Dupilumab-associated ocular adverse events are predicted by low tear break-up time and correlate with high IL-33 tear concentrations in patients with atopic dermatitis

Dupilumab, blocking IL-4 and IL-13 signals, improves atopic dermatitis and Quality of Life but might be also associated with the occurrence of ocular adverse events (OAEs). The main objective of our prospective study was to characterize the cytokine and chemokine profile in the tear fluid of dupilumab-treated patients with moderate-to- severe atopic dermatitis and to identify biomarkers predicting the occurrence of ocular adverse events. Patients with moderate-to-severe AD underwent dermatological and ophthalmological evaluation at the baseline (T0) and week 16 or at the time of an eventual ocular adverse events (T1). A multiplex immunoassay measuring multiple cytokines and chemokines in the tear fluid extracted during ocular examination at both T0 and T1 was performed. Thirty-nine patients with moderate-to-severe AD and treated with dupilumab were included in the study. Baseline tear fluid levels revealed a significantly higher concentration of type 2 cytokines and chemokines in AD patients than healthy controls. The occurrence of ocular adverse events during dupilumab therapy was associated with a significant increase of IL-33 tear fluid levels and a significantly lower tear break-up time, this latter also identified as predictive factor. Our findings suggest that the ophthalmological examination should be considered a valid support to identify patients at risk of developing OAEs and to provide their appropriate management.

Arabidopsis subtilases promote defense-related pectin methylesterase activity and robust immune responses to botrytis infection

Plants involve a fine modulation of pectin methylesterase (PME) activity against microbes. PME activity can promote the cell wall stiffening and the production of damage signals able to induce defense responses and plant resistance to pathogens. However, the molecular mechanisms underlying PME activation during disease remain largely unknown. In this study, we explored the role of subtilases (SBTs) as PME activators in Arabidopsis immunity. By using biochemical and reverse genetic approaches, we found that the expression of SBT3.3 and SBT3.5 influences the induction of defense-related PME activity and resistance to the fungus Botrytis cinerea. Arabidopsis sbt3.3 and sbt3.5 knockout mutants showed decreased induction of PME activity and increased susceptibility to the fungus. SBT3.3 expression was stimulated by oligogalacturonides. Overexpression of SBT3.3 overactivated PME activity during fungal infection and enhanced resistance to B. cinerea. A negative correlation was observed between SBT3.3 expression and cell wall methyl ester content in the genotypes analyzed after B. cinerea infection. Increased expression of defense-related genes, including PAD3, CYP81F2 and WAK2, was also revealed in SBT3.3 overexpressing lines. We also demonstrated that SBT3.3 and pro-PME17 are both secreted into the cell wall using distinct protein secretion pathways and different kinetics. Our results propose SBT3.3 and SBT3.5 as modulators of PME activity in Arabidopsis against Botrytis to promptly boost immunity limiting the growth-defense trade-off.

Expression of Exogenous GFP-CesA6 in Tobacco Enhances Cell Wall Biosynthesis and Biomass Production

Simple Summary

Cellulose is synthesized at the plasma membrane by an enzymatic complex constituted by different cellulose synthase (CesA) proteins. The overexpression of CesA genes has been assessed for increasing cellulose biosynthesis and plant biomass. In this study, we analyzed transgenic tobacco plants (F₃1 line), stably expressing the Arabidopsis CesA6 fused to GFP, for possible variations in the cellulose biosynthesis. We found that F₃1 plants were bigger than the wild-type (wt), showing significant increases of stem height, root length, and leaf area. They bloomed about 3 weeks earlier and yielded more flowers and seeds than wt. In the F₃1 leaves, the expression of the exogenous GFP-CesA6 prompted the overexpression of all CesAs involved in the synthesis of primary cell wall cellulose and of other proteins responsible for plant cell wall building and remodeling. Instead, secondary cell wall CesAs were not affected. In the F₃1 stem, showing a 3.3-fold increase of the secondary xylem thickness, both primary and secondary CesAs expression was differentially modulated. Significantly, the amounts of cellulose and matrix polysaccharides increased in the transformed seedlings. The results evidence the potentiality to overexpress primary CesAs in tobacco for biomass production increase.

Abstract

Improved cellulose biosynthesis and plant biomass represent important economic targets for several biotechnological applications including bioenergy and biofuel production. The attempts to increase the biosynthesis of cellulose by overexpressing CesAs proteins, components of the cellulose synthase complex, has not always produced consistent results. Analyses of morphological and molecular data and of the chemical composition of cell walls showed that tobacco plants (F₃1 line), stably expressing the Arabidopsis CesA6 fused to GFP, exhibits a “giant” phenotype with no apparent other morphological aberrations. In the F₃1 line, all evaluated growth parameters, such as stem and root length, leaf size, and lignified secondary xylem, were significantly higher than in wt. Furthermore, F₃1 line exhibited increased flower and seed number, and an advance of about 20 days in the anthesis. In the leaves of F₃1 seedlings, the expression of primary CesAs (NtCesA1, NtCesA3, and NtCesA6) was enhanced, as well as of proteins involved in the biosynthesis of non-cellulosic polysaccharides (xyloglucans and galacturonans, NtXyl4, NtGal10), cell wall remodeling (NtExp11 and XTHs), and cell expansion (NtPIP1.1 and NtPIP2.7). While in leaves the expression level of all secondary cell wall CesAs (NtCesA4, NtCesA7, and NtCesA8) did not change significantly, both primary and secondary CesAs were differentially expressed in the stem. The amount of cellulose and matrix polysaccharides significantly increased in the F₃1 seedlings with no differences in pectin and hemicellulose glycosyl composition. Our results highlight the potentiality to overexpress primary CesAs in tobacco plants to enhance cellulose synthesis and biomass production.

Evaluation of Dittrichia viscosa Aquaporin Nip1.1 Gene as Marker for Arsenic-Tolerant Plant Selection

Dittrichia viscosa (L.) Greuter is gaining attention for its high genetic plasticity and ability to adapt to adverse environmental conditions, including heavy metal and metalloid pollution. Uptake and translocation of cadmium, copper, iron, nickel, lead, and zinc to the shoots have been characterized, but its performance with arsenic is less known and sometimes contradictory. Tolerance to As is not related to a reduced uptake, but the null mutation of the aquaporin Nip1.1 gene in Arabidopsis makes the plant completely resistant to the metalloid. This aquaporin, localized in the endoplasmic reticulum, is responsible for arsenite and antimony (Sb) membrane permeation, but the uptake of arsenite occurs also in the null mutant, suggesting a more sophisticated action mechanism than direct uptake. In this study, the DvNip1 gene homologue is cloned and its expression profile in roots and shoots is characterized in different arsenic stress conditions. The use of clonal lines allowed to evidence that DvNip1.1 expression level is influenced by arsenic stress. The proportion of gene expression in roots and shoots can be used to generate an index that appears to be a promising putative selection marker to predict arsenic-resistant lines of Dittrichia viscosa plants.

