Pectic Composition Research Articles

Changes in the physicochemical characteristics and biological activities of polysaccharides from Panax ginseng during defense against red-skin disease

Red-skin roots are a common disease symptom in cultivation of Panax ginseng, which strongly affects its quality and production. Differences in polysaccharides between red-skin and healthy ginseng were examined for the first time to elucidate their function as resistance to disease and explore their potential as active ingredients. Fluorol Yellow 088 and ruthenium red staining revealed changes in the distribution and composition of ginseng polysaccharides during defense against red-skin disease. Acid pectin content was observed to increase significantly in cell walls of the diseased epidermal tissue. Furthermore, targeted extraction approaches were used to obtain water-solution polysaccharides (WPS) and pectic polysaccharides (PP) which marked different characteristics with the health group. WPS from red-skin roots exhibited novel pectic characteristics, consisting of 32.25% GalA which is 10 times more than the healthy sample, accompanied by a sharp decrease in starch content (approximately 50%). Another study on the adsorption and gel properties of PP indicated that it played an important role in disease resistance by reducing metal toxicity and increasing the strength of the cell wall. For further analysis of the abnormal pectic composition, DEAE-52 purification was used and various pectic fractions (WPS-1,2,3) consisting of the RG-Ⅰ pectic domain were obtained. The analysis of antioxidant and immunoactivity was performed to explore the effect of characteristic changes on biological activities. Higher radical scavenging ratios of DPPH and ABTS indicated that red-skin fractions had stronger antioxidant activities. Stronger promotion effect on Raw264.7 secretion of TNF-α and IL-1α represented the higher immunological activities. Therefore, the red-skin ginseng polysaccharides could be utilized in the pharmaceutical industry to compensate for the value loss caused by red-skin roots.

Patterns of cell elongation in the determination of the final shape in galls of Baccharopelma dracunculifoliae (Psyllidae) on Baccharis dracunculifolia DC (Asteraceae)

Cell redifferentiation, division, and elongation are recurrent processes, which occur during gall development, and are dependent on the cellulose microfibrils reorientation. We hypothesized that changes in the microfibrils orientation from non-galled tissues to galled ones occur and determine the final gall shape. This determination is caused by a new tissue zonation, its hyperplasia, and relative cell hypertrophy. The impact of the insect's activity on these patterns of cell development was herein tested in Baccharopelma dracunculifoliae-Baccharis dracunculifolia system. In this system, the microfibrils are oriented perpendicularly to the longest cell axis in elongated cells and randomly in isodiametric ones, either in non-galled or in galled tissues. The isodiametric cells of the abaxial epidermis in non-galled tissues divided and elongated periclinally, forming the outer gall epidermis. The anticlinally elongated cells of the abaxial palisade layer and the isodiametric cells of the spongy parenchyma originated the gall outer cortex with hypertrophied and periclinally elongated cells. The anticlinally elongated cells of the adaxial palisade layer originated the inner cortex with hypertrophied and periclinally elongated cells in young and mature galls and isodiametric cells in senescent galls. The isodiametric cells of the adaxial epidermis elongated periclinally in the inner gall epidermis. The current investigation demonstrates the role of cellulose microfibril reorientation for gall development. Once many factors other than this reorientation act on gall development, it should be interesting to check the possible relationship of the new cell elongation patterns with the pectic composition of the cell walls.

Pressure impact of autoclave treatment on water sorption and pectin composition of flax cellulosic-fibres

The tensile properties of flax fibres might permit them to be used in composites as reinforcement in organic resin, as long as their mechanical properties are reproducible and their water sorption are reduced. In this study, to minimise the variability of mechanical properties, several samples of flax fibres were blended as a non-woven fabric. In order to reduce the water absorption of this non-woven technical fibres, an autoclave treatment was performed which was expected to remove the pectins and then to reduce the water sorption on their negative charges. The impact of autoclave pressure (0.5, 1 and 2bars) on water sorption was investigated by using a gravimetric static equilibrium method. The Park model based on the three sorption modes: Langmuir, Henry's law and clustering, was successfully used to simulate the experimental sorption data. The lowest pressure treatments impacted only the Langmuir contribution while the 2bar autoclave-treatment positively impacted the water resistance in the core of fibres by reducing Henry's absorption rate. This was shown to be related to the chemical modifications at the surface and in the core of fibres. A schematic model is presented relating the water sorption and the pectic composition of the fabric.

