Pectin Polysaccharides Research Articles

Features of ultrafiltration process engineering calculation in concentration and purification of pectin polysaccharides

In this paper, we propose a mathematical model of the process of changing the productivity of a membrane, both through the formation of a continuous gel layer, and by blocking individual pores. Also, the results of modeling the process of dia- ultrafiltration (DUF) purification of pectin solutions and their concentration by ultrafiltration (UF) using hollow fiber membranes are presented. The effect of periodic washing of the membrane and the process of gelation along the membrane on the productivity of the plant was studied. Thus, the process is characterized by two parameters, and A is the main parameter of the problem, which is the same for all stages, and the second parameter, the ratio (k =F0/F'), characterizes the degree of pore purification with a general cleaning of the membrane surface and is thus one from the characteristics of a single cycle. The valuesof a number of parameters are determined experimentally. It is shown that when the system of differential equations, represented in the normal Cauchy form describing the given technological process, is jointly solved, the productivity of the DUF system can be increased by the frequency of flushing. The conducted experiments demonstrated the advantage of the use of the DUF process in the production of pectin and the features of purification and concentration of apple and sunflower pectins in this process. It is established that the use of DUF causes the introduction of an energy-saving technological process in the production of pectin to produce the target product that meets the required quality and environmental safety of production. The introduction of the proposed methods of DUF and UF into the production of pectin leads to an improvement in the quality and cost of the product.

Structural elucidation of a pectic polysaccharide from Fructus Mori and its bioactivity on intestinal bacteria strains

Many studies suggested that polysaccharides could impact on the gut microbiota. To discover new polysaccharides which influence intestinal beneficial bacteria, a pectin polysaccharide FMP-6-S2 with an average molecular weight of 86.83 kDa was purified from Fructus Mori. The monosaccharide residue analysis indicated that FMP-6-S2 was composed of rhamnose, galacturonic acid, galactose and arabinose in a molar ratio of 30.86: 24.78: 28.70: 15.61. The backbone of FMP-6-S2 contained 1, 4-linked α-GalpA and 1, 2-linked α-Rhap with branches substituted at C-4 position of rhamnose. The branches were composed of 1, 4-linked β-Galp, terminal (T) − and 1, 3, 6-linked β-Galp, T- and 1, 5-linked α-Araf. Bioactivity test results suggested that FMP-6-S2 and its degraded product could promote growth of intestinal bacteria, B. thetaiotaomicron, which is a dominate strain in the gut of human to benefit intestinal mucosa. These results suggested that FMP-6-S2 and its degraded product might improve human wellness by modulating B. thetaiotaomicron.

Fabrication and Evaluations of Dual Crosslinked Mesalamine containing Pectin-Chitosan gel micro beads for controlled and targeted colon delivery