An Optimized Energy-Harvesting Transmission Scheme for Diffusion-Based Molecular Communications

In this paper, we propose an optimized transmission scheme with energy-harvesting for a diffusion-based molecular communication system composed by nano-devices fed by piezoelectric nanogenerators. To this end, we firstly derive a system model that analytically describes the mean and the variance of the aggregated noise at the output of the receiver and the achievable Bit Error Rate. Then, we formulate an optimization problem that minimizes an objective function defined as a linear combination of the probability that the voltage across the ultra-nanocapacitor of the transmitter goes under a target value and the number of enqueued packets. We solve this problem by considering the actual energy budget, a target Bit Error Rate, and the need to achieve the simplicity of the transmitter as constraints. Finally, we use computer simulations to validate the formulated analytical models and demonstrate the unique ability of the proposed approach to guarantee BER = 5% and BER = 10% for communication distances up to 47μm and 50μm, respectively, while registering better results against baseline scenarios.

Analysis of the Phytochemical Composition of Pomegranate Fruit Juices, Peels and Kernels: A Comparative Study on Four Cultivars Grown in Southern Italy

The increasing popularity of pomegranate (Punica granatum L.), driven by the awareness of its nutraceutical properties and excellent environmental adaptability, is promoting a global expansion of its production area. This investigation reports the variability in the weight, moisture, pH, total soluble solids, carbohydrates, organic acids, phenolic compounds, fatty acids, antioxidant activities, and element composition of different fruit parts (juices, peels, and kernels) from four (Ako, Emek, Kamel, and Wonderful One) of the most widely cultivated Israeli pomegranate varieties in Salento (South Italy). To the best of our knowledge, this is the first systematic characterization of different fruit parts from pomegranate cultivars grown simultaneously in the same orchard and subjected to identical agronomic and environmental conditions. Significant genotype-dependent variability was observed for many of the investigated parameters, though without any correlation among fruit parts. The levels of phenols, flavonoids, anthocyanins, and ascorbic and dehydroascorbic acids of all samples were higher than the literature-reported data, as was the antioxidant activity. This is likely due to positive interactions among genotypes, the environment, and good agricultural practices. This study also confirms that pomegranate kernels and peels are, respectively, rich sources of punicic acid and phenols together, with several other bioactive molecules. However, the variability in their levels emphasizes the need for further research to better exploit their agro-industrial potential and thereby increase juice-production chain sustainability. This study will help to assist breeders and growers to respond to consumer and industrial preferences and encourage the development of biorefinery strategies for the utilization of pomegranate by-products as nutraceuticals or value-added ingredients for custom-tailored supplemented foods.

Ride to cell wall: Arabidopsis XTH11, XTH29 and XTH33 exhibit different secretion pathways and responses to heat and drought stress

The xyloglucan endotransglucosylase/hydrolases (XTHs) are enzymes involved in cell wall assembly and growth regulation, cleaving and re-joining hemicellulose chains in the xyloglucan-cellulose network. Here, in a homologous system, we compare the secretion patterns of XTH11, XTH33 and XTH29, three members of the Arabidopsis thaliana XTH family, selected for the presence (XTH11 and XTH33) or absence (XTH29) of a signal peptide, and the presence of a transmembrane domain (XTH33). We show that XTH11 and XTH33 reached, respectively, the cell wall and plasma membrane through a conventional protein secretion (CPS) pathway, whereas XTH29 moves towards the apoplast following an unconventional protein secretion (UPS) mediated by exocyst-positive organelles (EXPOs). All XTHs share a common C-terminal functional domain (XET-C) that, for XTH29 and a restricted number of other XTHs (27, 28 and 30), continues with an extraterminal region (ETR) of 45 amino acids. We suggest that this region is necessary for the correct cell wall targeting of XTH29, as the ETR-truncated protein never reaches its final destination and is not recruited by EXPOs. Furthermore, quantitative real-time polymerase chain reaction analyses performed on 4-week-old Arabidopsis seedlings exposed to drought and heat stress suggest a different involvement of the three XTHs in cell wall remodeling under abiotic stress, evidencing stress-, organ- and time-dependent variations in the expression levels. Significantly, XTH29, codifying the only XTH that follows a UPS pathway, is highly upregulated with respect to XTH11 and XTH33, which code for CPS-secreted proteins.

Actin and Microtubules Differently Contribute to Vacuolar Targeting Specificity during the Export from the ER

Plants rely on both actin and microtubule cytoskeletons to fine-tune sorting and spatial targeting of membranes during cell growth and stress adaptation. Considerable advances have been made in recent years in the comprehension of the relationship between the trans-Golgi network/early endosome (TGN/EE) and cytoskeletons, but studies have mainly focused on the transport to and from the plasma membrane. We address here the relationship of the cytoskeleton with different endoplasmic reticulum (ER) export mechanisms toward vacuoles. These emergent features of the plant endomembrane traffic are explored with an in vivo approach, providing clues on the traffic regulation at different levels beyond known proteins’ functions and interactions. We show how traffic of vacuolar markers, characterized by different vacuolar sorting determinants, diverges at the export from the ER, clearly involving different components of the cytoskeleton.

Application of response surface methodology (RSM) for the optimization of supercritical CO2 extraction of oil from patè olive cake: Yield, content of bioactive molecules and biological effects in vivo

The two-phase technology for olive oil extraction generates large amounts of patè olive cake (POC), a by-product that is rich in bioactive health-promoting compounds. Here, response surface methodology (RSM) was used to maximize supercritical-CO₂ oil extraction from POC, while minimizing operative temperature, pressure and time. Under the optimal parameters (40.2 °C, 43.8 MPa and time 30 min), the oil yield was 14.5 g·100 g^-1 dw (~65% of the total oil content of the freeze-dried POC matrix), as predicted by RSM. Compared with freeze-dried POC, the oil contained more phytosterols (13-fold), tocopherols (6-fold) and squalene (8-fold) and was a good source of pentacyclic triterpenes. When the biological effects of POC oil intake (20-40 µL·die^-1) were evaluated in the livers of BALB/c mice, no significant influence on redox homeostasis was observed. Notably, a decline in liver triglycerides alongside increased activities of NAD(P)H:Quinone Oxidoreductase 1, Carnitine Palmitoyl-CoA Transferase and mitochondrial respiratory complexes suggested a potential beneficial effect on liver fatty acid oxidation.

