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Mamey (Mammea americana L.) is a tropical fleshy fruit native from the West Indies and northern South America. It is very appreciated for its flavor and color but has been little described. The present study investigates the composition and histochemistry of the pulp cell walls of three mamey accessions readily available in Martinique. The impact of pulp processing into puree on cell wall composition is evaluated. The histology and rheology of mamey puree are assessed considering these characterizations. Mamey pulp cell wall composition is dominated by highly methyl-esterified pectins (DM: 66.2–76.7%) of high molecular weight, and show few hemicelluloses, mainly xyloglucans. Processing reduced methyl-esterified uronic acid contents and gave purees with significantly different viscosities. Mamey puree was composed of polydisperse particles (20–2343 µm), which size distributions were different depending on the accession: Ti Jacques was dominated by smaller particles (50% had approximated diameters lower than 160 µm), Sonson's by larger particles (50% had approximated diameters higher than 900 µm), and Galion's had an intermediate profile. This new knowledge on mamey pulp is valuable for future works on mamey processing into new food products, even more so for those including cell wall polysaccharide-degrading enzymes. [ABSTRACT FROM AUTHOR]

BACKGROUND: Aconitum carmichaelii is an industrially cultivated medicinal plant in China and its lateral and mother roots are used in traditional Chinese medicine due to the presence of alkaloids. However, the rootlets and aerial parts are discarded after collection of the roots, and the non‐toxic polysaccharides in this plant have attracted less attention than the alkaloids and poisonous features. In this study, five neutral and 14 acidic polysaccharide fractions were isolated systematically from different plant parts of A. carmichaelii, and their structural features and bioactivity were studied and compared. RESULTS: The neutral fraction isolated from the rootlets differed from those isolated from the lateral and mother roots. It consisted of less starch and more possible mannans, galactans, and/or xyloglucans, being similar to those of the aerial parts. Pectic polysaccharides containing homogalacturonan and branched type‐I rhamnogalacturonan (RG‐I) were present in all plant parts of A. carmichaelii. However, more arabinogalactan (AG)‐II side chains in the RG‐I backbone were present in the aerial parts of the plants, while more amounts of arabinans were found in the roots. Various immunomodulatory effects were observed, determined by complement fixation activity and anti‐inflammatory effects on the intestinal epithelial cells of all polysaccharide fractions. CONCLUSION: This study highlighted the diversity of polysaccharides present in A. carmichaelii, especially in the unutilized plant parts, and showed their potential medicinal value. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

During the development of legume-rhizobial symbiosis, the process of rhizobia internalization depends on the modification of the plant-microbial surfaces and, first of all, on the remodeling of cell walls of both plant cells and infection threads. The components of cell walls, intercellular matrix and plasma and symbiosome membranes in nitrogen-fixing nodules of two legume species belonging to different types—determinate (Glycine max L. Merrill) and indeterminate (Galega orientalis Lam.)—were studied. As a result, the localization and distribution of different types of pectins, fucosylated xyloglucans, cell wall proteins and arabinogalactan proteins were revealed. Species-specific features of the symbiotic interface were identified, namely the presence of the linear galactan side chain of rhamnogalacturonan I in the infection thread walls, the rhamnogalacturonan I backbone, Ca2+-linked homogalacturonan, and an increase in the labeling of low methylesterified homogalacturonan in the cell walls of uninfected cells in the indeterminate nodules of G. orientalis; the presence of the galactan side chain of rhamnogalacturonan I in the cell walls of uninfected cells and the predominant accumulation of fucosylated xyloglucan in the infection thread walls in the determinate nodules of G. max. In nodules of both species, arabinans (cross-linked with rhamnogalacturonan I and as part of arabinogalactan proteins) play a major role in the development of infection structures, in particular symbiosomes, namely, they are detected at early stages of symbiosome differentiation. [ABSTRACT FROM AUTHOR]

Different components of the symbiotic interface play an important role in providing positional information during rhizobial infection and nodule development: successive changes in cell morphology correspond to subsequent changes in the molecular architecture of the apoplast and the associated surface structures. The localisation and distribution of pectins, xyloglucans, and cell wall proteins in symbiotic nodules of Pisum sativum and Medicago truncatula were studied using immunofluorescence and immunogold analysis in wild-type and ineffective mutant nodules. As a result, the ontogenetic changes in the symbiotic interface in the nodules of both species were described. Some differences in the patterns of distribution of cell wall polysaccharides and proteins between wild-type and mutant nodules can be explained by the activation of defence reaction or premature senescence in mutants. The absence of fucosylated xyloglucan in the cell walls in the P. sativum nodules, as well as its predominant accumulation in the cell walls of uninfected cells in the M. truncatula nodules, and the presence of the rhamnogalacturonan I (unbranched) backbone in meristematic cells in P. sativum can be attributed to the most striking species-specific features of the symbiotic interface. [ABSTRACT FROM AUTHOR]

Fruit softening in tomato (Solanum lycopersicum) is closely associated with cell wall disassembly, which is brought about through the action of a range of cell wall structure-related enzymes and other proteins such as expansins. Xyloglucan endotransglucosylase/hydrolase (XTH) (EC 2.4.1.207 and/or EC 3.2.1.151) has been proposed to be key player involved in xyloglucan metabolism. SlXTH5 showed the highest expression level among all SlXTHs during tomato ripening. In this study, the role of SlXTH5 involved in tomato softening was investigated in CRISPR-based knockout mutants of SlXTH5. Loss-of-function of SlXTH5 in transgenic tomato lines resulted in slightly firmer fruit pericarp, but significantly decreased their color index compared with azygous wild type (WT) control fruits. Increased paste viscosity was detected in CRISPR mutants, indicating that the activity of SlXTH5 is responsible for maintaining cell wall structural integrity. Immunocytochemistry studies were performed using the monoclonal antibody probe LM25 to examine the localization and distribution of xyloglucan in the pericarp cells of the CRISPR mutant fruits. The data indicated more xyloglucan was retained in the pericarp of CRISPR mutant fruit than in WT control fruit. This study revealed the link between SlXTH5 and xyloglucan metabolism and indicated the potential of manipulating SlXTH5 to regulate fruit softening. [ABSTRACT FROM AUTHOR]

Plant primary cell walls are composite structures surrounding the protoplast and containing pectins, hemicelluloses, and cellulose polysaccharides, as well as proteins. Their composition changed during the evolution of the green lineage from algae to terrestrial plants, i.e., from an aquatic to a terrestrial environment. The constraints of life in terrestrial environments have generated new requirements for the organisms, necessitating adaptations, such as cell wall modifications. We have studied the cell wall polysaccharide composition of thalli of Marchantia polymorpha, a bryophyte belonging to one of the first land plant genera. Using a collection of specific antibodies raised against different cell wall polysaccharide epitopes, we were able to identify in polysaccharide-enriched fractions: pectins, including low-methylesterified homogalacturonans; rhamnogalacturonan I with arabinan side-chains; and hemicelluloses, such as xyloglucans with XXLG and XXXG modules, mannans, including galactomannans, and xylans. We could also show the even distribution of XXLG xyloglucans and galactomannans in the cell walls of thalli by immunocytochemistry. These results are discussed with regard to the cell wall proteome composition and in the context of the evolution of the green lineage. The cell wall polysaccharides of M. polymorpha illustrate the transition from the charophyte ancestors of terrestrial plants containing xyloglucans, xylans and mannans as hemicelluloses, and embryophytes which do not exhibit mannans as major primary cell wall polysaccharides. [ABSTRACT FROM AUTHOR]

Streptophyte algae are the closest relatives to land plants; their latest common ancestor performed the most drastic adaptation in plant evolution around 500 million years ago: the conquest of land. Besides other adaptations, this step required changes in cell wall composition. Current knowledge on the cell walls of streptophyte algae and especially on the presence of arabinogalactan‐proteins (AGPs), important signalling molecules in all land plants, is limited. To get deeper insights into the cell walls of streptophyte algae, especially in Charophyceae, we performed sequential cell wall extractions of four Chara species. The three species Chara globularis, Chara subspinosa and Chara tomentosa revealed comparable cell wall compositions, with pectins, xylans and xyloglucans, whereas Chara aspera stood out with higher amounts of uronic acids in the pectic fractions and lack of reactivity with antibodies binding to xylan‐ and xyloglucan epitopes. Search for AGPs in the four Chara species and in Nitellopsis obtusa revealed the presence of galactans with pyranosidic galactose in 1,3‐, 1,6‐ and 1,3,6‐linkage, which are typical galactan motifs in land plant AGPs. A unique feature of these branched galactans was high portions of 3‐O‐methylgalactose. Only Nitellopsis contained substantial amounts of arabinose A bioinformatic search for prolyl‐4‐hydroxylases, involved in the biosynthesis of AGPs, revealed one possible functional sequence in the genome of Chara braunii, but no hydroxyproline could be detected in the four Chara species or in Nitellopsis obtusa. We conclude that AGPs that is typical for land plants are absent, at least in these members of the Charophyceae. [ABSTRACT FROM AUTHOR]

