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Halstead-Nussloch G, Tanaka T, Copetti D, Paape T, Kobayashi F, Hatakeyama M, Kanamori H, Wu J, Mascher M, Kawaura K, Shimizu KK, Handa H. Multiple Wheat Genomes Reveal Novel Gli-2 Sublocus Location and Variation of Celiac Disease Epitopes in Duplicated α-Gliadin Genes. FRONTIERS IN PLANT SCIENCE 2021; 12:715985. [PMID: 34539709 PMCID: PMC8446623 DOI: 10.3389/fpls.2021.715985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/12/2021] [Indexed: 05/28/2023]
Abstract
The seed protein α-gliadin is a major component of wheat flour and causes gluten-related diseases. However, due to the complexity of this multigene family with a genome structure composed of dozens of copies derived from tandem and genome duplications, little was known about the variation between accessions, and thus little effort has been made to explicitly target α-gliadin for bread wheat breeding. Here, we analyzed genomic variation in α-gliadins across 11 recently published chromosome-scale assemblies of hexaploid wheat, with validation using long-read data. We unexpectedly found that the Gli-B2 locus is not a single contiguous locus but is composed of two subloci, suggesting the possibility of recombination between the two during breeding. We confirmed that the number of immunogenic epitopes among 11 accessions varied. The D subgenome of a European spelt line also contained epitopes, in agreement with its hybridization history. Evolutionary analysis identified amino acid sites under diversifying selection, suggesting their functional importance. The analysis opens the way for improved grain quality and safety through wheat breeding.
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Affiliation(s)
- Gwyneth Halstead-Nussloch
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Tsuyoshi Tanaka
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Dario Copetti
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zürich, Zurich, Switzerland
| | - Timothy Paape
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Brookhaven National Laboratory, Upton, NY, United States
| | - Fuminori Kobayashi
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Masaomi Hatakeyama
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Functional Genomics Center Zurich, Zurich, Switzerland
| | - Hiroyuki Kanamori
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Jianzhong Wu
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Martin Mascher
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Kanako Kawaura
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | - Kentaro K. Shimizu
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | - Hirokazu Handa
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
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Colombo F, Di Lorenzo C, Biella S, Bani C, Restani P. Ancient and Modern Cereals as Ingredients of the Gluten-Free Diet: Are They Safe Enough for Celiac Consumers? Foods 2021; 10:foods10040906. [PMID: 33924221 PMCID: PMC8074585 DOI: 10.3390/foods10040906] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/14/2021] [Accepted: 04/17/2021] [Indexed: 02/05/2023] Open
Abstract
Celiac disease is an autoimmune disorder that occurs in genetically predisposed individuals after consuming prolamins from some cereals. Although the products available for celiac subjects have increased significantly in quality and quantity over the last few decades, research still focuses on identifying new ingredients to improve the nutritional, sensorial and functional qualities of gluten-free products. In terms of toxicity for people with celiac disease, there is a wide variability between ancient and modern grains. The most contradictory results are related to the role of oats in the gluten-free diet. In order to clarify the role of minor cereals (such as oat) and ancient grains in the diets of celiac patients, this review discusses recent in vitro and in vivo studies performed on those cereals for which the toxicity for celiac subjects is still controversial. According to in vivo studies, selected oat varieties could be tolerated by celiac patients. On the other hands, although some wheat-ancient grains (Triticum monococcum, Triticum aestivum ssp. spelta and Kamut®) showed a reduced in vitro toxicity, to date, these grains are still considered toxic for celiac patients. Contradictory results underline the importance of studying the safety of "unusual" cereals in more detail.
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Ruiz-Carnicer Á, Comino I, Segura V, Ozuna CV, Moreno MDL, López-Casado MÁ, Torres MI, Barro F, Sousa C. Celiac Immunogenic Potential of α-Gliadin Epitope Variants from Triticum and Aegilops Species. Nutrients 2019; 11:E220. [PMID: 30678169 PMCID: PMC6413208 DOI: 10.3390/nu11020220] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/14/2019] [Accepted: 01/17/2019] [Indexed: 12/18/2022] Open
Abstract
The high global demand of wheat and its subsequent consumption arise from the physicochemical properties of bread dough and its contribution to the protein intake in the human diet. Gluten is the main structural complex of wheat proteins and subjects affected by celiac disease (CD) cannot tolerate gluten protein. Within gluten proteins, α-gliadins constitute the most immunogenic fraction since they contain the main T-cell stimulating epitopes (DQ2.5-glia-α1, DQ2.5-glia-α2, and DQ2.5-glia-α3). In this work, the celiac immunotoxic potential of α-gliadins was studied within Triticeae: diploid, tetraploid, and hexaploid species. The abundance and immunostimulatory capacity of CD canonical epitopes and variants (with one or two mismatches) in all α-gliadin sequences were determined. The results showed that the canonical epitopes DQ2.5-glia-α1 and DQ2.5-glia-α3 were more frequent than DQ2.5-glia-α2. A higher abundance of canonical DQ2.5-glia-α1 epitope was found to be associated with genomes of the BBAADD, AA, and DD types; however, the abundance of DQ2.5-glia-α3 epitope variants was very high in BBAADD and BBAA wheat despite their low abundance in the canonical epitope. The most abundant substitution was that of proline to serine, which was disposed mainly on the three canonical DQ2.5 domains on position 8. Interestingly, our results demonstrated that the natural introduction of Q to H at any position eliminates the toxicity of the three T-cell epitopes in the α-gliadins. The results provided a rational approach for the introduction of natural amino acid substitutions to eliminate the toxicity of three T-cell epitopes, while maintaining the technological properties of commercial wheats.