CesA6 and PGIP2 Endocytosis Involves Different Subpopulations of TGN-Related Endosomes

Endocytosis is an essential process for the internalization of plasma membrane proteins, lipids and extracellular molecules into the cells. The mechanisms underlying endocytosis in plant cells involve several endosomal organelles whose origins and specific role needs still to be clarified. In this study we compare the internalization events of a GFP-tagged polygalacturonase-inhibiting protein of Phaseolus vulgaris (PGIP2-GFP) to that of a GFP-tagged subunit of cellulose synthase complex of Arabidopsis thaliana (secGFP-CesA6). Through the use of endocytic traffic chemical inhibitors (tyrphostin A23, salicylic acid, wortmannin, concanamycin A, Sortin 2, Endosidin 5 and BFA) it was evidenced that the two protein fusions were endocytosed through distinct endosomes with different mechanisms. PGIP2-GFP endocytosis is specifically sensitive to tyrphostin A23, salicylic acid and Sortin 2; furthermore, SYP51, a tSNARE with interfering effect on late steps of vacuolar traffic, affects its arrival in the central vacuole. SecGFP-CesA6, specifically sensitive to Endosidin 5, likely reaches the plasma membrane passing through the trans Golgi network (TGN), since the BFA treatment leads to the formation of BFA bodies, compatible with the aggregation of TGNs. BFA treatments determine the accumulation and tethering of the intracellular compartments labeled by both proteins, but PGIP2-GFP aggregated compartments overlap with those labeled by the endocytic dye FM4-64 while secGFP-CesA6 fills different compartments. Furthermore, secGFP-CesA6 co-localization with RFP-NIP1.1, marker of the direct ER-to-Vacuole traffic, in small compartments separated from ER suggests that secGFP-CesA6 is sorted through TGNs in which the direct contribution from the ER plays an important role. All together the data indicate the existence of a heterogeneous population of Golgi-independent TGNs.

Variation in Membrane Trafficking Linked to SNARE AtSYP51 Interaction With Aquaporin NIP1;1

SYP51 and 52 are the two members of the SYP5 Qc-SNARE gene family in Arabidopsis thaliana. These two proteins, besides their high level of sequence identity (85%), have shown to have differential functional specificity and possess a different interactome. Here we describe a unique and specific interaction of SYP51 with an ER aquaporin, AtNIP1;1 (also known as NLM1) indicated to be able to transport arsenite [As(III)] and previously localized on PM. In the present work we investigate in detail such localization in vivo and characterize the interaction with SYP51. We suggest that this interaction may reveal a new mechanism regulating tonoplast invagination and recycling. We propose this interaction to be part of a regulatory mechanism associated with direct membrane transport from ER to tonoplast and Golgi mediated vesicle trafficking. We also demonstrate that NIP1;1 is important for plant tolerance to arsenite but does not alter its uptake or translocation. To explain such phenomenon the hypothesis that SYP51/NIP1;1 interaction modifies ER and vacuole ability to accumulate arsenite is discussed.

Trafficking routes to the plant vacuole: connecting alternative and classical pathways

Due to the numerous roles plant vacuoles play in cell homeostasis, detoxification, and protein storage, the trafficking pathways to this organelle have been extensively studied. Recent evidence, however, suggests that our vision of transport to the vacuole is not as simple as previously imagined. Alternative routes have been identified and are being characterized. Intricate interconnections between routes seem to occur in various cases, complicating the interpretation of data. In this review, we aim to summarize the published evidence and link the emerging data with previous findings. We discuss the current state of information on alternative and classical trafficking routes to the plant vacuole.

Td4IN2: A drought-responsive durum wheat (Triticum durum Desf.) gene coding for a resistance like protein with serine/threonine protein kinase, nucleotide binding site and leucine rich domains

Wheat, the main food source for a third of world population, appears strongly under threat because of predicted increasing temperatures coupled to drought. Plant complex molecular response to drought stress relies on the gene network controlling cell reactions to abiotic stress. In the natural environment, plants are subjected to the combination of abiotic and biotic stresses. Also the response of plants to biotic stress, to cope with pathogens, involves the activation of a molecular network. Investigations on combination of abiotic and biotic stresses indicate the existence of cross-talk between the two networks and a kind of overlapping can be hypothesized. In this work we describe the isolation and characterization of a drought-related durum wheat (Triticum durum Desf.) gene, identified in a previous study, coding for a protein combining features of NBS-LRR type resistance protein with a S/TPK domain, involved in drought stress response. This is one of the few examples reported where all three domains are present in a single protein and, to our knowledge, it is the first report on a gene specifically induced by drought stress and drought-related conditions, with this particular structure.

Glutathione S-transferase related detoxification processes are correlated with receptor-mediated vacuolar sorting mechanisms

KEY MESSAGE

Triticum durum Glutathione S-transferase Z1 is specifically responsive to glyphosate. Its expression influences the receptor-mediated vacuolar sorting mechanisms involved in tolerance mechanisms. A zeta subfamily glutathione S-transferase gene from Triticum durum (cv Cappelli) (TdGSTZ1) was characterized as part of a complex detoxification mechanism. The effect of different abiotic stresses on TdGSTZ1 revealed that the gene is unexpectedly responsive to glyphosate (GLY) herbicide despite it should not be part of tolerance mechanisms. Its role in the non-target-site mechanism of GLY resistance was then investigated. To analyze the GLY and the TdGSTZ1 overexpression effects on vacuolar sorting mechanisms, we performed transient transformation experiments in Nicotiana tabacum protoplasts using two vacuolar markers, AleuGFPgl133 and GFPgl133Chi, labeling the Sar1 dependent or independent sorting, respectively. We observed that the adaptive reaction of tobacco protoplasts vacuolar system to the treatment with GLY could be partially mimicked by the overexpression of TdGSTZ1 gene. To confirm the influence of GLY on the two vacuolar markers accumulation and the potential involvement of the secretion pathway activity in detoxification events, Arabidopsis thaliana transgenic plants overexpressing the non-glycosylated versions of the two markers were analyzed. The results suggested that GLY treatment specifically altered different vacuolar sorting characteristics, suggesting an involvement of the receptor-mediated AleuGFP sorting mechanism in GLY resistance. Finally, the expression analysis of selected genes confirmed that the non-target-site GLY resistance mechanisms are related to vacuolar sorting.

Three Pectin Methylesterase Inhibitors Protect Cell Wall Integrity for Arabidopsis Immunity to Botrytis

Infection by necrotrophs is a complex process that starts with the breakdown of the cell wall (CW) matrix initiated by CW-degrading enzymes and results in an extensive tissue maceration. Plants exploit induced defense mechanisms based on biochemical modification of the CW components to protect themselves from enzymatic degradation. The pectin matrix is the main CW target of Botrytis cinerea, and pectin methylesterification status is strongly altered in response to infection. The methylesterification of pectin is controlled mainly by pectin methylesterases (PMEs), whose activity is posttranscriptionally regulated by endogenous protein inhibitors (PMEIs). Here, AtPMEI10, AtPMEI11, and AtPMEI12 are identified as functional PMEIs induced in Arabidopsis (Arabidopsis thaliana) during B. cinerea infection. AtPMEI expression is strictly regulated by jasmonic acid and ethylene signaling, while only AtPMEI11 expression is controlled by PME-related damage-associated molecular patterns, such as oligogalacturonides and methanol. The decrease of pectin methylesterification during infection is higher and the immunity to B. cinerea is compromised in pmei10, pmei11, and pmei12 mutants with respect to the control plants. A higher stimulation of the fungal oxalic acid biosynthetic pathway also can contribute to the higher susceptibility of pmei mutants. The lack of PMEI expression does not affect hemicellulose strengthening, callose deposition, and the synthesis of structural defense proteins, proposed as CW-remodeling mechanisms exploited by Arabidopsis to resist CW degradation upon B. cinerea infection. We show that PME activity and pectin methylesterification are dynamically modulated by PMEIs during B. cinerea infection. Our findings point to AtPMEI10, AtPMEI11, and AtPMEI12 as mediators of CW integrity maintenance in plant immunity.