Summary: Although most xyloglucans (XyGs) biosynthesis enzymes have been identified, the molecular mechanism that defines XyG branching patterns is unclear. Four out of five XyG xylosyltransferases (XXT1, XXT2, XXT4, and XXT5) are known to add the xylosyl residue from UDP‐xylose onto a glucan backbone chain; however, the function of XXT3 has yet to be demonstrated.Single xxt3 and triple xxt3xxt4xxt5 mutant Arabidopsis (Arabidopsis thaliana) plants were generated using CRISPR‐Cas9 technology to determine the specific function of XXT3.Combined biochemical, bioinformatic, and morphological data conclusively established for the first time that XXT3, together with XXT4 and XXT5, adds xylosyl residue specifically at the third glucose in the glucan chain to synthesize XXXG‐type XyGs. We propose that the specificity of XXT3, XXT4, and XXT5 is directed toward the prior synthesis of the acceptor substrate by the other two enzymes, XXT1 and XXT2. We also conclude that XXT5 plays a dominant role in the synthesis of XXXG‐type XyGs, while XXT3 and XXT4 complementarily contribute their activities in a tissue‐specific manner.The newly generated xxt3xxt4xxt5 mutant produces only XXGG‐type XyGs, which further helps to understand the impact of structurally deficient polysaccharides on plant cell wall organization, growth, and development. [ABSTRACT FROM AUTHOR]

The use of hydrocolloids has greatly increased in recent years due to their pivotal role as functional ingredients. They can increase food consistency, control the microstructure that affects water absorption, alter texture and flavor, and improve the shelf life of baked products. In this work, we analyzed the effect of plant hemicelluloses such as Caesalpinia pulcherrima galactomannans and Tamarindus indica xyloglucans on the stability of frozen French bread dough. The amount of these additives used was optimized from an obtained central composite design- (CCD-) response surface methodology (RSM) of the alveograph parameters. Batches were characterized for moisture, water activity (aw), and texture using SEM, DSC, and TGA analyses when frozen for up to 60 days. Batches containing hemicelluloses showed better stability for aw over time. There was no difference between the texture parameters of the samples studied for 60 days. Both added hemicelluloses presented fewer fractures at 30 days and less wear at 60 days, in addition to better performance in the TGA analysis after less than 30 days of frozen storage. Batches containing only xyloglucans or galactomannans had a higher solidification peak temperature after 60 days. Both plant hemicelluloses reduced the damage caused by cold storage and improved stability for water activity. Also, dough preparations containing these additives showed better moisture retention, as well as less wear and tear and fewer fractures over their shelf life. Our evaluation suggests C. pulcherrima and T. indica are nonconventional sources of hydrocolloids that could be utilized in the bakery industry. [ABSTRACT FROM AUTHOR]

The integrity of the cell wall is important for plant cells. Mechanical or chemical distortions, tension, pH changes in the apoplast, disturbance of the ion homeostasis, leakage of cell compounds into the apoplastic space or breakdown of cell wall polysaccharides activate cellular responses which often occur via plasma membrane-localized receptors. Breakdown products of the cell wall polysaccharides function as damage-associated molecular patterns and derive from cellulose (cello-oligomers), hemicelluloses (mainly xyloglucans and mixed-linkage glucans as well as glucuronoarabinoglucans in Poaceae) and pectins (oligogalacturonides). In addition, several types of channels participate in mechanosensing and convert physical into chemical signals. To establish a proper response, the cell has to integrate information about apoplastic alterations and disturbance of its wall with cell-internal programs which require modifications in the wall architecture due to growth, differentiation or cell division. We summarize recent progress in pattern recognition receptors for plant-derived oligosaccharides, with a focus on malectin domain-containing receptor kinases and their crosstalk with other perception systems and intracellular signaling events. [ABSTRACT FROM AUTHOR]

In this paper, Phoenix dactylifera L. date palm seeds (RDS) were first characterized from a physicochemical point of view, in particular the proximate and ultimate composition, XRD, and SEM–EDX analyses. Based on findings RDS contains 77.4 % of total carbohydrates, 12.8 % of lignin, and a higher heating value (HHV) of 15.88 MJ kg−1. Immuno‐labeling intensity (OD) of non‐cellulosic RDS fraction was also determined thanks to the ELISA technique after the dissolution of polysaccharides in ionic liquid showing the presence of mannans and xyloglucans and the absence of arabinans in date seeds, a significant amount of homogalacturonans were also detected. The thermal decomposition and kinetic of date palm seeds (RDS) using TGA‐DTG, and DSC measurements were then investigated. The RDS samples were heated in the temperature ranges 25–600 °C at 5, 10, 15, and 20 °C/min. The decomposition of hemicelluloses, cellulose, and lignin, active pyrolysis of RDS, was held in a range of temperature 160–450 °C. The kinetic parameters such as activation energy (Ea) and pre‐exponential factor (A) were determined for two degradation steps by using iso‐conversional model‐free methods. The Ea and pre‐exponential factor obtained by the Kissinger method are 212 kJ mol−1 and 7.8×1019 min−1 for the first decomposition interval (I1) and 172 kJ mol−1 and 5.96×1013 min−1 for the second decomposition interval I2. The same average parameters calculated by model‐free methods are 126–156 kJ mol−1 and 180–213 kJ mol−1 and 3.36×1014 and 7.07×1017 min−1 respectively for the first and second intervals of thermal decomposition. Indicating that activation energy decreases in the final stages of the process and that the energy required for hemicelluloses degradation is lower than that of cellulose. The most probable reaction functions have been determined for these two stages, by Coats‐Redfern (CR) and Criado methods, leading to considerably improved calculation performance over the entire conversion range. The pyrolysis reaction models of RDS are described by reaction, second order F2 for cellulose and hemicelluloses. With the Arrhenius parameters obtained from the fitting model of CR, we attempt to reconstruct the temperature‐dependent mass conversion curves and have resulted in generally acceptable results. Based on the Arrhenius parameter values, obtained by the Kissinger equation, the changes in entropy, enthalpy, Gibbs free energy, and lifetime predictions have been estimated for the thermal degradation processes of RDS. [ABSTRACT FROM AUTHOR]

Simple Summary: Climatic factors, such as drought and high temperatures, drastically affect the productivity of cultivated plants. The identification of plants showing stress resistance characteristics, as well as the identification of morphological or molecular traits associated with drought tolerance, is extremely important, because progressive climate change is expected to further reduce water availability, with dramatic impacts on crop productivity. We investigated the drought stress responses of six varieties of Cichorium intybus L., i.e., Selvatica, Zuccherina di Trieste, Brindisina, Esportazione, Rossa Italiana and Galatina. Our results highlight that Selvatica and Zuccherina di Trieste varieties better tolerate a drought stress condition than other varieties, and this was used in the identification of potential markers for drought stress tolerance. Drought causes massive crop quality and yield losses. Limiting the adverse effects of water deficits on crop yield is an urgent goal for a more sustainable agriculture. With this aim, six chicory varieties were subjected to drought conditions during seed germination and at the six week-old plant growth stage, in order to identify some morphological and/or molecular markers of drought resistance. Selvatica, Zuccherina di Trieste and Galatina varieties, with a high vegetative development, showed a major germination index, greater seedling development (6 days of growth) and a greater dehydration resistance (6 weeks of growth plus 10 days without water) than the other ones (Brindisina, Esportazione and Rossa Italiana). Due to the reported involvement, in the abiotic stress response, of xyloglucan endotransglucosylase/hydrolases (XTHs) and late embryogenesis abundant (LEA) multigene families, XTH29 and LEA4 expression profiles were investigated under stress conditions for all analyzed chicory varieties. We showed evidence that chicory varieties with high CiXTH29 and CiLEA4 basal expression and vegetative development levels better tolerate drought stress conditions than varieties that show overexpression of the two genes only in response to drought. Other specific morphological traits characterized almost all chicory varieties during dehydration, i.e., the appearance of lysigen cavities and a general increase of the amount of xyloglucans in the cell walls of bundle xylem vessels. Our results highlighted that high CiXTH29 and CiLEA4 basal expression, associated with a high level of vegetative growth, is a potential marker for drought stress tolerance. [ABSTRACT FROM AUTHOR]

