Cell Wall Structure Research Articles

Experimental studies of dynamic compression of cellulose pulp fibers

The ability to control the structure of the wood-pulp fiber cell wall is an attractive means to obtain increased accessibility to the fiber interior, providing routes for functionalization of the fibers that support further processing and novel material concepts, e.g. improved degree of polymerization, nanofiltration as demonstrated in previous studies. It has been proposed that dynamic compression and decompression of the cellulose pulp fibers in the wet state make it possible to modify the cell wall significantly.We hypothesize that hydrostatic pressure exerted on fibers fully submerged in water will increase the accessibility of the fiber wall by penetrating the fiber through weak spots in the cell wall. To pursue this, we have developed an experimental facility that can subject wet cellulose pulp samples to a pressure pulse ∼10 ms long and with a peak pressure of ∼300 MPa. The experiment is thus specifically designed to elucidate the effect of a rapid high-pressure pulse passing through the cellulose sample and enables studies of changes in structural properties over different size ranges. Different characterization techniques, including Scanning electron microscopy, X-ray diffraction, and wide- and small-angle X-ray scattering, have been used to evaluate the material exposed to pulsed pressure. The mechanism of pressure build-up is estimated computationally to complement the results. Key findings from the experiments consider a decrease in crystallinity and changes in the surface morphology of the cellulose sample.

Sustainable extraction of bioactive compound from apple pomace through lactic acid bacteria (LAB) fermentation

Apple pomace (AP), a by-product of the juice industry, is a rich and inexpensive source of natural bioactive substances, including phenolic compounds, that exhibit health–promoting effects. The recovery of these compounds from plant material using only classical extraction techniques and environmentally friendly solvents is often ineffective due to the entrapment of some compounds in the complex structures of plant cell walls. Lactic Acid Bacteria (LAB) fermentation can be a simple technology to increase the content of phenolic compounds, as well as the antioxidant activity of plant material. In this study, pomace from conventionally grown apples (Malus Domestica) of the Ligol cultivar were fermented with selected LAB strains (Lpb. plantarum KKP 3182, Lpb. plantarum KKP 1527, Lpb. plantarum ZFB 200), commercial starter cultures of Lpb. plantarum, and spontaneously. The fermented material was then subjected to ultrasound-assisted extraction, and the resulting extracts were analysed for their composition (phenolic compounds, triterpenoids, simple organic acids), and antioxidant activity. We found that: (1) the total phenolic content of AP extracts fermented with Lpb. plantarum KKP 1527 was about 30% higher than that of non-fermented AP extracts, (2) extracts of AP fermented with Lpb. plantarum KKP 1527 characterized a higher value of the antioxidant activity, (3) an increase in gallic acid procyanidin A2, protocatechuic acid, and procyanidin B2, while a decrease in rutin and quercetin was observed. The results indicated that AP fermented with Lpb. plantarum KKP 1527 may be a powerful and low–cost source of natural antioxidants which have applications in many industries.

Optimization of delignification depth of wood surfaces for skin polymer impregnation

We controlled the degree of surface delignification of a wood specimen to impart functionality to its surface and injected a polymer into the porous structure to investigate using it as a functional material. Generally, balsa wood is used in studies aiming to impart functionality through polymer impregnation. However, we used a native Korean tree (Paulownia tomentosa), which has the lowest specific gravity. Peracetic acid (acetic acid and hydrogen peroxide mixture) was used as the delignification solution. Changes in wood surface properties were analyzed according to the delignification treatment duration. Changes in chemical composition, functional groups, cell wall structure, specific gravity, and pores were also observed. Depending on the delignification time, the specific gravity decreased from 0.24 to 0.12. The lignin content was reduced from 29.2% to 0.9%. Fourier Transform Infrared Spectroscopy revealed changes in the lignin functional groups (1 591, 1 507, and 1 240 cm−1), and changes in functional groups derived from hemicellulose (1 720 and 1 182 cm−1). Epoxy infiltration depth was adjusted according to delignification treatment depth to impart wood surface functionality. Our research results indicated that strength and durability could be improved by selectively impregnating polymers into the wood surface requiring functionality, unlike chemically modifying the entire interior of the wood.

