Cell Wall Pectin Research Articles

Border-like cell formation mediated by SgPG1 confers aluminum resistance in Stylosanthes guianensis.

Stylosanthes is an important forage legume in tropical areas with strong resistance to aluminum (Al) toxicity, though knowledge of mechanisms underlying this resistance remains fragmentary. We found that border-like cells (BLCs) were constitutively produced surrounding the root tips of all 54 examined Stylosanthes guianensis genotypes, but not the Stylosanthes viscose genotype TF0140. In genotypic comparisons under Al conditions, the S. guianensis genotype RY#2 retained significantly more Al in BLCs and thereby showed higher relative root growth than TF0140. Formation of BLCs accompanied changes in cell wall pectin epitopes and differential expression of genes involved in pectin metabolism, including a polygalacturonase (SgPG1). The expression pattern of SgPG1 was consistent with the formation of BLCs in both RY#2 and TF0140. SgPG1 was localized in cell walls and exhibited high activities mediating demethyl-esterified homogalacturonan degradation. Overexpressing SgPG1 changed cell wall pectin epitopes, enhanced BLCs production, and Al resistance in both Arabidopsis and Stylosanthes hairy roots. Furthermore, combining protein-DNA binding assays in vitro and in vivo, a bHLH transcription factor SgbHLH19 was demonstrated to be the upstream regulator of SgPG1. Our study demonstrates that S. guianensis Al resistance mainly relies on BLCs, whose formation involves cell wall pectin epitope modification by SgPG1.

T2T genomes of carrot and Alternaria dauci and their utility for understanding host-pathogen interactions during carrot leaf blight disease.

Carrot (Daucus carota) is one of the most popular and nutritious vegetable crops worldwide. However, significant yield losses occur every year due to leaf blight, a disease caused by a fungal pathogen (Alternaria dauci). Past research on resistance to leaf blight disease in carrots has been slow because of the low-quality genome assemblies of both carrot and the pathogen. Here, we report the greatly improved assemblies and annotations of telomere-to-telomere (T2T) reference genomes of carrot DH13M14 (451.04 Mb) and A. dauci A2016 (34.91 Mb). Compared with the previous carrot genome versions, our assembly featured notable improvements in genome size, continuity, and completeness of centromeres and telomeres. In addition, we generated a time course transcriptomic atlas during the infection of carrots by A. dauci and captured their dynamic gene expression reprogramming during the interaction process. During infection, A. dauci genes encoding effectors and enzymes responsible for the degradation of plant cell wall components, e.g., cellulose and pectin, were identified, which appeared to increase pathogenic ability through upregulation. In carrot, the coordinated gene expression of components of pattern- and effector-triggered immunity (PTI and ETI) in response to A. dauci attack was characterized. The biosynthesis or signal transduction of plant hormones, including JA, SA, and ethylene, was also involved in the carrot response to A. dauci. This work provides a foundation for understanding A. dauci pathogenic progression and carrot defense mechanisms to improve carrot resistance to leaf blight disease. The Carrot Database (CDB) developed also provides a useful resource for the carrot community.

Control of sporophyte secondary cell wall development in Marchantia by a Class II KNOX gene.

Land plants evolved from an ancestral alga around 470 mya, evolving complex multicellularity in both haploid gametophyte and diploid sporophyte generations. The evolution of water-conducting tissues in the sporophyte generation was crucial for the success of land plants, paving the way for the colonization of a variety of terrestrial habitats. Class II KNOX (KNOX2) genes are major regulators of secondary cell wall formation and seed mucilage (pectin) deposition in flowering plants. Here, we show that, in the liverwort Marchantia polymorpha, loss-of-function alleles of the KNOX2 ortholog, MpKNOX2, or its dimerization partner, MpBELL1, have defects in capsule wall secondary cell wall and spore pectin biosynthesis. Both genes are expressed in the gametophytic calyptra surrounding the sporophyte and exert maternal effects, suggesting intergenerational regulation from the maternal gametophyte to the sporophytic embryo. These findings also suggest the presence of a secondary wall genetic program in the non-vascular liverwort capsule wall, with attributes of secondary walls in vascular tissues.

Unraveling cell wall polysaccharides during blueberry ripening: insights into the roles of rhamnogalacturonan-I and arabinogalactan proteins in fruit firmness.