Apical F‐actin‐regulated exocytic targeting of NtPPME1 is essential for construction and rigidity of the pollen tube cell wall

In tip-confined growing pollen tubes, delivery of newly synthesized cell wall materials to the rapidly expanding apical surface requires spatial organization and temporal regulation of the apical F-actin filament and exocytosis. In this study, we demonstrate that apical F-actin is essential for the rigidity and construction of the pollen tube cell wall by regulating exocytosis of Nicotiana tabacum pectin methylesterase (NtPPME1). Wortmannin disrupts the spatial organization of apical F-actin in the pollen tube tip and inhibits polar targeting of NtPPME1, which subsequently alters the rigidity and pectic composition of the pollen tube cell wall, finally causing growth arrest of the pollen tube. In addition to mechanistically linking cell wall construction and apical F-actin, wortmannin can be used as a useful tool for studying endomembrane trafficking and cytoskeletal organization in pollen tubes.

Erratum to: The role of pectic composition of cell walls in the determination of the new shape-functional design in galls of Baccharis reticularia (Asteraceae)

Erratum to: The role of pectic composition of cell walls in the determination of the new shape-functional design in galls of Baccharis reticularia (Asteraceae)

The role of pectic composition of cell walls in the determination of the new shape-functional design in galls of Baccharis reticularia (Asteraceae)

The pectic composition of cell wall is altered during the processes of cell differentiation, plant growth, and development. These alterations may be time-dependent, and fluctuate in distinct regions of the same cell or tissue layer, due to the biotic stress caused by the activity of the gall inducer. Among the roles of the pectins in cell wall, elasticity, rigidity, porosity, and control of cell death may be crucial during gall development. Galls on Baccharis reticularia present species-specific patterns of development leading to related morphotypes where pectins were widely detected by Ruthenium red, and the pectic epitopes were labeled with specific monoclonal antibodies (LM1, LM2, LM5, LM6, JIM5, and JIM7) in distinct sites of the non-galled and the galled tissues. In the studied system B. reticularia, the epitopes for extensins were not labeled in the non-galled tissues, as well as in those of the rolling and kidney-shaped galls. The high methyl-esterified homogalacturonans (HGA) were labeled all over the tissues either of non-galled leaves or of the three gall morphotypes, while the intense labeling for arabinogalactans was obtained just in the rolling galls. The pectic composition of non-galled leaves denotes their maturity. The kidney-shaped gall was the most similar to the non-galled leaves. The pectic dynamics in the gall tissues was particularly altered in relation to low methyl-esterified HGA, which confers elasticity and expansion, as well as porosity and adhesion to cell walls, and are related to the homogenization and hypertrophy of gall cortex, and to translocation of solutes to the larval chamber. Herein, the importance of the pectic dynamics of cell walls to the new functional design established during gall development is discussed for the first time. The repetitive developmental patterns in galls are elegant models for studies on cell differentiation.

Sensory characteristics, quality and optical properties measured by time-resolved reflectance spectroscopy in stored apples

Time-resolved reflectance spectroscopy (TRS) studies have shown that in apples the absorption coefficient ( μ a) at 630 nm is linked to fruit maturity, whereas the scattering coefficient ( μ ′ s ) is related to fruit texture not only at a macroscopic level but also to cell wall and middle lamella pectic composition. This work aimed at studying the classification models based on the optical properties of absorption and scattering measured by TRS in order to select apples with distinctive quality and sensory characteristics at consumption. After 6 months’ storage in normal and controlled atmosphere plus 7 d of post-storage shelf life at 20 °C, ‘Jonagored’ apples were measured for TRS optical properties ( μ a and μ ′ s ) at 630, 670, 750 and 780 nm, and for quality characteristics (firmness, stiffness, percent juice, soluble solids content, titratable acidity, background and red side colour parameters) and assessed by a sensory panel for seven attributes (firm, crispy, mealy, juicy, sour, sweet, aromatic). Data of quality and sensory characteristics and of optical properties were processed together by Principal Component Analysis. According to sensory intensity scores, apples were either divided into three classes (low, medium, high intensity) separately for every attribute, or clustered into five groups, each one representing a specific sensory profile. The optical coefficients were used as variables to classify fruit according to either the class of intensity for every attribute, or according to the sensory profile. All the models showed better classification performances when also including selected absorption coefficients, as well as scattering coefficients. The performance of the classification models ranged from 57.3% for the juicy model to 71.9% for the mealy one. The model sorting apples into five different sensory profiles showed a lower percentage of well-classified fruit if compared to the classification models developed for each sensory descriptor, even if it was able to correctly classify almost 70% of fruit having either a mealy-dry texture without flavour or a not-mealy-juicy texture with a moderate flavour.