Comparison of Halophyte and Glycophyte Plants from the Amaranthaceae-Chenopodiaceae Family in Their Ion-Exchange Properties of Polymeric Matrix of Cell Walls

Ion-exchanging properties of the polymeric matrix of the cell walls isolated from leaves were examined. The glycophyte 55-day-old plants of spinach (Spinacia oleracea L., cv. Matador) grown on a nutrient solution containing 0.5, 150, or 250 mM NaCl and the halophyte seepweed (Suaeda altissima (L.) Pall.) of the same age grown at 0.5, 250, or 750 mM NaCl were compared. The ion-exchange capacity of the cell walls was estimated at different pH and ionic strength of a solution. In the structure of the leaf cell walls, three types of cation-exchange groups were found, namely, two types of carboxylic groups (one of them belongs to galacturonic acid residue) and phenolic OH-groups. The quantities of the groups of each type and their ionization constants were determined. The qualitative composition of the ion-exchange groups in the leaf cell walls was found to be uniform in both plant species regardless of their nutrition. However, the quantity of the carboxylic groups of galacturonic acid depended on the ambient salt concentration in a different manner in the glycophyte and halophyte. This change in the composition of functional groups of cell wall polymers was more pronounced in the halophyte and is apparently one of the responses of these plants to salinization. The sharp increase in the NaCl concentration in the medium leads to a decrease in pH in the extracellular water space due to ion-exchange reactions between sodium ions coming from the external medium and protons of the ionized carboxylic groups of the cell walls. The results are discussed in the aspect of participation of the leaf cell walls in plant responses to salinization.

Localization of Chromosomal Regions Determining Magnesium and Calcium Content in Rice Varieties

There has been a wide variation in the content of micro and macro elements, both between subspecies and within rice species and varieties. Magnesium as a cofactor is involved in more than 300 enzymatic reactions and is necessary for growth and development of both plants and humans. It affects carbohydrate and protein metabolism. Both adenosine triphosphate (ATP) production, nucleotide and glucose synthesis, and lipid oxidation regulation depend on its concentration. Calcium is also essential for the formation of cell wall structure and cell division. High concentrations of calcium change the composition and condition of red blood cell membranes and cell morphological characteristics. At the same time the variability in signs of domestic rice varieties has not yet been studied. There have been no studies on the localization of chromosomal regions responsible for the formation of traits of magnesium and calcium content in rice samples. Wide variation in calcium content (0.07–2.33%) and magnesium content in rice samples (2–14%) was established. Contrasting groups of varieties and sources by signs were identified. A search for chromosomal regions determining the quality of domestic samples was carried out using 58 molecular markers distributed across the rice genome (SSR). The data on phenotyping of native rice varieties by quality signs were used to divide them into groups with maximum trait value (1) and minimum trait value (2). The relationship between phenotypic manifestation of the trait and the genotype of the sample was established: by means of analysis of variance. Eight loci determining magnesium and calcium content in native rice varieties – were identified. The loci determining magnesium content are located on chromosomes 5, 6, 7, 8. Four loci associated with calcium content were identified two on the second chromosome and one each on the eighth and fifth chromosomes. On the fifth chromosome, it is located (RM 13, 28.6 cM) in close proximity to the RM 405 marker region (28 cM), which is connected with magnesium content.