Blueberries (Vaccinium corymbosum) undergo significant texture changes during development and ripening, notably a consistent decrease in firmness, which affects fruit quality, consumer preference, transportability, and shelf life. This study examined the composition and structural modifications of the cell wall in five commercially available blueberry varieties with differing firmness levels at harvest. Our approach integrated various biochemical techniques for a comprehensive analysis of cell wall components to elucidate firmness differences at the harvest stage. One of the conclusions was the relationship between a low degree of pectin methylesterification and the presence of increased egg-box structures, which correlated with increased firmness. The data suggest that low-abundance pectins in blueberry cell walls, such as rhamnogalacturonan-I participate in firmness modulation through their side branches or by linking to arabinogalactan proteins. Additionally, the xyloglucan structure can be one of the determinants of fruit firmness. Although, this work provides a broad insight into the relationship between cell wall composition and firmness in blueberry, a more detailed analysis, specifically focusing on pectin and hemicelluloses, would be of significant value.

Pengaruh Bulai pada Perubahan Indeks Kadar Klorofil, Serapan Fosforus dan Boron pada Jagung Manis

Maize production and quality are affected by infection with plant pathogens. One of the maize's essential and main diseases is downy mildew caused by Peronosclerospora spp. Downy mildew is a limiting factor in increasing production and can reduce production by 80-100%. It is because the affected plant cannot produce cobs. Pathogens obtain nutrients from the host cell, which can kill the cell and damage the surrounding tissues, resulting in visible downy mildew symptoms. Boron (B) plays a role in forming phloem, increasing the fruit's number, weight, bunch weight, and diameter. The primary function of B at the molecular level is the cross-linking of pectin in the plant cell wall. Ramnogalacturonan II (RG II) is a pectic polysaccharide that contributes to the mechanical strength and properties of the primary wall cross-linked by borate diesters. Phosphorus (P) controls the downsides in the greenhouse and field conditions. This study aims to measure changes in chlorophyll index, P and B uptakes in downy mildew affected plants. The field experiment used a group randomized design with six natural phosphate (FA) application treatments and four groups of borax doses as replicates. The results showed that the downy mildew decreased the chlorophyll index of the leaves at different levels of attack. The results of P concentration according to the position of healthy plant leaves were significantly different due to P treatment. In contrast to concentration B, there is no real difference. P and B uptake results in downy mildew-infested plants showed a significant difference only in P uptake in leaves with 1 FA treatment. Keywords: boron, downy mildew, maize, phosphate

Extraction of cell wall pectins and hemicellulose from agro-industrial wastes: A sustainable alternative source

The efficient repurposing of agro-industrial waste has significantly enhanced the utilization of food resources. This study aims to propose a methodology for extracting cell wall polysaccharides from residues of mango (Mangifera indica), passion fruit (Passiflora edulis), and cashew (Anacardium occidentale). Polysaccharide fractions were obtained through sequential extraction protocols involving water, cyclohexane-trans-1,2-diamine tetracetate (CDTA), sodium carbonate:CDTA, and potassium hydroxide. These fractions were categorized as water-soluble pectin (WSP), CDTA-soluble pectin (CSP), sodium carbonate-soluble pectin (SSP), and hemicellulose (HC), respectively. Each polysaccharide fraction was characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and Gel Permeation Chromatography (GPC). Monosaccharide composition was determined using Gas Chromatography-Mass Spectrometry (GC–MS). NMR spectra of WSP, CSP, and SSP fractions exhibited characteristic pectin features, while the HC fraction primarily comprised hemicellulose. Consequently, the proposed methodology demonstrates potential as a standardized protocol for the extraction of pectin and hemicellulose from various food sources.

MsMIOX2, encoding a MsbZIP53-activated myo-inositol oxygenase, enhances saline-alkali stress tolerance by regulating cell wall pectin and hemicellulose biosynthesis in alfalfa.

