Carotenoid Content Research Articles

Drought effects on growth, biochemical changes and leaf gas exchange in laurel (Laurus nobilis L.)

Abstract Drought is one of the abiotic factors that negatively affect the productivity of laurel (Laurus nobilis L.). Increasing water scarcity in arid and semi-arid regions is pushing the physiological limits of woody species, necessitating strong resistance to drought. Studies should be conducted on the effects of drought stress not only on forest trees but also some medicinal and ornamental species, and ways to increase their resistance should be explored. This study was carried out to determine the effect of drought stress on seedling growth and some physiological and biochemical properties in laurel. The seedlings were subjected to drought stress for about 4 months with three different irrigation regimes: watering once every 2–3 days (control), every 15 days, and every 30 days. Morphological properties (root collar diameter, height, dry weight, stem: root ratio, and number of leaves), physiological properties (midday xylem water potential and photosynthesis properties), and biochemical properties (photosynthetic pigments, total carbohydrate, and proline contents) were determined. Results have shown that drought stress has a negative effect on root collar diameter, seedling height, and dry weight. Likewise, leaf number and midday xylem water potential decreased due to increased drought stress. Furthermore, the net photosynthesis rate, stomatal conductance, and transpiration rate of the least irrigated (30th day) seedlings were quite low compared to those of control seedlings. The differences in chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid contents were also found to be statistically significant. Total carbohydrate and proline contents showed the highest values for the least irrigated seedlings and the lowest values for controlled irrigation seedlings. Our results reflect the improved tolerance capacity of laurel to increased drought stress.

Shaping the bioactive potential, health-promoting properties, and bioavailability of o/w nanoemulsions by modulating the dose of a carotenoid preparation isolated from Calendula officinalis L.

The use of nanotechnology in food production (in particular protein base nanoemulsion) is a solution that is gaining popularity, which allows to design of smart food with targeted health-promoting properties. This study aimed to assess the impact of the dose of the phytochemical extract (1%; 3%; 5% w/w) comprising isolated lipophilic compounds from Calendula officinalis L. on selected physicochemical properties of the emulsion, antioxidant, antidiabetic and antiaging effects, and its impact on carotenoids content and their in vitro bioavailability.The results showed that the use of a 3% extract dosage appears to be optimal for obtaining a nanoemulsion. This variant was characterized by the highest antidiabetic activity and there was no overloading of the nanostructure. Additionally, the use of a pea protein - lipophilic compounds - sunflower/hemp oil matrix to create nanoforms seems to be a promising solution in the context of pro-health properties and bioavailability of bioactive compounds.

Alleviation of Different Climatic Conditions by Foliar Application of Salicylic Acid and Sodium Nitroprusside and Their Interactive Effects on Pigments and Sugar Content of Maize Under Different Sowing Dates

The agricultural sector is seriously impacted by climate change, leading to potential risks to food security. In terms of global food production, maize ranks third. As a result, crop production and food security depend critically on assessing the effects of climate change and developing measures to adapt maize. Regarding adaptability, changing planting dates and using different agrochemicals are more effective than other management. Crop models are part of a global decision support system to help farmers maximize yields despite unpredictable weather patterns. To mitigate yield loss and protect the ecosystem, it is essential to use efficient maize-sowing practices in the field. This experiment was carried out to identify the most favorable sowing dates that maximize yield while ensuring the crop’s productivity and the integrity of the surrounding ecosystem remain intact. The main aim of this experiment was to mitigate the different climatic conditions by exogenous application of salicylic acid (SA) and sodium nitroprusside (SNP) on pigments and sugar content in maize under different sowing dates. A field experiment was carried out in the School of Agriculture, Lovely Professional University, Punjab, India, during the spring season of 2022. The experiment dealt with various maize crops, PMH-10, sourced from the Punjab Agricultural University (PAU), Punjab. The experiment was conducted in an open-air environment. The experimental setup was laid out in a split-plot design. The results stated that foliar application of salicylic acid and sodium nitroprusside successfully influenced high-temperature tolerance and low temperature at the reproductive phase and initial vegetative stages with other growing climatic conditions of maize in early and late sowings when controlled by increasing the chlorophyll index, carotenoids content, and sugar content of maize.