Objectives: The aim of the present work was to prepare and characterize mesalamine loaded microbeads (MLM) consisting of optimized ratios of chitosan and pectin polysaccharides using ionic gelation technique for management of inflammatory bowel disease. Methodology: Mesalamine loaded microbeads were prepared using ionotropic gelation method that was double cross linked with calcium chloride (3-6%, w/v) and sodium sulphate (2-4%, w/v) solutions. The formulation was optimized with the help of two levels and three factors factorial design method. The optimization parameters selected for formulation variables were viz., pectin-chitosan ratio, calcium chloride-sodium sulphate ratio and curing time. The prepared formulations were further characterized on the basis of particle size, shape, swelling index, entrapment efficiency, and percentage yield and in vitro drug release studies. The in vitro release studies using rat caecal content (2 and 4 % w/v) was also performed to simulate the human colonic condition. Results: The mean particle size, entrapment efficiency and percentage yield of MLM were ranged from 875.45 to 975.45 µm, 72.2 to 86.7% and 93.6 to 97.9% respectively. The swelling index of MLM formulations revealed lesser into acidic medium, while augmented swellings were found to be at pH 6.8 and 7.2 respectively. The swelling degree was found to be 7.34 to 13.88% into SIF at pH 6.8 whereas, intensely swelled was 16.24 to 46.02% into SCF at pH 7.2 during 8 h studies. In vitro drug release profile of MLM exhibited that only 1.28 to 4.42 drug was released at simulated gastric fluid (SGF, pH 1.2, 2 h), however optimum drug released was found into simulated intestinal fluid (SIF, pH 6.8, 3 h) i.e. 5.33 to 31.33% and into simulated colonic fluid (SCF, pH 7.2, 18 h) i.e. 32.13 to 87.12% correspondingly. Scanning electron microscopy (SEM) revealed that the microbeads were consisting of semispherical and wrinkled rough surfaces. Further, the rat caecal contents (2 and 4% w/v) release studies confirmed for complete polymeric degradation by colonic enzymes. The release kinetics and mathematical modeling studies carried out for optimized formulation shown that the optimized formulations were of non fickian mechanism (n=0.49 to 0.74) type governed by both diffusion and erosion controlled following Higuchi and Korsemeyer peppas model fittings. Conclusion: It can be concluded from the study that the optimized MLM formulations may be effective for colon targeting and treating inflammatory bowel disease.

Supramolecular Conformational Effect in Complexations of Pectin and Chitosan Polysaccharides with Some Cephalosporin and Aminoglycoside Antibiotics

The reactions of the polysaccharides pectin (Pc) and chitosan (CTS) with antibiotics of cephalosporin and aminoglycoside series were studied. The complexation between the drugs and polymers was found to occur via hydrogen bonding. Dilution of the chitosan polycation increased the probability of occurrence of the negative ions of the cephalosporin antibiotic near the chain and lowered the probability of occurrence of the positive ions of aminoglycoside antibiotics, which affected the amount of adducts. When the pectin polyanion was diluted, the opposite situation was observed.

Viscoelastic properties of pectin/cellulose composites studied by QCM-D and oscillatory shear rheology

The interactions between cellulose and pectin polysaccharides in primary plant cell walls are not fully understood, although several recent studies indicate that they might play an important role in wall properties. Studying polysaccharide interactions in planta is challenging, due to the complexity and heterogeneity of plant materials. Therefore, to investigate these interactions and the implications for the rheological properties of cell walls, we have taken a bottom-up approach in which cellulose/pectin composites are created either by adsorption of pectin polysaccharides (arabinan, galactan, homogalacturonan DE 69, homogalacturonan DE 33 and pectin DE 33) on cellulose-coated sensors in a quartz crystal microbalance with dissipation monitoring (QCM-D) or by incorporation of pectin during in vivo cellulose synthesis by Komagataeibacter bacteria. The viscoelastic behavior of the adsorbed layers was analyzed by applying the Voigt model to the QCM-D data, whilst the bulk viscoelastic properties of bacterial cellulose/pectin composites were studied by small amplitude oscillatory shear rheology. Our results show that all of the pectin polysaccharides studied have the ability to adsorb on the cellulose surfaces. The viscoelastic properties of the adsorbed layer varied depending on the substitution and degree of esterification of the pectin polysaccharides. Additionally, oscillatory rheology results showed that all bacterial cellulose-pectin composites had a gel nature (G′ > G″) with moduli varying in line with QCM-D determined viscoelasticity. Our interpretation of the results provides a better understanding of pectin-cellulose interactions and has implications for primary plant cell wall material properties.

Electrospun Pectin-Polyhydroxybutyrate Nanofibers for Retinal Tissue Engineering.