Bioinspired Large‐Area Atomically‐Thin Graphene Membranes

AbstractNanoporous graphene membranes are attractive for molecular separations, but it remains challenging to maintain sufficient mechanical strength during scalable fabrication and module development. Inspired by the composite structure of cell membranes and cell walls, a large‐area atomically thin nanoporous graphene membrane supported by a fiber‐reinforced structure with strong interlamellar adhesion is designed. Compared with other graphene‐based membranes of large scale, the fracture stress, fracture strength, and tensile stiffness of the composite membranes can be enhanced by a factor of 17, 67, and 94, respectively. This fiber‐reinforced structure also confers stability of the composite membrane to different curvature states and repeated bending processes after 10 000 times, which provides an opportunity for modularization. The breathable function of such membrane with an ultrahigh gas permeance (≈8.6–23 L m−2 d−1 Pa−1) and an ultralow water vapor transportation rate (WVTR) (≈23–129 g L m−2 d−1) is observed, superior to most commercial materials. This work provides a facile method to fabricate large‐area graphene membranes and paves the road to practical application in the membrane separation field for other 2D films.

Impact of Gamma irradiation pretreatment on the characteristics of native and defatted date palm seed flour and oil

Numerous beneficial compounds in date seeds are less accessible due to natural barriers. These compounds can be especially beneficial to human health when linked to their excellent antioxidant capacity. The aim of this study is to elucidate the effect of gamma irradiation on releasing these compounds in order to enhance the chemical composition of native and defatted date seed powder. To achieve this, date seed flour was exposed to two doses of gamma irradiation (1 and 5 kGy), and then the irradiated samples were assessed for their chemical properties. Additionally, after irradiation pretreatment, oil extraction was carried out using different solvents, and the native and defatted date seed flours were analyzed. The results showed that gamma irradiation had a significant effect on the color and chemical composition of the date seed powder. The solubility of amino acids in solvents was affected by gamma irradiation, resulting in defatted seed flours that were richer in some amino acids. Furthermore, irradiated-defatted seed powder exhibited higher levels of neutral sugars and esterified phenols, which contribute to a better antioxidant capacity. FTIR spectra confirmed that, after irradiation, there was a breakdown of the cell wall structure, allowing for a higher oil yield with more effective antimicrobial activities. In conclusion, irradiation pretreatment allowed the native and defatted date seed flour to gain additional benefits by making chemical compounds more extractable.

Mechanisms of methyl 2-methylbutyrate suppression on Aspergillus flavus growth and aflatoxin B1 biosynthesis

Aspergillus flavus and subsequently produced carcinogenic aflatoxins frequently contaminate postharvest food crops, resulting in a threat to global food safety. Chemical preservatives are currently the main antifungal agents. However, fungal resistance effect, biological toxicity, and environmental contamination limit their practical applications. The application of natural volatile organic compounds has great potential for controlling fungal and mycotoxin contamination of postharvest food crops. This study therefore investigated the antifungal and anti-aflatoxigenic activities of the volatile compound, methyl 2-methylbutyrate (M2M), against Aspergillus flavus and its potential mechanisms. M2M effectively inhibited A. flavus mycelia growth, with a minimum inhibitory concentration of 2.0 μL/mL. Moreover, M2M also suppressed aflatoxin production, sclerotia production, and the pathogenicity on peanut and corn flour. RNA-Seq results showed that 2899 differentially expressed genes (DEGs), and DEGs involved in ergosterol synthesis, cell wall structure, glycolysis, citric acid cycle, mitogen activated protein kinase signaling pathway, DNA replication, and aflatoxin biosynthesis, were down-regulated in A. flavus. Further studies showed that M2M strongly damaged the cell membrane and cell wall integrity, reduced ATP levels, and induced reactive oxygen species (ROS) accumulation and DNA damage. Notably, a GATA type zinc finger transcription factor, AfSreA (AFLA_132440), which is essential for A. flavus growth and aflatoxin production, was identified. The growth and aflatoxin yield in the ΔAfSreA strain decreased by 94.94 % and 71.82 %, respectively. Additionally, deletion of AfSreA destroyed cell wall integrity and decreased expressions of genes involved in aflatoxin biosynthesis. Taken together, our results identified the antifungal and anti-aflatoxigenic mechanisms of M2M against A. flavus, and confirmed the potential of M2M in protecting peanut and corn from fungal contamination.

Proteome insights of citric acid-mediated cadmium toxicity tolerance in Brassica napus L.