Factors that Affect the Quality of Olive Oil Produced Using Olives from Traditional Orchards in the Middle East

Traditional olive (Olea europaea) orchards have been grown for thousands of years and still occupy most of the world’s cultivated olive areas. To compete with olive oil produced in the higher-yielding intensive orchards, the oil from traditional orchards must be of high quality. We evaluated oil quality—potential and actual (under commercial conditions)—and tested the stages in the production chain that are likely to reduce oil quality in the traditional sector in the Middle East region. Our findings show a clear negative impact of growers’ traditional practices on both the chemical and sensory characteristics of olive oil. The oil originating from the commercial process had higher free fatty acid and lower polyphenol and carotenoid contents, lower stability, lower pungency, lower fruitiness, lower bitterness, and a higher prevalence of organoleptic defects than oil that originated from fruit picked from the same trees during the experimental procedure. The current common harvesting technique of pole beating significantly increased fruit injury and fruit with mold, leading to a reduction in oil polyphenols and an increase in free fatty acid levels compared with those resulting from manual picking. In addition, after harvest, storing the fruit for more than 48 hours in plastic bags dramatically reduced the oil quality. The traditional olive orchard could be a source of high-quality extra virgin olive oil. However, fruit handling—from the trees until the end of the oil extraction process—is performed incorrectly, thus adversely affecting the oil quality.

Antioxidant and Anti-Inflammatory Activities of the Extract and Bioaccessible Fraction of Mango Peel in Muffins.

Mango peel is a production waste and can cause environmental problems, but its nutritional value consists of bioactive compounds that could be beneficial for human health. The aim of this study is to determine the bioactive compounds, antioxidant and anti-inflammatory activities of mango peels and their use in muffins. The content of polyphenols, carotenoids and total phenols as well as the antioxidant activity of mango peel extract were evaluated. The anti-inflammatory activity of the extract was investigated using Caco-2 cell assay. The mango peel powder was then incorporated into muffin formulations. The sensory properties of these fortified muffins were evaluated. The total phenolic content, antioxidant activity and anti-inflammatory properties of the muffin extracts and their bioaccessible fractions were also analysed. The mango peel contained quercetin, phenolic compounds, α-carotene, β-carotene and lutein, which have antioxidant potential. In Caco-2 cells exposed to induced inflammation, the mango peel powder extract (γ=10, 50 and 100 µg/mL) attenuated the production of reactive oxygen species (ROS), tumour necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8), while maintaining cell viability. Muffins supplemented with 5 % mango peel powder showed good sensory properties, but not as good as those of plain muffins without mango peel powder. The total phenolic content and antioxidant activities in both the extract and the bioaccessible fraction of the supplemented muffins were higher than those observed in the standard muffins. Moreover, the extract and bioaccessible fraction of the supplemented muffins resulted in a higher reduction of ROS, IL-8 and TNF-α production in Caco-2 cells than those obtained from the standard muffins. This study is the first to investigate the protective effects of mango peel and muffins supplemented with mango peel powder against IL-1β-induced oxidative damage in Caco-2 cells. The results confirm that both mango peel and the supplemented muffins inhibited the production of inflammatory markers, including ROS and cytokines. These findings suggest that mango peel could be a valuable component of functional food formulations including dietary supplements.

Buriti (Mauritia flexuosa) shell flour: Nutritional composition, chemical profile, and antioxidant potential as a strategy for valuing waste from native Brazilian fruits

The Cerrado is one of the most biodiverse biomes in the world, characterized by a wealth of native fruits with unique nutritional characteristics. In this sense, the social, economic, and environmental importance of fully utilizing food is widely recognized. Therefore, generally considered waste, fruit shells can be transformed into a coproduct with high added value. The objective of this work was to carry out a comprehensive assessment of the physicochemical properties, carbohydrate and fatty acid profile, phytochemical compounds, phenolic profile, and antioxidant potential of the recovered extracts of buriti (Mauritia flexuosa) shells in natura and dehydrated at 55 °C (flour). In addition, the functional properties were verified by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) from buriti shell flour. The results indicated high fiber content and energy value for the sample processed at 55 °C (58.95 g/100 g and 378.91 kcal/100 g, respectively) and low lipid and protein content (1.03 g/100 g and 1.39 g/100 g, respectively). Regardless of the sample analyzed, maltose was the majority sugar (37.33 – 281.01 g/100 g). The main fatty acids detected were oleic acid (61.33 – 62.08 %) followed by palmitic acid (33.91 – 34.40 %). The analysis of the mineral profile demonstrated that the samples did not differ significantly from each other, showing that the drying process did not interfere with the results obtained (p ≤ 0.05). The analysis of individual phenolics allowed the identification of six phenolic compounds in buriti shells. However, it is possible to observe that the drying method had a positive and significant influence on the phenolic profile (p ≤ 0.05), with chlorogenic acid (2.63 – 8.27 mg/100 g) and trigonelline (1.06 – 41.52 mg/100 g), the majority compounds. On the other hand, it is important to highlight that buriti shells have a high content of carotenoids, mainly β-carotene (27.18 – 62.94 µg/100 g) and α-carotene (18.23 – 60.28 µg/100 g), also being positively influenced by the drying process at 55 °C (p ≤ 0.05). The dried shells showed a high content of phytochemical compounds and high antioxidant activity based on the different methods tested. The results show that buriti shell flour can be fully utilized and has nutritional and chemical aspects that can be applied to develop new sustainable, nutritious, and functional food formulations.

