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1.
Overview of Popular Techniques of Raman Spectroscopy and Their Potential in the Study of Plant Tissues.
Saletnik, A, Saletnik, B, Puchalski, C
Molecules (Basel, Switzerland). 2021;(6)
Abstract
Raman spectroscopy is one of the main analytical techniques used in optical metrology. It is a vibration, marker-free technique that provides insight into the structure and composition of tissues and cells at the molecular level. Raman spectroscopy is an outstanding material identification technique. It provides spatial information of vibrations from complex biological samples which renders it a very accurate tool for the analysis of highly complex plant tissues. Raman spectra can be used as a fingerprint tool for a very wide range of compounds. Raman spectroscopy enables all the polymers that build the cell walls of plants to be tracked simultaneously; it facilitates the analysis of both the molecular composition and the molecular structure of cell walls. Due to its high sensitivity to even minute structural changes, this method is used for comparative tests. The introduction of new and improved Raman techniques by scientists as well as the constant technological development of the apparatus has resulted in an increased importance of Raman spectroscopy in the discovery and defining of tissues and the processes taking place in them.
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2.
Advances in Cell Wall Matrix Research with a Focus on Mixed-Linkage Glucan.
Kim, SJ, Brandizzi, F
Plant & cell physiology. 2021;(12):1839-1846
Abstract
Mixed β(1,3;1,4)-linkage glucan (MLG) is commonly found in the monocot lineage, at particularly high levels in the Poaceae family, but also in the evolutionally distant genus, Equisetum. MLG has several properties that make it unique from other plant cell wall polysaccharides. It consists of β1,4-linked polymers of glucose interspersed with β1,3-linkages, but the presence of β1,3-linkages provides quite different physical properties compared to its closest form of the cell wall component, cellulose. The mechanisms of MLG biosynthesis have been investigated to understand whether single or multiple enzymes are required to build mixed linkages in the glucan chain. Currently, MLG synthesis by a single enzyme is supported by mutagenesis analyses of cellulose synthase-like F6, the major MLG synthase, but further investigation is needed to gather mechanistic insights. Because of transient accumulation of MLG in elongating cells and vegetative tissues, several hypotheses have been proposed to explain the role of MLG in the plant cell wall. Studies have been carried out to identify gene expression regulators during development and light cycles as well as enzymes involved in MLG organization in the cell wall. A role of MLG as a storage molecule in grains is evident, but the role of MLG in vegetative tissues is still not well understood. Characterization of a cell wall component is difficult due to the complex heterogeneity of the plant cell wall. However, as detailed in this review, recent exciting research has made significant impacts in the understanding of MLG biology in plants.
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3.
Cell wall-associated effectors of plant-colonizing fungi.
Tanaka, S, Kahmann, R
Mycologia. 2021;(2):247-260
Abstract
Plant-colonizing fungi secrete a cocktail of effector proteins during colonization. After secretion, some of these effectors are delivered into plant cells to directly dampen the plant immune system or redirect host processes benefitting fungal growth. Other effectors function in the apoplastic space either as released proteins modulating the activity of plant enzymes associated with plant defense or as proteins bound to the fungal cell wall. For such fungal cell wall-bound effectors, we know particularly little about their molecular function. In this review, we describe effectors that are associated with the fungal cell wall and discuss how they contribute to colonization.
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4.
How much water can wood cell walls hold? A triangulation approach to determine the maximum cell wall moisture content.
Thybring, EE, Digaitis, R, Nord-Larsen, T, Beck, G, Fredriksson, M
PloS one. 2020;(8):e0238319
Abstract
Wood is a porous, hygroscopic material with engineering properties that depend significantly on the amount of water (moisture) in the material. Water in wood can be present in both cell walls and the porous void-structure of the material, but it is only water in cell walls that affects the engineering properties. An important characteristic of wood is therefore the capacity for water of its solid cell walls, i.e. the maximum cell wall moisture content. However, this quantity is not straight-forward to determine experimentally, and the measured value may depend on the experimental technique used. In this study, we used a triangulation approach to determine the maximum cell wall moisture content by using three experimental techniques based on different measurement principles: low-field nuclear magnetic resonance (LFNMR) relaxometry, differential scanning calorimetry (DSC), and the solute exclusion technique (SET). The LFNMR data were furthermore analysed by two varieties of exponential decay analysis. These techniques were used to determine the maximum cell wall moisture contents of nine different wood species, covering a wide range of densities. The results from statistical analysis showed that LFNMR yielded lower cell wall moisture contents than DSC and SET, which were fairly similar. Both of the latter methods include factors that could either under-estimate or over-estimate the measured cell wall moisture content. Because of this and the fact that the DSC and SET methods are based on different measurement principles, it is likely that they provide realistic values of the cell wall moisture content in the water-saturated state.