Cadmium (Cd) is a toxic substance that is uptake by plants from soils, Cd easily transfers into the food chain. Considering global food security, eco-friendly, cost-effective, and metal detoxification strategies are highly demandable for sustainable food crop production. The purpose of this study was to investigate how citric acid (CA) alleviates or tolerates Cd toxicity in Brassica using a proteome approach. In this study, the global proteome level was significantly altered under Cd toxicity with or without CA supplementation in Brassica. A total of 4947 proteins were identified using the gel-free proteome approach. Out of these, 476 proteins showed differential abundance between the treatment groups, wherein 316 were upregulated and 160 were downregulated. The gene ontology analysis reveals that differentially abundant proteins were involved in different biological processes including energy and carbohydrate metabolism, CO2 assimilation and photosynthesis, signal transduction and protein metabolism, antioxidant defense, heavy metal detoxification, plant development, and cytoskeleton and cell wall structure in Brassica leaves. Interestingly, several candidate proteins such as superoxide dismutase (A0A078GZ68) L-ascorbate peroxidase 3 (A0A078HSG4), glutamine synthetase (A0A078HLB2), glutathione S-transferase DHAR1 (A0A078HPN8), glutamine synthetase (A0A078HLB2), cysteine synthase (A0A078GAD3), S-adenosylmethionine synthase 2 (A0A078JDL6), and thiosulfate/3-mercaptopyruvate sulfur transferase 2 (A0A078H905) were involved in antioxidant defense system and sulfur assimilation-involving Cd-detoxification process in Brassica. These findings provide new proteome insights into CA-mediated Cd-toxicity alleviation in Brassica, which might be useful to oilseed crop breeders for enhancing heavy metal tolerance in Brassica using the breeding program, with sustainable and smart Brassica production in a metal-toxic environment.

ZmDRR206 functions in maintaining cell wall integrity during maize seedling growth and defense response to external stresses

Plants adaptively change their cell wall composition and structure during their growth, development, and interactions with environmental stresses. Dirigent proteins (DIRs) contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds. A maize DIR, ZmDRR206, was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development. Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity (CWI) maintenance. Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection. ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance, revealing a tradeoff between growth and defense. Consistently, ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis, while increasing the contents of major cell wall components, defense phytohormones, and defense metabolites, and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings. ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben, and ZmDRR206 physically interacted with ZmCesA10, which is a cellulose synthase unit. Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth, and might be exploited for breeding strong disease resistance in maize.

Bacillus dicomae sp. nov., a new member of the Bacillus cereus group isolated from medicinal plant Dicoma anomala.

A Gram-stain-positive, endospore-forming endophytic bacterial strain designated MHSD28T was isolated from surface-sterilized leaves of Dicoma anomala collected from Eisleben, Botlokwa, Limpopo Province, South Africa. The phenotypic and phylogenetic characteristics of strain MHSD28T were consistent with those of members within the Bacillus cereus group. Comparative analysis between this strain and its relatives confirmed that it belongs to this group and forms a monophyletic branch. The digital DNA-DNA hybridization values between strain MHSD28T and its relatives were lower than the 70 % threshold for species delineation. To further determine its phylogenetic position, multi-locus sequence analysis (MLSA) based on five concatenated housekeeping gene (gyrB, atpD, DnaK, rpoB and rpoD) sequences, phenotypic analysis, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) biotyper identification, fatty acid and polar lipid profile analyses were carried out. Phenotypic characterization, MLSA, whole genome sequence based analyses and MALDI-TOF results placed strain MHSD28T within the B. cereus group. The major fatty acids were iso-C15 : 0 and summed feature 3 and the main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The respiratory quinone was menaquinone-7. The cell-wall peptidoglycan structure included meso-diaminopimelic acid. Considering the above results, strain MHSD28T represents a novel species of the B. cereus group, for which the name Bacillus dicomae sp. nov. is proposed. The type strain is MHSD28T (=BD 2262T=LMG 32287T=CECT 30671T).

Bacterial tolerance to host-exuded specialized metabolites structures the maize root microbiome.