Postharvest quality and ripening behaviour of un-explored genotypes of Himalayan plain mango diversity

India is renowned for its mango diversity, with more than 1000 genotypes reported. However, the Himalayan plains bear some elite genotypes which supposed to bear high postharvest value, the systemic postharvest study of which is yet to be attempted. The aim of present study is to evaluate the postharvest quality and ripening behviour of these important genotypes. Thus, 15 un-explored mango genotypes of this region were selected and evaluated for ripening behaviour and detailed postharvest profiling via internal (total phenolic and total flavonoid content), nutritional attributes (Brix: acid ratio, total carotenoid concentration, ascorbic acid content and antioxidant activity), sensory evaluation, fruit softening enzymes (polygalactouronase, pectin methylesterase and lipoxygenase), shelf life attributes (respiration rate, physiological loss in weight and storage life in days) external attributes (fruit weight, fruit firmness, peel thickness, fruit shape and dry seed weight) and mineral contents (Calcium, potassium and phosphorous) under ambient storage (25 ± 4 °C and 65 ± 5 % RH). The results revealed that the highest total flavonoid content (682.40 μg g−1), ascorbic acid (46.88 mg 100 g−1) and antioxidant activity (4.84 μmol TE g−1) exhibited by ‘Sukul’. The total phenolic content was recorded as the highest in ‘Safed Malda’ (510.42 μg GAE g-1 FW), and total carotenoid concentration was recorded as the highest in ‘Sipiya’ (7.30 mg 100 g-1) ‘Zardalu’ (7.04 mg 100 g-1) and ‘Mithua’ (6.98 mg 100 g-1). Interestingly, genotypes such as ‘Sukul’, Sipiya’ and ‘Krishna Bhog ‘exhibited a 4–5 days higher storage life than other selected genotypes. Screened genotypes exhibited a high diversity of nutritional and biochemical contents. The results of this study bear practical utility for research (quality improvement programme) and the processing industry.

Carotenoid deposition in yolks of laying hens fed with corn diets differing in grain hardness and supplemented with rapeseed oil and emulsifier

This study investigated the effects of supplementing diets consisting of two dent corn hybrids (soft- and hard-type) with different amounts of rapeseed oil (2, 3, and 4%) and with (0.05%) or without emulsifier (Lysoforte Extended, Kemin) on the content and deposition of carotenoids in egg yolk. The feeding trial was conducted with 216 Lohmann Brown laying hens which were by 3 located in 72 cages. The cages were randomly assigned to 12 dietary treatments (2 hybrids × 3 rapeseed oil levels × 2 emulsifier levels), resulting in 6 cages (replicates) per each dietary treatment. After depletion, hens were fed treatment diets without added pigment for 7 wk. After stabilization of the carotenoid profile (lutein, zeaxanthin, α- and β-cryptoxanthin and β-carotene and total carotenoids), eggs were collected once a week until the end of the experiment and deposition efficiency was calculated based on carotenoid content in yolk and diets, yolk weight, egg production and diet intake. Corn hybrid and rapeseed oil affected (P < 0.05) the yolk content and deposition efficiency of most carotenoids. Moreover, a significant (P < 0.05) hybrid × rapeseed oil level interaction for all carotenoids indicated hybrid-specific responses to rapeseed oil supplementation. In the soft-type hybrid, the addition of 3% rapeseed oil enhanced the carotenoid content compared to 2% of rapeseed oil, whereas for the hard-type hybrid, 2 and 3% of rapeseed oil resulted in similar contents. Supplementation of 4% rapeseed oil reduced the content regardless of the hybrid. Emulsifier addition positively affected (P < 0.05) the deposition efficiency of all carotenoids except β-carotene. In conclusion, supplementing corn diets with rapeseed oil and emulsifier affected carotenoid utilization and these responses varied in hybrids differing in grain hardness, which should be considered when using corn as the sole source of carotenoids in hen diets.

Changes in the Physicochemical and Bioactive Properties of Yerba Mate Depending on the Brewing Conditions.