Natural polysaccharide pectin has for the first time been grafted with polyhydroxybutyrate (PHB) via ring-opening polymerization of β-butyrolactone. This copolymer, pectin-polyhydroxybutyrate (pec-PHB), was blended with PHB in various proportions and electrospun to produce nanofibers that exhibited uniform and bead-free nanostructures, suggesting the miscibility of PHB and pec-PHB. These nanofiber blends exhibited reduced fiber diameters from 499 to 336–426 nm and water contact angles from 123.8 to 88.2° on incorporation of pec-PHB. They also displayed 39–335% enhancement of elongation at break relative to pristine PHB nanofibers. pec-PHB nanofibers were found to be noncytotoxic and biocompatible. Human retinal pigmented epithelium (ARPE-19) cells were seeded onto pristine PHB and pec-PHB nanofibers as scaffold and showed good proliferation. Higher proportions of pec-PHB (pec-PHB10 and pec-PHB20) yielded higher densities of cells with similar characteristics to normal RPE cells. We propose, therefore, that nanofibers of pec-PHB have significant potential as retinal tissue engineering scaffold materials.

Mucoadhesive functionality of cell wall structures from fruits and grains: Electrostatic and polymer network interactions mediated by soluble dietary polysaccharides

We demonstrate the enhancement of intestinal mucin (Muc2) binding to plant cell wall structures from fruit (parenchymal apple tissue) and grain (wheat endosperm) mediated by soluble dietary fibers embedded within cellulose networks. Mucin binding occurs through two distinct mechanisms; for pectin polysaccharides characteristic of fruits and vegetables, it is governed by molecular mucoadhesive interactions, while for neutral polysaccharides, arabinoxylan and β-glucan characteristic of cereal grains, the interaction stems from the properties of their polymer network. Based on microrheological and microscopic measurements, we show that neutral dietary fiber polysaccharides do not adhere to intestinal mucin, but are capable of disrupting the mucin network, which facilitates interpenetration of mucin molecules into the polysaccharide mesh. This effect becomes significant in the context of ‘whole foods’, where soluble fibers are incorporated within the gel-like matrix of cellulose-reinforced plant cell wall structures. The result of mucoadhesion assay and analysis of microscopy images points to the critical role of entanglements between mucin and polysaccharides as a lock-in mechanism preventing larger mucin from escaping out of plant cell wall structures. These results provide the first indication that non-pectin soluble dietary fiber may influence mucosal interactions, mucus barrier properties, and transmucosal transport of nutrients.

Protection of blue color in a spirulina derived phycocyanin extract from proteolytic and thermal degradation via complexation with beet-pectin

The focus of the presented work was on improvement of spirulina based phycocyanin (PhyC) extracts as a potential natural blue colorant by enhancement of color stability via polysaccharide complexation. Beet pectin (β-pectin), guar gum and soluble soy polysaccharides (SSPS) were assessed for their ability to protect the color of a commercial phycocyanin (PhyC) extract from thermal and proteolytic degradation. Both the beet pectin and guar gum studied formed stable and homogenous solutions with the PhyC extract; SSPS did not. Color change was assessed throughout by measurement of L, a, and b color space values (Hunter, 1948) before and after thermal or proteolytic treatment. Beet pectin improved color stability, over PhyC alone, with respect to heating at 65 °C (20 min) and proteolysis by Alcalase 2.4L, papain and bromelain. For these treatments beet pectin reduced color change values (ΔEab) from 13.0 ± 0.1 to 6.2 ± 0.4 following thermal treatment and from 12.7 ± 0.2 to 5.9 ± 0.7, 19.6 ± 1.3 to 12.5 ± 0.8, and 10.8 ± 0.4 to 4.6 ± 0.6 for the Alcalase, papain and bromelain treatments, respectively. Intrinsic fluorescence (excitation at 285 nm, emission at 325 nm) of beet pectin complexed PhyC indicates an increased presence of exposed tryptophan residues compared to PhyC alone. Furthermore, measured zeta-potentials following complex heating generally diverged to slightly more negative values for PhyC-beet pectin complexes at elevated temperatures compared to PhyC alone, suggesting that maintenance of a negatively charged environment may be important to pigment color stability in PhyC complexes.