Alfalfa is one of the most widely cultivated forage crops worldwide. However, soil salinization restricts alfalfa growth and development and affects global productivity. The plant cell wall is the first barrier against various stresses. Therefore, elucidating the alterations in cell wall architecture is crucial for stress adaptation. This study aimed to clarify the impact of myo-inositol oxygenase 2 (MsMIOX2) on cell wall pectin and hemicellulose biosynthesis under saline-alkali stress and identify the upstream transcription factors that govern MsMIOX2. MsMIOX2 activation induced cell wall pectin and hemicellulose accumulation under saline-alkali stress. The effects of MsMIOX2 in saline-alkali tolerance were investigated by characterizing its overexpression and RNA interference lines. MsMIOX2 overexpression positively regulated the antioxidant system and photosynthesis in alfalfa under saline-alkali stress. MsMIOX2 exhibited myo-inositol oxygenase activity, which increased polysaccharide contents, facilitated pectin and hemicellulose biosynthesis, and extended the cell wall thickness. However, MsMIOX2 RNA interference decreased cell wall thickness and alleviated alfalfa saline-alkali stress tolerance. In addition, MsbZIP53 was identified as an upstream transcriptional MsMIOX2 regulator by yeast one-hybrid, electrophoretic mobility shift assay, dual-luciferase, and beta-glucuronidase assays. MsbZIP53 overexpression increased MsMIOX2 expression, elevated MIOX activity, reinforced the antioxidant system and photosynthesis, and increased saline-alkali stress tolerance in alfalfa. In conclusion, this study presents a novel perspective for elucidating the molecular mechanisms of saline-alkali stress tolerance in alfalfa and emphasizes the potential use of MsMIOX2 in alfalfa breeding.

Aberrant growth and expansion in Penium margaritaceum triggered by disruption of microtubules and the cell wall.

Penium margaritaceum, a unicellular zygnematophyte (Streptophyta), was employed to elucidate changes in cell expansion when cells were challenged with the fungal pectinolytic enzyme, pectate lyase, and/or the microtubule disrupting agent, amiprophos-methyl (APM). Microtubule disruption by APM results in significant swelling at expansion zones. These swollen zones provide an easy marker for the location of expansion zones, particularly in cells with altered cell wall pectin. Short term treatment with pectate lyase shows pectin degradation primarily at the isthmus expansion zone and two satellite bands, corresponding with the location of future expansion in daughter cells. When the homogalacturonan lattice of the cell wall is removed by treatment with pectate lyase during long treatments, cell division is maintained, but daughter cell products are considerably smaller. Treatment of cells with a mixture of both pectate lyase and APM results in a distinct phenotype, consisting of "dumbbell"-shaped cells, as APM-induced swelling occurs at the novel expansion centers exposed by pectate lyase treatment. These cells also possess other curious alterations including an extensive, chloroplast-free cytoplasmic zone at the center of the cell, a septum containing ß-glycan, arabinogalactan and homogalacturonan epitopes, unique stacks of ER, displaced Golgi bodies and an extensive network of vacuoles. These results provide insight into the importance of cell wall integrity in defining the location of cell growth and division in P. margaritaceum. Understanding these processes in a unicellular zygnematophyte may provide insights into steps involved in the evolution of land plants.

Foliar spraying of boron prolongs preservation period of strawberry fruits by altering boron form and boron distribution in cell.

Boron (B), an essential micronutrient for fruit development, also plays a crucial role in maintaining the shelf life of strawberries (Fragaria ananassa Duch.) by affecting cell wall structure and components. We investigated the distribution pattern of B within cells and cell walls in strawberry fruits under different B levels and revealed the relationship between the B distribution in cell walls and fruit firmness after harvesting. Foliar spraying of 0.1% H3BO3 promoted the growth of strawberry seedlings and improved fruit yield and flesh firmness by 45.7% and 25.6%. During the fruit softening and decay process, the content of bound B and cell wall-B decreased while more B was allocated to the protoplast and apoplast. The changes in B distribution in cells were attributed to cell damage during fruit decay, and B extended the freshness period of the fruits by alleviating the decrease of B distribution in cell walls. After leaving the fruits at room temperature for 10 h, the B content in different cell wall components significantly decreased, while foliar spraying of B alleviated the reduction of B content in covalently bound pectin (CBP), cellulose, and hemicellulose. Meanwhile, B spraying on fruit decreased the activity of cell wall degradation enzymes, including polygalacturonase (PG) and pectin lyase (PL), by 20.2% and 38.1%, while enhancing the demethylation of pectin by increasing pectin methylesterase (PME) activity from 21.6 U/g to 25.7 U/g. Thus, foliar spraying of 0.1% H3BO3 enhances the cross-linking of B with cell wall components and maintains cell wall structure, thereby prolonging the shelf life of strawberry fruits.

