Dataset on the effects of different pre-harvest factors on the metabolomics profile of lettuce (Lactuca sativa l.) leaves

The study of the relationship between cultivated plants and environmental factors can provide information ranging from a deeper understanding of the plant biological system to the development of more effective management strategies for improving yield, quality, and sustainability of the produce. In this article, we present a comprehensive metabolomics dataset of two phytochemically divergent lettuce (Lactuca sativa L.) butterhead varieties under different growing conditions. Plants were cultivated in hydroponics in a growth chamber with ambient control. The pre-harvest factors that were independently investigated were light intensity (two levels), the ionic strength of the nutrient solutions (three levels), and the molar ratio of three macroelements (K, Mg, and Ca) in the nutrient solution (three levels). We used an untargeted, mass-spectrometry-based approach to characterize the metabolomics profiles of leaves harvested 19 days after transplant. The data revealed the ample impact on both primary and secondary metabolism and its range of variation. Moreover, our dataset is useful for uncovering the complex effects of the genotype, the environmental factor(s), and their interaction, which may deserve further investigation

Foliar application of different vegetal-derived protein hydrolysates distinctively modulates tomato root development and metabolism

Despite the scientific evidence supporting their biostimulant activity, the molecular mechanism(s) underlying the activity of protein hydrolysates (PHs) and the specificity among different products are still poorly explored. This work tested five different protein hydrolysates, produced from different plant sources using the same enzymatic approach, for their ability to promote rooting in tomato cuttings following quick dipping. Provided that all the different PHs increased root length (45\u201393%) and some of them increased root number (37\u201356%), untargeted metabolomics followed by multivariate statistics and pathway analysis were used to unravel the molecular processes at the basis of the biostimulant activity. Distinct metabolomic signatures could be found in roots following the PHs treatments. In general, PHs shaped the phytohormone profile, modulating the complex interaction between cytokinins and auxins, an interplay playing a pivotal role in root development, and triggered a down accumulation of brassinosteroids. Concerning secondary metabolism, PHs induced the accumulation of aliphatic glucosinolates, alkaloids, and phenylpropanoids, potentially eliciting crop resilience to stress conditions. Here, we confirm that PHs may have a hormone-like activity, and that their application can modulate plant growth, likely interfering with signaling processes. Noteworthy, the heterogenicity of the botanical origin supported the distinctive and peculiar metabolomic responses we observed across the products tested. While supporting their biostimulant activity, these findings suggest that a generalized crop response to PHs cannot be defined and that specific effects are rather to be investigated

Lentil seed coat as a source of phenolic compounds: influence of geographical origin and genotype

Lentils (Lens culinaris spp.) are promising legumes whose seed coats, the by-products produced from dehulling, can represent a valuable source of functional components. This work aimed at valorizing lentils seed coat as functional ingredients, by investigating its profile across 11 genotypes grown in two different growing locations in Italy. The total phenolic, flavonoids, and condensed tannins contents (mg/g dry weight,) ranged from 30.60 to 70.37 gallic acid equivalents, 0.86 to 2.21 catechin equivalents, and 22.34 to 77.49 catechin equivalents, respectively. The untargeted phenolic profiling through UHPLC/QTOF-MS, followed by multivariate statistics, revealed differences in the quality and quantity of polyphenols. A broad and diverse profile could be highlighted, including 420 compounds, mainly ascribable to flavonoids, phenolic acids, and low-molecular-weight phenolic compounds. Unsupervised cluster analysis highlighted that origin is hierarchically more important than genotype in determining the phenolic profiles. Pearson’s correlation analysis showed that color was only partially related to phenolic content, while the geographic location and the genotype were more relevant. The significant accumulation of phenolics in some genotypes suggests that the genetic background should be taken into account, when lentils seed coat is to be included in food design as a sustainable source of phenolic compounds

Extraction kinetics of total polyphenols, flavonoids, and condensed tannins of lentil seed coat: Comparison of solvent and extraction methods

The lentil seed coat is a waste by-product still rich in phenolic compounds, specifically condensed tannins. The effect of different solvents, as well as different processes, namely conventional solid–liquid extraction (CSLE) and ultrasound-assisted extraction (UAE), on the extraction yield of specific phenolic compound classes was studied. Four empirical two-parameter models were examined to select the one that better fit the experimental data obtained under different operating conditions. Additionally, ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-ESI/QTOF-MS) was employed to profile the phenolic compounds obtained under distinct extraction conditions. In the operative conditions adopted here, the bioactive compounds yield achieved using UAE was lower than that obtained with CSLE. The kinetics of polyphenols, flavonoids, and condensed tannins extraction from the lentil seed coat were successfully fitted to the power-law models, yielding mean values of the root mean square < 5.4%, standard error of estimation < 0.53, and coefficient of determination > 0.8. In addition, the UHPLC-ESI/QTOF-MS of the lentil seed coat extracts allowed the putative recognition of nearly 500 compounds, mainly flavonoids and phenolic acids