Yerba Mate drink made from dried and crushed leaves and twigs of Paraguayan holly (Ilex paraguariensis A. St.-Hil.), which is a valuable source of bioactive substances, in particular antioxidants. The available literature lacks data on changes in the content and profile of bioactive compounds such as tannins, caffeine, the phenolic acid profile of flavonoids and carotenoids, as well as total polyphenol content and antioxidant activity in Yerba Mate infusions depending on different brewing conditions, and how different brewing conditions affect the physicochemical properties of these infusions. Therefore, this study evaluated the physicochemical properties of dried and Yerba Mate infusions prepared via single and double brewing processes at 70 °C and 100 °C. The organoleptic evaluation, as well as the instrumental color measurement, showed significant changes in the total color difference (ΔE) and the L*a*b* chromatic coordinates of dried Yerba Mate samples and their infusions. Moreover, the research showed higher contents of tannins (mean 1.36 ± 0.14 g/100 g d.m.), caffeine (mean 17.79 ± 3.49 mg/g d.m.), carotenoids (mean 12.90 ± 0.44 μg/g d.m.), phenolic acids (mean 69.97 ± 7.10 mg/g d.m.), flavonoids (mean 5.47 ± 1.78 mg/g d.m.), total polyphenols (mean 55.26 ± 8.51 mg GAE/g d.m.), and antioxidant activity (mean 2031.98 ± 146.47 μM TEAC/g d.m.) in single-brewed Yerba Mate infusions compared to double-brewed (0.77 ± 0.12 g/100 g d.m., 14.28 ± 5.80 mg/g d.m., 12.67 ± 0.62 μg/g d.m., 57.75 ± 8.73 mg/g d.m., 3.64 ± 0.76 mg/g d.m., 33.44 ± 6.48 mg GAE/g d.m. and 1683.09 ± 155.34 μM TEAC/g d.m., respectively). In addition, infusions prepared at a lower temperature (70 °C) were characterized by a higher content of total polyphenols and higher antioxidant activity, in contrast to the tannin and carotenoid contents, the levels of which were higher at 100 °C than at 70 °C. Considering the high amount of bioactive ingredients, in particular antioxidants, and a wide range of health benefits, it is worth including Yerba Mate in the daily diet.

The Medicinal Species of the Lycium Genus (Goji Berries) in East Asia: A Review of Its Effect on Cell Signal Transduction Pathways.

Natural plants contain numerous chemical compounds that are beneficial to human health. The berries from the Lycium genus are widely consumed and are highly nutritious. Moreover, their chemical constituents have attracted attention for their health-promoting properties. In East Asia, there are three varieties of the Lycium genus (Lycium barbarum L., Lycium chinense Miller, and L. ruthenicum Murray) that possess medicinal value and are commonly used for treating chronic diseases and improving metabolic disorders. These varieties are locally referred to as "red Goji berries" or "black Goji berries" due to their distinct colors, and they differ in their chemical compositions, primarily in terms of carotenoid and anthocyanin content. The pharmacological functions of these berries include anti-aging, antioxidant, anti-inflammatory, and anti-exercise fatigue effects. This review aims to analyze previous and recent studies on the active ingredients and pharmacological activities of these Lycium varieties, elucidating their signaling pathways and assessing their impact on the gut microbiota. Furthermore, the potential prospects for using these active ingredients in the treatment of COVID-19 are evaluated. This review explores the potential targets of these Lycium varieties in the treatment of relevant diseases, highlighting their potential value in drug development.

Effect of MnO2 Nanoparticles Stabilized with Cocamidopropyl Betaine on Germination and Development of Pea (Pisum sativum L.) Seedlings.

This study aimed to synthesize, characterize, and evaluate the effect of cocamidopropyl betaine-stabilized MnO2 nanoparticles (NPs) on the germination and development of pea seedlings. The synthesized NPs manifested as aggregates ranging from 50-600 nm, comprising spherical particles sized between 19 to 50 nm. These particles exhibited partial crystallization, indicated by peaks at 2θ = 25.37, 37.62, 41.18, 49.41, 61.45, and 65.79°, characteristic of MnO2 with a tetragonal crystal lattice with a I4/m spatial group. Quantum chemical modelling showed that the stabilization process of MnO2 NPs with cocamidopropyl betaine is energetically advantageous (∆E > 1299.000 kcal/mol) and chemically stable, as confirmed by the positive chemical hardness values (0.023 ≤ η ≤ 0.053 eV). It was revealed that the interaction between the MnO2 molecule and cocamidopropyl betaine, facilitated by a secondary amino group (NH), is the most probable scenario. This ascertain is supported by the values of the difference in total energy (∆E = 1299.519 kcal/mol) and chemical hardness (η = 0.053 eV). These findings were further confirmed using FTIR spectroscopy. The effect of MnO2 NPs at various concentrations on the germination of pea seeds was found to be nonlinear and ambiguous. The investigation revealed that MnO2 NPs at a concentration of 0.1 mg/L resulted in the highest germination energy (91.25%), germinability (95.60%), and lengths of roots and seedlings among all experimental samples. However, an increase in the concentration of preparation led to a slight growth suppression (1-10 mg/L) and the pronounced inhibition of seedling and root development (100 mg/L). The analysis of antioxidant indicators and phytochemicals in pea seedlings indicated that only 100 mg/L MnO2 NPs have a negative effect on the content of soluble sugars, chlorophyll a/b, carotenoids, and phenols. Conversely, lower concentrations showed a stimulating effect on photosynthesis indicators. Nevertheless, MnO2 NPs at all concentrations generally decreased the antioxidant potential of pea seedlings, except for the ABTS parameter. Pea seedlings showed a notable capacity to absorb Mn, reaching levels of 586.5 μg/L at 10 mg/L and 892.6 μg/L at 100 mg/L MnO2 NPs, surpassing the toxic level for peas according to scientific literature. However, the most important result was the observed growth-stimulating activity at 0.1 mg/L MnO2 NPs stabilized with cocamidopropyl betaine, suggesting a promising avenue for further research.