Enhanced Extracellular Polysaccharide Production and Self-Sustainable Electricity Generation for PAMFCs by Scenedesmus sp. SB1.

In this study, a freshwater microalga, Scenedesmus sp. SB1, was isolated, purified, and identified by its internal transcribed spacer region (ITS1-5.8S-ITS2). Media optimization through the Plackett–Burman Design and response surface methodology (RSM) showed a maximum exopolysaccharide (EPS) production of 48 mg/L (1.8-fold higher than that for unoptimized media). Characterization using gas chromatography–mass spectrometry, Fourier transform infrared, X-ray diffraction, and thermogravimetric analysis reveals that the EPS is a sulfated pectin polysaccharide with a crystallinity index of 15.2% and prompt thermal stability. Furthermore, the photoelectrogenic activity of Scenedesmus sp. SB1 inoculated in BG-11 and RSM-optimized BG-11 (ROBG-11) media was tested by cyclic voltammogram studies, revealing the potential of the inoculated strain in ROBG-11 toward photosynthetic algal microbial fuel cells over normal BG-11. To the best of our knowledge, functional group characterization, physical and thermal property and media optimization for EPS production by RSM and electrogenic activity studies are reported for the first time in Scenedesmus sp. SB1.

Comparative Assessment of the Prebiotic Activity of Some Pectin Polysaccharides

The isolation of pectinic polysaccharides from the aerial part of Ferula kuhistanica growing wild in Uzbekistan, Malus sieversii rosemary variety apples cultivated under local conditions (apple pomace after juice production was used), and tangerine peels (Citrus reticulata, tangerine variety) is reported. Their prebiotic activities for several probiotic cultures of Bifidobacterium longum 17x and Propionibacterium avidum 1 in addition to monocultures of Lactobacillus delbrueckii subsp. bulgaricus 906 and Lactobacillus rhamnosus 925ak were determined. According to the results, pectinic polysaccharide from F. kuhistanica was most promising in this respect.

A transcriptomics-based kinetic model for enzyme-induced pectin degradation in apple (Malus × domestica) fruit

Modifications of cell wall pectin during apple softening involve the concerted action of several enzymes. A mathematical model was developed to describe the action of cell wall hydrolases resulting in specific modifications in cell wall pectin polysaccharides during softening of ‘Jonagold’ apple. A conceptual model of enzyme-induced pectin breakdown was formulated based on current knowledge. Activities of different cell wall enzymes were considered to be directly correlated to the expression levels of the respective genes. The first pectin modification to occur was assumed to be cleavage of side chain neutral sugars from the polymer backbone, by the action of side chain debranching enzymes, beta-galactosidase and alpha-l-arabinofuranosidase. It was considered that this increases cell wall porosity, facilitating the action of pectin methyl esterase, which de-methylates pectin polysaccharides, providing a substrate for polygalacturonase. Polygalacturonase degrades the de-methylated pectin chain, producing smaller pectin fragments which are easily solubilised in water. Coupled differential equations were written based on these reactions. The model was calibrated using data on expression of cell wall-related genes, activities of enzymes encoded by these genes, and the associated modifications in pectin polysaccharides during softening in ‘Jonagold’ apples stored at 1°C under regular atmosphere or controlled atmosphere. The model could explain 79% of the variation in the data. Using the model, in silico investigations on the impact of downregulation of different key cell wall-related genes on softening were carried out, and the results were compared successfully with currently available literature data.

Recent View on Pectin-Based Polysaccharide Nanoscience and Their Biological Applications

Polysaccharide polymer has advantageous applications in bio-field, engineering and food industry because of remarkable properties such as biocompatibility and biodegradability. In this review, we describe the pectin polysaccharide nanomaterials and how the chemistry of pectin works in the development of nanoparticles and nanowires fabrication. We also discussed the recent advances of pectin-based nanomaterials including their synthesis strategies and applications. This pectin nanoscience review can be more useful to gain insight into the pectin nanochemistry for the nanosciences of engineering.

