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Journal ArticleDOI

Study of grain cell wall structures by microscopic analysis with four different staining techniques

TL;DR: Four different grain cell wall staining techniques were compared and AX was mostly concentrated in nucellar epidermis and aleurone cells, whereas β-glucan was concentrated more in subaleur one cells, giving new insight into the structure of the cereal dietary fiber complex.
About: This article is published in Journal of Cereal Science.The article was published on 2011-08-12. It has received 62 citations till now. The article focuses on the topics: Aleurone & Endosperm.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors used optical and Raman microscopy to localize wheat and barley grain components using selective stains and autofluorescence to image the ferulic acid and other fluorescing substances.

71 citations

Journal ArticleDOI
TL;DR: Speciation analysis suggests that Fe is bound to nicotianamine rather than phytate in the nucellar projection, and that more complex Fe structures may also be present, as well as revealing the complexity of the physiological processes responsible for element accumulation and bioaccessibility.
Abstract: Several studies have suggested that the majority of iron (Fe) and zinc (Zn) in wheat grains are associated with phytate, but a nuanced approach to unravel important tissue-level variation in element speciation within the grain is lacking. Here, we present spatially resolved Fe-speciation data obtained directly from different grain tissues using the newly developed synchrotron-based technique of X-ray absorption near-edge spectroscopy imaging, coupling this with high-definition μ-X-ray fluorescence microscopy to map the co-localization of essential elements. In the aleurone, phosphorus (P) is co-localized with Fe and Zn, and X-ray absorption near-edge structure imaging confirmed that Fe is chelated by phytate in this tissue layer. In the crease tissues, Zn is also positively related to P distribution, albeit less so than in the aleurone. Speciation analysis suggests that Fe is bound to nicotianamine rather than phytate in the nucellar projection, and that more complex Fe structures may also be present. In the embryo, high Zn concentrations are present in the root and shoot primordium, co-occurring with sulfur and presumably bound to thiol groups. Overall, Fe is mainly concentrated in the scutellum and co-localized with P. This high resolution imaging and speciation analysis reveals the complexity of the physiological processes responsible for element accumulation and bioaccessibility.

63 citations

Journal ArticleDOI
TL;DR: The sample with the highest digestibility was observed to have intensified cellulose staining, possibly reflecting the increased accessibility of cellulose, and the highest yields were obtained from the samples with a low xylan and diferulate content.

56 citations


Cites methods from "Study of grain cell wall structures..."

  • ...For light microscopy, pieces of straw samples were pre-embedded into 2% (w/v) agar, fixed and embedded into resin as described in Dornez et al. (2011). Semi-thin (2 lm) cross sections of wheat straws in polymerised sample blocks were cut in a rotary microtome HM 355 (Microm Laborgeräte GmbH, Walldorf, Germany) using a tungsten carbon knife....

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Journal ArticleDOI
TL;DR: A model for endosperm cell wall structural organisation is proposed, based on a core of cellulose and interacting non-cellulosic polysaccharides which anchors AX that in turn retains MLGs through physical entanglement.

56 citations

Journal ArticleDOI
TL;DR: Derivative X-ray absorption spectra suggest that mineral complexation in the transfer region of ferritin-expressing grains is quite different from that in wild-type grain, which may explain why the raised levels of minerals transported to the developing grain accumulate within the crease region of the transgenic grain.
Abstract: We have used synchrotron-based X-ray fluorescence and absorption techniques to establish both metal distribution and complexation in mature wheat grains. In planta, extended X-ray absorption fine structure (EXAFS) spectroscopy reveals iron phytate and zinc phytate structures in aleurone cells and in modified aleurone cells in the transfer region of the grain: iron is coordinated octahedrally by six oxygen atoms and fewer than two phosphorous atoms. Zinc is coordinated tetrahedrally by four oxygen atoms and approximately 1.5 phosphorus atoms in an asymmetric coordination shell. We also present evidence of modified complexation of both metals in transgenic grain overexpressing wheat ferritin. For zinc, there is a consistent doubling of the number of complexing phosphorus atoms. Although there is some EXAFS evidence for iron phytate in ferritin-expressing grain, there is also evidence of a structure lacking phosphorus. This change may lead to an excess of phosphorus within the storage regions of grain, and in turn to the demonstrated increased association of phosphorus with zinc in ferritin-expressing grains. Derivative X-ray absorption spectra also suggest that mineral complexation in the transfer region of ferritin-expressing grains is quite different from that in wild-type grain. This may explain why the raised levels of minerals transported to the developing grain accumulate within the crease region of the transgenic grain.

47 citations

References
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Journal ArticleDOI
TL;DR: This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells consistent with the physical properties of the wall and its components.
Abstract: Advances in determination of polymer structure and in preservation of structure for electron microscopy provide the best view to date of how polysaccharides and structural proteins are organized into plant cell walls. The walls that form and partition dividing cells are modified chemically and structurally from the walls expanding to provide a cell with its functional form. In grasses, the chemical structure of the wall differs from that of all other flowering plant species that have been examined. Nevertheless, both types of wall must conform to the same physical laws. Cell expansion occurs via strictly regulated reorientation of each of the wall's components that first permits the wall to stretch in specific directions and then lock into final shape. This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells. We provide structural models of two distinct types of walls in flowering plants consistent with the physical properties of the wall and its components.

3,417 citations

Journal ArticleDOI
TL;DR: In this paper, a simple and rapid method for the preparation of alditol acetates from monosaccharides is described, which can be performed in a single tube without transfers or evaporations.

1,880 citations

Journal ArticleDOI
01 Jun 1996
TL;DR: This review focuses on the chemistry of the unique polysaccharides, aromatic substances, and proteins of the grasses and how these structural elements are synthesized and assembled into dynamic and functional cell walls.
Abstract: The chemical structures of the primary cell walls of the grasses and their progenitors differ from those of all other flowering plant species. They vary in the complex glycans that interlace and cross-link the cellulose microfibrils to form a strong framework, in the nature of the gel matrix surrounding this framework, and in the types of aromatic substances and structural proteins that covalently cross-link the primary and secondary walls and lock cells into shape. This review focuses on the chemistry of the unique polysaccharides, aromatic substances, and proteins of the grasses and how these structural elements are synthesized and assembled into dynamic and functional cell walls. Despite wide differences in wall composition, the developmental physiology of grasses is similar to that of all flowering plants. Grass cells respond similarly to environmental cues and growth regulators, exhibit the same alterations in physical properties of the wall to allow cell growth, and possess similar patterns of wall biogenesis during the development of specific cell and tissue types. Possible unifying mechanisms of growth are suggested to explain how grasses perform the same wall functions as other plants but with different constituents and architecture.

828 citations

Journal ArticleDOI
TL;DR: Several structural models have been put forward based on enzymic degradation studies and structure elucidation of oligosaccharides by NMR, methylation, and periodate oxidation techniques as mentioned in this paper.

806 citations

Journal ArticleDOI
TL;DR: The relationship between the molecular-structural characteristics of β-glucans and physicochemical properties in aqueous dispersions and in food systems as well as their physiological functions in the gastro-intestinal tract is discussed in this article.

566 citations

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The results give new insight into the structure of the cereal dietary fiber complex.