Coupling the PROSAIL Model and Machine Learning Approach for Canopy Parameter Estimation of Moso Bamboo Forests from UAV Hyperspectral Data

Parameters such as the leaf area index (LAI), canopy chlorophyll content (CCH), and canopy carotenoid content (CCA) are important indicators for evaluating the ecological functions of forests. Currently, rapidly developing unmanned aerial vehicles (UAV) equipped with hyperspectral technology provide advanced technical means for the real-time dynamic acquisition of regional vegetation canopy parameters. In this study, a hyperspectral sensor mounted on a UAV was used to acquire the data in the study area, and the canopy parameter estimation model of moso bamboo forests (MBF) was developed by combining the PROSAIL radiative transfer model and the machine learning regression algorithm (MLRA), inverted the canopy parameters such as LAI, CCH, and CCA. The method first utilized the extended Fourier amplitude sensitivity test (EFAST) method to optimize the global sensitivity analysis and parameters of the PROSAIL model, and the successive projections algorithm (SPA) was used to screen the characteristic wavebands for the inversion of MBF canopy parameter inversion. Then, the optimized PROSAIL model was used to construct the ‘LAI-CCH-CCA-canopy reflectance’ simulation dataset for the MBF; multilayer perceptron regressor (MLPR), extra tree regressor (ETR), and extreme gradient boosting regressor (XGBR) employed used to construct PROSAIL_MLPR, PROSAIL_ETR, and PROSAIL_XGBR, respectively, as the three hybrid models. Finally, the best hybrid model was selected and used to invert the spatial distribution of the MBF canopy parameters. The following results were obtained: Waveband sensitivity analysis reveals 400–490 and 710–1000 nm as critical for LAI, 540–650 nm for chlorophyll, and 490–540 nm for carotenoids. SPA narrows down the feature bands to 43 for LAI, 19 for CCH, and 9 for CCA. The three constructed hybrid models were able to achieve high-precision inversion of the three parameters of the MBF, the model fitting accuracy of PROSAIL_MLRA reached more than 95%, with lower RMSE values, and the PROSAIL_XGBR model yielded the best fitting results. Our study provides a novel method for the inversion of forest canopy parameters based on UAV hyperspectral data.

Effects of Gold Nanoparticles on Mentha spicata L., Soil Microbiota, and Human Health Risks: Impact of Exposure Routes.

Nanoparticles, due to their extensive production and application, can have significant consequences for the environment, including soil and plant pollution. Therefore, it is very important to assess how nanoparticles will affect plants depending on the exposure pathways. The effect of gold nanoparticles in a concentration range of 1-100 mg/L on Mentha spicata L. during a 28-day experiment was investigated. Two routes of nanoparticles exposure were applied: root and foliar. Transmission electron microscopy was used to characterize nanoparticles and their effect on plant leaves' ultrastructure. Gold content in soil and plant segments was determined using k0-neutron activation analysis. For root exposure, gold was mainly accumulated in soil (15.2-1769 mg/kg) followed by root systems (2.99-454 mg/kg). The maximum accumulation of gold in leaves (5.49 mg/kg) was attained at a nanoparticle concentration of 100 mg/L. Foliar exposure resulted in the maximum uptake of gold in leaves (552 mg/kg) and stems (18.4 mg/kg) at the highest applied nanoparticle concentration. The effect of nanoparticles on the Mentha spicata L. leaves' biochemical composition was assessed. Nanoparticles affected the content of chlorophyll and carotenoids and led to an increase in antioxidant activity. Root exposure to gold nanoparticles resulted in an increase in the number of starch grains in chloroplasts and also suppressed the activity of the soil microbiota. Gold extraction from mint leaves into herbal infusion varied from 2 to 90% depending on the concentration of nanoparticles in the solution and the exposure route. The health risk as a result of gold exposure via herbal tea intake was assessed through estimated daily intake. The hazard quotient values were found to be less than the cutoff, indicating that a cup of tea infusion should not cause a serious impact to human health.