Plant Cell Wall Polysaccharide O-Acetyltransferases.

Plant cell walls are largely composed of polysaccharide polymers, including cellulose, hemicelluloses (xyloglucan, xylan, mannan, and mixed-linkage β-1,3/1,4-glucan), and pectins. Among these cell wall polysaccharides, xyloglucan, xylan, mannan, and pectins are often O-acetylated, and polysaccharide O-acetylation plays important roles in cell wall assembly and disease resistance. Genetic and biochemical analyses have implicated the involvement of three groups of proteins in plant cell wall polysaccharide O-acetylation: trichome birefringence-like (TBL)/domain of unknown function 231 (DUF231), reduced wall acetylation (RWA), and altered xyloglucan 9 (AXY9). Although the exact roles of RWAs and AXY9 are yet to be identified, members of the TBL/DUF231 family have been found to be O-acetyltransferases responsible for the O-acetylation of xyloglucan, xylan, mannan, and pectins. Here, we provide a comprehensive overview of the occurrence of O-acetylated cell wall polysaccharides, the biochemical properties, structural features, and evolution of cell wall polysaccharide O-acetyltransferases, and the potential biotechnological applications of manipulations of cell wall polysaccharide acetylation. Further in-depth studies of the biochemical mechanisms of cell wall polysaccharide O-acetylation will not only enrich our understanding of cell wall biology, but also have important implications in engineering plants with increased disease resistance and reduced recalcitrance for biofuel production.

Optical properties related to cell wall pectin contribute to determine the firmness and microstructural changes during apple softening

The modification of cell wall pectin is a major contributing factor to apple softening, associated with intensive variations of firmness and microstructure. Thus, a better understanding of the relationship between fruit optical properties, firmness, 3D microstructure and pectin is important for improving the optical detection of apple firmness. This work explored the optical properties in the wavelength range of 430 – 1650 nm related to cell wall pectin during apple softening, in order to better determine their firmness and 3D microstructural changes. An automatic single integrating sphere system was used to quantify absorption coefficient (μa) and reduced scattering coefficient (μs′). Micro-CT imaging, SEM and TEM were used to quantify the porosity, cell numbers, cell volume, volume fraction and microstructure of Fuji apples during storage. Firmness, pectin fractions, soluble solids content (SSC), titratable acid content (TAC), and moisture content were also measured. Results showed that depolymerization of pectin substances induces an increase in porosity (r = 0.97) and modification of cellular structure, leading to a decrease in firmness (r = 0.90). The reduction in firmness and cell numbers exhibited a strong positive correlation with both μa in the range of 1000 – 1650 nm and μs′ between 430 and 1000 nm with mean r of 0.88–0.96, whereas increases in covalent-soluble pectin (CSP) and porosity displayed a negatively correlated with these bands. The linear relationship indicates that Vis-NIRS at 980 nm could better predict apple firmness than μa or μs′ alone, with a coefficient of determination R2 of 0.97. Our findings suggest that the mechanism of optical technology for detecting apple firmness may be the interaction between tissue structure and pectin on μs′ and μa.

Three-dimensional mass transfer modeling and phenolic chemistry exploration for ultrasound-assisted and microwave drying of goji berry

Herein, goji berries were pretreated with sodium carbonate (Na2CO3) and then dried via ultrasound-assisted air drying or microwave drying. Water migration and phenolic chemistry of goji berries were studied under drying. A three-dimensional ellipsoid water transport model, accounting for porosity and temperature fluctuations, was established to explore the intricacies of the drying mechanism. Generally, microwave drying promoted interior water transport compared to ultrasound drying. Among all the drying methods, microwave drying at 240 W (MW-240 W) exhibited the highest De (from 7.34 × 10−9 to 9.61 × 10−9 m2/s) and kc (6.78 × 10−4 m/s) values. The goji berries received a considerably high water content gradient between its surface and center within the first 2 s of all the drying treatments. Microwave drying diminished the water content gradient earlier than air drying and ultrasound-assisted air drying treatments. Furthermore, most correlations observed among phenolics, oxidase activity, and cell wall pectin did not align with the established theories, highlighting the highly nonlinear nature of phenolic chemistry during goji berry drying. This study provides a three-dimensional model to study the mass transfer mechanism of goji berries and analyzes the evolution of polyphenols during the drying process.

