Summary
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.
Significance Statement
The cellular distribution of three xyloglucan endotransglucosylase/hydrolases (XTHs) was monitored comparatively while expressing respective fluorescent constructs in Arabidopsis cotyledons. We show that XTH11 and XTH33 follow conventional protein secretion towards cell wall and plasma membrane, respectively, whereas XTH29, the only XTH predicted to lack a signal peptide, is secreted into the wall via exocyst‐positive organelle‐mediated unconventional protein secretion (UPS). Significantly, XTH29, poorly expressed in physiological conditions, demonstrates upregulation under drought and high temperature conditions, suggesting a specific possible role for UPS‐secreted XTH29 in stress responses.
Changes in bioactive compounds and antioxidant activities of an ordinary (Rio Grande) and three high-lycopene (HLY 13, HLY 18 and Lyco 2) tomato cultivars (cvs) were studied at four different fruit ...ripening stages (green, green-orange, orange-red and red-ripe). Lipophilic and hydrophilic antioxidant activities (LAA and HAA, respectively) were determined and their correlations with ascorbic acid (AsA), dehydroascorbic acid (DHA), total vitamin C (AsA+DHA), phenolics, flavonoids, total carotenoid and lycopene contents were investigated. The stage of ripening significantly influenced the total carotenoid and lycopene contents, as well as the LAA of all investigated tomato cvs. Good correlations between LAA and both total carotenoid and lycopene contents were found using either the TEAC assay or the FRAP assay. During ripening, cvs HLY 13 and HLY 18 exhibited more than 100% higher total carotenoid and lycopene contents compared to Rio Grande. At the red-ripe stage, cv HLY 18 accumulated the highest phenolic and flavonoid contents. However, Lyco 2 showed the highest levels of DHA and total vitamin C. Although, the HAA of studied tomato cvs were also significantly influenced by the ripening stages, HAA resulted correlated only to the levels of phenolics and flavonoids when the TEAC assay was used. However, using the FRAP assay, the HAA were well correlated to the total vitamin C and DHA contents.
Fourteen cultivars of cherry tomatoes and four cultivars of high-pigment tomato hybrids were cultivated in southern Italy, and the red-ripe fruits were analyzed for their content in different classes ...of antioxidants and for their antioxidant activity. Among the different cultivars, significant differences were found between lycopene, beta-carotene, alpha-tocopherol, vitamin C (ascorbic acid and dehydroascorbic acid), and total phenolic and flavonoid contents. LS203 and Corbus appear to be the cultivars with the highest content of lipophilic and hydrophilic antioxidants among cherry tomatoes, respectively. All cultivars of high-pigment tomato hybrids showed an expected exceptionally high lycopene content. Among them, the highest content of lipophilic and hydrophilic antioxidants was found in cv. HLY 13. Hydrophilic and lipophilic antioxidant activities were both significantly influenced by genotype. Such results highlight an existing unexploited variability in tomato germplasm and stress the need to evaluate the biodiversity and to support conventional breeding programs to improve tomato nutritional value.
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.
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.
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.
The immune system is essential to maintain the mutualistic homeostatic interaction between the host and its micro- and mycobiota. Living as a commensal, Saccharomyces cerevisiae could potentially ...shape the immune response in a significant way. We observed that S. cerevisiae cells induce trained immunity in monocytes in a strain-dependent manner through enhanced TNFα and IL-6 production upon secondary stimulation with TLR ligands, as well as bacterial and fungal commensals. Differential chitin content accounts for the differences in training properties observed among strains, driving induction of trained immunity by increasing cytokine production and direct antimicrobial activity both in vitro and in vivo. These chitin-induced protective properties are intimately associated with its internalization, identifying a critical role of phagosome acidification to facilitate microbial digestion. This study reveals how commensal and passenger microorganisms could be important in promoting health and preventing mucosal diseases by modulating host defense toward pathogens and thus influencing the host microbiota-immune system interactions.
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.
Significant differences were detected among tomato cvs in all studied antioxidant components, as well as in the antioxidant activity of their hydrophilic and lipophilic fractions. High-lycopene ...tomato cvs showed higher lycopene, β-carotene, HAA and LAA when compared to cv Donald. Cv HLY 18 showed the highest lycopene and β-carotene content with 232.9
mg/kg fresh weight (fw) and 19.4
mg/kg fw, respectively. Except for Kalvert, high-lycopene tomato cvs also obtained higher total vitamin C levels, with cv HLY 13 top ranking with an average of 352.8
mg/kg fw. LAA ranged from 133.5
μM Trolox/100
g fw in cv Donald to 540.1
μM Trolox/100
g fw in cv Lyco 2 and was significantly correlated to lycopene (
r
=
0.53;
p
<
0.01) and β-carotene (
r
=
0.56;
p
<
0.01) contents. A variation between 2.7- and 4.0-fold was found in LAA of high-lycopene tomato cvs compared to Donald. HAA was significantly correlated to the amount of DHA (
r
=
0.61;
p
<
0.01) and total vitamin C (
r
=
0.60;
p
<
0.01). Although these data require confirmation over a longer period of time, this investigation suggests a promising use of the high-lycopene tomato cvs for the production of tomatoes with higher nutritional quality.