Background: The development of drug resistance among causative agents has resulted in the need to change the paradigm toward alternative therapeutic approaches for uncomplicated urinary tract infections (UTIs). The objective of the present study was to evaluate the efficacy of an oral medical device containing xyloglucan, hibiscus, and propolis in clinical practice with a cohort of women from Switzerland with UTI-like symptoms and the administration of concomitant drugs. Materials and Methods: This work describes an observational, prospective, and multicenter study involving 103 women attending a primary care physician for a symptomatic episode, or recurrence, of acute uncomplicated cystitis between August 2018 and June 2019. Utipro®Plus was administered orally, with patients being prescribed two capsules per day for 5 days to control discomfort symptoms or one capsule per day for 15 consecutive days per month (followed by a 15-day break for a 3-month cycle) to prevent recurrences. Results: A total of 84 women (81.6%) did not require an additional consultation, whereas 17 (16.5%) required a second one. Inadequate treatment response was found in 7 women out of the 19 who required a further consultation (36.8%): 3 women with no history of cystitis (out of 13, 23.1%) and 4 with recurrent cystitis (out of 6, 66.7%). None of the women from the study reported an adverse event. Conclusions: The studied product containing xyloglucan, hibiscus, and propolis is safe and effective for the treatment of a broad spectrum of women with acute uncomplicated or recurrent UTI-like symptoms. [ABSTRACT FROM AUTHOR]

Background: To survive harsh environmental conditions, desert plants show various adaptions, such as the evolution of trichomes, which are protective epidermal protrusions. Currently, the morphogenesis and function of trichomes in desert plants are not well understood. Salsola ferganica is an annual halophyte distributed in cold deserts; at the seedling stage, its rod-shaped true leaves are covered with long and thick trichomes and are affected by habitat conditions. Therefore, we evaluated the trichomes on morphogenesis and cell wall composition of S. ferganica compared to Arabidopsis thaliana and cotton, related gene expression, and preliminary function in salt accumulation of the leaves. Results: The trichomes of S. ferganica were initiated from the epidermal primordium, followed by two to three rounds of cell division to form a multicellular trichome, while some genes associated with them were positively involved. Cell wall composition analysis showed that different polysaccharides including heavily methyl-esterified and fully de-esterified pectins (before maturation, probably in the primary wall), xyloglucans (in the mid-early and middle stages, probably in the secondary wall), and extensin (during the whole developmental period) were detected, which were different from those found in trichomes of Arabidopsis and cotton. Moreover, trichome development was affected by abiotic stress, and might accumulate salt from the mesophyll cells and secrete outside. Conclusions: S. ferganica has multicellular, non-branched trichomes that undergo two to three rounds of cell division and are affected by abiotic stress. They have a unique cell wall composition which is different from that of Arabidopsis and cotton. Furthermore, several genes positively or negatively regulate trichome development. Our findings should contribute to our further understanding of the biogenesis and adaptation of plant accessory structures in desert plant species. [ABSTRACT FROM AUTHOR]

Cyanobacterial toxins (known as cyanotoxins) disrupt the plant cytoskeleton (i.e. microtubules and F-actin), which is implicated in the regulation of cell wall architecture. Therefore, cyanotoxins are also expected to affect cell wall structure and composition. However, the effects of cyanobacterial toxicity on plant cell wall have not been yet thoroughly studied. Accordingly, the alterations of cell wall matrix after treatments with pure microcystin-LR (MC-LR), or cell extracts of one MC-producing and one non-MC-producing Microcystis strain were studied in differentiated Oryza sativa (rice) root cells. Semi-thin transverse sections of variously treated LR-White-embedded roots underwent immunostaining for various cell wall epitopes, including homogalacturonans (HGs), arabinogalactan-proteins (AGPs), and hemicelluloses. Homogalacturonan and arabinan distribution patterns were altered in the affected roots, while a pectin methylesterase (PME) activity assay revealed that PMEs were also affected. Elevated intracellular Ca2+ levels, along with increased callose and mixed linkage glucans (MLGs) deposition, were also observed after treatment. Xyloglucans appeared unaffected and lignification was not observed. The exact mechanism of cyanobacterial toxicity against the cell wall is to be further investigated. [Display omitted] • New targets of cyanotoxins against the plant cell wall are described. • Major cell wall matrix components are affected by MC-LR and cyanobacterial extracts. • Both MC-rich and MC-free extracts rapidly affect cell wall matrix components. • Intense presence of glucans is accompanied by reduced presence of homogalacturonans. • PME activity is compromised by both pure MC-LR and cyanobacterial extracts. [ABSTRACT FROM AUTHOR]

Background and Aims Intervessel pit membranes (PMs) are important cell wall structures in the vessel system that may impact a plant's water transport and its susceptibility to vascular diseases. Functional roles of intervessel PMs largely depend on their structure and polysaccharide composition, which are the targets of this study. Methods With grapevine used as a model plant, this study applied an immunogold-scanning electron microscopy technique to simultaneously analyse at high resolution intervessel PM structures and major pectic and hemicellulosic polysaccharides that make up intervessel PMs. Key Results Intervessel PMs in functional xylem showed significant structural variation, with about 90 % of them being structurally intact with smooth or relatively smooth surfaces and the remaining 10 % with progressively degraded structures. The results also elucidated details of the removal process of cell wall materials from the intervessel PM surface toward its depth during its natural degradation. Four groups of pectic and hemicellulosic polysaccharides were immunolocalized in intervessel PMs and differed in their spatial distribution and abundance. Weakly methyl-esterified homogalacturonans (WMe-HGs, detected by JIM5) were abundant in the surface layer, heavily methyl-esterified homogalacturonans (HMe-HGs, detected by JIM7) and xylans detected by CCRC-M140 were mostly found in deeper layers, and fucosylated xyloglucans (F-XyGs, detected by CCRC-M1) were more uniformly distributed at different depths of the intervessel PM. Conclusions Intervessel PMs displayed diverse structural variations in grapevine. They contained certain major groups of pectic and hemicellulosic polysaccharides with different spatial distributions and abundance. This information is crucial to reveal the polysaccharide profiling of the primary cell wall and to understand the roles of intervessel PMs in the regulation of water transport as well as in a plant's susceptibility to vascular diseases. [ABSTRACT FROM AUTHOR]

Cell wall modifications are of pivotal importance during plant development. Among cell wall components, xyloglucans are the major hemicellulose polysaccharide in primary cell walls of dicots and non-graminaceous monocots. They can connect the cellulose microfibril surface to affect cell wall mechanical properties. Changes in xyloglucan structure are known to play an important role in regulating cell growth. Therefore, the degradation of xyloglucan is an important modification that alters the cell wall. The α - XYLOSIDASE1 (XYL1) gene encodes the only α-xylosidase acting on xyloglucans in Arabidopsis thaliana. Here, we showed that mutation of XYL1 strongly influences seed size, seed germination, and fruit elongation. We found that the expression of XYL1 is directly regulated in developing seeds and fruit by the MADS-box transcription factor SEEDSTICK. We demonstrated that XYL1 complements the stk smaller seed phenotype. Finally, by atomic force microscopy, we investigated the role of XYL1 activity in maintaining cell stiffness and growth, confirming the importance of cell wall modulation in shaping organs. [ABSTRACT FROM AUTHOR]

Background: The polyphyletic group of seagrasses shows an evolutionary history from early monocotyledonous land plants to the marine environment. Seagrasses form important coastal ecosystems worldwide and large amounts of seagrass detritus washed on beaches might also be valuable bioeconomical resources. Despite this importance and potential, little is known about adaptation of these angiosperms to the marine environment and their cell walls. Results: We investigated polysaccharide composition of nine seagrass species from the Mediterranean, Red Sea and eastern Indian Ocean. Sequential extraction revealed a similar seagrass cell wall polysaccharide composition to terrestrial angiosperms: arabinogalactans, pectins and different hemicelluloses, especially xylans and/or xyloglucans. However, the pectic fractions were characterized by the monosaccharide apiose, suggesting unusual apiogalacturonans are a common feature of seagrass cell walls. Detailed analyses of four representative species identified differences between organs and species in their constituent monosaccharide composition and lignin content and structure. Rhizomes were richer in glucosyl units compared to leaves and roots. Enhalus had high apiosyl and arabinosyl abundance, while two Australian species of Amphibolis and Posidonia, were characterized by high amounts of xylosyl residues. Interestingly, the latter two species contained appreciable amounts of lignin, especially in roots and rhizomes whereas Zostera and Enhalus were lignin-free. Lignin structure in Amphibolis was characterized by a higher syringyl content compared to that of Posidonia. Conclusions: Our investigations give a first comprehensive overview on cell wall composition across seagrass families, which will help understanding adaptation to a marine environment in the evolutionary context and evaluating the potential of seagrass in biorefinery incentives. [ABSTRACT FROM AUTHOR]

