Search

Banana peel (BP) is the primary by-product generated during banana processing which causes numerous environmental issues. This study examines the physical attributes, proximate analysis, glycoarray profiling, antioxidant abilities, and prebiotic activity of BP. The analysis demonstrated that carbohydrates constituted the primary components of BP and the glycoarray profiling indicated that BP contains multiple pectin and hemicellulose structures. BP also contained phenolic compounds, including (+)-catechin and gallic acid, flavonoid compounds, and antioxidant activities. BP demonstrated prebiotic effects by promoting the proliferation of advantageous gut bacteria while inhibiting the growth of harmful bacteria. The prebiotic index scores demonstrated that BP exhibited a greater capacity to promote the growth of beneficial bacteria in comparison to regular sugar. The study demonstrated the potential of the BP as a valuable source of dietary fibre, bioactive compounds, and prebiotics. These components have beneficial characteristics and can be utilised in the production of food, feed additives, and functional food. [ABSTRACT FROM AUTHOR]

Succulence is found across the world as an adaptation to water‐limited niches. The fleshy organs of succulent plants develop via enlarged photosynthetic chlorenchyma and/or achlorophyllous water storage hydrenchyma cells. The precise mechanism by which anatomical traits contribute to drought tolerance is unclear, as the effect of succulence is multifaceted. Large cells are believed to provide space for nocturnal storage of malic acid fixed by crassulacean acid metabolism (CAM), whilst also buffering water potentials by elevating hydraulic capacitance (CFT). The effect of CAM and elevated CFT on growth and water conservation have not been compared, despite the assumption that these adaptations often occur together. We assessed the relationship between succulent anatomical adaptations, CAM, and CFT, across the genus Clusia. We also simulated the effects of CAM and CFT on growth and water conservation during drought using the Photo3 model. Within Clusia leaves, CAM and CFT are independent traits: CAM requires large palisade chlorenchyma cells, whereas hydrenchyma tissue governs interspecific differences in CFT. In addition, our model suggests that CAM supersedes CFT as a means to maximise CO2 assimilation and minimise transpiration during drought. Our study challenges the assumption that CAM and CFT are mutually dependent traits within succulent leaves. Summary statement: Many succulent taxa use crassulacean acid metabolism (CAM) and elevated hydraulic capacitance (CFT) to buffer leaf water potentials. We show that CAM and elevated CFT are independent traits across the genus Clusia and that these adaptations have distinct impacts on plant performance during drought. [ABSTRACT FROM AUTHOR]

Copyright of Plants, People, Planet is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: Grape skins, usually discarded during wine making, are a valuable source of cellulose (20–50%), hemicelluloses (15–20%), lignin (17–30%) and other compounds, e.g., polyphenols, which can be used as biomaterials in the manufacturing of a variety of new products, such as bioethanol or pharmaceutical products. However, to obtain these biomaterials, the complex polysaccharides of the grape cell walls must be broken down into smaller molecules to allow the extraction of compounds. The degradation process is often performed enzymatically or hydrothermally. Microorganisms that produce the required enzymes while using this waste product as a growth medium can have interesting economic advantages. Here, we created two genetically engineered wine yeast strains that produce grape cell wall degrading enzymes. These yeasts, when grown on grape pomace, induced enzymatic structural changes to the grape cell walls. A collection of antibodies binding to the different cell wall molecules were used to monitor the impact on the cell wall structure of the enzymes, confirming increased extractability of key cell wall polymers when relatively low levels of enzymes are present, illustrating the potential to develop and optimise yeast for grape waste valorisation applications. Industrial wine yeast strains expressing hydrolytic enzymes were fermented on Chardonnay pomace and were shown to unravel the cell walls of the berry tissues according to the enzyme activities. The yeasts produced a native endo-polygalacturonase (Saccharomyces cerevisiae × Saccharomyces paradoxus hybrid, named PR7) and/or a recombinant endo-glucanase (S. cerevisiae strains named VIN13 END1 and PR7 END1). The impact of the enzymes during the fermentations was evaluated by directly studying the cell wall changes in the berry tissues using a Comprehensive Microarray Polymer Profiling technique. By the end of the fermentation, the endo-glucanase did not substantially modify the berry tissue cell walls, whereas the endo-polygalacturonase removed some homogalacturonan. The recombinant yeast strain producing both enzymes (PR7 END1) unravelled the cell walls more fully, enabling polymers, such as rhamnogalacturonan-I, β-1,4-D-galactan and α-1,5-L-arabinan, as well as cell wall proteins to be extracted in a pectin solvent. This enzyme synergism led to the enrichment of rhamnogalacturonan-type polymers in the subsequent NaOH fractions. This study illustrated the potential utilisation of a recombinant yeast in pomace valorisation processes and simulated consolidated bioprocessing. Furthermore, the cell wall profiling techniques were confirmed as valuable tools to evaluate and optimise enzyme producing yeasts for grape and plant cell wall degradation. [ABSTRACT FROM AUTHOR]