Cisplatin, Oxaliplatin, and Kiteplatin Subcellular Effects Compared in a Plant Model

The immediate visual comparison of platinum chemotherapeutics’ effects in eukaryotic cells using accessible plant models of transgenic Arabidopsis thaliana is reported. The leading anticancer drug cisplatin, a third generation drug used for colon cancer, oxaliplatin and kiteplatin, promising Pt-based anticancer drugs effective against resistant lines, were administered to transgenic A. thaliana plants monitoring their effects on cells from different tissues. The transgenic plants’ cell cytoskeletons were labelled by the green fluorescent protein (GFP)-tagged microtubule-protein TUA6 (TUA6-GFP), while the vacuolar organization was evidenced by two soluble chimerical GFPs (GFPChi and AleuGFP) and one transmembrane GFP-tagged tonoplast intrinsic protein 1-1 (TIP1.1-GFP). The three drugs showed easily recognizable effects on plant subcellular organization, thereby providing evidence for a differentiated drug targeting. Genetically modified A. thaliana are confirmed as a possible rapid and low-cost screening tool for better understanding the mechanism of action of human anticancer drugs.

Drought and Heat Differentially Affect XTH Expression and XET Activity and Action in 3-Day-Old Seedlings of Durum Wheat Cultivars with Different Stress Susceptibility

Heat and drought stress have emerged as major constraints for durum wheat production. In the Mediterranean area, their negative effect on crop productivity is expected to be exacerbated by the occurring climate change. Xyloglucan endotransglucosylase/hydrolases (XTHs) are chief enzymes in cell wall remodeling, whose relevance in cell expansion and morphogenesis suggests a central role in stress responses. In this work the potential role of XTHs in abiotic stress tolerance was investigated in durum wheat. The separate effects of dehydration and heat exposure on XTH expression and its endotransglucosylase (XET) in vitro activity and in vivo action have been monitored, up to 24 h, in the apical and sub-apical root regions and shoots excised from 3-day-old seedlings of durum wheat cultivars differing in stress susceptibility/tolerance. Dehydration and heat stress differentially influence the XTH expression profiles and the activity and action of XET in the wheat seedlings, depending on the degree of susceptibility/tolerance of the cultivars, the organ, the topological region of the root and, within the root, on the gradient of cell differentiation. The root apical region was the zone mainly affected by both treatments in all assayed cultivars, while no change in XET activity was observed at shoot level, irrespective of susceptibility/tolerance, confirming the pivotal role of the root in stress perception, signaling, and response. Conflicting effects were observed depending on stress type: dehydration evoked an overall increase, at least in the apical region of the root, of XET activity and action, while a significant inhibition was caused by heat treatment in most cultivars. The data suggest that differential changes in XET action in defined portions of the root of young durum wheat seedlings may have a role as a response to drought and heat stress, thus contributing to seedling survival and crop establishment. A thorough understanding of the mechanisms underlying these variations could represent the theoretical basis for implementing breeding strategies to develop new highly productive hybrids adapted to future climate scenarios.

Integrated Medicine with vegetable derived antioxidant and vitamin D : effects on oxidative stress and bone mineral metabolism of aged patients with renal disease

Background: Aging and chronic kidney disease (CKD) are associated with bone mineral metabolism disorders, in addition to disarrangement of trabeculae structure and bone architecture. Increased alkaline phosphatase (ALP) and parathyroid hormone (PTH) have been related with abnormal bone turn over. Lycopene, a plant derived micronutrient, has strong quenching and free radical scavenging attitude. Objectives: This study aimed to evaluate the effects of lycopene and calcifediol (25 OH D3) based Integrated Medicine on ALP, PTH and oxidative stress. Methods: In octogenarians, nonagenarians and centenarians with chronic kidney disease (GFR :45 ±10,4 ml/min/1,73 m2), vitamin D deficiency and abnormal ALP, PTH blood values, the effects of daily lycopene supplementation on blood oxysterols and on 4-hydroxy-2,3-trans- nonenal (4-HNE) as markers of oxidative stress were evaluated. The effects of calcifediol administration together with daily lycopene supplementation on PTH and ALP blood concentrations were also investigated. Results: Daily lycopene supplementation induced a reduction of oxysterols (α-triol: 0.40 ± 0.07 μg / L vs 0.32 ± 0, 04 μg / L and β-epoxi cholesterol: 5.3 ± 1.3 μg / L vs 3.7 ± 0.6 μg / L) but not of 4-HNE (0.27 ± 0.18 nmol / L vs 0.25 ± 0.20 nmol / L). Vitamin D added to lycopene for two weeks decreased the blood values of ALP (106 ± 40 U / L vs 69 ± 19 U / L) and PTH (108 ±42 pg/ml vs 66± 21 pg/ml). Conclusion: Tomato derived lycopene, with daily supplements, decreased cholesterol oxidation products. Calcifediol and vegetable derived antioxidant daily supplementations were associated to normalization of ALP and PTH. Keywords: oxysterols; 4-hydroxynonenal; lycopene; alkaline phosphatase; parathyroid hormone; chronic kidney disease (CKD) 

Fractionate analysis of the phytochemical composition and antioxidant activities in advanced breeding lines of high-lycopene tomatoes

The results of the first study characterizing new high-lycopene tomato advanced breeding lines, to determine the phytochemical content as well asin vitroantioxidant activities of peel, pulp and seed fractions are presented.

Α-Cyclodextrin encapsulation of supercritical CO₂ extracted oleoresins from different plant matrices: A stability study

Here we describe the encapsulation in α-cyclodextrins (α-CDs) of wheat bran, pumpkin and tomato oleoresins, extracted by supercritical carbon dioxide, to obtain freeze-dried powders useful as ready-to-mix ingredients for novel functional food formulation. The stability of tocochromanols, carotenoids and fatty acids in the oleoresin/α-CD complexes, compared to the corresponding free oleoresins, was also monitored over time in different combinations of storage conditions. Regardless of light, storage at 25°C of free oleoresins determined a rapid decrease in carotenoids, tocochromanols and PUFAs. α-CD encapsulation improved the stability of most bioactive compounds. Storage at 4°C synergized with encapsulation in preventing degradation of bioactives. Unlike all other antioxidants, lycopene in tomato oleoresin/α-CD complex resulted to be more susceptible to oxidation than in free oleoresin, likely due to its selective sequestration from the interaction with other lipophilic molecules of the oleoresin.