α-Xylosidases release the α-d-xylopyranosyl side chain from di- and oligosaccharides derived from xyloglucans and are involved in xyloglucan degradation. In this study, an extracellular α-xylosidase, named AxyB, is identified and characterized in Aspergillus oryzae. AxyB belongs to the glycoside hydrolase family 31 and releases d-xylose from isoprimeverose (α-d-xylopyranosyl-(1 → 6)-d-glucopyranose) and xyloglucan oligosaccharides. In the hydrolysis of xyloglucan oligosaccharides (XLLG, Glc4Xyl3Gal2 nonasaccharide; XLXG/XXLG, Glc4Xyl3Gal1 octasaccharide; and XXXG, Glc4Xyl3 heptasaccharide), AxyB releases one molecule of the xylopyranosyl side chain attached to the non-reducing end of the β-1,4-glucan main chain of these xyloglucan oligosaccharides to yield GLLG (Glc4Xyl2Gal2), GLXG/GXLG (Glc4Xyl2Gal1), and GXXG (Glc4Xyl2). A. oryzae has both extracellular and intracellular α-xylosidase, suggesting that xyloglucan oligosaccharides are degraded by a combination of isoprimeverose-producing oligoxyloglucan hydrolase and intracellular α-xylosidase and a combination of extracellular α-xylosidase and β-glucosidase(s) in A. oryzae. Key points: • An extracellular α-xylosidase, AxyB, is identified in Aspergillus oryzae. • AxyB releases the xylopyranosyl side chain from xyloglucan oligosaccharides. • Different sets of glycosidases degrade xyloglucan oligosaccharides in A. oryzae. [ABSTRACT FROM AUTHOR]

The valuable cannabinoid and terpenoid metabolites of Cannabis sativa L. are produced by floral glandular trichomes. The trichomes consist of secretory disk cells, which produce the abundant lipidic metabolites, and an extracellular storage cavity. The mechanisms of apoplastic cavity formation to accumulate and store metabolites in cannabis glandular trichomes remain wholly unexplored. Here, we identify key wall components and how they change during cannabis trichome development. While glycome and monosaccharide analyses revealed that glandular trichomes have loosely bound xyloglucans and pectic polysaccharides, quantitative immunolabeling with wall-directed antibodies revealed precise spatiotemporal distributions of cell wall epitopes. An epidermal-like identity of early trichome walls matured into specialized wall domains over development. Cavity biogenesis was marked by separation of the subcuticular wall from the underlying surface wall in a homogalacturonan and α-1,5 arabinan epitope-rich zone and was associated with a reduction in fucosylated xyloglucan epitopes. As the cavity filled, a matrix with arabinogalactan and α-1,5 arabinan epitopes enclosed the metabolite droplets. At maturity, the disk cells' apical wall facing the storage cavity accumulated rhamnogalacturonan-I epitopes near the plasma membrane. Together, these data indicate that cannabis glandular trichomes undergo spatiotemporal remodeling at specific wall subdomains to facilitate storage cavity formation and metabolite storage. [ABSTRACT FROM AUTHOR]

Chromerids are a group of alveolates, found in corals, that show peculiar morphological and genomic features. These organisms are evolutionary placed in‐between symbiotic dinoflagellates and parasitic apicomplexans. There are two known species of chromerids: Chromera velia and Vitrella brassicaformis. Here, the biochemical composition of the C. velia cell wall was analyzed. Several polysaccharides adorn this structure, with glucose being the most abundant monosaccharide (approx. 80%) and predominantly 4‐linked (approx. 60%), suggesting that the chromerids cell wall is mostly cellulosic. The presence of cellulose was cytochemically confirmed with calcofluor white staining of the algal cell. The remaining wall polysaccharides, assuming structures are similar to those of higher plants, are indicative of a mixture of galactans, xyloglucans, heteroxylans, and heteromannans. The present work provides, for the first time, insights into the outermost layers of the photosynthetic alveolate C. velia. [ABSTRACT FROM AUTHOR]

Lotus tenuis is a glycophytic forage legume (Fabaceae) used in feeding ruminants that can grow under salinity and waterlogging stresses. Plants obtained in controlled conditions were affected negatively in their growth by the effect of salt. Results from sequential extraction of plant cell wall polysaccharides and chemical characterization were related to those from nutritional parameters used to assess ruminants feedstuffs (Van Soest detergent system). Shoots and leaves were analyzed, and the most important differences were found for shoots. The salt-stressed shoots gave lower values of neutral detergent fiber and acid detergent fiber; they produced higher amounts of reserve α-glucans, and hemicelluloses (xyloglucans and glucuronoxylans from primary and secondary cell walls, respectively) and pectins, leaving less material resistant to extraction. This effect was clearly confirmed by an in vitro gas production assay. In addition, observations by light microcopy (LM) and transmission electron microscopy (TEM), showed in some tissues thicker walls and more opened cell wall structures in regard to control samples, which could allow easier access of degrading enzymes in the rumen. Although the plant biomass of Lotus tenuis produced under salt stress was lower, its quality as forage improved due to production of increased quantities of more digestible polysaccharides. ∙ Plants of Lotus tenuis were affected negatively in their growth by salt stress ∙ Shoots and leaves produced increased amounts of material soluble in KOH solutions ∙ KOH extracts from shoots comprised xyloglucans, glucuronoxylans and also pectins ∙ In some tissues thicker but more opened cell wall structures were found ∙ Quality as forage improved by increased amounts of more digestible polysaccharides [ABSTRACT FROM AUTHOR]

The charophycean green algae (CGA or basal streptophytes) are of particular evolutionary significance because their ancestors gave rise to land plants. One outstanding feature of these algae is that their cell walls exhibit remarkable similarities to those of land plants. Xyloglucan (XyG) is a major structural component of the cell walls of most land plants and was originally thought to be absent in CGA. This study presents evidence that XyG evolved in the CGA. This is based on a) the identification of orthologs of the genetic machinery to produce XyG, b) the identification of XyG in a range of CGA and, c) the structural elucidation of XyG, including uronic acid-containing XyG, in selected CGA. Most notably, XyG fucosylation, a feature considered as a late evolutionary elaboration of the basic XyG structure and orthologs to the corresponding biosynthetic enzymes are shown to be present in Mesotaenium caldariorum. Mikkelsen et al. demonstrate molecular and cellular evidence of the evolution of xyloglucan (XyG), a structural component of the cell walls of most land plants, in charophyte algae. This study describes the structure of XyG in charophyte algae, including identification of fucosylated XyG, and furthermore identifies orthologs required to produce XyG. [ABSTRACT FROM AUTHOR]

SUMMARY: Cell walls are dynamic and multi‐component materials that play important roles in many areas of plant biology. The composition and interactions of the structural elements give rise to material properties, which are modulated by the activity of wall‐related enzymes. Studies of the genes and enzymes that determine wall composition and function have made great progress, but rarely take account of potential compensatory changes in wall polymers that may accompany and accommodate changes in other components, particularly for specific polysaccharides. Here, we present a method that allows the simultaneous examination of the mass distributions and quantities of specific cell wall matrix components, allowing insight into direct and indirect consequences of cell wall manipulations. The method employs gel‐permeation chromatography fractionation of cell wall polymers followed by enzyme‐linked immunosorbent assay to identify polymer types. We demonstrate the potential of this method using glycan‐directed monoclonal antibodies to detect epitopes representing xyloglucans, heteromannans, glucuronoxylans, homogalacturonans (HGs) and methyl‐esterified HGs. The method was used to explore compositional diversity in different Arabidopsis organs and to examine the impacts of changing wall composition in a number of previously characterized cell wall mutants. As demonstrated in this article, this methodology allows a much deeper understanding of wall composition, its dynamism and plasticity to be obtained, furthering our knowledge of cell wall biology. [ABSTRACT FROM AUTHOR]

Nanoparticles are interesting area of research developed for several diagnostic and therapeutic applications. Tamarind flower extract is rich in Xyloglucan, a starch like polysaccharide which promotes proliferation and various application areas like drug-delivery technology. In recent years researchers are evaluating nanoliposome using in vitro and in vivo studies to discover their biomedical applications. Considering the importance and feasibility of nanoliposome, the present study is focused on synthesis of liposomes via biological method. The biological molecules of Tamarindus indica flower were used for the synthesis of nanoliposome. The synthesized Tamarindus indica flower extract lipid nanoparticles (TifeLiNPs) loaded with xyloglucans were characterized and evaluated for therapeutic applications (antibacterial, antioxidant, antidiabetic, anticancer and anti-inflammatory activities) under in vitro condition. UV‐Vis spectral analysis revealed the emission of peak at 232 nm. Further, the chemical characterization using FTIR revealed the presence of components in the functional group. EDX analysis exhibited the presence of O, Na, P and Cl, while DLS confirmed bilayer formation of xyloglucan and liposomes with uniform size (70–80 nm) and spherical shape. The Physicochemical characterization of tamarind flower extract for its chemical composition revealed the presence of carbohydrates, alkaloids, terpenoids, glycosides, saponins, tannins and flavonoids in confirmatory test. Presence of carbohydrate polymers such as rhamnose, arabinose, galactose, glucose and xylose revealed using high performance anion exchange (HPAE) chromatography under basic conditions on an ion chromatographic system were measured using Pulsed Amperometric Detection (PAD). The synthesized nanoliposome evaluated against Gram negative and Gram positive bacteria showed potential antibacterial activity. TifeLiNPs demonstrated significant in vitro antioxidant potential, antidiabetic, anti-cancer and anti-inflammatory activity. Overall, the present study exhibited the potential application of TifeLiNPs for biomedical purposes. [ABSTRACT FROM AUTHOR]