Background and Aims The necrotrophic fungus Botrytis cinerea infects a broad range of fruit crops including domesticated grapevine Vitis vinifera cultivars. Damage caused by this pathogen is severely detrimental to the table and wine grape industries and results in substantial crop losses worldwide. The apoplast and cell wall interface is an important setting where many plant–pathogen interactions take place and where some defence-related messenger molecules are generated. Limited studies have investigated changes in grape cell wall composition upon infection with B. cinerea , with much being inferred from studies on other fruit crops. Methods In this study, comprehensive microarray polymer profiling in combination with monosaccharide compositional analysis was applied for the first time to investigate cell wall compositional changes in the berries of wine (Sauvignon Blanc and Cabernet Sauvignon) and table (Dauphine and Barlinka) grape cultivars during Botrytis infection and tissue maceration. This was used in conjunction with scanning electron microscopy (SEM) and X-ray computed tomography (CT) to characterize infection progression. Key Results Grapes infected at veraison did not develop visible infection symptoms, whereas grapes inoculated at the post-veraison and ripe stages showed evidence of significant tissue degradation. The latter was characterized by a reduction in signals for pectin epitopes in the berry cell walls, implying the degradation of pectin polymers. The table grape cultivars showed more severe infection symptoms, and corresponding pectin depolymerization, compared with wine grape cultivars. In both grape types, hemicellulose layers were largely unaffected, as was the arabinogalactan protein content, whereas in moderate to severely infected table grape cultivars, evidence of extensin epitope deposition was present. Conclusions Specific changes in the grape cell wall compositional profiles appear to correlate with fungal disease susceptibility. Cell wall factors important in influencing resistance may include pectin methylesterification profiles, as well as extensin reorganization. [ABSTRACT FROM AUTHOR]

Aloe vera gel is a globally popular natural product used for the treatment of skin conditions. Its useful properties are attributed to the presence of bioactive polysaccharides. Nearly 25% of the 600 species in the genus Aloe are used locally in traditional medicine, indicating that the bioactive components in Aloe vera may be common across the genus Aloe. The complexity of the polysaccharides has hindered development of relevant assays for authentication of Aloe products. Carbohydrate detecting microarrays have recently been suggested as a method for profiling Aloe polysaccharide composition. The aim of this study was to use carbohydrate detecting microarrays to investigate the seasonal variation in the polysaccharide composition of two medicinal and two non-medicinal Aloe species over the course of a year. Microscopy was used to explore where in the cells the bioactive polysaccharides are present and predict their functional role in the cell wall structure. The carbohydrate detecting microarrays analyses showed distinctive differences in the polysaccharide composition between the different species and carbohydrate detecting microarrays therefore has potential as a complementary screening method directly targeting the presence and composition of relevant polysaccharides. The results also show changes in the polysaccharide composition over the year within the investigated species, which may be of importance for commercial growing in optimizing harvest times to obtain higher yield of relevant polysaccharides. [ABSTRACT FROM AUTHOR]

Pectin is a major component of primary cell walls and performs a plethora of functions crucial for plant growth, development and plant-defense responses. Despite the importance of pectic polysaccharides their biosynthesis is poorly understood. Several genes have been implicated in pectin biosynthesis by mutant analysis, but biochemical activity has been shown for very few. We used reverse genetics and biochemical analysis to study members of Glycosyltransferase Family 92 (GT92) in Arabidopsis thaliana. Biochemical analysis gave detailed insight into the properties of GALS1 (Galactan synthase 1) and showed galactan synthase activity of GALS2 and GALS3. All proteins are responsible for adding galactose onto existing galactose residues attached to the rhamnogalacturonan-I (RG-I) backbone. Significant GALS activity was observed with galactopentaose as acceptor but longer acceptors are favored. Overexpression of the GALS proteins in Arabidopsis resulted in accumulation of unbranched β-1, 4-galactan. Plants in which all three genes were inactivated had no detectable β-1, 4-galactan, and surprisingly these plants exhibited no obvious developmental phenotypes under standard growth conditions. RG-I in the triple mutants retained branching indicating that the initial Gal substitutions on the RG-I backbone are added by enzymes different from GALS. [ABSTRACT FROM AUTHOR]

Euglena gracilis is an alga of great biotechnological interest and extensive metabolic capacity, able to make high levels of bioactive compounds, such as polyunsaturated fatty acids, vitamins and β-glucan. Previous work has shown that Euglena expresses a wide range of carbohydrate-active enzymes, suggesting an unexpectedly high capacity for the synthesis of complex carbohydrates for a single-celled organism. Here, we present an analysis of some of the carbohydrates synthesised by Euglena gracilis. Analysis of the sugar nucleotide pool showed that there are the substrates necessary for synthesis of complex polysaccharides, including the unusual sugar galactofuranose. Lectin- and antibody-based profiling of whole cells and extracted carbohydrates revealed a complex galactan, xylan and aminosugar based surface. Protein N-glycan profiling, however, indicated that just simple high mannose-type glycans are present and that they are partially modified with putative aminoethylphosphonate moieties. Together, these data indicate that Euglena possesses a complex glycan surface, unrelated to plant cell walls, while its protein glycosylation is simple. Taken together, these findings suggest that Euglena gracilis may lend itself to the production of pharmaceutical glycoproteins. [ABSTRACT FROM AUTHOR]

Pectic homogalacturonan ( HG) is one of the main constituents of plant cell walls. When processed to low degrees of esterification, HG can form complexes with divalent calcium ions. These macromolecular structures (also called egg boxes) play an important role in determining the biomechanics of cell walls and in mediating cell-to-cell adhesion. Current immunological methods enable only steady-state detection of egg box formation in situ. Here we present a tool for efficient real-time visualisation of available sites for HG crosslinking within cell wall microdomains. Our approach is based on calcium-mediated binding of fluorescently tagged long oligogalacturonides ( OGs) with endogenous de-esterified HG. We established that more than seven galacturonic acid residues in the HG chain are required to form a stable complex with endogenous HG through calcium complexation in situ, confirming a recently suggested thermodynamic model. Using defined carbohydrate microarrays, we show that the long OG probe binds exclusively to HG that has a very low degree of esterification and in the presence of divalent ions. We used this probe to study real-time dynamics of HG during elongation of Arabidopsis pollen tubes and root hairs. Our results suggest a different spatial organisation of incorporation and processing of HG in the cell walls of these two tip-growing structures. [ABSTRACT FROM AUTHOR]