Lipid/detergent mixed micelles as a tool for transferring antioxidant power from hydrophobic natural extracts into bio-deliverable liposome carriers: the case of lycopene rich oleoresins

Lipid/detergent mixed micelles promote and modulate the incorporation of carotenoids from natural oleoresins into bio-deliverable liposome carriers.

Molecular dissection of Phaseolus vulgaris polygalacturonase-inhibiting protein 2 reveals the presence of hold/release domains affecting protein trafficking toward the cell wall

The plant endomembrane system is massively involved in the synthesis, transport and secretion of cell wall polysaccharides and proteins; however, the molecular mechanisms underlying trafficking toward the apoplast are largely unknown. Besides constitutive, the existence of a regulated secretory pathway has been proposed. A polygalacturonase inhibitor protein (PGIP2), known to move as soluble cargo and reach the cell wall through a mechanism distinguishable from default, was dissected in its main functional domains (A, B, C, D), and C sub-fragments (C1-10), to identify signals essential for its regulated targeting. The secretion patterns of the fluorescent chimeras obtained by fusing different PGIP2 domains to the green fluorescent protein (GFP) were analyzed. PGIP2 N-terminal and leucine-rich repeat domains (B and C, respectively) seem to operate as holding/releasing signals, respectively, during PGIP2 transit through the Golgi. The B domain slows down PGIP2 secretion by transiently interacting with Golgi membranes. Its depletion leads, in fact, to the secretion via default (Sp2-susceptible) of the ACD-GFP chimera faster than PGIP2. Depending on its length (at least the first 5 leucine-rich repeats are required), the C domain modulates B interaction with Golgi membranes allowing the release of chimeras and their extracellular secretion through a Sp2 independent pathway. The addition of the vacuolar sorting determinant Chi to PGIP2 diverts the path of the protein from cell wall to vacuole, suggesting that C domain is a releasing rather than a cell wall sorting signal.

Subcellular compartmentalization in protoplasts from Artemisia annua cell cultures: engineering attempts using a modified SNARE protein

Plants are ideal bioreactors for the production of macromolecules but transport mechanisms are not fully understood and cannot be easily manipulated. Several attempts to overproduce recombinant proteins or secondary metabolites failed. Because of an independent regulation of the storage compartment, the product may be rapidly degraded or cause self-intoxication. The case of the anti-malarial compound artemisinin produced by Artemisia annua plants is emblematic. The accumulation of artemisinin naturally occurs in the apoplast of glandular trichomes probably involving autophagy and unconventional secretion thus its production by undifferentiated tissues such as cell suspension cultures can be challenging. Here we characterize the subcellular compartmentalization of several known fluorescent markers in protoplasts derived from Artemisia suspension cultures and explore the possibility to modify compartmentalization using a modified SNARE protein as molecular tool to be used in future biotechnological applications. We focused on the observation of the vacuolar organization in vivo and the truncated form of AtSYP51, 51H3, was used to induce a compartment generated by the contribution of membrane from endocytosis and from endoplasmic reticulum to vacuole trafficking. The artificial compartment crossing exocytosis and endocytosis may trap artemisinin stabilizing it until extraction; indeed, it is able to increase total enzymatic activity of a vacuolar marker (RGUSChi), probably increasing its stability. Exploring the 51H3-induced compartment we gained new insights on the function of the SNARE SYP51, recently shown to be an interfering-SNARE, and new hints to engineer eukaryote endomembranes for future biotechnological applications.

Enzyme-aided extraction of lycopene from high-pigment tomato cultivars by supercritical carbon dioxide

This work reports a novel enzyme-assisted process for lycopene concentration into a freeze-dried tomato matrix and describes the results of laboratory scale lycopene supercritical CO2 (SC-CO2) extractions carried out with untreated (control) and enzyme-digested matrices. The combined use of food-grade commercial plant cell-wall glycosidases (Celluclast/Novozyme plus Viscozyme) allows to increase lycopene (∼153%) and lipid (∼137%) concentration in the matrix and rises substrate load onto the extraction vessel (∼46%) compared to the control. The addition of an oleaginous co-matrix (hazelnut seeds) to the tomato matrix (1:1 by weight) increases CO2 diffusion through the highly dense enzyme-treated matrix bed and provides lipids that are co-extracted increasing lycopene yield. Under the same operative conditions (50 MPa, 86 °C, 4 mL min(-1) SC-CO2 flow) extraction yield from control and Celluclast/Novozyme+Viscozyme-treated tomato matrix/co-matrix mixtures was similar, exceeding 75% after 4.5h of extraction. However, the total extracted lycopene was ∼3 times higher in enzyme-treated matrix than control.

Cellular localization and biochemical characterization of a chimeric fluorescent protein fusion of Arabidopsis cellulose synthase-like A2 inserted into Golgi membrane

Cellulose synthase-like (Csl) genes are believed to encode enzymes for the synthesis of cell wall matrix polysaccharides. The subfamily of CslA is putatively involved in the biosynthesis of β -mannans. Here we report a study on the cellular localization and the enzyme activity of an Arabidopsis CslA family member, AtCslA2. We show that the fluorescent protein fusion AtCslA2-GFP, transiently expressed in tobacco leaf protoplasts, is synthesized in the ER and it accumulates in the Golgi stacks. The chimera is inserted in the Golgi membrane and is functional since membrane preparations obtained by transformed protoplasts carry out the in vitro synthesis of a 14C-mannan starting from GDP-D-[U-14C]mannose as substrate. The enzyme specific activity is increased by approximately 38% in the transformed protoplasts with respect to wild-type. Preliminary tests with proteinase K, biochemical data, and TM domain predictions suggest that the catalytic site of AtCslA2 faces the Golgi lumen.

Two glycosylated vacuolar GFPs are new markers for ER-to-vacuole sorting

Vacuolar Sorting Determinants (VSDs) have been extensively studied in plants but the mechanisms for the accumulation of storage proteins in somatic tissues are not yet fully understood. In this work we used two mutated versions of well-documented vacuolar fluorescent reporters, a GFP fusion in frame with the C-terminal VSD of tobacco chitinase (GFPChi) and an N-terminal fusion in frame with the sequence-specific VSD of the barley cysteine protease aleurain (AleuGFP). The GFP sequence was mutated to present an N-glycosylation site at the amino-acid position 133. The reporters were transiently expressed in Nicotiana tabacum protoplasts and agroinfiltrated in Nicotiana benthamiana leaves and their distribution was identical to that of the non-glycosylated versions. With the glycosylated GFPs we could highlight a differential ENDO-H sensitivity and therefore differential glycan modifications. This finding suggests two different and independent routes to the vacuole for the two reporters. BFA also had a differential effect on the two markers and further, inhibition of COPII trafficking by a specific dominant-negative mutant (NtSar1h74l) confirmed that GFPChi transport from the ER to the vacuole is not fully dependent on the Golgi apparatus.