Key message: CsSh5.1, which controls hypocotyl elongation under high temperature conditions in cucumber, was mapped to a 57.1 kb region on chromosome 5 containing a candidate gene encoding a xyloglucan galactosyltransferase. Hypocotyl growth is a vital process in seedling establishment. Hypocotyl elongation after germination relies more on longitudinal cell elongation than cell division. Cell elongation is largely determined by the extensibility of the cell wall. Here, we identified a spontaneous mutant in cucumber (Cucumis sativus L.), sh5.1, which exhibits a temperature-insensitive short hypocotyl phenotype. Genetic analysis showed that the phenotype of sh5.1 was controlled by a recessive nuclear gene. CsSh5.1 was mapped to a 57.1 kb interval on chromosome 5, containing eight predicted genes. Sequencing analysis revealed that the Csa5G171710 is the candidate gene of CsSh5.1, which was further confirmed via co-segregation analysis and genomic DNA sequencing in natural cucumber variations. The result indicated that hypocotyl elongation might be controlled by this gene. CsSh5.1 encodes a xyloglucan galactosyltransferase that specifically adds galactose to xyloglucan and forms galactosylated xyloglucans, which determine the strength and extensibility of the cell walls. CsSh5.1 expression in wild-type (WT) hypocotyl was significantly higher than that in sh5.1 hypocotyl under high temperature, suggesting its important role in hypocotyl cell elongation under high temperature. The identification of CsSh5.1 is helpful for elucidating the function of xyloglucan galactosyltransferase in cell wall expansion and understanding the mechanism of hypocotyl elongation in cucumber. [ABSTRACT FROM AUTHOR]

Aspergillus species are closely associated with humanity through fermentation, infectious disease, and mycotoxin contamination of food. Members of this genus produce various enzymes to degrade plant polysaccharides, including starch, cellulose, xylan, and xyloglucan. This review focus on the machinery of the xyloglucan degradation using glycoside hydrolases, such as xyloglucanases, isoprimeverose-producing oligoxyloglucan hydrolases, and α-xylosidases, in Aspergillus species. Some xyloglucan degradation-related glycoside hydrolases are well conserved in this genus; however, other enzymes are not. Cooperative actions of these glycoside hydrolases are crucial for xyloglucan degradation in Aspergillus species. Key points: •Xyloglucan degradation-related enzymes of Aspergillus species are reviewed. •Each Aspergillus species possesses a different set of glycoside hydrolases. •The machinery of xyloglucan degradation of A. oryzae is overviewed. [ABSTRACT FROM AUTHOR]

• Revalorization of vine shoots by a low time consuming and sustainable treatment. • Synergic effect of the temperature and reaction time during the autohydrolysis. • Simulation of microwave-assisted autohydrolysis conditions by conventional heating. • Similar characteristic of the products independently of the heating method. This work deals with the revalorization of an important winery residue such as the vine shoots by the obtaining of oligosaccharides with potential prebiotic activity. The manufacture of these added-value products was performed by an autohydrolysis treatment assisted with microwaves to make the process less time consuming and more environmentally friendly. The influence of the reaction time (0–40 min) and the temperature (140–200) on the production of oligosaccharides during the microwave-assisted autohydrolysis was evaluated. The highest concentration of oligosaccharides (168.3 g/Kg oven-dried vines shoots) was achieved during the treatment carried out at 180 °C for 20 min. To assess the benefits of the assistance of the autohydrolysis treatment with the microwaves a conventionally heated treatment was performed using conditions (180 °C for 15 min) that provoked similar effects on the solubilisation of the hemicellulosic fraction. This treatment permitted the obtaining of 203.5 g oligosaccharides/Kg oven-dried vines shoots using 61.0% more of the time needed to carry out the microwaves-assisted autohydrolysis. Although the microwave-assisted treatment permitted the manufacture of a lower amount of oligosaccharides, only consumed 28.8% of the energy needed to perform the conventionally heated treatment. The oligosaccharides manufactured by the two treatments were substituted xyloglucans with different polymerization and acetylation degrees, which due to their potential prebiotic activity could be highly appreciated by pharmaceuticals and food industries. Thus, this work demonstrated the environmental sustainability of the microwave-assisted autohydrolysis for the revalorisation of the vine shoots. [ABSTRACT FROM AUTHOR]

Since the 2018 Farm Bill, US growers have been allowed to cultivate hemp (Cannabis sativa L.), prompting interest in exploring the use of hemp products in ruminant diets. Extraction of cannabidiol (CBD) oil from hemp biomass generates spent inflorescent material that could be upcycled as a feedstuff, yet little is known about its fiber composition. A recent study measured in vitro true digestibility and fermentation parameters of multiple hemp cultivars, some intact and some CBD-extracted (Altman et al., 2022). Both categories of hemp inflorescence material had similar or greater total digestible nutrients (TDN) than an alfalfa cube control, supporting hemp's potential as a feedstuff. However, comparisons between non-extracted and CBD-extracted samples could not be made, and the fiber content was only described as neutral detergent fiber (NDF). Fiber composition can significantly impact ruminal digestibility, and in-depth characterizations of cell wall carbohydrate composition can provide further insight into the digestibility of a specific plantbased feed. Therefore, in the present study, we examined the effect of CBD oil extraction on the cell wall carbohydrate composition of the inflorescent material of two hemp cultivars. Intact (Biomass) and CBDextracted (Spent) inflorescent material from two hemp cultivars, Mary and Zelios, were analyzed. The scell wall monosaccharides of the samples were released via two complementary acid hydrolyses, methanolysis and Saeman (sulfuric acid) hydrolysis, and separated and quantified using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). Additionally, the carbohydrate linkage patterns were assessed by generating partially methylated alditol acetates (PMAAs). Student's unpaired t-tests were run in GraphPad Prism, and no differences (P > 0.05) in monosaccharide concentrations based upon treatment (CBD extraction) or cultivar were found with either hydrolysis method except for the methanolysis glucose concentration between the biomass forms of the two cultivars where Mary Biomass possessed more glucose than Zelios Biomass (P

Fusarium graminearum produces an α-L-fucosidase, FgFCO1, which so far appears to be the only known fungal GH29 α-L-fucosidase that catalyzes the release of fucose from fucosylated xyloglucan. In our quest to synthesize bioactive glycans by enzymatic catalysis, we observed that FgFCO1 is able to catalyze a transglycosylation reaction involving transfer of fucose from citrus peel xyloglucan to lactose to produce 2'-fucosyllactose, an important human milk oligosaccharide. In addition to achieving maximal yields, control of the regioselectivity is an important issue in exploiting such a transglycosylation ability successfully for glycan synthesis. In the present study, we aimed to improve the transglycosylation efficiency of FgFCO1 through protein engineering by transferring successful mutations from other GH29 α-L-fucosidases. We investigated several such mutation transfers by structural alignment, and report that transfer of the mutation F34I from BiAfcB originating from Bifidobacterium longum subsp. infantis to Y32I in FgFCO1 and mutation of D286, near the catalytic acid/base residue in FgFCO1, especially a D286M mutation, have a positive effect on FgFCO1 transfucosylation regioselectivity. We also found that enzymatic depolymerization of the xyloglucan substrate increases substrate accessibility and in turn transglycosylation (i.e., transfucosylation) efficiency. The data include analysis of the active site amino acids and the active site topology of FgFCO1 and show that transfer of point mutations across GH29 subfamilies is a rational strategy for targeted protein engineering of a xyloglucan-active fungal α-L--fucosidase. [ABSTRACT FROM AUTHOR]

Tamarind Kernel Powder (TKP) is a polysaccharide obtained from the endosperm of the tamarind seed of the tamarind tree. Botanical name of Tamarind is Tamarindusindica Linn. This TKP based gum is a valuable thickener and stabilizer, used in different industries. TKP is abundantly available and has a good economic viability. TKP is also known as Xyloglucan. This TKP based thickener is hydrolyzed within 48-72 hours. The hydrolysis is primarily attributed to the growth of bacteria and fungi. These microorganisms are isolated by various isolation methods. Isolates were identified by Gram staining, Biochemical tests and hydrolytic activity of the isolates on proteins, lipids, carbohydrates and 16S rRNA sequencing. Viscosity was monitored without preservatives and with preservatives at different concentration and temperature. Fourier Transforms Infrared Spectroscopy was performed to check any major or minor changes in the TKP based thickener with and without preservatives. [ABSTRACT FROM AUTHOR]