Effects of Cations and Anions on the Softening of Cooked Japanese Radish Roots and on the Pectic Composition after Cooking

Effects of Cations and Anions on the Softening of Cooked Japanese Radish Roots and on the Pectic Composition after Cooking

Effects of Harvest Time and Position of the Segments of Japanese Radish Roots on Softening during Cooking, Pectic Composition, and Dietary Fibers

Effects of Harvest Time and Position of the Segments of Japanese Radish Roots on Softening during Cooking, Pectic Composition, and Dietary Fibers

Seasonal changes in the ion‐mediated increase of xylem hydraulic conductivity in stems of three evergreens: any functional role?

Changes in hydraulic conductivity (Kh) were measured monthly in stems of Laurus nobilis between July 2005 and June 2006 and in March and June 2006 in stems of Prunus laurocerasus and Phillyrea latifolia. Percent enhancement of Kh (ΔKh) was recorded as KCl injected into stems compared with deionized water. Stems of L. nobilis perfused with increasing [KCl] saturated the hydraulic effect at 50 mM KCl, while P. laurocerasus and Ph. latifolia showed saturation at 17 and less than 5 mM KCl, respectively. Impressive seasonal changes in ΔKh were recorded in L. nobilis, from +120% in February to +20% during the growth period. ΔKh was negatively correlated to minimum air temperatures and was highest during winter frost. Negative correlation also existed between ΔKh and conduit lengths as detected during transition of plants from activity to winter rest and from winter to spring. In the winter, the thermal effect was prevailing. High cavitation‐induced Kh loss coincided with high ΔKh. Similar but much smaller seasonal effects on ΔKh were recorded in the other two species where, however, also smaller seasonal changes in conduit lengths were recorded. We conclude that (1) the K+‐induced effect on Kh was because of interference of the cation with pectins of intervessel pit membranes (increasingly crossed by the ionic solution in stems with shorter conduits); (2) winter frost might have an effect on ΔKh and (3) seasonal changes in ΔKh because of possible change in pectic composition may represent a mechanism to regulate water flows in planta.

Effect of osmosis time on structure, texture and pectic composition of strawberry tissue

The effect on strawberry tissue of an osmotic step applied at atmospheric pressure for different lengths of time, was analysed. In this work, the specific influence of osmotic treatments with sucrose solutions at 25 °C on cellular structure, texture, pectin composition and their relationship are discussed. Osmotic dehydration induced a significant texture loss: The longer the immersion time, the higher the texture loss. From 1 h onwards of osmosis there was a gradual disconnection and breakdown of the tissue, with a loss of shape of cellular walls together with loss of turgor pressure. A good agreement was obtained between texture, structure changes and pectic composition modifications. Besides a pectin solubilization, there was an hemicelluloses solubilization, most likely due to an accelerated ripening of strawberry fruit, linked to the anaerobic conditions, caused by a sugar peripheral layer formation.

Changes of pectic composition of ‘Annurca’ apple fruit after storage

‘Annurca’ apple fruit, which is commonly cultivated in Southern Italy and undergoes, after harvest, a typical reddening treatment to turn the apples’ skin red, is noticeable for its high firmness. An ‘Annurca’ variety, called ‘Bella del Sud’ is examined for its pectic composition after reddening and just after cold storage. Pectins, extracted with water and potassium oxalate, change their composition after different storage regimes with respect to unstored fruit. ‘Annurca’ pectin, as analyzed by gel-permeation chromatography, is composed of three types of polymers (high MW, >350 kDa, medium MW 350–110 kDa, low MW 40–9 kDa). Gel-permeation chromatograms revealed that the medium MW polymers decreased after normal atmosphere storage. Eluates were subjected to enzymatic and chemical hydrolysis, then to HPLC analysis. The high and medium MW polysaccharides were rich in galacturonic acid. Low MW were rich in neutral sugars. The storage-induced differences in sugar composition revealed that the most important changes are loss of galacturonic acid in medium MW fragments, increase of glucose, rhamnose and arabinose and depletion of mannose–galactose units in low MW fragments.