The strength of the nutrient solution modulates the functional profile of hydroponically grown lettuce in a genotype-dependent manner

Considering that functional components of plant foods are mainly secondary-metabolism products, we investigated the shaping of health-promoting compounds in hydroponically grown butterhead lettuce (Lactuca sativa L. var. capitata) as a function of the strength of the nutrient solution utilized. To this aim, untargeted metabolomics profiling, in vitro antioxidant capacity (total phenolics, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,20-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays), and the inhibition of selected enzyme activities were investigated in two butterhead lettuce cultivars with different pigmentation, i.e., green and red Salanova. Full-strength nutrition, together with half- and quarter-strength solutions of macronutrients, was tested. Our results indicate that by reducing the nutrients strength, we could elicit a distinctive shaping of the phenolic profile of lettuce. It is noteworthy that only specific classes of phenolics (namely, lignans and phenolic acids, followed by flavones and anthocyanins) were modulated by the induction of nutritional eustress (fold-change values in the range between 125 and +11). This indicates that specific responses, rather than a generalized induction of phenolic compounds, could be observed. Nonetheless, a genotype-dependent response could be observed, with the red cultivar being much more responsive to nutritional deprivation than the green Salanova lettuce. Indeed, analysis of variance (ANOVA) confirmed a genotype x nutrition interaction in red Salanova (p < 0.001). As a consequence of the changes in phenolic composition, also the antioxidant capacity (p < 0.001) and amylase inhibition (p < 0.001) properties were affected by the growing conditions. However, the effect on cholinesterase and tyrosinase inhibition was poorly affected by the nutritional strength. Provided that yields are not compromised, the application of a controlled nutritional eustress in hydroponically cultivated lettuce may represent a valuable strategy to produce food with tailored functional features in a sustainable manner

Plant biostimulants from seaweeds or vegetal proteins enhance the salinity tolerance in greenhouse lettuce by modulating plant metabolism in a distinctive manner

The use of plant biostimulants such as seaweed extracts (SWE) and protein hydrolysates (PH) has grown in the recent years due to their beneficial effects on yield under both optimal and sub-optimal conditions such as salt stress. The comprehension of the mode of action of these two important categories of biostimulants on plant performance will allow to use them more efficiently under different growth conditions. This study aimed to examine the efficacy of a seaweed and plant-based biostimulants on greenhouse lettuce (Lactuca sativa L.) grown under non-saline (0 mM NaCl) and saline conditions (40 mM NaCl) in terms of growth, yield, SPAD index, leaf mineral composition and metabolomic profiling. Shoot fresh weight of lettuce was reduced by 15.3% under 40 mM of NaCl. Nonetheless, it was boosted by both used biostimulants by 9 and 18%, on average, under 0 and 40 mM NaCl salinity, respectively. Na content under saline conditions was reduced in the presence of the biostimulants treatment, where PH reduced it significantly by 15.6% and SWE by 9.4%. On the other hand, Cl content was significantly reduced only under PH treatment. Both biostimulants elicited a broad metabolic reprogramming, involving the accumulation of stress-related compounds such as glucosinolates, terpenoid phytoalexins, and jasmonates. Interestingly, distinctive metabolomic signatures could be observed following the application of the different biostimulants under salinity conditions. In more detail, PH promoted the accumulation of glucosinolates and phytoalexins precursors, while SWE induced a down accumulation of secondary metabolites. Our findings indicate different processes being modulated by PH and SWE, with possible synergistic effects, thus paving the way towards integrated strategies to alleviate the detrimental effects of salinity in lettuce

Impact of cold versus hot brewing on the phenolic profile and antioxidant capacity of rooibos (Aspalathus linearis) herbal tea

Consumption of rooibos (Aspalathus linearis) as herbal tea is growing in popularity worldwide and its health-promoting attributes are mainly ascribed to its phenolic composition, which may be affected by the brewing conditions used. An aspect so far overlooked is the impact of cold brewing vs regular brewing and microwave boiling on the poly(phenolic) profile and in vitro antioxidant capacity of infusions prepared from red (‘fermented’, oxidized) and green (‘unfermented’, unoxidized) rooibos, the purpose of the present study. By using an untargeted metabolomics-based approach (UHPLC-QTOF mass spectrometry), 187 phenolic compounds were putatively annotated in both rooibos types, with flavonoids, tyrosols, and phenolic acids the most represented type of phenolic classes. Multivariate statistics (OPLS-DA) highlighted the phenolic classes most affected by the brewing conditions. Similar antioxidant capacities (ORAC and ABTS assays) were observed between cold-and regular-brewed green rooibos and boiled-brewed red rooibos. However, boiling green and red rooibos delivered infusions with the highest antioxidant capacities and total polyphenol content. The polyphenol content strongly correlated with the in vitro antioxidant capacities, especially for flavonoids and phenolic acids. These results contribute to a better understanding of the impact of the preparation method on the potential health benefits of rooibos tea