Plants exude specialized metabolites from their roots, and these compounds are known to structure the root microbiome. However, the underlying mechanisms are poorly understood. We established a representative collection of maize root bacteria and tested their tolerance against benzoxazinoids (BXs), the dominant specialized and bioactive metabolites in the root exudates of maize plants. In vitro experiments revealed that BXs inhibited bacterial growth in a strain- and compound-dependent manner. Tolerance against these selective antimicrobial compounds depended on bacterial cell wall structure. Further, we found that native root bacteria isolated from maize tolerated the BXs better compared to nonhost Arabidopsis bacteria. This finding suggests the adaptation of the root bacteria to the specialized metabolites of their host plant. Bacterial tolerance to 6-methoxy-benzoxazolin-2-one (MBOA), the most abundant and selective antimicrobial metabolite in the maize rhizosphere, correlated significantly with the abundance of these bacteria on BX-exuding maize roots. Thus, strain-dependent tolerance to BXs largely explained the abundance pattern of bacteria on maize roots. Abundant bacteria generally tolerated MBOA, while low abundant root microbiome members were sensitive to this compound. Our findings reveal that tolerance to plant specialized metabolites is an important competence determinant for root colonization. We propose that bacterial tolerance to root-derived antimicrobial compounds is an underlying mechanism determining the structure of host-specific microbial communities.

Optimization of hydrodynamic degumming of flax fiber for improved biochemical profile

Flax fibers have bioactive properties due to their biochemical composition. The quality of the fibers is the main parameter that determines the application, and the process of obtaining fibers has a crucial impact on the composition and properties of fibers. Therefore, this study aimed to enhance the quality of flax fibers by optimizing the hydrodynamic degumming process of decorticated flax fibers. Flax fibers, both non-transgenic (Nike) and transgenic (B14) fibers with overexpression of the β-1,3-glucanase gene from potato, were obtained through nine processes that varied in the degumming temperature, degumming time, and rinsing temperature. The content of phenolic, terpene and polyamine compounds as well as antioxidant activity was determined in the fibers. Two processes, due to having the highest content of bioactive compounds, were selected for further analyses: determination of the chemical composition and structure of plant cell walls, and in vitro tests on the culture of the V79 hamster lung fibroblast cell line. Both processes led to an increase in the content of cellulose and hemicellulose, along with a decrease in the amount of pectin in B14 fibers, indicating changes in the structure of the cell wall. Water extract containing phenolic compounds obtained from flax fiber resulted in increased viability of the V79 fibroblasts and did not show changes in the level of transcripts of inflammatory genes. Based on the obtained results, process VI was identified as the most effective for obtaining flax fibers of the best quality. Additionally, the study confirmed that transgenic B14 fibers exhibited better quality than non-transgenic fibers. The findings highlight the potential of the methods used to obtain flax fibers, which may significantly impact their properties.

Sulfoglycolipids and Related Analogues of Mycobacterium tuberculosis: Chemical Synthesis and Immunological Studies.

Mycobacterium tuberculosis (Mtb) causes tuberculosis as one major threat to human health, which has been deteriorated owing to the emerging multidrug resistance. Mtb contains a complex lipophilic cell wall structure that is important for bacterial persistence. Among the lipid components, sulfoglycolipids (SGLs), known to induce immune cell responses, are composed of a trehalose core attached with a conserved sulfate group and 1-4 fatty acyl chains in an asymmetric pattern. At least one of these acyl chains is polymethylated with 3-12 methyl branches. Although Mtb SGL can be isolated from bacterial culture, resulting SGL is still a homologous mixture, impeding accurate research studies. This up-to-date review covers the chemical synthesis and immunological studies of Mtb SGLs and structural analogues, with an emphasis on the development of new glycosylation methods and the asymmetric synthesis of polymethylated scaffolds. Both are critical to advance further research on biological functions of these complicated SGLs.