Compartmented cells in the mesophyll of Araucaria angustifolia (Araucariaceae)

The compartmented cells of the immature and mature leaves of young and adult plants of Araucaria angustifolia (Bert.) O. Ktze. are characterised by the presence of pectinous partitions in the cell lumen, forming a system of compartments. The function of these cells is possibly related to water storage and translocation. The morphology of compartmented cells differs from that of immature and mature leaves: at the time of maturity the compartment system or secretion is more defined. These cells undergo the programmed cell death (PCD) process, because they are enucleated in adult plants. The compartmented cells' cytology and pectic composition are similar to the mucilage cells of Lauraceae and Cactaceae.

Freezing effect on some quality parameters of transgenic parthenocarpic eggplants

Parthenocarpy is the development of fruits in the absence of fertilization. It confers advantages to horticultural crops; the most important are fruit production under adverse environmental conditions and seedless fruits. Parthenocarpy has been obtained in eggplant by genetic engineering using a chimeric gene and an ovule-specific promoter which allows the plant to increase the content and/or the activity of indol-3-acetic acid. Two transgenic hybrids, P1 and P2, were compared with the corresponding control hybrids C1 and C2 in open field. All parthenocarpic hybrids were seedless, so increasing fruit quality. In order to evaluate the quality of transgenic eggplants, particularly their suitability for freezing, analyses on colour, texture and pectic composition were carried out on raw fruits and after 15 months of frozen storage at −20 °C. Fresh and frozen parthenocarpic eggplants showed a slower browning of the pulp with respect to the controls. Texture data showed a higher decrease of firmness for the transgenic, while pectin analysis suggests that there are lower molecular weight fragments in the transgenic eggplants than in the controls.

Pectinesterase and polygalacturonase in changes of pectic matter in olives (cv. Hojiblanca) intended for milling

AbstractVirgin olive oil is a highly valued product, and it is important to optimize extraction yield. The pectic composition and the related enzymatic activities, present in the raw material, are variables that may affect that process. The pectinolytic activities producing modifications in the pectic matter of olive fruits (variety Hojiblanca) during ripening and the associated changes in texture were studied. Pectinesterase (PE) activity increased with ripeness until reaching a peak when anthocyanin synthesis in the fruit became marked (turning color stage). From then on, it decreased. In contrast, polygalacturonase (PG) activity in the ripe‐green fruit decreased sharply when anthocyanin formation began (small reddish spots stage) and then increased, reaching a maximum in the ripe‐black fruit. Parallel changes were noted in the texture and pectic content of the olives, related to endo‐ and exo‐PG enzymatic activities, together with a decrease in the degree of esterification of the pectic matter, which could be associated with PE action. The distribution of the pectic fractions in the raw material and the changes in them during the olive oil extraction process showed the role of PE and PG in the fruits that was related to the yield of extracted oil.

Developmental regulation of pectic epitopes during potato tuberisation

We show, by immunogold labelling, that potato (Solanum tuberosum L. cv Karnico) pectic epitopes are developmentally regulated within regions of the stolon, in addition to showing tissue-specific differences in abundance and localisation. The (1-->4)-beta-D-galactan and (1-->5)-alpha-arabinan epitopes demarcate two distinct zones within stolons; galactans are enriched in primary walls of elongating cells proximal to the stolon hook, whilst arabinans predominate in younger cells distal to the hook. Low-methoxyl homogalacturonan epitopes are concentrated in the middle lamella and show a proximo-distal gradient in stolons similar to that of galactans, whilst high-methoxyl homogalacturonan is uniformly abundant. Calcium pectate is restricted to the middle lamella at cell corners and pit fields. Calcium-binding sites are uniformly present in stolon cell walls, but their total density is reduced and they become localised to a few cell corners in mature tubers, as determined by image-electron energy loss spectroscopy. During the transition from elongation growth to isodiametric expansion during tuberisation of the stolon hook, there were no detectable changes in pectic epitope abundance or localisation. As tubers matured, all epitopes increased in abundance in parenchymal cell walls, except for calcium pectate. We conclude that potentially significant changes in pectic composition occur as young cells distal to the stolon hook move into the zone of cell elongation proximal to the hook.