In this study, the antioxidant components and of six high-lycopene (Lyco 1, Lyco 2, HLY 02, HLY 13, HLY 18 and Kalvert) and one ordinary (Donald) tomato cultivars (cvs) grown simultaneously in an open-field of the Southern Italy were investigated. Lycopene, β-carotene, lutein, total phenols, flavonoids, ascorbic acid (AsA), dehydroascorbic acid (DHA) and total vitamin C (AsA
+
DHA) contents, as well as hydrophilic and lipophilic antioxidant activities (HAA and LAA) were determined. Significant differences were detected among tomato cvs in all studied antioxidant components, as well as in the antioxidant activity of their hydrophilic and lipophilic fractions. High-lycopene tomato cvs showed higher lycopene, β-carotene, HAA and LAA when compared to cv Donald. Cv HLY 18 showed the highest lycopene and β-carotene content with 232.9
mg/kg fresh weight (fw) and 19.4
mg/kg fw, respectively. Except for Kalvert, high-lycopene tomato cvs also obtained higher total vitamin C levels, with cv HLY 13 top ranking with an average of 352.8
mg/kg fw. LAA ranged from 133.5
μM Trolox/100
g fw in cv Donald to 540.1
μM Trolox/100
g fw in cv Lyco 2 and was significantly correlated to lycopene (
r
=
0.53;
p
<
0.01) and β-carotene (
r
=
0.56;
p
<
0.01) contents. A variation between 2.7- and 4.0-fold was found in LAA of high-lycopene tomato cvs compared to Donald. HAA was significantly correlated to the amount of DHA (
r
=
0.61;
p
<
0.01) and total vitamin C (
r
=
0.60;
p
<
0.01). Although these data require confirmation over a longer period of time, this investigation suggests a promising use of the high-lycopene tomato cvs for the production of tomatoes with higher nutritional quality.
•Supercritical CO2-extracted pumpkin oil was rich in lipophilic bioactive compounds.•Pumpkin oil/α-cyclodextrin complex was a ready-to-mix powder apt to supplement pasta.•Supplemented pasta was ...mostly enriched in carotenoids, tocochromanols and squalene.•Cyclodextrin oil chlatration increased carotenoid stability during pasta cooking.•Supplemented pasta provided a substantial proportion of RDA for A and E vitamins.
The feasibility of producing durum wheat pasta enriched with a lipophilic phytocomplex, extracted using supercritical carbon dioxide (SC-CO2), from ripe pumpkin, as free oil or as ready-to-mix oil/α-cyclodextrins (α-CDs) powder, was explored. Four types of pasta were prepared: (i) control spaghetti (S-CTRL); (ii) spaghetti supplemented with α-CDs (S-α-CD); (iii) spaghetti supplemented with pumpkin oil (S-Oil) and (iv) spaghetti supplemented with the pumpkin oil/α-CD powder (S-Oil/α-CD). The chemical, antioxidant, textural and sensory attributes of the different pasta were evaluated and compared. S-Oil and S-Oil/α-CD spaghetti were significantly enriched with phytosterols, squalene, carotenoids, tocochromanols and unsaturated fatty acids. Spaghetti containing α-CDs were slightly improved in terms of fiber content. Oil chlatration increased the stability of some bioactives during pasta production and ameliorated poor textural and sensory characteristics of the cooked spaghetti compared with S-Oil sample. S-Oil/α-CD spaghetti might be accepted by customers, if the potential health benefits were also explained.
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.
•The new Antioxidant/Oxidant Balance (AOB) is presented for the first time.•AOB simultaneously considers serum Antioxidant Capacity (AC) and oxidant level.•AOB assesses very well serum antioxidant ...status while AC cannot do it.•A lipophilic antioxidant-enriched pasta strongly improves serum AOB.•Contrarily, a hydrophilic/phenolic antioxidant-enriched pasta is ineffective.
Effectiveness in improving serum antioxidant status of two functional pastas was evaluated by the novel Antioxidant/Oxidant Balance (AOB) parameter, calculated as Antioxidant Capacity (AC)/Peroxide Level ratio, assessed here for the first time. In particular, Bran Oleoresin (BO) and Bran Water (BW) pastas, enriched respectively with either lipophilic (tocochromanols, carotenoids) or hydrophilic/phenolic antioxidants extracted from durum wheat bran, were studied. Notably, BO pasta was able to improve significantly (+65%) serum AOB during four hours after intake similarly to Lisosan G, a wheat antioxidant-rich dietary supplement. Contrarily, BW pasta had oxidative effect on serum so as conventional pasta and glucose, thus suggesting greater effectiveness of lipophilic than hydrophilic/phenolic antioxidants under our experimental conditions. Interestingly, no clear differences between the two pastas were observed, when AC measurements of either serum after pasta intake or pasta extracts by in vitro assays were considered, thus strengthening effectiveness and reliability of AOB approach.
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