Enhancing spinach (Spinacia oleracea L.) resilience in pesticide-contaminated soil: Role of pesticide-tolerant Ciceribacter azotifigens and Serratia marcescens in root architecture, leaf gas exchange attributes and antioxidant response restoration

This study unveils the detoxification potential of insecticide-tolerant plant beneficial bacteria (PBB), i.e., Ciceribacter azotifigens SF1 and Serratia marcescens SRB1, in spinach treated with fipronil (FIP), profenofos (PF) and chlorantraniliprole (CLP) insecticides. Increasing insecticide doses (25–400 μg kg−1 soil) significantly curtailed germination attributes and growth of spinach cultivated at both bench-scale and in greenhouse experiments. Profenofos at 400 μg kg−1 exhibited maximum inhibitory effects and reduced germination by 55%; root and shoot length by 78% and 81%, respectively; dry matter accumulation in roots and shoots by 79% and 62%, respectively; leaf number by 87% and leaf area by 56%. Insecticide application caused morphological distortion in root tips/surfaces, increased levels of oxidative stress, and cell death in spinach. Application of insecticide-tolerant SF1 and SRB1 strains relieved insecticide pressure resulting in overall improvement in growth and physiology of spinach grown under insecticide stress. Ciceribacter azotifigens improved germination rate (10%); root biomass (53%); shoot biomass (25%); leaf area (10%); Chl-a (45%), Chl-b (36%) and carotenoid (48%) contents of spinach at 25 μg CLP kg−1 soil. PBB inoculation reinvigorated the stressed spinach and modulated the synthesis of phytochemicals, proline, malondialdehyde (MDA), superoxide anions (O2•–), and hydrogen peroxide (H2O2). Scanning electron microscopy (SEM) revealed recovery in root tip morphology and stomatal openings on abaxial leaf surfaces of PBB-inoculated spinach grown with insecticides. Ciceribacter azotifigens inoculation significantly increased intrinsic water use efficiency, transpiration rate, vapor pressure deficit, intracellular CO2 concentration, photosynthetic rate, and stomatal conductance in spinach exposed to 25 μg FIP kg−1. Also, C. azotifigens and S. marcescens modulated the antioxidant defense systems of insecticide-treated spinach. Bacterial strains were strongly colonized to root surfaces of insecticide-stressed spinach seedlings as revealed under SEM. The identification of insecticide-tolerant PBBs such as C. azotifigens and S. marcescens hold the potential for alleviating abiotic stress to spinach, thereby fostering enhanced and safe production within polluted agroecosystems.

Deciphering of the morpho-physiological traits of two native grasses from Argentina with contrasting drought resistance strategies

Context Semiarid environments, such as the Patagonian shrublands, are characterised by having shrubby patches surrounded by grasses with different ecophysiological strategies to tolerate long dry periods. Aims We hypothesised that coexisting grasses of the Patagonian rangeland, already classified as drought-escaping or drought-tolerant, have different traits according to the season and the annual rainfall events. Methods Two dominant native grasses were selected: Pappostipa speciosa (evergreen) and Poa ligularis (deciduous). Samples were collected in the four seasons for the term of 1 year. Rainfall events and soil water content of each season were determined. Spring was the wettest season and autumn the driest. Physiological (relative water content, pigments, hormones), biochemical (polyphenols, antioxidant activity) and morphological traits were measured in the four seasons. Key results P. speciosa was characterised by keeping evergreen leaves with high production of polyphenols as secondary metabolites with high antioxidant capacity during the dry autumn and winter seasons. P. ligularis was characterised by high contents of gibberellin (GA1), auxin (IAA), total phenols, total flavonoids and tartaric acid esters, and high antioxidant capacity in roots during the autumn dry season. In addition, P. ligularis leaves had higher content of carotenoids and polyphenols than P. speciosa during the summer dry season. Conclusions The major adaptive strategy to tolerate dry periods is the high activity of the secondary metabolism, mainly in leaves in P. speciosa (a drought-tolerant grass) and in roots in P. ligularis (a drought-escaping grass). Implications Rainfall variations during a year can affect the phenological growth stages and the metabolism of two native grasses from Argentina characterised by different drought resistance mechanisms.