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Affiliation(s)
- Ángela Ruiz-Carnicer
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
| | - Isabel Comino
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
| | - Verónica Segura
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
| | - Carmen V Ozuna
- Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible (IAS-CSIC), 14004 Córdoba, Spain.
| | - María de Lourdes Moreno
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
| | | | - María Isabel Torres
- Departamento de Biología Experimental, Campus Universitario Las Lagunillas, 23071 Jaén, Spain.
| | - Francisco Barro
- Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible (IAS-CSIC), 14004 Córdoba, Spain.
| | - Carolina Sousa
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
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Escarnot E, Gofflot S, Sinnaeve G, Dubois B, Bertin P, Mingeot D. Reactivity of gluten proteins from spelt and bread wheat accessions towards A1 and G12 antibodies in the framework of celiac disease. Food Chem 2018; 268:522-532. [DOI: 10.1016/j.foodchem.2018.06.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/25/2018] [Accepted: 06/19/2018] [Indexed: 11/28/2022]
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Abstract
Gluten is among the 14 major food allergens officially recognized by Regulation (EU) No. 1169/2011. The risk to coeliac patients from gluten presence in the food products they consume is likely due to the unintentional contamination of naturally gluten-free (GF) and GF-labelled products, or to hidden sources of gluten in processed GF products. The aim of this paper is to provide a snapshot of gluten risk analysis, with emphasis on immunological methods currently used in gluten detection. The study highlights that immunoassays have some advantages over other analytical methods in gluten determination and are suitable for routine tests. However, some factors (e.g., complexity of the food matrix, type of the applied antibody, gluten extraction procedures and lack of reference material) affect the reliability of obtained results. Hence, efforts are required at an analytical level to overcome the drawbacks of the immunological methods currently available. Harmonization is necessary, so as to assist both consumers in making safe food choices, and the food industry in gluten risk assessment, management and communication.
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Dubois B, Bertin P, Hautier L, Muhovski Y, Escarnot E, Mingeot D. Genetic and environmental factors affecting the expression of α-gliadin canonical epitopes involved in celiac disease in a wide collection of spelt (Triticum aestivum ssp. spelta) cultivars and landraces. BMC PLANT BIOLOGY 2018; 18:262. [PMID: 30382818 PMCID: PMC6211434 DOI: 10.1186/s12870-018-1487-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/17/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Celiac disease (CD) is an autoimmune disorder affecting genetically predisposed individuals whose dietary gluten proteins trigger an inflammatory reaction in the small intestine. Gluten is found in the seeds of cereals like bread wheat (Triticum aestivum ssp. aestivum) and spelt (Triticum aestivum ssp. spelta). The development of new varieties lacking immunogenic peptides is one of the strategies currently investigated to address the CD problem. Among gluten proteins, α-gliadins display the strongest immunogenicity with four main T-cell stimulatory epitopes. The objective of this work was to study the expression of α-gliadin epitopes related to CD in a wide collection of 121 spelt accessions (landraces and varieties, spring and winter accessions) from different provenances, and to analyze the correlation between the presence of epitope sequences in gDNA and their expression (cDNA). The effect of environmental factors (harvest year and N fertilization) on the epitope expression was also investigated. RESULTS TaqMan probes targeting the canonical form of the epitopes were used to evaluate the epitope expression levels. Significant variations in the amount of epitope transcripts were identified between accessions and according to the provenances. Spring accessions showed a significantly higher immunogenicity than winter ones and no influence of spelt breeding on the epitope expression levels could be assessed when comparing landraces and varieties from Northwestern Europe. No correlation was observed between quantitative PCR results obtained from cDNA and gDNA for 45 accessions tested, stressing the need to use markers focusing on epitope transcripts rather than on genomic sequences. A relative stability of the amount of epitopes expressed by a same accession across four harvest years was detected. The fertilization strategy, evaluated through seven N fertilization modalities applied to two commercial spelt varieties, did not influence the epitope expression of the first variety, whereas it had a slight effect for the second one. CONCLUSIONS The results obtained in this work showed that the CD-related epitope expression greatly fluctuated among the spelt accessions studied. This expression was not correlated to the epitope genomic occurrence and environmental factors had almost no influence on the amount of epitope transcripts.
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Affiliation(s)
- Benjamin Dubois
- Unit of Bioengineering, Department of Life Sciences, Walloon Agricultural Research Center, Gembloux, Belgium
- Earth and Life Institute-Agronomy, Catholic University of Louvain, Louvain-la-Neuve, Belgium
| | - Pierre Bertin
- Earth and Life Institute-Agronomy, Catholic University of Louvain, Louvain-la-Neuve, Belgium
| | - Louis Hautier
- Unit of Plant protection and ecotoxicology, Department of Life Sciences, Walloon Agricultural Research Center, Gembloux, Belgium
| | - Yordan Muhovski
- Unit of Bioengineering, Department of Life Sciences, Walloon Agricultural Research Center, Gembloux, Belgium
| | - Emmanuelle Escarnot
- Unit of Breeding and biodiversity, Department of Life Sciences, Walloon Agricultural Research Center, Gembloux, Belgium
| | - Dominique Mingeot
- Unit of Bioengineering, Department of Life Sciences, Walloon Agricultural Research Center, Gembloux, Belgium
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