Comparative genomics reveals candidate carotenoid pathway regulators of ripening watermelon fruit

Background

Many fruits, including watermelon, are proficient in carotenoid accumulation during ripening. While most genes encoding steps in the carotenoid biosynthetic pathway have been cloned, few transcriptional regulators of these genes have been defined to date. Here we describe the identification of a set of putative carotenoid-related transcription factors resulting from fresh watermelon carotenoid and transcriptome analysis during fruit development and ripening. Our goal is to both clarify the expression profiles of carotenoid pathway genes and to identify candidate regulators and molecular targets for crop improvement.

Results

Total carotenoids progressively increased during fruit ripening up to ~55 μg g^-1 fw in red-ripe fruits. Trans-lycopene was the carotenoid that contributed most to this increase. Many of the genes related to carotenoid metabolism displayed changing expression levels during fruit ripening generating a metabolic flux toward carotenoid synthesis. Constitutive low expression of lycopene cyclase genes resulted in lycopene accumulation. RNA-seq expression profiling of watermelon fruit development yielded a set of transcription factors whose expression was correlated with ripening and carotenoid accumulation. Nineteen putative transcription factor genes from watermelon and homologous to tomato carotenoid-associated genes were identified. Among these, six were differentially expressed in the flesh of both species during fruit development and ripening.

Conclusions

Taken together the data suggest that, while the regulation of a common set of metabolic genes likely influences carotenoid synthesis and accumulation in watermelon and tomato fruits during development and ripening, specific and limiting regulators may differ between climacteric and non-climacteric fruits, possibly related to their differential susceptibility to and use of ethylene during ripening.

Effect of drying and co-matrix addition on the yield and quality of supercritical CO₂ extracted pumpkin (Cucurbita moschata Duch.) oil

In this work a process for obtaining high vitamin E and carotenoid yields by supercritical carbon dioxide (SC-CO₂) extraction from pumpkin (Cucurbita moschata Duch.) is described. The results show that the use of a vacuum oven-dried [residual moisture (∼8%)] and milled (70 mesh sieve) pumpkin flesh matrix increased SC-CO₂ extraction yields of total vitamin E and carotenoids of ∼12.0- and ∼8.5-fold, respectively, with respect to the use of a freeze-dried and milled flesh matrix. The addition of milled (35 mesh) pumpkin seeds as co-matrix (1:1, w/w) allowed a further ∼1.6-fold increase in carotenoid yield, besides to a valuable enrichment of the extracted oil in vitamin E (274 mg/100 g oil) and polyunsaturated fatty acids. These findings encourage further studies in order to scale up the process for possible industrial production of high quality bioactive ingredients from pumpkin useful in functional food or cosmeceutical formulation.

AtSYP51/52 functions diverge in the post-Golgi traffic and differently affect vacuolar sorting

Plant sensitive factor attachment protein receptors (SNAREs) encoded by genes of the same sub-family are generally considered as redundant in promoting vesicle-associated membrane fusion events. Nonetheless, the application of innovative experimental approaches highlighted that members of the same gene sub-family often have different functional specificities. In this work, two closely related Qc-SNAREs--the AtSYP51 and the AtSYP52--are compared in their ability to influence different secretory pathways. Their role in the vesicle sorting to the central vacuole has been revised and they were found to have a novel inhibitory function. When transiently overexpressed, the SYP51 and the SYP52 distributed between the TGN and the tonoplast. Our data demonstrate that these SYPs (syntaxin of plants) act as t-SNARE when present on the membrane of TGN/PVC, whereas they behave as inhibitory or interfering SNAREs (i-SNAREs) when they accumulate on the tonoplast. Moreover, the performed functional analysis indicated that the AtSYP51 and the AtSYP52 roles differ in the traffic to the vacuole. The findings are a novel contribution to the functional characterization of plant SNAREs that reveals additional non-fusogenic roles.

Possible use of the carbohydrates present in tomato pomace and in byproducts of the supercritical carbon dioxide lycopene extraction process as biomass for bioethanol production

This study provides information about the carbohydrate present in tomato pomace (skins, seeds, and vascular tissues) as well as in the byproducts of the lycopene supercritical carbon dioxide extraction (SC-CO₂) such as tomato serum and exhausted matrix and reports their conversion into bioethanol. The pomace, constituting approximately 4% of the tomato fruit fresh weight, and the SC-CO₂-exhausted matrix were enzyme saccharified with 0.1% Driselase leading to sugar yields of ~383 and ~301 mg/g dw, respectively. Aliquots of the hydrolysates and of the serum (80% tomato sauce fw) were fermented by Saccharomyces cerevisiae . The bioethanol produced from each waste was usually >50% of the calculated theoretical amount, with the exception of the exhausted matrix hydolysate, where a sugar concentration >52.8 g/L inhibited the fermentation process. Furthermore, no differences in the chemical solubility of cell wall polysaccharides were evidenced between the SC-CO₂-lycopene extracted and unextracted matrices. The deduced glycosyl linkage composition and the calculated amount of cell wall polysaccharides remained similar in both matrices, indicating that the SC-CO₂ extraction technology does not affect their structure. Therefore, tomato wastes may well be considered as potential alternatives and low-cost feedstock for bioethanol production.

Quality and Efficacy of Tribulus terrestris as an Ingredient for Dermatological Formulations

Tribulus terrestris L. (Zygophyllaceae) is an annual plant commonly known as Puncture vine. It is dramatically gaining interest as a rich source of saponins. T. terrestris is a promising ingredient for many industries and recent patents on dermatological applications support the use of this plant for cosmetics and hygiene. Nonetheless problems arise in the selection of the material to be used. The extracts of different origins may differ substantially. Natural speciation processes normally influence ‘variations’ in wild-crafted medicinal plants. The genus Tribulus is emblematic. Taxonomic status of T. terrestris is complicated by the wide geographical distribution leading to high levels of genetic polymorphism. Being aware of such variability we selected 3 commercial Tribulus extracts and compared their biological effect on Candida albicans with the effect produced by an extract from local plants (South of Apulia, Italy). One of the commercial extracts with the best anti-candida performance was used to substitute triclosan in a detergent formulation and it proved to improve the product performance in the control of potentially pathogenic skin flora such as C. albicans.