Cellulose-Derived Oligomers Act as Damage-Associated Molecular Patterns and Trigger Defense-Like Responses

The plant cell wall, often the site of initial encounters between plants and their microbial pathogens, is composed of a complex mixture of cellulose, hemicellulose, and pectin polysaccharides as well as proteins. The concept of damage-associated molecular patterns (DAMPs) was proposed to describe plant elicitors like oligogalacturonides (OGs), which can be derived by the breakdown of the pectin homogalacturon by pectinases. OGs act via many of the same signaling steps as pathogen- or microbe-associated molecular patterns (PAMPs) to elicit defenses and provide protection against pathogens. Given both the complexity of the plant cell wall and the fact that many pathogens secrete a wide range of cell wall-degrading enzymes, we reasoned that the breakdown products of other cell wall polymers may be similarly biologically active as elicitors and may help to reinforce the perception of danger by plant cells. Our results indicate that oligomers derived from cellulose are perceived as signal molecules in Arabidopsis (Arabidopsis thaliana), triggering a signaling cascade that shares some similarities to responses to well-known elicitors such as chitooligomers and OGs. However, in contrast to other known PAMPs/DAMPs, cellobiose stimulates neither detectable reactive oxygen species production nor callose deposition. Confirming our idea that both PAMPs and DAMPs are likely to cooccur at infection sites, cotreatments of cellobiose with flg22 or chitooligomers led to synergistic increases in gene expression. Thus, the perception of cellulose-derived oligomers may participate in cell wall integrity surveillance and represents an additional layer of signaling following plant cell wall breakdown during cell wall remodeling or pathogen attack.

Development of nanoformulation approaches for the control of weeds

The nanoformulation of pesticides has the potential to increase food productivity, while resolving the drawbacks of conventional agrochemicals, which have negative environmental impacts. In this study, herbicide (metsulfuron methyl)-loaded pectin (polysaccharide) nanoparticles were synthesized and evaluated for herbicidal activity and cytotoxicity. The optimum formulation of nanoparticles was obtained using the Central Composite Design. The basic properties (mean particle size, stability, morphology, and interaction between polymer and herbicide) were characterized using a particle size analyzer (PSA), zeta potential, transmission electron microscopy (TEM), and Fourier Transform infrared spectroscopy (FTIR), respectively. The nanoparticles were found to be in size range of 50–90nm with zeta potential value of −35.9mV. The herbicide loading and herbicide encapsulation efficiency of the nanoparticles were determined to be 6.30% and 63±2%, respectively. The cytotoxicity of the herbicide-loaded nanoparticles was evaluated using healthy cell lines (Vero cell lines) and compared with that of commercial herbicide. In addition, an in-field evaluation of our nanoformulation's effects on the Chenopodium album plant was performed using a pectin nanocarrier. The results showed that application of herbicide-loaded nanoparticles could be used to reduce the use of herbicides with improved efficacy and environmental safety.

Prevention of postoperative adhesions by biodegradable cryogels from pectin and chitosan polysaccharides

The main complication that may arise after surgery is the formation of adhesions. The current trend in the prevention of postoperative adhesions is the application of anti-adhesive barrier materials for the separation of wound tissue during the critical period of mesothelial repair and healing. In this work, cryogels based on pectin and chitosan were obtained by the ionic cryotropic gelation method. It was found that the Heracleum L. pectin cryogels are more elastic (73 ± 6 kPa) than the apple pectin cryogels (29 ± 11 kPa). The addition of chitosan with different physical and chemical characteristics did not significantly affect the elasticity of pectin–chitosan cryogels. The greatest swelling ability was achieved during in vivo incubation of Heracleum L. pectin cryogels and Heracleum L. pectin with reacetylated chitosan cryogels (17.1 ± 1.6 and 14.2 ± 2.0 g/g, respectively). It was found that the complete biodegradation of apple pectin cryogels occurred within 24 h of incubation in the rat abdominal cavity. Heracleum L. pectin cryogels were encapsulated in a fibrous capsule and detected in the abdominal cavity after 168 h. Maximum anti-adhesion effect was observed through the use of apple pectin cryogels (0 ± 0.5 score). Significant anti-adhesive effect was also observed through the use of apple pectin–reacetylated chitosan cryogels (1 ± 0.5 score). Due to the high anti-adhesive activity, such cryogels can be recommended for the development of a new barrier material for use in surgery. The potential anti-adhesive mechanism of apple pectin cryogels which may be attributed to a combination of barrier function and bioactivity of cryogels components was discussed.

