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ObjectiveDiagnosing juvenile idiopathic arthritis (JIA) is challenging. Our study aimed to investigate the clinical significance of anti-α-1,4-D-polygalacturonic acid (PGA) antibodies in JIA, focusing on their role in diagnosis and assessing disease activity.MethodsIn this prospective case–control study, we examined variations in serum levels of PGA-IgA and PGA-IgG among children with different types of JIA and healthy controls. Serum PGA-IgA and PGA-IgG levels were assessed concurrently in children with active and inactive JIA.ResultsThis study included 126 patients diagnosed with JIA, 13 neonates, and 76 healthy children. Serum PGA-IgA and PGA-IgG levels were assessed, which revealed significant differences in PGA-IgA levels between various JIA subtypes and controls. An analysis of PGA-IgA levels in various JIA states revealed a statistically significant difference. Receiver operating characteristic (ROC) analysis demonstrated the robust predictive capability of PGA-IgA, with an AUC of 0.879 (p < 0.001), along with a specificity of 0.842 and sensitivity of 0.848.ConclusionIncreased levels of anti-PGA antibodies, particularly PGA-IgA, were significantly associated with JIA. PGA-IgA may serve as a sensitive biomarker for disease activity in JIA and could potentially aid in the diagnosis of JIA.Key Points• This study found a significant correlation between blood levels of PGA-IgA and juvenile idiopathic arthritis (JIA), which may provide valuable diagnostic insights.• PGA-IgA shows potential as a sensitive biomarker for the assessment of disease activity in JIA patients, helping to determine disease activity.

Pathogen-induced fruit decay is a significant threat to the kiwifruit industry, leading to considerable economic losses annually. The cell-wall-degrading enzymes (CWDEs) secreted by these pathogens are crucial for penetrating the cell wall and accessing nutrients. Among them, Diaporthe species are recognized as major causal agents of soft rot in kiwifruit, yet their pathogenic mechanisms are not well understood. In this study, we explored the production of various CWDEs secreted by Diaporthe Z1-1N, including polygalacturonase (PG), polymethylgalacturonase (PMG), polygalacturonic acid transeliminase (PGTE), pectin methyltranseliminase (PMTE), endoglucanase (Cx), and β-glucosidase (β-glu), both in liquid cultures and within infected kiwifruit tissues. Our findings revealed significant activities of two pectinases (PG and PMG) and cellulases (Cx and β-glu) in the infected tissues. In contrast, very low levels of PMTE and PGTE activities were observed under the same conditions. When orange pectin served as the carbon source, PG and PMG showed notable activities, while PMTE and PGTE remained inactive. Moreover, the activities of Cx and β-glu significantly decreased by more than 63 times in the liquid medium with carboxymethyl cellulose (CMC) as the carbon source compared to their levels in infected kiwifruit. A further analysis indicated that the necrotic lesions produced by pectinase extracts were larger than those produced by cellulase extracts. Notably, four enzymes—PG, PMG, Cx, and β-glu—exhibited high activities on the third or fourth day post-infection with Diaporthe Z1-1N. These results suggest that Diaporthe Z1-1N secretes a range of CWDEs that contribute to kiwifruit decay by enhancing the activities of PG, PMG, Cx, and β-glu. This study sheds light on the pathogenicity of Diaporthe in kiwifruit and highlights the importance of these enzymes in the decay process.

Curvularia lunata (Wakker) Boed, the causal agent of Curvularia leaf spot, is an important fungal pathogen in maize. Iron deficiency or excess plays a crucial role in mycelial growth and virulence of plant pathogenic fungi. In this study, the following pathogenic characteristics of C. lunata under different Fe3+ concentrations were investigated: mycelial growth, conidiation, conidium germination, virulence in maize, toxin and cell wall degrading enzymes (CWDEs) activity. The results showed that iron had a limited impact on the mycelial growth, while it had an obvious impact on mycelial biomass, conidiation, and the conidial germination at a concentration of 40–50 μM Fe3+. Exogenous supplementary of Fe3+ also significantly enhanced the pathogenicity of C. lunata CX-3 strain on maize inbred line Huangzaosi. However, toxin activity was independent of Fe3+ concentration. Exogenous iron application improved polygalacturonase (PG) activity in the early stages of infection, and the activity of cellulase (Cx), pectin polymethyl galacturonase (PMG), polygalacturonic acid transeliminase (PGTE) and pectin methyl transeliminase (PMTE) after 72 h of infection in maize.