Objective: The skin acts as a mechanical and protective barrier against viral, fungal, and bacterial infections. Skin conditions such as atopic dermatitis and psoriasis are characterized by alterations of the skin barrier, often caused by injury and by bacterial infections. In the last years, non-pharmacological interventions have gained great importance in epidermis-related diseases. Xyloglucan (XG) is a polysaccharide that possesses a "mucin-like" molecular structure that confers mucoadhesive properties, allowing XG-containing formulations to act as a protective barrier for the management of different diseases. Moreover, there is also increasing interest in the use of proteins due to their film-forming features. This study aimed to evaluate the barrier-protective properties of a product containing XG and pea protein (PP) in an in vitro model, assessing its effects on the membrane permeability of keratinocytes infected by Staphylococcus aureus. Methods: HaCaT keratinocytes were pretreated with XG and PP for 3 h and then infected with S. aureus cells (106 bacteria/well) at a multiplicity of infection of 10 for 1 h. The number of bacterial colonies and membrane integrity were measured, respectively. Results: We observed that pretreatment with XG and PP in human HaCaT keratinocytes infected with S. aureus significantly increased trans-epithelial electrical resistance (a marker of skin barrier function) measurement, reduced lucifer yellow (a marker of membrane integrity) permeation across the monolayer, and released lactate dehydrogenase (a marker of tissue damage). Moreover, XG and PP pretreatment was able to reduce bacterial adherence, avoiding S. aureus infection. Conclusion: In summary, we demonstrated that the product containing XG and PP was able to maintain barrier permeability preserving its integrity, and therefore, it can be considered as an interesting approach for the management of epidermis-related diseases. [ABSTRACT FROM AUTHOR]

The dynamics of cell wall polysaccharides may modulate the cell wall mechanics and thus control the expansion growth of plant cells. The unique composition of type II primary cell wall characteristic of grasses suggests that they employ specific mechanisms for cell enlargement. We characterized the transcriptomes in five zones along maize root, clustered the expression of genes for numerous glycosyltransferases and performed extensive immunohistochemical analysis to relate the changes in cell wall polysaccharides to critical stages of cell development in Poaceae. Specific patterns of cell wall formation differentiate the initiation, realization and cessation of elongation growth. Cell walls of meristem and early elongation zone represent a mixture of type I and type II specific polysaccharides. Xyloglucans and homogalacturonans are synthesized there actively together with mixed-linkage glucans and glucuronoarabinoxylans. Rhamnogalacturonans-I with the side-chains of branched 1,4-galactan and arabinan persisted in cell walls throughout the development. Thus, the machinery to generate the type I primary cell wall constituents is completely established and operates. The expression of glycosyltransferases responsible for mixed-linkage glucan and glucuronoarabinoxylan synthesis peaks at active or late elongation. These findings widen the number of jigsaw pieces which should be put together to solve the puzzle of grass cell growth. [ABSTRACT FROM AUTHOR]

Rhizobia are nitrogen-fixing soil bacteria that can infect legume plants to establish root nodules symbiosis. To do that, a complex exchange of molecular signals occurs between plants and bacteria. Among them, rhizobial Nops (Nodulation outer proteins), secreted by a type III secretion system (T3SS) determine the host-specificity for efficient symbiosis with plant roots. Little is known about the molecular function of secreted Nops (also called effectors (T3E)) and their role in the symbiosis process. We performed the structure-function characterization of NopAA, a T3E from Sinorhizobium fredii by using a combination of X-ray crystallography, biochemical and biophysical approaches. This work displays for the first time a complete structural and biochemical characterization of a symbiotic T3E. Our results showed that NopAA has a catalytic domain with xyloglucanase activity extended by a N-terminal unfolded secretion domain that allows its secretion. We proposed that these original structural properties combined with the specificity of NopAA toward xyloglucan, a key component of root cell wall which is also secreted by roots in the soil, can give NopAA a strategic position to participate in recognition between bacteria and plant roots and to intervene in nodulation process. [ABSTRACT FROM AUTHOR]

Background: Lytic polysaccharide monooxygenases (LPMOs) are powerful enzymes that oxidatively cleave plant cell wall polysaccharides. LPMOs classified as fungal Auxiliary Activities family 9 (AA9) have been mainly studied for their activity towards cellulose; however, various members of this AA9 family have been also shown to oxidatively cleave hemicelluloses, in particularly xyloglucan (XG). So far, it has not been studied in detail how various AA9 LPMOs act in XG degradation, and in particular, how the mode-of-action relates to the structural configuration of these LPMOs. Results: Two Neurospora crassa (Nc) LPMOs were found to represent different mode-of-action towards XG. Interestingly, the configuration of active site segments of these LPMOs differed as well, with a shorter Segment 1 (−Seg1) and a longer Segment 2 (+Seg2) present in NcLPMO9C and the opposite for NcLPMO9M (+Seg1−Seg2). We confirmed that NcLPMO9C cleaved the non-reducing end of unbranched glucosyl residues within XG via the oxidation of the C4-carbon. In contrast, we found that the oxidative cleavage of the XG backbone by NcLPMO9M occurred next to both unbranched and substituted glucosyl residues. The latter are decorated with xylosyl, xylosyl–galactosyl and xylosyl–galactosyl–fucosyl units. The relationship between active site segments and the mode-of-action of these NcLPMOs was rationalized by a structure-based phylogenetic analysis of fungal AA9 LPMOs. LPMOs with a −Seg1+Seg2 configuration clustered together and appear to have a similar XG substitution-intolerant cleavage pattern. LPMOs with the +Seg1−Seg2 configuration also clustered together and are reported to display a XG substitution-tolerant cleavage pattern. A third cluster contained LPMOs with a −Seg1−Seg2 configuration and no oxidative XG activity. Conclusions: The detailed characterization of XG degradation products released by LPMOs reveal a correlation between the configuration of active site segments and mode-of-action of LPMOs. In particular, oxidative XG-active LPMOs, which are tolerant and intolerant to XG substitutions are structurally and phylogenetically distinguished from XG-inactive LPMOs. This study contributes to a better understanding of the structure–function relationship of AA9 LPMOs. [ABSTRACT FROM AUTHOR]

Under the effect of disturbances, like unbalanced stem, but also during normal development, poplar trees can develop a specific secondary xylem, called "tension wood" (TW), which is easily identifiable by the presence of a gelatinous layer in the secondary cell walls (SCW) of the xylem fibers. Since TW formation was mainly performed on 2-year-old poplar models, an in vitro poplar that produces gelatinous fibers (G-fibers) while offering the same experimental advantages as herbaceous plants has been developed. Using specific cell wall staining techniques, wood structural features and lignin/cellulose distribution were both detailed in cross-sections obtained from the curved stem part of in vitro poplars. A supposed delay in the SCW lignification process in the G-fibers, along with the presence of a G-layer, could be observed in the juvenile plants. Moreover, in this G-layer, the immunolabeling of various polymers carried out in the SCW of TW has allowed detecting crystalline cellulose, arabinogalactans proteins, and rhamnogalacturonans I; however, homogalacturonans, xylans, and xyloglucans could not be found. Interestingly, extensins were detected in this typical adaptative or stress-induced structure. These observations were corroborated by a quantitation of the immunorecognized polymer distribution using gold particle labeling. In conclusion, the in vitro poplar model seems highly convenient for TW studies focusing on the implementation of wall polymers that provide the cell wall with greater plasticity in adapting to the environment. [ABSTRACT FROM AUTHOR]

Xyloglucans and mixed-linkage β-glucans are the major components of hemicelluloses in lignocellulosic biomass. In this study, a novel β-1,4-glucanase Pgl5A belonging to the glycoside hydrolase family 5 subfamily 4 (GH5_4), was identified from Paenibacillus sp. S09. Pgl5A is a 70.9-kDa protein containing an N-terminal GH5_4 module, a carbohydrate-binding module (CBM)_X2 and a CBM3. Full-length Pgl5A and its CBM deletion mutants Pgl5A∆C and Pgl5A-CD were expressed in E. coli. All three enzymes showed maximal activity at 55 °C and pH 4.5–5.0, and possessed similar activity toward xyloglucan, barley β-glucan, and lichenan. Deletion of the CBM modules can improve thermostability and acid-tolerant properties of Pgl5A. Circular dichroism (CD) and intrinsic fluorescence spectroscopy analysis verified that C-terminus truncation improves the enzyme acid-tolerant properties. Homology modeling and CD spectra indicated that Pgl5A has an architectural (β/α) 8 fold of GH5_4 enzymes. The catalytic efficiency (k cat / K m) of Pgl5A toward xyloglucan, but not mixed-linkage β-glucan, was reduced due to C-terminus truncation. TLC and LC-MS analysis showed that Pgl5A cleaves xyloglucan and mixed-linkage β-glucan into a series of xyloglucan oligosaccharides and gluco-oligosaccharides, respectively. The favorable enzymatic characteristics and high catalytic activities toward both xyloglucan and mixed-linkage β-glucan make Pgl5A a promising candidate for biotechnological industrial applications. [ABSTRACT FROM AUTHOR]