Transgenic modification of potato pectic polysaccharides also affects type and level of cell wall xyloglucan.

Genes encoding pectic enzymes were introduced into wild-type potato Karnico. Cell wall materials were extracted from Karnico and transgenic lines expressing β-galactosidase (β-Gal-14) or rhamnogalacturonan lyase (RGL-18). Pectic polysaccharides from the β-Gal-14 transgenic line exhibited rhamnogalacturonan-I structural elements with shorter galactan side chains, whereas the RGL-18 transgenic line had less rhamnogalacturonan-I structures than Karnico. Xyloglucan in primary cell walls interacts with pectin and other cell wall polysaccharides and controls cell growth. Xyloglucan extracts from transgenic lines had different levels of monosaccharides compared to wild-type. Most XXGG-type xyloglucans from Karnico and RGL-18 alkali-extractable extracts predominantly consisted of XXGG and XSGG building blocks. Karnico and RGL-18 4 mol L-1 extracts had small proportions of the XXXG-type xyloglucan, whereas β-Gal-14 extracts also contained the XXXG-type xyloglucan. The peak ratios of XSGG/XXGG were 1.9, 2.4 and 1.1 for 4 mol L-1 extracts of Karnico, RGL-18 and β-Gal-14 lines, respectively. After transgenic modification on pectin, the xyloglucan building blocks may have been changed. The β-Gal-14 lines mostly present XXXG-type repeating units instead of the XXGG-type in 4 mol L-1 extracts. The ratio of XSGG/XXGG repeating units also changed, indicating that the transgenic modification of pectin altered xyloglucan structure during plant development. © 2016 Society of Chemical Industry.

THE STUDY OF RHEOLOGICAL AND SORPTION PROPERTIES OF PECTINESTERASE SOLUTIONS FROM THE LEAVES OF SORBARIA SORBIFOLIA

Currently, searching for new sources of raw materials of biologically active substances of plant origin is very important. Widespread distribution, relatively easy isolation and high physiological activity have made the practical use of pectins attractive. That is why nowadays an intensive study of the relationship between the structure and physico-chemical properties of pectin polysaccharides is being carried out, and the studies of the sorption and complexing pectin properties are also being expanded. The aim of the work was to study rheological properties of aqueous solutions of pectin substances obtained from the leaves of Sorbaria sorbifolia (L.). Materials and methods. Secretion of polysaccharides from the leaves of Sorbaria sorbifolia was carried out fraction by fraction on the basis of N. K. Kochetkov and M. Sinner’s method. We evaluated the adsorption capacity basing on the experimental data. From the literature data it follows that the adsorption process can be described by Freundlich’s or Langmuir’s equation. The applicability of the particular equation depends on the nature of the adsorbent and the concentration of the adsorbate. Results and discussion . In the course of the work polysaccharides were isolated from the leaves of Sorbaria sorbifolia and some of their physico-chemical properties were studied. The average molar mass of pectic substances was determined as 32923. The influence of the pH medium on the viscosity of solutions of pectin substances was studied and it was found out that a distinct minimum viscosity is observed at pH 5.2. In such an environment the molecules of pectic substances are electrically neutral and the polyelectrolyte is in the isoelectric state. The obtained data show that the maximal binding of Pb2 + ions by pectin leaves of Sorbaria sorbifolia within 50 minutes is 60.0%. Conclusion. The determination of the average molar mass and the isoelectric point makes it possible to specify the possibility of the most effective use of plant raw materials. Physical and technological properties of pectic substances depend on their molar mass. By the value of the obtained isotherms we should arrive at the conclusion that the dependence of the adsorption amount on the equilibrium concentration of lead ions is more subject to Langmuir’s equation.

