Differences in mineral and osmotic balances enhance zinc translocation in an aquaporin overexpressing poplar.

Zinc (Zn) is an essential micronutrient for plants, but it is toxic beyond a certain threshold. Populus alba (L.) 'Villafranca' clone is known for its good tolerance to high Zn concentration compared to other poplar species. A line of this species overexpressing the tonoplast intrinsic aquaporin AQUA1 gene has showed an improved tolerance to Zn excess in comparison to the wild-type (wt) line. The aims of this work were to: 1) verify if AQUA1 plants can uptake Zn more efficiently after a longer period of exposure; 2) evaluate if a higher Zn uptake in transgenic lines can have negative effects; 3) assess Zn competing elements (iron and manganese), soluble sugars, osmolytes, and potassium to investigate differences in water and osmotic homeostasis between lines. Under Zn excess, AQUA1 plants showed a twofold Zn translocation factor and a higher xylem sap Zn concentration than the wt plants. Transgenic plants preferentially allocated Zn in aerial biomass and this different behaviour matched with modified manganese and iron balances suggesting that the increased Zn uptake might be related to a decrease in iron transport in the transgenic line. Moreover, a higher instantaneous water use efficiency in control conditions and an increase in bark soluble sugars under Zn excess could allow a higher resistance of AQUA1 plants to the water and osmotic perturbations caused by Zn. Indeed, the Zn excess increased the xylem osmolyte content only in wt plants. Further investigations are required to understand the role of AQUA1 in osmotic regulation.

Olive Fruit Ripening Degree and Water Content Relationships with Phenolic Acids and Alcohols, Secoiridoids, Flavonoids and Pigments in Fruit and Oil.

Olive drupe traits (i.e., ripening index and pericarp water content) and minor components (i.e., phenols and pigments in both fruit and oil) are important for human health and are affected by agronomic background. The aim of this study was to investigate the relationship between fruit traits, phenols, and pigments in samples derived from different soil and water management practices. Chromatographic (UHPLC-MS/MS) and spectroscopic (1HNMR and near UV-Vis spectroscopy) techniques were employed for the characterization of olive fruits and oils. The use of various techniques allowed the identification of interesting trace compounds. We observed that most of the fruit phenols (a total of 29 compounds) were correlated with the degree of ripening: most of the phenolic acids (and their derivatives), phenolic alcohols, and secoiridoids were negatively correlated, whereas the majority of the studied flavonoids were positively correlated. The relationship between the ripening index and fruit phenolic compounds appears to be dependent on the metabolic pathway that controls the synthesis of each individual compound. Conversely, the secoiridoids and pigments in olive oil showed a negative correlation with pulp moisture, probably because of the influence of the water content on the extractability and transfer in the oil phase of these minor components.

Method for selecting ornamental species for different shading intensity in urban green spaces.

In urban areas, ornamental plants face different constraints, such as the shading of buildings and trees. Therefore, the selection of suitable species and their integration or combination with pre-existing plants is very important. Trees, shrubs, and herbaceous plant species must be distributed according to plant light requirements and shading intensity. Ornamental plants are classified into two groups based on their light intensity or shade tolerance: sun and shade species. To properly position the plants, especially in the immediate vicinity of buildings, it is necessary to study the projection of shadows during the year and the most critical periods, such as July and August. The position of ornamental species with different shading tolerances can be obtained by characterizing the leaf gas exchange for each species. Among the physiological parameters, the most important is the light compensation point, which is the light intensity corresponding to a net photosynthesis equal to zero. This means that the assimilation of carbon dioxide through photosynthesis is equal to the carbon dioxide emitted by respiration. This steady state represents the most critical condition for plants to endure the summer. The distribution of species inside a green area should be determined by considering the minimum light intensity that allows sufficient photosynthesis to compensate for the respiration rate. In this context, non-destructive leaf gas exchange, chlorophyll a fluorescence, and chlorophyll content can be useful tools for selecting suitable ornamental plants under diverse shading conditions.

New Strategies to Increase the Abiotic Stress Tolerance in Woody Ornamental Plants in Mediterranean Climate.

The native flora of different Mediterranean countries, often woody species, was widely recognized for its ornamental potential. The shrubs, in particular, are a typology of plants very widespread in the Mediterranean environment and constituent the 'Macchia', the typical vegetation of this ecosystem. The use of native shrubs for the realization of ornamental green areas has been recently examined for their adaptability to abiotic stress. Abiotic stresses, in fact, are the major limiting growth factor in urban and peri-urban areas. The identification and use of tolerant ornamental species allow the reduction of management costs and preserve the aesthetical value of green areas. Tolerance to drought stress, for instance, in the Mediterranean climate can improve the ecosystem services of these plants in the urban environment. In this review, the possibility to early individuate different plant species' mechanisms to tolerate or avoid the stresses is analysed, as well as the possibility to increase abiotic stress tolerance through genetic and agronomic strategies. The exploration of wild or spontaneous species can be a good source for selecting tolerant plants to be used as ornamental plants in urban areas. Among agronomic strategies, biostimulants, mulching, and plant combination can provide a useful solution to counteract abiotic stress in the urban environment.