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5.
Changes of cell wall components during embryogenesis of Castanea mollissima.
Du, B, Zhang, Q, Cao, Q, Xing, Y, Qin, L, Fang, K
Journal of plant research. 2020;(2):257-270
Abstract
The Chinese chestnut (Castanea mollissima Blume) 'Huaihuang' was chosen as the experimental material to observe embryogenesis and the dynamic changes of cell wall components during this process. Various developmental stages of embryos, including globular embryos, heart embryos, torpedo embryos and cotyledon embryos, were observed. The results showed that during embryogenesis, cellulose increased, and callose rapidly degraded. In the cell walls of developing embryos, pectic homogalacturonan (HG), especially low-esterified HG, was abundant, suggesting rapid synthesis and de-methyl-esterification of HG. Extensin and galactan increased with the development of the embryos. In contrast, the arabinan epitopes decreased in developing embryos but were more abundant than galactan epitopes at all stages. Xylan epitopes showed explicit boundaries between the outer epidermal wall and the rest of the inner tissues, and the fluorescence intensity of the outer epidermal wall was significantly higher than that of the inner tissues. Furthermore, the results indicated that the outer epidermal wall contained high amounts of cellulose, HG pectin and hemicellulose, especially arabinan and xylan. These results suggested the presence of rapid pectin metabolism, cellulose synthesis, rapid degradation of callose, different distributive patterns and dynamic changes of hemicellulose (galactan, arabinan and xylan) and extensin during embryogenesis. Various cell wall components exist in different tissues of the embryo, and dynamic changes in cell wall components are involved in the embryonic development process.
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6.
Scedosporium Cell Wall: From Carbohydrate-Containing Structures to Host-Pathogen Interactions.
Rollin-Pinheiro, R, Xisto, MIDDS, Rochetti, VP, Barreto-Bergter, E
Mycopathologia. 2020;(6):931-946
Abstract
Scedosporium species are filamentous fungi usually found in sewage and soil from human-impacted areas. They cause a wide range of diseases in humans, from superficial infections, such as mycetoma, to invasive and disseminated cases, especially associated in immunocompromised patients. Scedosporium species are also related to lung colonization in individuals presenting cystic fibrosis and are considered one of the most frequent fungal pathogens associated to this pathology. Scedosporium cell wall contains glycosylated molecules involved in important biological events related to virulence and pathogenicity and represents a significant source of antigens. Polysaccharides, peptidopolysaccharides, O-linked oligosaccharides and glycosphingolipids have been identified on the Scedosporium surface. Their primary structures were determined based on a combination of techniques including gas chromatography, ESI-MS, and 1H and 13C nuclear magnetic resonance. Peptidorhamnnomannans are common cell wall components among Scedosporium species. Comparing different species, minor structural differences in the carbohydrate portions were detected which could be useful to understand variations in virulence observed among the species. N- and O-linked peptidorhamnomannans are major pathogen-associated molecular patterns and, along with α-glucans, play important roles in triggering host innate immunity. Glycosphingolipids, such as glucosylceramides, have highly conserved structures in Scedosporium species and are crucial for fungal growth and virulence. The present review presents current knowledge on structural and functional aspects of Scedosporium glycoconjugates that are relevant for understanding pathogenicity mechanisms and could contribute to the design of new agents capable of inhibiting growth and differentiation of Scedosporium species. Other cell components such as melanin and ectophosphatases will be also included.
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7.
Banana MaBZR1/2 associate with MaMPK14 to modulate cell wall modifying genes during fruit ripening.