Enzymatic pre-treatment defines the water-binding and rheological properties of dynamic ultra-high-pressure homogenised pea hull suspensions

Pulse hulls are composed of cell wall polysaccharides and are a concentrated source of dietary fibre. However, the dense microstructure hinders their industrial application, resulting in poor techno-functional properties. To improve their functionality, the cell wall (cellulose, hemicellulose, and pectin) is disrupted by combining enzymatic pre-treatments and microfluidization. This work aims to study the impact of a fixed reduction of the insoluble mass by selective enzymatic pre-treatment of pulse hulls on the composition, microstructure, water binding, and rheological properties of microfluidized suspensions. To that end, enzymatic pre-treatments using cellulase, hemicellulase, pectinase, and their binary and ternary mixtures were conducted to reduce insoluble mass content. The combined treatment improved the water-binding properties, leading to the formation of viscoelastic gels. Microfluidized suspensions enzymatically pre-treated with a binary mixture of cellulase and hemicellulase presented the highest water binding capacity, viscosity, and viscoelasticity. The partial enzymatic degradation of the cellulose-hemicellulose network weakened the interactions between both polysaccharides. It facilitates the disruption of the particles and the release of high molecular weight soluble dietary fibre (HMWSDF), which are gelling substances. On the contrary, an enzymatic pre-treatment using only cellulase increased the content of low molecular weight soluble compounds, resulting in low viscous and viscoelastic suspensions. Thus, the concentration of remaining microfibrillated cellulose and HMWSDF are key parameters controlling the rheological behaviour of the suspensions. This study enhances comprehension regarding pea hulls' molecular and macromolecular modifications, potentially enabling the production of tailor-made pulse hull suspensions.

Natural variation of TBR confers plant zinc toxicity tolerance through root cell wall pectin methylesterification

Zinc (Zn) is an essential micronutrient but can be cytotoxic when present in excess. Plants have evolved mechanisms to tolerate Zn toxicity. To identify genetic loci responsible for natural variation of plant tolerance to Zn toxicity, we conduct genome-wide association studies for root growth responses to high Zn and identify 21 significant associated loci. Among these loci, we identify Trichome Birefringence (TBR) allelic variation determining root growth variation in high Zn conditions. Natural alleles of TBR determine TBR transcript and protein levels which affect pectin methylesterification in root cell walls. Together with previously published data showing that pectin methylesterification increase goes along with decreased Zn binding to cell walls in TBR mutants, our findings lead to a model in which TBR allelic variation enables Zn tolerance through modulating root cell wall pectin methylesterification. The role of TBR in Zn tolerance is conserved across dicot and monocot plant species.

Bamboo vinegar regulates the phytoremediation efficiency of Perilla frutescens (L.) Britt. by reducing membrane lipid damage and increasing cadmium retention

The gap between serious soil heavy metals pollution and inefficient soil remediation threatens human health. This study proposed a method to improve the phytoremediation efficiency using bamboo vinegar (BV) solution and the potential mechanism was discussed. The results demonstrated that the application of BV increases the content of cadmium (Cd) in vacuole and cell wall hemicellulose 2 in leaves of Perilla frutescens. Simultaneously, it enhanced enzyme activities of superoxide dismutase and catalase in leaves. Therefore, this process alleviated the damage of Cd to functional tissues of Perilla frutescens, thus improving the tolerance of plants to Cd. Moreover, the BV application reduced the Cd content bound by root cell wall pectin fractions and insoluble phosphate, subsequently improving the ability of oxalic acids to carry Cd to the aerial parts. Consequently, the aerial parts obtained a larger amount of Cd enrichment. Overall, the Transfer Factor of Cd from roots to stems and enrichment of Cd in Perilla frutescens were maximally increased by 57.70 % and 54.03 % with the application of 50-fold and 300-fold diluted BV under 2 mg·L−1 Cd stress, respectively. The results can provide a theoretical basis for the promotion of phytoremediation of Cd-contaminated soil treatment technology.