Biofortification of baby leafy vegetables using nutrient solution containing selenium.

BACKGROUND: Biofortification of vegetables is an important innovation technique in the horticultural sector. Vegetables can be a vector of different minor elements that have beneficial effects on human health. Selenium (Se) is an important element for human nutrition and plays a significant role in defence mechanisms. The aim of this work was to investigate the effect of Se in the nutrient solutions on the crop biofortification ability, yield, and quality parameters of four baby leafy vegetables destined to the minimally processed industry. Experiments were performed on lamb's lettuce, lettuce, wild rocket, and spinach. These crops were cultivated in the floating systems with nutrient solution enriched with 0, 2.6, 3.9, and 5.2 µmol L-1 Se provided as sodium selenate. RESULTS: At harvest, Se concentrations, yield, nitrate concentration, sugars, and some mineral elements were measured. Data collected and analyses showed that yield, nitrate, sucrose, and reducing sugars were not affected by Se treatments, even if varied among species. Se concentrations linearly increased in leaves of different species by increasing the Se concentration in the nutrient solution. Rocket was the species with the highest accumulation ability and reached a concentration of 11 µg g-1 fresh weight Se in plants grown with 5.2 µmol L-1 Se. CONCLUSION: A floating system with Se-enriched nutrient solution is an optimal controlled growing biofortification system for leafy vegetables. The accumulation ability decreased in different species in the order wild rocket, spinach, lettuce, and lamb's lettuce, highlighting a crop-dependent behaviour and their attitude to biofortification. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cocoa Bar Antioxidant Profile Enrichment with Underutilized Apples Varieties.

The impact of dried apples (Malus × domestica Borkh.) addition on improving the antioxidant characteristics of dark chocolate was evaluated. The antioxidant activity was measured through DPPH scavenging activity and showed an increase in the cocoa bar with 'Nesta' dry apple (17.3% vs. 46.8%) in comparison to cocoa mass. The 15 polyphenols analyzed by UHPLC-ESI-MS/MS indicated great variability among the apple varieties. Quercetin was detected in the highest concentrations (ranged from 753.3 to 1915.5 µg g-1), while the lowest were for kaempferol 7-O-glucoside, measured only in 'Mora' and 'Nesta' cocoa bars (from 0.034 to 0.069 µg g-1, respectively). P-coumaric acid, trans-ferulic acid, and chlorogenic acid contribute largely to the antioxidant activity in cocoa bars. Principal component analysis shows that a cocoa bar with the addition of 'Nesta' dry apple differ from others due to its higher content of polyphenols (1614 ± 61.8 mg gallic acid equivalents per 100 g). In conclusion, data confirm that cocoa bars with dry apples might be considered as a polyphenol-enriched food.

Multiple linear regression and linear mixed models identify novel traits of salinity tolerance in Olea europaea L.

Olive can be considered as moderately tolerant to salinity, with marked differences among cultivars. In the present study, two olive cultivars with different salt tolerance, 'Leccino' (sensitive) and 'Frantoio' (tolerant), were treated with 120 mM of NaCl for 30 days. We measured the expression of genes involved in the management of sodium in the leaves, such as NHX, SOS1 and H+ ATPase, and the concentration of Na+, K+, Mn2+, Mg2+ and Ca2+ in the roots, bark, xylem and leaves of the olive plants. The results were analyzed with multiple linear models and mixed models. Furthermore, we utilized the analysis of covariance to find significant relationships in our data. Both cultivars significantly reduced net photosynthesis and increased water-use efficiency after 30 days of treatment. Sodium accumulated significantly in the roots of both cultivars, and 'Leccino' plants were also able to translocate it to the leaves and the bark. The NHX and vacuolar ATPase subunit E genes were significantly overexpressed in both the cultivars treated with NaCl. The SOS1, ATPase11 and ATPase8 genes were overexpressed in 'Frantoio'. The covariance between gene expression and element concentrations data was analyzed to identify significant interactions between cultivars and treatments. Na+ accumulation in the roots of 'Frantoio' was positively related to the accumulation of K+, Mn2+, Mg2+ and Ca2+ in the xylem, bark and leaves. 'Frantoio' capability to mobilize elements, especially Ca2+, together with the overexpression of key genes for sodium management, could be crucial for salt tolerance.

Cations and Phenolic Compounds Concentrations in Fruits of Fig Plants Exposed to Moderate Levels of Salinity.