Rapid SERS detection of diverse filamentous fungi by superparamagnetic particles and flexible silver nanowires

In clinical practice, infections caused by Aspergillus species are common and associated with high mortality rates. However, isolating Aspergillus from clinical samples and cultures is challenging, and serological tests cannot differentiate between strains. Furthermore, the complex cell wall structure in Aspergillus species hinders DNA extraction and subsequent nucleic acid detection. Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger are common and frequently encountered pathogenic species. This study aimed to establish an efficient and rapid method for detecting Aspergillus species in clinical samples. Fe3O4@PEI.NH2 nanoparticles with large particle sizes were employed to capture Aspergillus from the samples. Flexible silver nanowires (AgNWs) were prepared and used as the surface-enhanced Raman scattering (SERS) substrate for Aspergillus detection. Through SERS spectroscopy, the identification of captured Aspergillus species was confirmed. Furthermore, the SERS spectrum underwent principal component analysis employing orthogonal partial least-squares discrimination analysis (OPLS-DA) as a multivariate analysis technique to distinguish between the various Aspergillus species effectively. After 10-fold cross-validation, the trained model achieved a testing accuracy of 99.15%, indicating excellent classification performance. By utilizing pre-prepared Fe3O4@PEI.NH2 and AgNWs, the detection process was completed within 60 min without disrupting the cell wall of Aspergillus.

Preparation Optimization of Enhanced Poplar Wood by Organic-Inorganic Hybrid Treatment via Response Surface Methodology.

In this work, a strategy for hybrid treatment was proposed, aiming to present a hybrid impregnation agent including lignin-derived resin (LR) and surface-modified montmorillonite (GMMT) to treat fast-growing poplar wood. The treating agents could penetrate the wood, fill the cavities of the wood interior, and strengthen the cell wall structure. The optimal WPG of 36.2% was obtained upon the response surface methodology (RSM) at the conditions of 34% LR, 1.8% GMMT, 1.2 MPa impregnation pressure, and 99 min impregnation time. The density, water uptake (WU), modulus of rupture (MOR), modulus of elasticity (MOE), and compressive strength (CS) of the samples were tested to evaluate the enhancement of the physical and mechanical properties. In addition, these samples were investigated via cone calorimeter (CONE), Fourier Transform Infrared spectrometer (FTIR), and X-ray diffraction (XRD). The results showed that the density of the treated samples increased significantly up to 0.72 g/cm3. Compared with 134.8% of the control, the WU of the treated wood sample could decrease to 60.3%. In addition, the MOR and MOE of the resulting samples reached up to 131.8 MPa and 18.14 GPa, respectively, which were 62.3% and 77.7% higher than the control. Notably, the CS was 84.7 MPa with an increase of up to 94.7%. Moreover, the peak heat release rate (HRR) of the treated sample was obviously reduced to 231.33 kW/m2, a decrease of 17.5% compared to the control (271.71 kW/m2).

Restraining Quiescence Release-Related Ageing in Plant Cells: A Case Study in Carrot.

The blackening of cut carrots causes substantial economic losses to the food industry. Blackening was not observed in carrots that had been stored underground for less than a year, but the susceptibility to blackening increased with the age of the carrots that were stored underground for longer periods. Samples of black, border, and orange tissues from processed carrot batons and slices, prepared under industry standard conditions, were analyzed to identify the molecular and metabolic mechanisms underpinning processing-induced blackening. The black tissues showed substantial molecular and metabolic rewiring and large changes in the cell wall structure, with a decreased abundance of xyloglucan, pectins (homogalacturonan, rhamnogalacturonan-I, galactan and arabinan), and higher levels of lignin and other phenolic compounds when compared to orange tissues. Metabolite profiling analysis showed that there was a major shift from primary to secondary metabolism in the black tissues, which were depleted in sugars, amino acids, and tricarboxylic acid (TCA) cycle intermediates but were rich in phenolic compounds. These findings suggest that processing triggers a release from quiescence. Transcripts encoding proteins associated with secondary metabolism were less abundant in the black tissues, but there were no increases in transcripts associated with oxidative stress responses, programmed cell death, or senescence. We conclude that restraining quiescence release alters cell wall metabolism and composition, particularly regarding pectin composition, in a manner that increases susceptibility to blackening upon processing.