Sphingomonas cynarae sp. nov., a proteobacterium that produces an unusual type of sphingan

Strain SPC-1T was isolated from the phyllosphere of Cynara cardunculus L. var. sylvestris (Lamk) Fiori (wild cardoon), a Mediterranean native plant considered to be the wild ancestor of the globe artichoke and cultivated cardoon. This Gram-stain-negative, catalase-positive, oxidase-negative, non-spore-forming, rod-shaped and non-motile strain secreted copious amounts of an exopolysaccharide, formed slimy, viscous, orange-pigmented colonies and grew optimally at around pH 6.0–6.5 and 26–30 °C in the presence of 0–0.5 % NaCl. Phylogenetic analysis based on comparisons of 16S rRNA gene sequences demonstrated that SPC-1T clustered together with species of the genus Sphingomonas sensu stricto. The G+C content of the DNA (66.1 mol%), the presence of Q-10 as the predominant ubiquinone, sym-homospermidine as the predominant polyamine, 2-hydroxymyristic acid (C14 : 0 2-OH) as the major hydroxylated fatty acid, the absence of 3-hydroxy fatty acids and the presence of sphingoglycolipid supported this taxonomic position. 16S rRNA gene sequence analysis showed that SPC-1T was most closely related to Sphingomonas hankookensis ODN7T, Sphingomonas insulae DS-28T and Sphingomonas panni C52T (98.19, 97.91 and 97.11 % sequence similarities, respectively). However, DNA–DNA hybridization analysis did not reveal any relatedness at the species level. Further differences were apparent in biochemical traits, and fatty acid, quinone and polyamine profiles leading us to conclude that strain SPC-1T represents a novel species of the genus Sphingomonas , for which the name Sphingomonas cynarae sp. nov. is proposed; the type strain is SPC-1T ( = JCM 17498T = ITEM 13494T). A component analysis of the exopolysaccharide suggested that it represents a novel type of sphingan containing glucose, rhamnose, mannose and galactose, while glucuronic acid, which is commonly found in sphingans, was not detected.

Isoprenoid, lipid, and protein contents in intact plastids isolated from mesocarp cells of traditional and high-pigment tomato cultivars at different ripening stages

This study reports quali-quantitative analyses on isoprenoids, phospholipids, neutral lipids, phytosterols, and proteins in purified plastids isolated from fresh fruits of traditional (Donald and Incas) and high-pigment (Kalvert and HLY-18) tomato cultivars at four ripening stages. In all of the investigated cultivars, lycopene, β-catotene, lutein, and total carotenoids varied significantly during ripening. Chromoplasts of red-ripe tomato fruits of high-pigment cultivars accumulated twice as much as lycopene (307.6 and 319.2 μg/mg of plastid proteins in Kalvert and HLY-18, respectively) than ordinary cultivars (178.6 and 151.7 μg/mg of plastid proteins in Donald and Incas, respectively); differences in chlorophyll and α-tocopherol contents were also evidenced. Phospholipids and phytosterols increased during ripening, whereas triglycerides showed a general decrease. Regardless of the stage of ripening, palmitic acid was the major fatty acid in all cultivars (ranging from 35 to 52% of the total fatty acids), followed by stearic, oleic, linoleic, linolenic, and myristic acids, but their relative percentage was affected by ripening. Most of the bands detected on the SDS-PAGEs of plastid proteins were constantly present during chloroplast-to-chromoplast conversion, some others disappeared, and only one, with a molecular weight of ~41.6 kDa, was found to increase in intensity.

Dynamic protein trafficking to the cell wall

Recently we have studied the secretion pattern of a pectin methylesterase inhibitor protein (PMEI1) and a polygalacturonase inhibitor protein (PGIP2) in tobacco protoplast using the protein fusions, secGFP-PMEI1 and PGIP2-GFP. Both chimeras reach the cell wall by passing through the endomembrane system but using distinct mechanisms and through a pathway distinguishable from the default sorting of a secreted GFP. After reaching the apoplast, sec-GFP-PMEI1 is stably accumulated in the cell wall, while PGIP2-GFP undergoes endocytic trafficking. Here we describe the final localization of PGIP2-GFP in the vacuole, evidenced by co-localization with the marker Aleu-RFP, and show a graphic elaboration of its sorting pattern. A working model taking into consideration the presence of a regulated apoplast-targeted secretion pathway is proposed.

Protein trafficking to the cell wall occurs through mechanisms distinguishable from default sorting in tobacco

The secretory pathway in plants involves sustained traffic to the cell wall, as matrix components, polysaccharides and proteins reach the cell wall through the endomembrane system. We studied the secretion pattern of cell-wall proteins in tobacco protoplasts and leaf epidermal cells using fluorescent forms of a pectin methylesterase inhibitor protein (PMEI1) and a polygalacturonase inhibitor protein (PGIP2). The two most representative protein fusions, secGFP-PMEI1 and PGIP2-GFP, reached the cell wall by passing through ER and Golgi stacks but using distinct mechanisms. secGFP-PMEI1 was linked to a glycosylphosphatidylinositol (GPI) anchor and stably accumulated in the cell wall, regulating the activity of the endogenous pectin methylesterases (PMEs) that are constitutively present in this compartment. A mannosamine-induced non-GPI-anchored form of PMEI1 as well as a form (PMEI1-GFP) that was unable to bind membranes failed to reach the cell wall, and accumulated in the Golgi stacks. In contrast, PGIP2-GFP moved as a soluble cargo protein along the secretory pathway, but was not stably retained in the cell wall, due to internalization to an endosomal compartment and eventually the vacuole. Stable localization of PGIP2 in the wall was observed only in the presence of a specific fungal endopolygalacturonase ligand in the cell wall. Both secGFP-PMEI1 and PGIP2-GFP sorting were distinguishable from that of a secreted GFP, suggesting that rigorous and more complex controls than the simple mechanism of bulk flow are the basis of cell-wall growth and differentiation.

Vorinostat synergises with capecitabine through upregulation of thymidine phosphorylase

Background:

Potentiation of anticancer activity of capecitabine is required to improve its therapeutic index. In colorectal cancer (CRC) cells, we evaluated whether the histone deacetylase-inhibitor vorinostat may induce synergistic antitumour effects in combination with capecitabine by modulating the expression of thymidine phosphorylase (TP), a key enzyme in the conversion of capecitabine to 5-florouracil (5-FU), and thymidylate synthase (TS), the target of 5-FU.

Methods:

Expression of TP and TS was measured by real-time PCR, western blotting and immunohistochemistry. Knockdown of TP was performed by specific small interfering RNA. Antitumour activity of vorinostat was assessed in vitro in combination with the capecitabine active metabolite deoxy-5-fluorouridine (5′-DFUR) according to the Chou and Talay method and by evaluating apoptosis as well as in xenografts-bearing nude mice in combination with capecitabine.

Results:

Vorinostat induced both in vitro and in vivo upregulation of TP as well as downregulation of TS in cancer cells, but not in ex vivo treated peripheral blood lymphocytes. Combined treatment with vorinostat and 5′-DFUR resulted in a synergistic antiproliferative effect and increased apoptotic cell death in vitro. This latter effect was impaired in cells where TP was knocked. In vivo, vorinostat plus capecitabine potently inhibited tumour growth, increased apoptosis and prolonged survival compared with control or single-agent treatments.

Conclusions:

Overall, this study suggests that the combination of vorinostat and capecitabine is an innovative antitumour strategy and warrants further clinical evaluation for the treatment of CRC.

