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Langenaeken NA, Ieven P, Hedlund EG, Kyomugasho C, van de Walle D, Dewettinck K, Van Loey AM, Roeffaers MBJ, Courtin CM. Arabinoxylan, β-glucan and pectin in barley and malt endosperm cell walls: a microstructure study using CLSM and cryo-SEM. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1477-1489. [PMID: 32412127 DOI: 10.1111/tpj.14816] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/29/2020] [Accepted: 05/05/2020] [Indexed: 05/14/2023]
Abstract
The architecture of endosperm cell walls in Hordeum vulgare (barley) differs remarkably from that of other grass species and is affected by germination or malting. Here, the cell wall microstructure is investigated using (bio)chemical analyses, cryogenic scanning electron microscopy (cryo-SEM) and confocal laser scanning microscopy (CLSM) as the main techniques. The relative proportions of β-glucan, arabinoxylan and pectin in cell walls were 61, 34 and 5%, respectively. The average thickness of a single endosperm cell wall was 0.30 µm, as estimated by the cryo-SEM analysis of barley seeds, which was reduced to 0.16 µm after malting. After fluorescent staining, 3D confocal multiphoton microscopy (multiphoton CLSM) imaging revealed the complex cell wall architecture. The endosperm cell wall is composed of a structure in which arabinoxylan and pectin are colocalized on the outside, with β-glucan depositions on the inside. During germination, arabinoxylan and β-glucan are hydrolysed, but unlike β-glucan, arabinoxylan remains present in defined cell walls in malt. Integrating the results, an enhanced model for the endosperm cell walls in barley is proposed.
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Affiliation(s)
- Niels A Langenaeken
- Laboratory of Food Chemistry and Biochemistry, Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, Leuven, 3001, Belgium
| | - Pieter Ieven
- Laboratory of Food Chemistry and Biochemistry, Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, Leuven, 3001, Belgium
| | - Erik G Hedlund
- Centre for Surface Chemistry and Catalysis, KU Leuven, Leuven, 3001, Belgium
| | - Clare Kyomugasho
- Laboratory of Food Technology, Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, Heverlee, 3001, Belgium
| | - Davy van de Walle
- Laboratory of Food Technology and Engineering, Department of Food Technology, Safety and Health, Ghent University, Coupure Links 653, Ghent, 9000, Belgium
| | - Koen Dewettinck
- Laboratory of Food Technology and Engineering, Department of Food Technology, Safety and Health, Ghent University, Coupure Links 653, Ghent, 9000, Belgium
| | - Ann M Van Loey
- Laboratory of Food Technology, Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, Heverlee, 3001, Belgium
| | | | - Christophe M Courtin
- Laboratory of Food Chemistry and Biochemistry, Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, Leuven, 3001, Belgium
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Monat C, Schreiber M, Stein N, Mascher M. Prospects of pan-genomics in barley. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:785-796. [PMID: 30446793 DOI: 10.1007/s00122-018-3234-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/07/2018] [Indexed: 05/10/2023]
Abstract
The concept of a pan-genome refers to intraspecific diversity in genome content and structure, encompassing both genes and intergenic space. Pan-genomic studies employ a combination of de novo sequence assembly and reference-based alignment to discover and genotype structural variants. The large size and complex structure of Triticeae genomes were for a long time an obstacle for genomic research in barley and its relatives. Now that a reference genome is available, computational pipelines for high-quality sequence assembly are in place, and sequence costs continue to drop, investigations into the structural diversity of the barley genome seem within reach. Here, we review the recent progress on pan-genomics in the model grass Brachypodium distachyon, and the cereal crops rice and maize, and devise a multi-tiered strategy for a pan-genome project in barley. Our design involves: (1) the construction of high-quality de novo sequence assemblies for a small core set of representative genotypes, (2) short-read sequencing of a large diversity panel of genebank accessions to medium coverage and (3) the use of complementary methods such as chromosome-conformation capture sequencing and k-mer-based association genetics. The in silico representation of the barley pan-genome may inform about the mechanisms of structural genome evolution in the Triticeae and supplement quantitative genetics models of crop performance for better accuracy and predictive ability.
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Affiliation(s)
- Cécile Monat
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Seeland, Germany
| | - Mona Schreiber
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Seeland, Germany
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Seeland, Germany
- Center for Integrated Breeding Research (CiBreed), Georg-August-University Göttingen, 37075, Göttingen, Germany
| | - Martin Mascher
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Seeland, Germany.
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.
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