Effects of different pretreatment on the drying characteristics and pectin properties of jujube by microwave coupled with pulsed vacuum drying

AbstractThe effects of ultrasound (US), ultrahigh pressure (UP), cold plasma (CP), and high pressure and pulsed electric fields (PEF) pretreatments were evaluated for drying characteristics, bioactive components, and pectin properties of jujube slices during microwave coupled with pulsed vacuum drying (MPVD). US, CP, and PEF reduced drying time by 18.75%, while UP reduced it by 6.25%. Samples treated with US and PEF showed improved color and rehydration (345.11%, 319.24%), with SEM revealing larger pores post‐pretreatment. PEF‐treated jujube had highest phenol (16.95 mg GAE/g DW) and water‐soluble pectin(WSP) (43.71 mg/g AIR), correlating positively with rehydration (r = 0.67). CP had highest flavonoid content (17.01 mg RE/g DW) and US showed highest antioxidant activity (DPPH 80.57%, ABTS 89.65%). Chelate‐soluble pectin (CSP) Sodium carbonate‐soluble pectin (NSP) was positively correlated with hardness (r = 0.71, 0.69). These findings suggest pretreatments improve drying efficiency, nutrient retention, and pectin functionality in jujube products. Practical ApplicationsDrying for jujube (Ziziphus jujuba Mill.) is the most common method of processing and ensure the sale. Three kinds of non‐thermal processing pretreatment method (ultrasound, ultrahigh pressure, and cold plasma) combined with novel drying method, microwave coupled pulsed vacuum drying (MPVD) was studied in the application on the dehydration of jujube slice in this paper. The drying characteristics and pectin properties of winter jujube were analyzed and treated by MPVD compared with freeze drying and hot air drying, for both technological research and processing practice. The drying kinetics, bioactive compounds, antioxidant capacity, sensory attributes, and pectin properties were also used as descriptors in order to promising dehydration method for obtaining high value‐added jujube products. Moreover, the relationship between the cell wall pectin and the phenols, hardness and crispness were analyzed, which give a new insight to study the changing scheme in the nutrients and the texture during the dehydration for fruits and vegetables.

Transformation of cell wall pectin profile during postharvest ripening process alters drying behavior and regulates the sugar content of dried plums

This study evaluated the effects of postharvest ripening (0–6 days, D0–6) on cell wall pectin profile, infrared-assisted hot air-drying characteristics, and sugar content. Results showed that during postharvest ripening progress, the content of water-soluble pectin (WSP) and chelate-soluble pectin (CSP) increased while the content of Na2CO3-soluble pectin (NSP) and hemicellulose (HC) decreased. In addition, the average molecular weight of WSP increased while the average molecular weight of NSP decreased. Secondly, the drying time of plums with different postharvest ripening periods was in the order: D3 < D4 < D2 < D1 < D0 < D5 < D6. Furthermore, the sugar content of dried plums was mainly influenced by drying time, with three stages of sugar changes observed, tied to moisture content: (1) Sucrose hydrolyzes (50–85%); (2) Fructose and glucose degrade (15–50%); (3) Sorbitol degrades (15–42%). These findings indicate that the transformation of cell wall pectin profile during the postharvest ripening process alters drying behavior and regulates the sugar content of dried plums. Chemical compounds studied in this articleGalacturonic acid (PubChem CID: 439215); Acetone (PubChem CID: 180); Distilled water (PubChem CID: 962); Trans-1,2-Diaminocyclohexane-N, N, N, N′-tetraacetic acid (PubChem CID: 2723845); Na2CO3 (PubChem CID: 10340); Glucose (PubChem CID: 5793); fructose (PubChem CID: 2723872) sucrose (PubChem CID: 5988) sorbitol (PubChem CID: 5780) and Sodium borohydride (PubChem CID: 4311764).

