheries catch is predicted to decline because of ocean warming and declining oxygen. Freshwater warming is also expected to alter ecosystems and reduce inland fisheries catch. In addition to limiting greenhouse gas production, adaptive strategies include postharvest fortification of foods; micronutrient supplementation; biofortification of staple crops with zinc and iron; plant breeding or genetic approaches to increase zinc, iron, and provitamin A carotenoid content of plant foods; and developing staple crops that are tolerant of abiotic stressors such as elevated carbon dioxide, elevated temperature, and increased soil salinity.
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Affiliation(s)
| | - Sufia Askari
- Children's Investment Fund Foundation, London, United Kingdom
| | - Sarah Gibson
- Children's Investment Fund Foundation, London, United Kingdom
| | - Martin W Bloem
- Johns Hopkins Center for a Livable Future, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA,Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Klaus Kraemer
- Sight and Life, Basel, Switzerland,Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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Yang A, Li Q, Chen L, Zhang WH. A rice small GTPase, Rab6a, is involved in the regulation of grain yield and iron nutrition in response to CO2 enrichment. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:5680-5688. [PMID: 32525991 PMCID: PMC7501819 DOI: 10.1093/jxb/eraa279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 06/09/2020] [Indexed: 05/31/2023]
Abstract
Despite extensive studies on the effects of elevated atmospheric CO2 concentrations ([CO2]) on rice, the molecular mechanisms and signaling events underlying the adaptation of plants remain largely elusive. Here, we report that OsRab6a, which encodes a small GTPase, is involved in the regulation of rice growth, grain yield, and accumulation of iron (Fe) in response to elevated [CO2] (e[CO2]). We generated transgenic plants with OsRab6a-overexpression (-OE) together with OsRab6a-RNAi lines, and found no differences in growth and grain yield among them and wild-type (WT) plants under ambient [CO2] conditions. Under e[CO2] conditions, growth and grain yield of the WT and OsRab6a-OE plants were enhanced, with a greater effect being observed in the latter. In contrast, there were no effects of e[CO2] on growth and grain yield of the OsRab6a-RNAi plants. Photosynthetic rates in both the WT and OsRab6a-OE plants were stimulated by e[CO2], with the magnitude of the increase being higher in OsRab6a-OE plants. Fe concentrations in vegetative tissues and the grain of the WT and transgenic plants were reduced by e[CO2], and the magnitude of the decrease was lower in the OE plants than in the WT and RNAi plants. Genes associated with Fe acquisition in the OsRab6a-OE lines exhibited higher levels of expression than those in the WT and the RNAi lines under e[CO2]. Analysis of our data using Dunnett's multiple comparison test suggested that OsRab6a is an important molecular regulator that underlies the adaptation of rice to e[CO2] by controlling photosynthesis and Fe accumulation.
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Affiliation(s)
- An Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
| | - Qian Li
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China
| | - Lei Chen
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Wen-Hao Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
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