Biochemical Insights into the Ability of Lemna minor L. Extract to Counteract Copper Toxicity in Maize

Metal trace elements (MTE) can damage crops if present in excessive amounts in the environment. This research investigated the effect of a plant extract of an aquatic species, Lemna minor L. (duckweed) (LE), on the ability of maize to cope with copper (Cu) toxicity. LE reversed the effects of Cu2+ on photosynthetic activity (Pn), evapotranspiration (E), stomatal conductance (gs), sub-stomatal CO2 concentration (Ci) and biomass which did not differ from the untreated controls. LE did not regulate the amount of copper in maize leaves, but compared to Cu-treated samples, the extract decreased the hydrogen peroxide (H2O2; −26% on average) and malondialdehyde (MDA; −47% on average) content, regardless of the dosage applied. Furthermore, the activity of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) was significantly increased by LE compared to samples treated with Cu alone. Untargeted metabolomic profiling revealed that LE activated maize secondary metabolism, eliciting the content of non-enzymatic antioxidants (flavonoids, glutathione and glutathione-related compounds, tocopherols and tocotrienols) and modulating plant stress-related hormones (brassinosteroids and ABA derivatives). The results of this study are promising and pave the way for using duckweed as a biostimulant to trigger beneficial effects in maize and increase its resistance to MTEs

A metabolomics insight into the Cyclic Nucleotide Monophosphate signaling cascade in tomato under non-stress and salinity conditions

Cyclic Nucleotides Monophosphate (cNMP) are key signalling compounds whose role in plant cell signal transduction is still poorly understood. In this work we used sildenafil, a phosphodiesterase (PDE) inhibitor used in human, to amplify the signal cascade triggered by cNMP using tomato as model plant. Metabolomics was then used, together with plant growth and root architecture parameters, to unravel the changes elicited by PDE inhibition either under non-stress and 100 mM NaCl salinity conditions. The PDE inhibitor elicited a significant increase in biomass (+62 %) and root length (+56 %) under no stress conditions, and affected root architecture in terms of distribution over diameter classes. Together with cGMP, others cNMP were modulated by the treatment. Moreover, PDE inhibition triggered a broad metabolic reprogramming involving photosynthesis and secondary metabolism. A complex crosstalk network of phytohormones and other signalling compounds could be observed in treated plants. Nonetheless, metabolites related to redox imbalance processes and NO signalling could be highlighted in tomato following PDE application. Despite salinity damped down the growth-promoting effects of sildenafil, interesting implications in plant mitigation to stress-related detrimental effects could be observed

Untargeted metabolomic profiling of three Crataegus species (hawthorn) and their in vitro biological activities

BACKGROUND: In this investigation, the chemical and biological profiles of three Turkish Crataegus species (Crataegus orientalis, Crataegus szovitsii and Crataegus tanacetifolia) were studied in order to provide the first comprehensive characterization and their health-promoting potential. In this respect, polyphenolic profiles were evaluated using ultrahigh-performance liquid chromatography\u2013quadrupole time-of-flight mass spectrometry. The in vitro antioxidant activities of the Crataegus samples were evaluated by using free-radical scavenging, phosphomolybdenum, ferrous-ion chelating, and reducing power assays. The inhibitory activities against \u3b1-glucosidase, amylase, cholinesterases (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)), and tyrosinase were also established. RESULTS: The untargeted metabolomic approach highlighted the effect of both extraction types and species on the phenolic profiles of different Crateagus tissues (i.e. leaves and twigs). The methanolic extracts showed the maximum radical scavenging and reducing activity in all test systems, whereas for ferrous-ion chelating assays the decocted and infused extracts showed the highest activity. Only the methanolic extracts were effective against AChE and BChE. The extract tested showed remarkable inhibitory effects against tyrosinase and \u3b1-glucosidase, whereas all the extracts exhibited modest inhibition against \u3b1-amylase. Overall, the twig extracts of the three species studied showed superior antioxidant and enzyme inhibitory activities. CONCLUSION: On the basis of these results, the three Crataegus species can be classified as potent bioresources for high-value phytochemicals, which warrant further investigations for developing novel nutraceuticals. \ua9 2019 Society of Chemical Industry