The aim of this study was to investigate the roles of follicular helper CD4 T cells (Tfh) and serum anti-α-1,4-d-polygalacturonic acid (PGA) antibody in the pathogenesis of Henoch-Schönlein purpura (HSP). ELISA was performed to determine serum PGA-IgA and PGA-IgG. Flow cytometry was utilized to determine the peripheral CD4 CXCR5 and CD4 CXCR5 ICOS Tfh cells. Real-time PCR was conducted to determine the expression of Bcl-6 gene. Then the change of Tfh cells was analyzed, together with the association with the anti-PGA antibody as well as the roles in the pathogenesis of HSP. Compared with the cases with acute respiratory infection and elective surgery, the proportion of CD4 CXCR5 and CD4 CXCR5 ICOS Tfh cells in the HSP group showed significant elevation ( < 0.001). A significant correlation was noticed between PGA-IgA and CD4 CXCR5 Tfh cells ( = 0.380 and = 0.042) and CD4 CXCR5 ICOS Tfh cells ( = 0.906 and < 0.001). The expression of Bcl-6 in the HSP group showed no statistical difference compared with that in the acute respiratory infection and the surgery control ( < 0.05). Increased activity of Tfh cells, which is closely related to mucosal immunity, may be a major contributor in the elevation of PGA-IgA, and Tfh cells and PGA-IgA are closely related to the occurrence of HSP.

A study on mass transfer using new coating materials (namely alginic acid and polygalacturonic acid) during osmotic dehydration—and hence in a laboratory-scale convective dryer to evaluate drying performance—was carried out. Potato and apple samples were examined as model heat-sensitive products in this study. Results indicate that the coating material containing both alginic acid and polygalacturonic acid causes higher water loss of about 17% and 7.5% and lower solid gain of about 4% and 8%, respectively, compared to uncoated potato sample after a typical 90 min osmotic dehydration process. Investigation of drying performance using both coating materials showed a higher reduction in the moisture content of about 22% and 18%, respectively, compared with uncoated samples after the 3 h drying period. Comparisons between the two proposed coating materials were also carried out. Samples (potato) coated with alginic acid demonstrated better performance in terms of higher water loss (WL), lower solid gain (SG), and notable enhancement of drying performance of about 7.5%, 8%, and 8%, respectively, compared to polygalacturonic acid. Similar outcomes were observed using apple samples. Additionally, an accurate model of the drying process based on the experimental dataset was created using an artificial neural network (ANN). The obtained mean square errors (MSEs) for the predicted water loss and solid gain outputs of the potato model were 4.0948e−5 and 3.924e−6, respectively. However, these values for the same parameters were 3.164e−5 and 4.4915e−6 for the apple model. The coefficient of determination (r2) values for the two outputs of the potato model were found to be 0.99969 and 0.99895, respectively, while they were 0.99982 and 0.99913 for the apple model, which reinforces the modeling phase.

Pectin is synthesized in a highly methylesterified form in the Golgi cisternae and partially de‐methylesterified in muro by pectin methylesterases (PMEs). Arabidopsis thaliana produces a local and strong induction of PME activity during the infection of the necrotrophic fungus Botrytis cinerea. AtPME17 is a putative A. thaliana PME highly induced in response to B. cinerea. Here, a fine tuning of AtPME17 expression by different defence hormones was identified. Our genetic evidence demonstrates that AtPME17 strongly contributes to the pathogen‐induced PME activity and resistance against B. cinerea by triggering jasmonic acid–ethylene‐dependent PDF1.2 expression. AtPME17 belongs to group 2 isoforms of PMEs characterized by a PME domain preceded by an N‐terminal PRO region. However, the biochemical evidence for AtPME17 as a functional PME is still lacking and the role played by its PRO region is not known. Using the Pichia pastoris expression system, we demonstrate that AtPME17 is a functional PME with activity favoured by an increase in pH. AtPME17 performs a blockwise pattern of pectin de‐methylesterification that favours the formation of egg‐box structures between homogalacturonans. Recombinant AtPME17 expression in Escherichia coli reveals that the PRO region acts as an intramolecular inhibitor of AtPME17 activity. AtPME17 contributes to resistance against Botrytis cinerea by triggering jasmonic acid–ethylene‐dependent PDF1.2 expression. AtPME17 activity is inhibited by its PRO region and produces a blockwise pectin de‐methylesterification.

