1,720,983 research outputs found
Ride to cell wall: Arabidopsis XTH11, XTH29 and XTH33 exhibit different secretion pathways and responses to heat and drought stress
No full textThe 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
Bioactive Compounds and Antioxidant Activities in Different Fractions of Mango Fruits (Mangifera indica L., Cultivar Tommy Atkins and Keitt)
No full textThis study aims to describe and compare the distribution of bioactive compounds, the fatty acids profiles, and the TEAC hydrophilic and lipophilic antioxidant activities in different fruit fractions (pulp, peel, and kernel) of two mango cultivars (Tommy Atkins and Keitt). All fractions are sources of health‐promoting bioactive compounds. Regardless of cultivars, pulp had the highest content of phytosterols (~150 mg/100 g dw), peels ranked first for pentaciclic triterpenes (from 14.2 to 17.7 mg/100 g dw), tocopherols, carotenoids, and chlorophylls, and kernels for phenolic compounds (from 421.6 to 1464.8 mg/100 g dw), flavonoids, condensed tannins, as well as hydrophilic and lipophilic antioxidant activities. Differences between the two cultivars were evidenced for ascorbic acid, which showed the highest levels in the peels and kernels of Keitt and Tommy Atkins fruits, respectively. Similarly, the concentration of dehydroascorbic acid was higher in the pulp of Tommy Atkins than Keitt. The highest percentage of saturated fatty acids was observed in pulp (~42%) and kernels (~50%), monounsaturated fatty acids in kernels (up to 41%), and polyunsaturated fatty acids in peels (up to 52%). Our results add information to the current knowledge on nutraceuticals’ distribution in different fractions of mango fruit, supporting its consumption as a healthy fruit and suggesting the great potential value of peels and kernels as sources of novel ingredients. Indeed, mango by‐products generated during agronomic‐to‐industrial processing not only causes a significant environmental impact, but economic losses too. In this scenario, boosting research on conventional recovery methods offers eco‐friendly solutions. However, green, novel biorefinery technologies may offer eco‐friendly and profitable solutions, allowing the recovery of several more profitable by‐products, sustaining their continuous growth since many bioactive compounds can be recovered from mango by‐products that are potentially useful in the design of innovative nutraceutical, cosmeceutical, and pharmaceutical formulations
Organically grown high-lycopene tomatoes: A novel adventure within functional quality
No full textTomato (Solanum lycopersicum L.) is one of the most important agricultural crops all over the world. It has hailed functional properties being characterized by the presence of many natural health promoting antioxidant compounds including vitamins, phenolics and carotenoids, particularly lycopene. The demand for organically grown produce has widely increased because of the commercial opportunities offered by such products, the increasing consumer awareness of the relationship between foods and health as well as environmental concerns. Introgression of the high-pigment (hp) and/or old-gold crimson (og c ) colour mutations into elite genotypes has led to the release of tomato cultivars with increased lycopene and functional quality. However, most of the commercially available high-lycopene (HLY) tomato cultivars were turned out and grown mainly under conventional farming systems. Hence there is a need to focus on the behaviour of HLY tomato cultivars under organic farming system. In this study the nutritional properties of two field HLY tomato cultivars (recently bred by the lab of Horticulture, INRAT) and the ordinary ‘Rio Grande’ grown organically in an open-field was determined. Significant differences were found between cultivars in the content of lycopene, total phenols and flavonoids, as well as hydrophilic, lipophilic and total antioxidant activities. Although these data require confirmation over a longer period of time, this investigation emphasizes the satisfactory behaviour of the studied HLY cultivars
Agronomic Performance and Nutraceutical Quality of a Tomato Germplasm Line Selected under Organic Production System
Full text linkOrganic tomato production is increasing worldwide, thus making necessary the development of varieties adapted to this farming system. It is now well known that the implementation of local tomato plant breeding programs for organic farming is required to increase the performance of varieties in this typology of cultivation regime. In this research, the agronomic performance, nutraceutical contents, and radical scavenging activity of a tomato germplasm line (OSTGL), selected under organically grown conditions, were evaluated for two consecutive years (2018 and 2019) in comparison with the variety ‘Rio Grande’, frequently grown organically in Tunisia. Carotenoids, phenolics, vitamin C, and radical scavenging capacity were assayed spectrophotometrically, while tocopherols were analyzed by HPLC. All data were not affected by year-to-year variability. The OSTGL line showed significantly higher marketable yield, total phenol, flavonoid, vitamin C, α-tocopherol and γ-tocopherol contents, along with radical scavenging activity. The OSTGL red-ripe berries also showed comparable values for average weight, soluble solids, pH, titratable acidity, firmness and coloration, as well as lycopene and β-carotene contents. This open pollinated tomato germplasm line demonstrated to be an effective sustainable variety for improving fruit yield, agronomic, and nutraceutical characteristics under an organic management system
Watermelon chromoplasts: bio-factories for the synthesis and accumulation of carotenoids.