Cell wall architecture of tension wood fibres represents a suitable biological system to study the mechanism of growth and maintenance of posture of trees growing under various physical and physiological growth constraints. In the present study, we investigated the spatial distributions of β-(1–4)-D-galactan, xyloglucan and xylans (both less and highly substituted) in the opposite and tension wood fibres of bent Leucaena leucocephala by immunolabelling with monoclonal antibodies LM5, CCRCM1, LM10 and LM11 specific to these carbohydrate epitopes. The presence of non-lignified, tertiary wall layer is the typical tension wood characteristic associated with the reaction xylem fibres in Leucaena. LM5 labelling of opposite fibres showed weak labelling in the cell walls indicating less concentration of β-(1–4)-D-galactans while tension wood showed strong labelling in the tertiary wall layer suggesting the gelatinous layer (G-layer) has a strong cross linking with β-(1–4)-D-galactans. Xyloglucan distribution was more in the compound middle lamellae and the primary wall-S1 layer boundary of tension wood fibres as compared to that of opposite wood. A weak labelling was also evident near the boundary between the G-layer and the secondary wall of tension wood fibres. The secondary wall of opposite and tension wood fibres showed a strong distribution of both ls ACG Xs (LM10) and hs ACG Xs (LM11) while a weak labelling was noticed in the compound middle lamella. Tension wood fibres also showed strong xylan labelling mainly confined to the lignified secondary walls while the G-layer showed weak xylan labelling. In conclusion, our results suggest that β-(1–4)-D-galactans and xyloglucans could be implicated in the tensile stress generation within the G-layer of tension wood fibres of Leucaena leucocephala. • Immuno-localization of cell wall polymers. • Variation in cell wall topochemistry of tension wood and normal wood fibres in L. leucocephala. • Gelatinous layer showed distinct variation in distribution pattern of β-(1–4)-D-galactans and xylans. • Secondary wall lignification and xylan distribution may be related. • Probable role of β-(1–4)-D-galactans, xyloglucans and xylans in tensile stress generation. [ABSTRACT FROM AUTHOR]

The xyloglucans of monocotyledons are known to vary in the abundance of fucosylated side chains, with most commelinid monocotyledons having xyloglucans with lower proportions than non-commelinid monocotyledons. In many commelinid species, and some non-commelinid species that have lower proportions of fucosylated side chains, these side chains have been shown to be cell-type specific. To determine whether it is just the fucosylated side chains that are cell-type specific, or whether xyloglucan is cell-type specific in these species, we used the monoclonal antibody LM15 in conjunction with immmunofluorescence microscopy. We examined the distribution of cell-wall labelling among cell types in these species. The primary walls of all cell types were shown to contain xyloglucans in all species that had cell-type specific distributions of fucosylated side chains. This indicates that it is the fucosylated side chains of xyloglucans that is cell-type specific. Although the functional significance of xyloglucan fucosylation remains unknown, such cell-type specificity supports hypotheses that the fucosylated side chains may indeed have a functional role within the cell wall. Image 1 • Cell walls of monocotyledons without fucogalactoxyloglucans do contain xyloglucans. • The primary cell walls of all cell types examined contain xyloglucans. • Fucosylation of monocotyledon xyloglucans must be regulated by cell type. [ABSTRACT FROM AUTHOR]

Abstract Blueberry powder was sequentially fractionated to water (WSF), chelator (CSF) and sodium carbonate (NSF) soluble fractions. Uronic acid content was above 22 μg/mg AIS. The 4% potassium hydroxide (4KSF) and 24% potassium hydroxide (24KSF) soluble fractions were hemicellulose rich fractions. Cell wall glycan-directed monoclonal antibodies (mAbs) based glycome profiling analyses revealed that WSF, CSF and NSF fractions had epitopes of homogalacturonan (HG), arabinogalactan (AG), and xyloglucan (XG), but no xylan. 4KSF and 24KSF fractions had higher abundance of xyloglucan and xylan epitopes in addition to pectic epitopes. Arabinose and galactose were the two major neutral sugars in the WSF, CSF, and NSF. Xylose represented about 70 mol% neutral sugar in 4KSF and 24KSF fractions. Increased flexibility and presence of protein likely influence the propensity of pectin to bind anthocyanins. Graphical abstract Image 1 Highlights • Water soluble blueberry fraction has lower than 50% DE. • Water soluble fraction is rich in xyloglucans, low in homogalactan. • Chelator soluble fraction is rich in xyloglucan, rhamnogalactan and xylan. • Protein content is higher in alkali soluble fraction. • Increased protein and flexibility of pectin may increase anthocyanin binding. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Developed an AFM technique to probe adhesion in cellulose-based networks. • Characterized the nanoscale adhesion forces between cellulose fibres. • Assessed the effect of xyloglucan and arabinoxylan on nano-scale adhesion forces. • Provided insights into the effect of xyloglucan on cellulose-cellulose adhesion. Abstract Inter-fibre adhesion is a key contributing factor to the mechanical response and functionality of cellulose-based biomaterials. 'Dip-and-Drag' lateral force atomic force microscopy technique is used here to evaluate the influence of arabinoxylan and xyloglucan on interactions between nanoscale cellulose fibres within a hydrated network of bacterial cellulose. A cohesive zone model of the detachment event between two nano-fibres is used to interpret the experimental data and evaluate inter-fibre adhesion energy. The presence of xyloglucan or arabinoxylan is found to increase the adhesive energy by a factor of 4.3 and 1.3, respectively, which is consistent with these two hemicellulose polysaccharides having different specificity of hydrogen bonding with cellulose. Importantly, xyloglucan's ability to strengthen adhesion between cellulose nano-fibres supports emergent models of the primary plant cell walls (Park & Cosgrove, 2012b), which suggest that xyloglucan chains confined within cellulose-cellulose junctions play a key role in cell wall's mechanical response. [ABSTRACT FROM AUTHOR]

Highlights • Comparative structural characterization of leaf cell walls of desiccation-tolerant and desiccation-sensitive Selaginella species. • Leaf cell walls Selaginella species are mainly composed of hemicellulosic polysaccharides namely arabinoxylan, mannan and xyloglucan. • Desiccation induces significant structural alterations of the xyloglucan and arabinoxylan in S. involvens compared to S. kraussiana and S. moellendorffii. • Structural remodeling of these hemicellulosic polysaccharides is an important process leading to desiccation tolerance in Selaginella plants. Abstract Drought-induced dehydration of vegetative tissues in lycopods affects growth and survival. Different species of Selaginella have evolved a series of specialized mechanisms to tolerate desiccation in vegetative tissues in response to water stress. In the present study, we report on the structural characterization of the leaf cell wall of the desiccation-tolerant species S. involvens and two desiccation-sensitive species, namely S. kraussiana and S. moellendorffii. Isolated cell walls from hydrated and desiccated leaves of each species were fractionated and the resulting oligosaccharide fragments were analyzed to determine their structural features. Our results demonstrate that desiccation induces substantial modifications in the cell wall composition and structure. Altogether, these data highlight the fact that structural remodeling of cell wall hemicellulosic polysaccharides including XXXG-rich xyloglucan, arabinoxylan and acetylated galactomannan is an important process in order to mitigate desiccation stress in Selaginella. [ABSTRACT FROM AUTHOR]