Effects of black bean cell wall pectin by exogenous calcium ions: Insight into the metabolomics, physicochemical properties and anti-digestive capacity

In this work, the metabolomics, physicochemical and in vitro digestion properties of black beans influenced by different calcium ion solutions (0, 0.5 %, 1 %, and 2 %) were explored. The addition of calcium ions had a significant effect on the metabolic processing of black beans, including 16 differential metabolites and 4 metabolic pathways related to the cell wall. From the results of FT-IR and ICP-OES, it was confirmed that calcium ions can interact with COO− in non-methylated galacturonic acid in pectin to form calcium carboxylate strengthening the middle lamellae of the cell wall. Based on this mechanism, the soaked beans with an intact and dense cell structure were verified by the analyses of SEM and CLSM. Compared with other soaked beans, BB-2 exhibited lower cell permeability with electrical conductivity value decreased to 0.60 μs·cm−1. Additionally, BB-2 demonstrated slower digestion properties with digestion rate coefficient at 0.0020 min−1 and digestion extent only at 30.83 %, which is attributed to its increasingly compact cell wall and densely cellular matrix. This study illustrates the effect of calcium ions on the cellular structure of black beans, providing an effective process method for low glycemic index diets.

Rhamnogalacturonan lyase 1 (RGL1), as a suppressor of E3 ubiquitin ligase Arabidopsis thaliana ring zinc finger 1 (AtRZF1), is involved in dehydration response to mediate proline synthesis and pectin rhamnogalacturonan-I composition.

Proline metabolism plays a crucial role in both environmental stress responses and plant growth. However, the specific mechanism by which proline contributes to abiotic stress processes remains to be elucidated. In this study, we utilized atrzf1 (Arabidopsis thaliana ring zinc finger 1) as a parental line for T-DNA tagging mutagenesis and identified a suppressor mutant of atrzf1, designated proline content alterative 31 (pca31). The pca31 mutant suppressed the insensitivity of atrzf1 to dehydration stress during early seedling growth. Using Thermal Asymmetric Interlaced-PCR, we found that the T-DNA of pca31 was inserted into the promoter region of the At2g22620 gene, which encodes the cell wall enzyme rhamnogalacturonan lyase 1 (RGL1). Enzymatic assays indicated that RGL1 exhibited rhamnogalacturonan lyase activity, influencing cell wall pectin composition. The decrease in RGL1 gene expression suppressed the transcriptomic perturbation of the atrzf1 mutant. Silencing of the RGL1 gene in atrzf1 resulted in a sensitive phenotype similar to pca31 under osmotic stress conditions. Treatment with mannitol, salt, hydrogen peroxide, and abscisic acid induced RGL1 expression. Furthermore, we uncovered that RGL1 plays a role in modulating root growth and vascular tissue development. Molecular, physiological, and genetic experiments revealed that the positive modulation of RGL1 during abiotic stress was linked to the AtRZF1 pathway. Taken together, these findings establish that pca31 acts as a suppressor of atrzf1 in abiotic stress responses through proline and cell wall metabolisms.

Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp.

Seed germination is a complex process that can be negatively affected by numerous stresses. Trichoderma spp. are known as effective biocontrol agents as well as plant growth and germination stimulators. However, understanding of the early interactions between seeds and Trichoderma spp. remains limited. In the present paper, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to reveal the nature of tomato seed germination as stimulated by Trichoderma. A rapid response of tomato seeds to Trichoderma spp. was observed within 48 h on Murashige and Skoog medium (MS) substrate, preceding any physical contact. Raman analysis indicated that both Trichoderma species stimulated phenolic compound synthesis by triggering plant-specific responses in seed radicles. The impact of T. harzianum and T. brevicompactum on two tomato cultivars resulted in alterations to the middle lamella pectin, cellulose, and xyloglucan in the primary cell wall. The Raman spectra indicated increased xylan content in NA with T9 treatment as well as increased hemicelluloses in GZ with T4 treatment. Moreover, T4 treatment resulted in elevated conjugated aldehydes in lignin in GZ, whereas the trend was reversed in NA. Additionally, FTIR analysis revealed significant changes in total protein levels in Trichoderma spp.-treated tomato seed radicles, with simultaneous decreases in pectin and/or xyloglucan. Our results indicate that two complementary spectroscopic methods, FTIR and Raman spectroscopy, can give valuable information on rapid changes in the plant cell wall structure of tomato radicles during germination stimulated by Trichoderma spp.