Improving enzyme accessibility in the aqueous enzymatic extraction process by microwave-induced porous cell walls to increase oil body and protein yields

Aqueous enzymatic extraction (AEE) is a green and sustainable extraction method. However, the intact cell wall hinders the accessibility of enzymes, severely limiting the efficiency and application of the AEE method. In this study, microwave-assisted aqueous enzymatic extraction (MAAEE) was used to degrade the peanut cell wall and improve the yield of oil and protein. Transmission electron microscopy, scanning electron microscopy, BET-specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction, and chemical composition analysis were used to characterize the structure and chemical changes of the peanut cell wall. The results showed that microwave treatment could break the structure of the peanut cell wall, increase the porosity of raw materials, accelerate the efficiency of enzymatic hydrolysis, and promote the extraction of oil and protein. Compared with raw peanut powder (MC-0), microwaved peanut powder (MC-4) had a higher oil body yield (>44%) and protein release rate (>76%). At the microscopic level, cell wall rupture, oil accumulation, and cell contents scattered outside the cell were observed. The mean pore size, pore volume, and specific surface area increased by 54.1%, 149.4%, and 63.5%, respectively, while the crystallinity decreased by 4.4%. The content of hemicellulose and CDTA-soluble pectin (CSP) decreased by 18.6% and 32.9%, respectively. The degradation rates of cellulase and pectinase on cell wall components were significantly increased by 8.5%–43.2% (p < 0.05). In summary, microwave-induced porous cell walls could significantly improve enzyme accessibility, accelerate enzymatic hydrolysis efficiency, and promote oil and protein extraction.

Facilitating enzymatic hydrolysis efficiency of rape straw by pretreatment with a novel glycerol-based deep eutectic solvent

Deep eutectic solvent (DES) pretreatment plays an indispensable role in destroying the natural anti-degradation barrier structure of lignocellulose. Here, the cetyltrimethylammonium bromide and glycerol were used to synthesize novel DES and introduced to the pretreatment process to facilitate the enzymatic hydrolysis efficiency of rape straw (RS). The results showed that the delignification and xylan removal could extremely reach 46.1% and 52.7% under optimal conditions (molar ratio of 1:6, 200 °C, 90 min), respectively. It also resulted in 171.4 mg/g higher accessibility, 7.2% higher crystallinity, and 122.3 m2/g lower lignin surface area in RS concerning morphological changes of deconstructed and porous cell wall structure. Ultimately, the reducing sugar yield of RS was increased from 27.4% to 67.9% after pretreatment with this type of DES. This study exploited a novel DES for facilely reducing the recalcitrance of lignocellulose and a promising process for efficient saccharification using renewable biomass.

Xylan clustering on the pollen surface is required for exine patterning.

Xylan is a crosslinking polymer that plays an important role in the assembly of heterogeneous cell wall structures in plants. The pollen wall, a specialized cell wall matrix, exhibits diverse sculpted patterns that serve to protect male gametophytes and facilitate pollination during plant reproduction. However, whether xylan is precisely anchored into clusters and its influence on pollen wall patterning remain unclear. Here, we report xylan clustering on the mature pollen surface in different plant species that is indispensable for the formation of sculpted exine patterns in dicot and monocot plants. Chemical composition analyses revealed that xylan is generally present at low abundance in the mature pollen of flowering plants and shows plentiful variations in terms of substitutions and modifications. Consistent with the expression profiles of their encoding genes, genetic characterization revealed IRREGULAR XYLEM10-LIKE (IRX10L) and its homologous proteins in the GT47 family of glycosyltransferases as key players in the formation of these xylan micro-/nano-compartments on the pollen surface in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). A deficiency in xylan biosynthesis abolished exine patterning on pollen and compromised male fertility. Therefore, our study outlines a mechanism of exine patterning and provides a tool for manipulating male fertility in crop breeding.