Pectin, as a sustainable biopolymer with its two complementary functionalities (carboxyl and hydroxyl moieties) imparted in the α-1,4-galacturonic acid repeating unit, has gained increasing attention in the last few years. The interest in this ubiquitously occurring plant originating polysaccharide (PS) has shifted slowly from applications as a food additive to a broader range of potential applications in medicine, cosmetics, and other industries. Due to the increasing interest in alternatives for petrochemical materials, PSs as biomaterials have gained increasing attention in industrial processes in general. In the last decade, an increasing number of chemical transformations related to pectin have been published, and this is a prerequisite for the design of the structure and hence properties of novel biopolymer-based materials. This work aims to review the chemical modifications of pectin by covalent linkage of the last decade and analyze the materials obtained with these chemical methods critically.

The extent of spoilage of fruits and vegetables increases post harvest, and fungal attack is one of the greatest causes. The effect of sodium silicate on Aspergillus flavus and its cell wall degrading enzymes, namely polygalacturonic acid transeliminase (PGTE), pectin methyltranseliminase (PMTE), and pectin lyase (PL), was investigated via molecular docking. On the 4th day, 100 mM of sodium silicate completely inhibited A. flavus, while it reflected 79.70, 61.16, 56.82, and 37.23% inhibition at 6, 8,10, and 12 days, respectively. The PGTE (369.33 ± 2.08 U/mL) showed maximum activity at the 8th day in the medium without sodium silicate. Also at 20 to 80 mM sodium silicate, their maximum activity was recorded at the 8th day, while it reached to maximum at the 10th day in the medium with 100 mM sodium silicate. The PMTE recorded the highest activity at the 6th day (414.00 ± 1.73 U/mL) without sodium silicate, at the 8th day when sodium silicate ranged from 20 to 80 mM, and at the 10th day (97.67 ± 1.25 U/mL) with 100 mM sodium silicate. The maximum PL activity was recorded on day 8. Sodium silicate demonstrates potent interaction with the active sites of the studied proteins, suggesting its potential as a molecular inhibitor of studied enzymes.

Key messageGhMYB4 acts as a negative regulator in lignin biosynthesis, which results in alteration of cell wall integrity and activation of cotton defense response.Verticillium wilt of cotton (Gossypium hirsutum) caused by the soil-borne fungus Verticillium dahliae (V. dahliae) represents one of the most important constraints of cotton production worldwide. Mining of the genes involved in disease resistance and illuminating the molecular mechanisms that underlie this resistance is of great importance in cotton breeding programs. Defense-induced lignification in plants is necessary for innate immunity, and there are reports of a correlation between increased lignification and disease resistance. In this study, we present an example in cotton whereby plants with reduced lignin content also exhibit enhanced disease resistance. We identified a negative regulator of lignin synthesis, in cotton encoded in GhMYB4. Overexpression of GhMYB4 in cotton and Arabidopsis enhanced resistance to V. dahliae with reduced lignin deposition. Moreover, GhMYB4 could bind the promoters of several genes involved in lignin synthesis, such as GhC4H-1, GhC4H-2, Gh4CL-4, and GhCAD-3, and impair their expression. The reduction of lignin content in GhMYB4-overexpressing cotton led to alterations of cell wall integrity (CWI) and released more oligogalacturonides (OGs) which may act as damage-associated molecular patterns (DAMPs) to stimulate plant defense responses. In support of this hypothesis, exogenous application with polygalacturonic acid (PGA) in cotton activated biosynthesis of jasmonic acid (JA) and JA-mediated defense against V. dahliae, similar to that described for cotton plants overexpressing GhMYB4. This study provides a new candidate gene for cotton disease-resistant breeding and an increased understanding of the relationship between lignin synthesis, OG release, and plant immunity.

Pectin is an important component of cell wall polysaccharides and is important for normal plant growth and development. As a major component of pectin in the primary cell wall, homogalacturonan (HG) is a long-chain macromolecular polysaccharide composed of repeated α-1,4-D-GalA sugar units. At the same time, HG is synthesized in the Golgi apparatus in the form of methyl esterification and acetylation. It is then secreted into the plasmodesmata, where it is usually demethylated by pectin methyl esterase (PME) and deacetylated by pectin acetylase (PAE). The synthesis and modification of HG are involved in polysaccharide metabolism in the cell wall, which affects the structure and function of the cell wall and plays an important role in plant growth and development. This paper mainly summarizes the recent research on the biosynthesis, modification and the roles of HG in plant cell wall.