Shan, W, Guo, YF, Wei, W, Chen, JY, Lu, WJ, Yuan, DB, Su, XG, Kuang, JF
Plant cell reports. 2020;(1):35-46
Abstract
Banana MaBZR1/2 interact with MaMPK14 to enhance the transcriptional inhibition of cell wall modifying genes including MaEXP2, MaPL2 and MaXET5. Fruit ripening and softening, the major attributes to perishability in fleshy fruits, are modulated by various plant hormones and gene expression. Banana MaBZR1/2, the central transcription factors of brassinosteroid (BR) signaling, mediate fruit ripening through regulation of ethylene biosynthesis, but their possible roles in fruit softening as well as the underlying mechanisms remain to be determined. In this work, we found that MaBZR1/2 directly bound to and repressed the promoters of several cell wall modifying genes such as MaEXP2, MaPL2 and MaXET5, whose transcripts were elevated concomitant with fruit ripening. Moreover, yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated that MaBZR1/2 physically interacted with a mitogen-activated protein kinase MaMPK14, and this interaction strengthened the MaBZR1/2-mediated transcriptional inhibitory abilities. Collectively, our study provides insight into the mechanism of MaBZR1/2 contributing to fruit ripening and softening, which may have potential for banana molecular improvement.
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8.
Dietary fiber polysaccharides of amaranth, buckwheat and quinoa grains: A review of chemical structure, biological functions and food uses.
Zhu, F
Carbohydrate polymers. 2020;:116819
Abstract
Seeds of amaranth (Amaranthus spp.), buckwheat (Fagopyrum esculentum and F. tataricum) and quinoa (Chenopodium quinoa) become popular foods due to their attractive health effects. Cell wall polysaccharides are the major components of dietary fiber and significantly contribute to diverse health effects of the grains. This review summarizes chemical and physical structure, biological functions and food uses of the cell wall polysaccharides and fractions as fiber components from the 3 pseudocereals. The properties and uses of the polysaccharides and fractions are compared with those of fiber polysaccharides from common sources such as fruits and vegetables. Overall, the fiber polysaccharide composition of the pseudocereals is more similar to that of fruits and vegetables than to that of cereals. The fiber polysaccharides showed a range of biological functions such as antioxidation, anticancer and immunomodulation. The fiber polysaccharides of amaranth, buckwheat and quinoa have potential to be used in formulations of functional foods.
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9.
Evolutionary Overview of Molecular Interactions and Enzymatic Activities in the Yeast Cell Walls.
Teparić, R, Lozančić, M, Mrša, V
International journal of molecular sciences. 2020;(23)
Abstract
Fungal cell walls are composed of a polysaccharide network that serves as a scaffold in which different glycoproteins are embedded. Investigation of fungal cell walls, besides simple identification and characterization of the main cell wall building blocks, covers the pathways and regulations of synthesis of each individual component of the wall and biochemical reactions by which they are cross-linked and remodeled in response to different growth phase and environmental signals. In this review, a survey of composition and organization of so far identified and characterized cell wall components of different yeast genera including Saccharomyces, Candida, Kluyveromyces, Yarrowia, and Schizosaccharomyces are presented with the focus on their cell wall proteomes.
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10.
Impacts of thermal and non-thermal processing on structure and functionality of pectin in fruit- and vegetable- based products: A review.
Liu, J, Bi, J, McClements, DJ, Liu, X, Yi, J, Lyu, J, Zhou, M, Verkerk, R, Dekker, M, Wu, X, et al
Carbohydrate polymers. 2020;:116890
Abstract
Pectin, a major polysaccharide found in the cell walls of higher plants, plays major roles in determining the physical and nutritional properties of fruit- and vegetable-based products. An in-depth understanding of the effects of processing operations on pectin structure and functionality is critical for designing better products. This review, therefore, focuses on the progress made in understanding the effects of processing on pectin structure, further on pectin functionality, consequently on product properties. The effects of processing on pectin structure are highly dependent on the processing conditions. Targeted control of pectin structure by applying various processing operations could enhance textural, rheological, nutritional properties and cloud stability of products. While it seems that optimizing product quality in terms of physical properties is counteracted by optimizing the nutritional properties. Therefore, understanding plant component biosynthesis mechanisms and processing mechanisms could be a major challenge to balance among the quality indicators of processed products.