No full textLocalization of seed oil body proteins in tobacco protoplasts reveals specific mechanisms of protein targeting to leaf lipid droplets
No full textOleosin, caleosin and steroleosin are normally expressed in developing seed cells and are targeted to oil bodies. In the present work, the cDNA of each gene tagged with fluorescent proteins was transiently expressed into tobacco protoplasts and the fluorescent patterns observed by confocal laser scanning microscopy. Our results indicated clear differences in the endocellular localization of the three proteins. Oleosin and caleosin both share a common structure consisting of a central hydrophobic domain flanked by two hydrophilic domains and were correctly targeted to lipid droplets (LD), whereas steroleosin, characterized by an N-terminal oil body anchoring domain, was mainly retained in the endoplasmic reticulum (ER). Protoplast fractionation on sucrose gradients indicated that both oleosin and caleosin-green fluorescent protein (GFP) peaked at different fractions than where steroleosin-GFP or the ER marker binding immunoglobulin protein (BiP), were recovered. Chemical analysis confirmed the presence of triacylglycerols in one of the fractions where oleosin-GFP was recovered. Finally, only oleosin- and caleosin-GFP were able to reconstitute artificial oil bodies in the presence of triacylglycerols and phospholipids. Taken together, our results pointed out for the first time that leaf LDs can be separated by the ER and both oleosin or caleosin are selectively targeted due to the existence of selective mechanisms controlling protein association with these organelles. © 2011 Institute of Botany, Chinese Academy of Sciences
Inside and beyond color: Comparative overview of functional quality of tomato and watermelon fruits
No full textThe quali-quantitative evaluation and the improvement of the levels of plant bioactive secondary metabolites are increasingly gaining consideration by growers, breeders and processors, particularly in those fruits and vegetables that, due to their supposed health promoting properties, are considered “functional.” Worldwide, tomato and watermelon are among the main grown and consumed crops and represent important sources not only of dietary lycopene but also of other health beneficial bioactives. Tomato and watermelon synthesize and store lycopene as their major ripe fruit carotenoid responsible of their typical red color at full maturity. It is also the precursor of some characteristic aroma volatiles in both fruits playing, thus, an important visual and olfactory impact in consumer choice. While sharing the same main pigment, tomato and watermelon fruits show substantial biochemical and physiological differences during ripening. Tomato is climacteric while watermelon is non-climacteric; unripe tomato fruit is green, mainly contributed by chlorophylls and xanthophylls, while young watermelon fruit mesocarp is white and contains only traces of carotenoids. Various studies comparatively evaluated in vivo pigment development in ripening tomato and watermelon fruits. However, in most cases, other classes of compounds have not been considered. We believe this knowledge is fundamental for targeted breeding aimed at improving the functional quality of elite cultivars. Hence, in this paper, we critically review the recent understanding underlying the biosynthesis, accumulation and regulation of different bioactive compounds (carotenoids, phenolics, aroma volatiles, and vitamin C) during tomato and watermelon fruit ripening. We also highlight some concerns about possible harmful effects of excessive uptake of bioactive compound on human health. We found that a complex interweaving of anabolic, catabolic and recycling reactions, finely regulated at multiple levels and with temporal and spatial precision, ensures a certain homeostasis in the concentrations of carotenoids, phenolics, aroma volatiles and Vitamin C within the fruit tissues. Nevertheless, several exogenous factors including light and temperature conditions, pathogen attack, as well as pre- and post-harvest manipulations can drive their amounts far away from homeostasis. These adaptive responses allow crops to better cope with abiotic and biotic stresses but may severely affect the supposed functional quality of fruits
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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