Optimisation of biological and physical parameters for lycopene supercritical CO2 extraction from ordinary and high-pigment tomato cultivars

BACKGROUND

Lycopene is used for several industrial applications. Supercritical CO(2) (SC-CO(2)) extraction from red-ripe tomato fruits is an excellent technique to replace the use of harmful solvents. In this study, starting from red-ripe tomatoes of ordinary and high-lycopene cultivars, the effect of different agronomical and technical aspects on lycopene content, stability and yield was evaluated throughout the production process from fresh tomatoes to the final SC-CO(2)-extracted oleoresin containing lycopene.

RESULTS

Red-ripe tomato cultivars differed in their lycopene content. Irrigation excess or deficit caused an increase in the amount of lycopene in the fruits. Fresh tomatoes were processed into a lyophilised matrix suitable for SC-CO(2) extraction, which could be stored for more than 6 months at -20 degrees C without lycopene loss. Under the optimal extraction conditions, efficiencies of up to 80% were achieved, but the recovery of lycopene in the extracted oleoresin was very low (approximately 24%). Co-extraction of the tomato matrix mixed with a lipid co-matrix allowed the recovery of approximately 90% of lycopene in the oleoresin. Using the high-lycopene cultivars, the yield of total extracted lycopene increased by approximately 60% with respect to the ordinary cultivars. Lipids and other biologically active molecules were present in the oleoresin.

CONCLUSION

A method for extracting, from a tomato matrix, a natural and solvent-free oleoresin containing lycopene dissolved in a highly unsaturated vegetable oil has been described. The oleoresin represents an excellent product for testing on cancer and cardiovascular disease prevention.

In muro feruloylation and oxidative coupling in monocots: a possible role in plant defense against pathogen attacks

Recently we have suggested that (glucurono)arabinoxylans [(G)AX] feruloylation and oxidative coupling occur both intra-protoplasmically and, extra-protoplasmically, in the plant cell wall. In this work we illustrate a model of two possible mechanisms of polysaccharide feruloylation and oxidative coupling in plants. Moreover, we take into consideration the possible role of in muro feruloylation as a rapid defense mechanism against potential plant pathogen and parasite infections.

Evidence for intra- and extra-protoplasmic feruloylation and cross-linking in wheat seedling roots

The sub-cellular feruloylation and oxidative coupling sites of cell wall polysaccharides were investigated in planta by monitoring the kinetics of appearance of arabinosyl- and feruloyl-radiolabelled polysaccharides in the protoplasmic compartment and their secretion in the wall either in the presence or absence of brefeldin A (BFA). By using root apical segments excised from wheat seedlings (Triticum durum Desf.), incubated with trans-[U-(14)C]cinnamic acid, we demonstrated that [14C]ferulate, likely [14C]diferulate, as well as trimers and larger products of ferulate are incorporated into the protoplasmic polysaccharides very rapidly within 1-3 min of [14C]cinnamate feeding. This agrees with the assumption that (glucurono)arabinoxylans [(G)AX] feruloylation and oxidative coupling occur intracellularly, likely in the Golgi apparatus. Simultaneously, polymer bound radioactive hydroxycinnamic acids appeared to be incorporated into the cell wall of root apical segments as early as 2 min after trans-[U-(14)C]cinnamic acid feeding. On the contrary, starting from L-[1-(14)C]arabinose as tracer, the secretion of the pentose-containing polymers into the wall was between 5 to 10 min. These results indicated that (G)AX feruloylation and oxidative coupling occur both intra-protoplasmically and in muro. The occurrence of in muro feruloylation and oxidative coupling was confirmed by the use of BFA a well known inhibitor of secretion. The drug caused a strong inhibition of the synthesis and secretion into the wall of the 14C-pentosyl-labelled polymers as well as of 14C-feruloyl-polymers. In spite of this, the total amount of 14C-feruloyl-polymers incorporated into the wall was only slightly affected by BFA. This indicates the existence of a mechanism involved into secretion of the activated hydroxycinnamoyl precursors to the wall, alternative to that involved in polysaccharide secretion.

Water stress and cell wall polysaccharides in the apical root zone of wheat cultivars varying in drought tolerance

Glycosyl composition and linkage analysis of cell wall polysaccharides were examined in apical root zones excised from water-stressed and unstressed wheat seedlings (Triticum durum Desf.) cv. Capeiti ("drought-tolerant") and cv. Creso ("drought sensitive"). Wall polysaccharides were sequentially solubilized to obtain three fractions: CDTA+Na(2)CO(3) extract, KOH extract and the insoluble residue (alpha-cellulose). A comparison between the two genotypes showed only small variations in the percentages of matrix polysaccharides (CDTA+Na(2)CO(3) plus KOH extract) and of the insoluble residues (alpha-cellulose) in water-stressed and unstressed conditions. Xylosyl, glucosyl and arabinosyl residues represented more than 90 mol% of the matrix polysaccharides. The linkage analysis of matrix polysaccharides showed high levels of xyloglucans (23-39 mol%), and arabinoxylans (38-48 mol%) and a low amount of pectins and (1-->3), (1-->4)-beta-D-glucans. The high level of xyloglucans was supported by the release of the diagnostic disaccharide isoprimeverose after Driselase digestion of KOH-extracted polysaccharides. In the "drought-tolerant" cv. Capeiti the mol% of side chains of rhamnogalacturonan I and II significantly increased in response to water stress, whereas in cv. Creso, this increase did not occur. The results support a role of the pectic side chains during water stress response in a drought-tolerant wheat cultivar.

Water stress and cell wall polysaccharides in the apical root zone of wheat cultivars varying in drought tolerance

Glycosyl composition and linkage analysis of cell wall polysaccharides were examined in apical root zones excised from water-stressed and unstressed wheat seedlings (Triticum durum Desf.) cv. Capeiti ("drought-tolerant") and cv. Creso ("drought sensitive"). Wall polysaccharides were sequentially solubilized to obtain three fractions: CDTA+Na(2)CO(3) extract, KOH extract and the insoluble residue (alpha-cellulose). A comparison between the two genotypes showed only small variations in the percentages of matrix polysaccharides (CDTA+Na(2)CO(3) plus KOH extract) and of the insoluble residues (alpha-cellulose) in water-stressed and unstressed conditions. Xylosyl, glucosyl and arabinosyl residues represented more than 90 mol% of the matrix polysaccharides. The linkage analysis of matrix polysaccharides showed high levels of xyloglucans (23-39 mol%), and arabinoxylans (38-48 mol%) and a low amount of pectins and (1-->3), (1-->4)-beta-D-glucans. The high level of xyloglucans was supported by the release of the diagnostic disaccharide isoprimeverose after Driselase digestion of KOH-extracted polysaccharides. In the "drought-tolerant" cv. Capeiti the mol% of side chains of rhamnogalacturonan I and II significantly increased in response to water stress, whereas in cv. Creso, this increase did not occur. The results support a role of the pectic side chains during water stress response in a drought-tolerant wheat cultivar.