Molecular Architecture of Natural Polysaccharide Based Thin Films

Natural biodegradable and biocompatible polysaccharides chitosan, pectin, carrageenan and heparin were used to form thin nanostructured films. In this study using atomic force microscopy (AFM) and force spectroscopy the special characteristics of formation and structure of thin coatings were investigated, three models of the polymers interaction were proposed. Different mechanisms of polymers influence on each other in the bilayers formation were shown, coatings with different surface structure and mechanical properties were formed. The obtained data can be used for the preparation of nanostructured coatings with desired surface parameters.

Study on Effect of Polysaccharide Based Edible Coating on the Shelf Life of Sapota Fruits Stored in Room Temperature

Background: The marketability of food products mainly depends upon appearance, flavor, color, texture, nutritional value and microbial safety. These can be maintained by using suitable biodegradable packaging such as edible films and coatings. In the present work the effect of polysaccharide based edible coating was studied on the shelf life of sapota fruits. Objective: The main objective of this project was to increase the shelf life of sapota fruits at ambient condition using the edible coating made up of easily available polysaccharide components. Methods: The edible coating containing sodium alginate (2%), pectin (2%) along with glycerol plasticizer (2.5%) was prepared. Coating of the fruits was done using dipping method with two dipping times (2 and 4 minutes). The both coated and control sapota fruits were stored at ambient condition (25±2ºC, 75-85% humidity). Results: The coated fruits with 2 minutes dipping time showed reduced rate of changes in the physicochemical properties and showed shelf life extension upto 12 days. The coated fruits with 4 minutes dipping time were spoilt on 11th day and control fruits were in the edible state upto 6th day of storage at room temperature. Conclusion: The edible coating containing pectin and sodium alginate polysaccharides was found to be effective in delaying the changes in physicochemical properties and hence ripeness of the sapota fruits at room temperature storage. From the sensory evaluation it was found that, there was no adverse effect of the edible coating on the organoleptic properties of coated sapota fruits. Keywords: Sodium alginate, pectin, sapota fruits, edible coating, physico-chemical properties, shelf life.

Rice putative methyltransferase gene OsTSD2 is required for root development involving pectin modification.

Pectin synthesis and modification are vital for plant development, although the underlying mechanisms are still not well understood. Here, we report the functional characterization of the OsTSD2 gene, which encodes a putative methyltransferase in rice. All three independent T-DNA insertion lines of OsTSD2 displayed dwarf phenotypes and serial alterations in different zones of the root. These alterations included abnormal cellular adhesion and schizogenous aerenchyma formation in the meristematic zone, inhibited root elongation in the elongation zone, and higher lateral root density in the mature zone. Immunofluorescence (with LM19) and Ruthenium Red staining of the roots showed that unesterified homogalacturonan (HG) was increased in Ostsd2 mutants. Biochemical analysis of cell wall pectin polysaccharides revealed that both the monosaccharide composition and the uronic acid content were decreased in Ostsd2 mutants. Increased endogenous ABA content and opposite roles performed by ABA and IAA in regulating cellular adhesion in the Ostsd2 mutants suggested that OsTSD2 is required for root development in rice through a pathway involving pectin synthesis/modification. A hypothesis to explain the relationship among OsTSD2, pectin methylesterification, and root development is proposed, based on pectin's function in regional cell extension/division in a zone-dependent manner.