Abstract Dietary fiber is an important food source for members of the human gut microbiome. Members of the dominant Bacteroidetes phylum capture diverse polysaccharides via the action of multiple cell surface proteins encoded within polysaccharide utilization loci (PUL). The independent activities of PUL-encoded glycoside hydrolases (GHs) and surface glycan-binding proteins (SGBPs) for the harvest of various glycans have been studied in detail, but how these proteins work together to coordinate uptake is poorly understood. Here, we combine genetic and biochemical approaches to discern the interplay between the BoGH9 endoglucanase and the xyloglucan-binding proteins SGBP-A and SGBP-B from the Bacteroides ovatus xyloglucan utilization locus (XyGUL). The expression of BoGH9, a weakly active xyloglucanase in isolation, is required in a strain that expresses a non-binding version of SGBP-A (SGBP-A*). The crystal structure of the BoGH9 enzyme suggests the molecular basis for its robust activity on mixed-linkage β-glucan compared to xyloglucan. However, catalytically inactive site-directed mutants of BoGH9 fail to complement the deletion of the active BoGH9 in a SGBP-A* strain. We also find that SGBP-B is needed in an SGBP-A* background to support growth on xyloglucan, but that the non-binding SGBP-B* protein acts in a dominant negative manner to inhibit growth on xyloglucan. We postulate a model whereby the SGBP-A, SGBP-B, and BoGH9 work together at the cell surface, likely within a discrete complex, and that xyloglucan binding by SGBP-B and BoGH9 may facilitate the orientation of the xyloglucan for transfer across the outer membrane. Graphical Abstract Unlabelled Image Highlights • Xyloglucan (Xyg) is a dietary fiber utilized by the gut symbiont Bacteroides ovatus. • How XyG is captured at the cell surface by SGBP-A, SGBP-B, and BoGH9 is unclear. • The BoGH9 structure reveals the molecular basis for activity. • Functional BoGH9 and SGBP-B are required for XyG uptake in an SGBPA mutant. • SGBP-A, SGBP-B, and BoGH9 work together, and SGBP-B and BoGH9 may orient XyG for uptake. [ABSTRACT FROM AUTHOR]

Abstract Xyloglucan endotransglycosylase/hydrolases (XTH) may have endotransglycosylase (XET) and/or hydrolase (XEH) activities. Previous studies confirmed XET activity for PrXTH1 protein from radiata pine. XTHs could interact with many hemicellulose substrates, but the favorite substrate of PrXTH1 is still unknown. The prediction of union type and energy stability of the complexes formed between PrXTH1 and different substrates (XXXGXXXG, XXFGXXFG, XLFGXLFG and cellulose) were determined using bioinformatics tools. Molecular Docking, Molecular Dynamics, MM-GBSA and Electrostatic Potential Calculations were employed to predict the binding modes, free energies of interaction and the distribution of electrostatic charge. The results suggest that the enzyme formed more stable complexes with hemicellulose substrates than cellulose, and the best ligand was the xyloglucan XLFGXLFG (free energy of −58.83 ± 0.8 kcal mol−1). During molecular dynamics trajectories, hemicellulose fibers showed greater stability than cellulose. Aditionally, the kinetic properties of PrXTH1 enzyme were determined. The recombinant protein was active and showed an optimal pH 5.0 and optimal temperature of 37 °C. A Km value of 20.9 mM was determined for xyloglucan oligomer. PrXTH1 is able to interact with different xyloglycans structures but no activity was observed for cellulose as substrate, remodeling cell wall structure in response to inclination. Graphical abstract Image 1 Highlights • PrXTH1 expressed heterologous in Pichia pastoris was active. • The enzyme showed a Km value of 20.9 mM and optimal pH 5.0 • Different xyloglucans structures interact with PrXTH1. • No activity was observed when cellulose was used as substrate. • Structural analysis by molecular docking correlate biochemical determinations. [ABSTRACT FROM AUTHOR]

Highlights • Xyloglucan and two pectic polymers were submitted to in vitro fecal fermentation. • Depending on pectic polymers structure, more acetate or propionate was produced. • Xyloglucan fermentation resulted in elevated rates of propionate production. • Specific bacterial groups were stimulated with each kind of tested dietary fiber. • Major microbiota shifts occurred during xyloglucan fermentation. Abstract Xyloglucans and pectic polymers can be obtained from a variety of plants ubiquitous in the human diet, however, their fermentability in the colon and consequent nutritional benefits are poorly understood. Here, we evaluated metabolite profiles and bacterial shifts during in vitro fecal fermentations of two isolated pectic polymers and a xyloglucan. Depending on their chemical structure, pectic polymers were more acetogenic or propiogenic. Xyloglucan fermentation also resulted in elevated propionate if compared to FOS. Bacteroides plebeius, B. uniformis , Parabacteroides distasonis and bacterial groups such as Blautia , Lachnospira, Clostridiales and Lachnospiraceae , presented distinct abundances on each dietary fiber ferment. PCA and heat map analysis showed that major microbiota shifts occurred during xyloglucan fermentation, but not pectin fermentation. These data suggest that uncommon carbohydrate structures (i.e. isolated, soluble xyloglucan) in the diet hold the potential to generate larger shifts in microbiota communities than commonly consumed fibers (i.e. pectins). [ABSTRACT FROM AUTHOR]

Abstract During grape postharvest withering, a worldwide practice used to produce important high-quality wines, the solute concentration increases due to dehydration, and many organoleptic and quality traits, especially related to the berry skin, are affected in a cultivar-specific manner. Nevertheless, a complete comprehension of the underlying processes is still lacking. In this work, we applied ATR-FTIR micro-spectroscopy combined with PCA to monitor cell wall biochemical changes at three stages during postharvest withering on the internal and external sides of the berry skin of the Vitis vinifera cv. Corvina, an important local variety of the Verona province in Italy. The obtained results were integrated by profiling xylogucans and pectins through immunohistochemistry and by genome-wide transcriptomic analysis performed at the same withering stages. Our analysis indicates a gradual passive polymer concentration due to water loss in the first two months of postharvest withering, followed by active structural modifications in the last month of the process. Such rearrangements involve xyloglucans in the internal surface, cuticle components and cellulose in the external surface, and pectins in both surfaces. Moreover, by investigating the expression trend of cell wall metabolism-related genes, we identified several putative molecular markers associated to the polymer dynamics. The present study represents an important step towards an exhaustive comprehension of the postharvest withering process, which is of great interest from both the biological and technological points of view. Highlights • FT-IR, immunohistochemistry and transcriptomics study on both sides of berry skin. • Passive polymer concentration in the first two months of postharvest withering. • Active polymer modifications in the final month of postharvest withering. • Methylated pectins increase, galactans decrease (both internal and external sides). • Xyloglucans (int. side) cuticle components and cellulose (ext. side) decrease. [ABSTRACT FROM AUTHOR]

l‐Galactose (l‐Gal) is one of the components of plant cell wall polysaccharides. In the GDP‐l‐fucose‐deficient Arabidopsis thaliana mutant mur1, l‐fucose (l‐Fuc) residues in xyloglucan are substituted by l‐Gal residues. l‐Gal only differs from l‐Fuc by the presence of an oxygen at C‐6. Thus, we hypothesized that the A. thaliana xyloglucan α1,2‐l‐fucosyltransferase (AtFUT1) is also responsible for the l‐galactosyl transfer to d‐galactose residues in xyloglucan. In this study, we heterologously produced AtFUT1 in fission yeast and carried out an in vitro assay for the activities of AtFUT1 on GDP‐l‐Gal and xyloglucan oligosaccharide. We show that the recombinant AtFUT1 catalyzes l‐Gal transfer to xyloglucan oligosaccharides although the initial velocity of l‐Gal transfer is 3.1 times lower than that of l‐Fuc transfer. [ABSTRACT FROM AUTHOR]

Highlights • Isoprimeverose-producing enzyme (IPase) is vital for xyloglucan degradation. • IPase releases a disaccharide, isoprimeverose, from xyloglucan oligosaccharides. • The structure of IPase is solved for the first time. • Aspergillus oryzae IPase (IpeA) has subsites specific for isoprimeverose recognition. • The substrate recognition mechanisms of IPases are clarified by this study. Abstract Isoprimeverose-producing enzymes (IPases) release isoprimeverose (α- d -xylopyranosyl-(1 → 6)- d -glucopyranose) from the non-reducing end of xyloglucan oligosaccharides. Aspergillus oryzae IPase (IpeA) is classified as a member of the glycoside hydrolase family 3 (GH3); however, it has unusual substrate specificity compared with other GH3 enzymes. Xylopyranosyl branching at the non-reducing ends of xyloglucan oligosaccharides is vital for IpeA activity. We solved the crystal structure of IpeA with isoprimeverose at 2.4 Å resolution, showing that the structure of IpeA formed a dimer and was composed of three domains: an N-terminal (β/α) 8 TIM-barrel domain, α/β/α sandwich fold domain, and a C-terminal fibronectin-like domain. The catalytic TIM-barrel domain possessed a catalytic nucleophile (Asp300) and acid/base (Glu524) residues. Interestingly, we found that the cavity of the active site of IpeA was larger than that of other GH3 enzymes, and subsite −1′ played an important role in its activity. The glucopyranosyl and xylopyranosyl residues of isoprimeverose were located at subsites −1 and −1′, respectively. Gln58 and Tyr89 contributed to the interaction with the xylopyranosyl residue of isoprimeverose through hydrogen bonding and stacking effects, respectively. Our findings provide new insights into the substrate recognition of GH3 enzymes. [ABSTRACT FROM AUTHOR]