Association of Candidate Single-Nucleotide Polymorphism Genotypes With Plasma and Skin Carotenoid Concentrations in Adults Provided a Lycopene-Rich Juice

BackgroundCarotenoids are fat-soluble phytochemicals with biological roles, including ultraviolet protective functions in skin. Spectroscopic skin carotenoid measurements can also serve as a noninvasive biomarker for carotenoid consumption. Single-nucleotide polymorphisms (SNPs) in metabolic genes are associated with human plasma carotenoid concentrations; however, their relationships with skin carotenoid concentrations are unknown. ObjectivesThe objective of this study was to determine the relationship between 13 candidate SNPs with skin and plasma carotenoid concentrations before and after a carotenoid-rich tomato juice intervention. MethodsIn this randomized, controlled trial, participants (n = 80) were provided with lycopene-rich vegetable juice providing low (13.1 mg), medium (23.9 mg), and high (31.0 mg) daily total carotenoid doses for 8 wk. Plasma carotenoid concentrations were measured by high-pressure liquid chromatography, and skin carotenoid score was assessed by reflection spectroscopy (Veggie Meter) at baseline and the end-of-study time point. Thirteen candidate SNPs in 5 genes (BCO1, CD36, SCARB1, SETD7, and ABCA1) were genotyped from blood using PCR-based assays. Mixed models tested the effects of the intervention, study time point, interaction between intervention and study time point, and SNP genotype on skin and plasma carotenoids throughout the study. Baseline carotenoid intake, body mass index, gender, and age are covariates in all models. ResultsThe genotype of CD36 rs1527479 (P = 0.0490) was significantly associated with skin carotenoid concentrations when baseline and the final week of the intervention were evaluated. Genotypes for BCO1 rs7500996 (P = 0.0067) and CD36 rs1527479 (P = 0.0018) were significant predictors of skin carotenoid concentrations in a combined SNP model. ConclusionsThese novel associations between SNPs and skin carotenoid concentrations expand on the understanding of how genetic variation affects interindividual variation in skin carotenoid phenotypes in humans.This trial was registered at clinicaltrials.gov as NCT03202043.

Physiology and transcriptomic analysis revealed the mechanism of silicon promoting cadmium accumulation in Sedum alfredii Hance

Silicon (Si) effectively promote the yield of many crops, mainly due to its ability to enhance plants resistance to stress. However, how Si helps hyperaccumulators to extract Cadmium (Cd) from soil has remained unclear. In this study, Sedum alfredii Hance (S. alfredii) was used as material to study how exogenous Si affected biomass, Cd accumulation, antioxidation, cell ultrastructure, subcellular distribution and changes in gene expression after Cd exposure. The study has shown that as Si concentration increases (1, 2 mM), the shoot biomass of plants increased by 33.1%–63.6%, the Cd accumulation increased by 31.9%–96.6%, and the chlorophyll, carotenoid content, photosynthetic gas exchange parameters significantly increased. Si reduced Pro and MDA, promoted the concentrations of SOD, CAT and POD to reduce antioxidant stress damage. In addition, Si promoted GSH and PC to chelate Cd in vacuoles, repaired damaged cell ultrastructure, improved the fixation of Cd and cell wall (especially in pectin), and reduced the toxic effects of Cd. Transcriptome analysis found that genes encoding Cd detoxification, Cd absorption and transport were up-regulated by Si supplying, including photosynthetic pathways (PSB, LHCB, PSA), antioxidant defense systems (CAT, APX, CSD, RBOH), cell wall biosynthesis such as pectinesterase (PME), chelation (GST, MT, NAS, GR), Cd absorption (Nramp3, Nramp5, ZNT) and Cd transport (HMA, PCR). Our result revealed the tentative mechanism of Si promotes Cd accumulation and enhances Cd tolerance in S. alfredii, and thereby provides a solid theoretical support for the practical use of Si fertilizer in phytoextraction.

The halotolerant exopolysaccharide-producing Rhizobium azibense increases the salt tolerance mechanism in Phaseolus vulgaris (L.) by improving growth, ion homeostasis, and antioxidant defensive enzymes