‘Annurca’ apple fruit, a southern Italy apple cultivar: textural properties and aroma composition

‘Annurca’ apple fruit, which is commonly cultivated in southern Italy and undergoes a typical reddening treatment and, is notable for its high firmness and its characteristic flavour, was examined for its pectic and aroma composition. Pectin, extracted with a water solution of potassium oxalate and dimethylsulphoxide, was found to be quantitavely and qualitatively important for its contribution to the high tissue firmness. Pectin changes its composition during the reddening process and there is even a difference in the pectic composition of the two ‘Annurca’ clones examined in this paper, ‘Standard’ and ‘Rossa del Sud’. Volatile compounds were collected by headspace sampling of intact unreddened and reddened fruits. Thirty-one compounds of several chemical classes were identified, to establish their role in the characteristic flavor of this apple cv. Among these compounds, n -pentanol was unusually present in large amounts; also δ-octalactone, never found in apples, was present.

Occurrence of xyloglucan containing protuberances in the storage cell walls of cotyledons of Hymenaea courbaril L.

Despite the suggestions of its pectic composition, no clear evidence for this has been presented. Here we show the occurrence of such a structure in walls of cells from cotyledons of Hymenaea courbariI L. These cells are known to accumulate large amounts of storage xyloglucan in the wall and, in this case, the protuberances seem to contain this storage polysaccharide rather than pectin. A hypothetical sequence of events leading from wall strands to protuberances was assembled based on scanning electron microscopy observations. On this basis, a tentative model for how polysaccharides are distributed into the wall, near the regions where protuberances are found, is proposed to explain the presence of storage xyloglucan in their composition.

Oven‐dried table olives: textural properties as related to pectic composition

Oven‐dried table olives: textural properties as related to pectic composition

Calcium deficiency in potato (Solanum tuberosum ssp. tuberosum) leaves and its effects on the pectic composition of the apoplastic fluid

Potato plants (Solanum tuberosum ssp. tuberosum cv. Adelheid), multiplied in vitro, were cultivated in growth chambers on nutrient solution at calcium regimes of 1000, 90, 60 or 30 μM Ca. An absolute Ca deficiency, particularly at the low Ca‐supply levels of 30 and 60 μM Ca, manifested itself initially in the form of marginal necrosis in younger, but not in the youngest, leaves of the potato plants. Further symptoms were rolling of the leaf lamina, browning of veins and roots, and finally necrosis also of the youngest leaves. Only in an advanced stage of Ca deficiency, the meristem of the shoots died. Ca‐deficiency symptoms could be expected at a Ca content in the leaves of less than 5 mg Ca (g dry weight)−1. However, there was no close negative correlation between the extent of leaf damage and the total Ca content of the leaves. In order to obtain information about the Ca concentration in the apoplast fluid of the leaves, apoplastic washing fluid was extracted by an infiltration‐centrifugation technique. A low Ca supply reduced the Ca concentration both in the apoplast fluid of the leaves and in the cell walls. Up to 60% more diffusible pectin fragments were then found in the apoplast of younger leaves, as compared to the control supplied with an optimum Ca level of 1000 μM. The amount of diffusible pectins accounted for 1–2% of the total pectin content of younger potato leaves. The size of the existing pectin fragments varied depending on the Ca supply. Compared with an optimum Ca supply of 1000 μM, fewer monomers and up to 7 times more diffusible pectin fragments with a degree of polymerization 9–20 were present at the low Ca‐supply level (30 μM). In addition, polygalacturonase activity in tissue homogenates increased remarkably with Ca deficiency. Thus it appears that one major effect of Ca deficiency was a stimulation of the activity of polygalacturonase, which could control the breakdown of pectic polysaccharides in the cell wall. Whether the release of potentially biologically active pectic fragments in cell walls might be involved in the occurrence of Ca‐deficiency symptoms is discussed.