Globally, agricultural productivity is facing a serious problem due to soil salinity which often causes osmotic, ionic, and redox imbalances in plants. Applying halotolerant rhizobacterial inoculants having multifarious growth-regulating traits is thought to be an effective and advantageous approach to overcome salinity stress. Here, salt-tolerant (tolerating 300 mM NaCl), exopolysaccharide (EPS) producing Rhizobium azibense SR-26 (accession no. MG063740) was assessed for salt alleviation potential by inoculating Phaseolus vulgaris (L.) plants raised under varying NaCl regimes. The metabolically active cells of strain SR-26 produced a significant amount of phytohormones (indole-3-acetic acid, gibberellic acid, and cytokinin), ACC deaminase, ammonia, and siderophore under salt stress. Increasing NaCl concentration variably affected the EPS produced by SR-26. The P-solubilization activity of the SR-26 strain was positively impacted by NaCl, as demonstrated by OD shift in NaCl-treated/untreated NBRIP medium. The detrimental effect of NaCl on plants was lowered by inoculation of halotolerant strain SR-26. Following soil inoculation, R. azibense significantly (p ≤ 0.05) enhanced seed germination (10%), root (19%) shoot (23%) biomass, leaf area (18%), total chlorophyll (21%), and carotenoid content (32%) of P. vulgaris raised in soil added with 40 mM NaCl concentration. Furthermore, strain SR-26 modulated the relative leaf water content (RLWC), proline, total soluble protein (TSP), and sugar (TSS) of salt-exposed plants. Moreover, R. azibense inoculation lowered the concentrations of oxidative stress biomarkers; MDA (29%), H2O2 content (24%), electrolyte leakage (31%), membrane stability (36%) and Na+ ion uptake (28%) when applied to 40 mM NaCl-treated plants. Further, R. azibense increases the salt tolerance mechanism of P. vulgaris by upregulating the antioxidant defensive responses. Summarily, it is reasonable to propose that EPS-synthesizing halotolerant R. azibense SR-26 should be applied as the most cost-effective option for increasing the yields of legume crops specifically P. vulgaris in salinity-challenged soil systems.

Can SPAD Values and CIE L*a*b* Scales Predict Chlorophyll and Carotenoid Concentrations in Leaves and Diagnose the Growth Potential of Trees? An Empirical Study of Four Tree Species

Photosynthetic pigments are fundamental for plant photosynthesis and play an important role in plant growth. Currently, the frequently used method for measuring photosynthetic pigments is spectrophotometry. Additionally, the SPAD-502 chlorophyll meter, with its advantages of easy operation and non-destructive testing, has been widely applied in land agriculture. However, the application prospects of its test results in horticultural plants have not yet been proven. This study examines the reliability of SPAD values for predicting chlorophyll concentrations. Using fresh and senescent leaves from four common horticultural plants, we measured SPAD values, photosynthetic pigment concentrations, and leaf color parameters. A generalized linear mixed model demonstrated that SPAD values are a reliable indicator for predicting chlorophyll concentrations, yet interspecific variations exist. Based on the predictive power of SPAD values for chlorophyll, we first propose an Enrichment Index (CEI) and a Normal Chlorophyll Concentration Threshold (NCCT). The CEI can be used to compare SPAD values among different species, and the NCCT value can serve as a more accurate indicator for assessing the growth potential of old trees. However, due to a limited sample size, further research with larger samples is needed to refine the diagnosis of plant growth potential and enhance the management of ornamental plant cultivation.

Influence of Harvesting Stages on Phytonutrients and Antioxidant Properties of Leaves of Five Purple-Fleshed Sweet Potato (Ipomoea batatas) Genotypes.

Sweet potatoes (Ipomoea batatas) are highly profitable, contribute to food security, and their leaves rich in phytonutrients. This study examined the optimal leaf harvesting stage by harvesting newly formed leaves (leaves 1 to 5) to achieve the highest concentration of carotenoids, phenolic compounds, antioxidant properties and mineral content. Leaves of five purple-fleshed sweet potato genotypes '2019-11-2' and '2019-1-1', 'Purple-purple', and from the USA '08-21P' and '16-283P' were harvested based on tuber life cycle [vegetative 8 weeks after planting (VS-8WAP), tuber initiation (TIS-12WAP), and tuber maturation phases (TMS-16WAP)]. At the 8WAP stage, leaves of genotype '2019-11-2' had the highest concentrations of cyanidin-caffeoyl-sophoroside-glucoside (17.64 mg/kg), cyanidin-caffeoyl-feruloyl-sophoroside-glucoside (41.51 mg/kg), peonidin-caffeoyl-hydroxybenzoyl-sophoriside-glucoside (45.25 mg/kg), and peonidin caffeoyl-feruloyl-sophoriside-glucoside (24.47 mg/kg), as well as antioxidant scavenging activity. In contrast, 'Purple-purple' harvested at TIS-12WAP showed the highest concentration of caffeoylquinic acid derivatives. Zeaxanthin, lutein, all trans-β-carotene, and cis-β-carotene are the most abundant carotenoids in genotype '08-21P' at VS-8WAP. As a result, local genotypes '2019-11-2' harvested at 8WAP and 'Purple-purple' harvested at 12WAP are potential sources of anthocyanins and caffeoylquinic acid derivatives. Conversely, USA's genotype '08-21P' at the VS-8WAP stage is an excellent source of carotenoids. The leaves of USA's '08-21P' genotype and the local '2019-11-2' genotype at TMS-16WAP exhibited the highest content of Fe and Mn, respectively. The study identified the optimal leaf stage for consumption of leaves and for use as a functional ingredient.