Fig trees are often grown in areas affected by salinity problems. We investigated changes in the concentrations of 15 phenolic compounds and mineral elements (Mg, Ca, K, Zn, Cu, Mn, Mo, Fe, Na) in fruits of fig plants (Ficus carica L. cv. Dottato) subjected to irrigation with saline water (100 mM of NaCl) for 28 days. We used UHPLC-MS/MS techniques to determine chlorogenic acid, tiliroside, catechin, epicatechin (ECTC), p-coumaric acid, trans-ferulic acid, phloridzin, phloretine, quercetagetin 7-O-glucoside, rutin, quercetin 3-O-glucoside, kaempferol 3-O-rutinoside, kaempferol 7-O-glucoside, kaempferol 3-O-glucoside, and quercetin. There was a steep gradient of Na+ concentrations between the root and the canopy of salinized plants, but leaf Na+ was similar in control and salt-treated plants. Quercetin, ECTC, and chlorogenic acid were the most abundant phenolic compounds in fig fruits. Salinity increased total phenols by 5.6%, but this increase was significant only for ECTC. Salt stress significantly increased Zn and Mg concentration in the fruit. Leaf levels of K, Mg, Ca, and Mn were similar in control and salinized plants. Moderate salt stress appears to improve fig fruit quality because of its positive effect on nutrients and antioxidant compounds such as epicatechin.

Removal of multi-contaminants from water by association of poplar and Brassica plants in a short-term growth chamber experiment.

The plant association of Populus alba L. 'Villafranca', Brassica oleracea var. acephala sebellica (kale), and B. oleracea var. capitata 'sonsma' (cabbage) was exposed to Zn, Cd, and exogenous caffeine (13CFN)-contaminated water under growth chamber conditions. In the short term of treatment (15 days), poplar increased the root dry biomass (+ 25%) and decreased the chlorophyll content in new leaves (- 32%), compared to control. On the contrary, cabbage decreased the root dry biomass, enhancing the shoot dry biomass (+ 50%). Heavy metals were mainly concentrated in plant roots and in poplar reached the highest concentrations of 705 ± 232.6 and 338 ± 85.5 µg g-1 DW for Zn and Cd, respectively. The ability of poplar to accumulate more Zn and Cd than kale and cabbage in plant biomass was confirmed by heavy metal contents, following the order: poplar > kale = cabbage. However, poplar and Brassica sp. association was very useful for Zn and Cd decontaminations as reported by the bioconcentration factors (> 1). The concentration of 13CFN was below 2.4 ng g-1 FW in poplar and 7.4 ng g-1 FW in Brassica species, suggesting the caffeine uptake and degradation by plant association. Under our experimental conditions, the removal efficiency of the system was upper to 79%, indicating the capability of Populus-Brassica association to efficiently remove Zn, Cd, and 13CFN from mixed inorganic-organic-contaminated water in short term.

Near UV-Vis and NMR Spectroscopic Methods for Rapid Screening of Antioxidant Molecules in Extra-Virgin Olive Oil.

Several spectroscopic techniques have been optimized to check extra-virgin olive oil quality and authenticity, as well as to detect eventual adulterations. These methods are usually complementary and can give information about different olive oil chemical components with bioactive and antioxidant properties. In the present work, a well-characterized set of extra-virgin olive oil (cultivar Frantoio) samples from a specific area of Tuscany (Italy) were investigated by combining near UV-Vis absorption spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) to identify and quantify different chemical components, such as pigments, secoiridoids and squalene, related to the nutritional and quality properties of olive oils. Moreover, the pigmentation index of olives, organoleptic and sensory properties, total phenolic compound contents and the lipidic fractions of olive oils were investigated. The results obtained are, finally, compared and discussed in order to correlate several properties of both olives and olive oils with specific features of the cultivation area.

Osmotic adjustments support growth of poplar cultured cells under high concentrations of carbohydrates.

KEY MESSAGE: Poplar callus maintained a specific difference in osmotic potential with respect to media when supplemented with different carbohydrate concentrations. This balance in osmotic potential guaranteed the growth capacity. Osmotic stress is caused by several abiotic factors such as drought, salinity, or freezing. However, the threshold of osmotic potential that allows the growth under stress conditions has not been thoroughly studied. In this study, different levels of osmotic stress in Populus alba (L.) callus have been induced with the addition of mannitol or sorbitol in the medium (from 0 to 500 mM). The key factor for preserving the growth was observed to be the restoration of a constant difference in osmotic potential between callus and medium for all the tested conditions. The osmotic adjustments were primarily achieved with the uptake of mannitol or sorbitol from the media considering their chemical properties instead of their biological functions. The decrease in water content (from - 1 to - 10% after 21 days) and mineral elements, such as potassium, calcium, and magnesium, together with the alterations in cell morphology, did not show negative effects on growth. The activity of sorbitol dehydrogenase was detected for the first time in poplar (+ 4.7 U l-1 in callus treated with sorbitol compared to control callus). This finding suggested the importance of choosing carefully the molecules used to exert osmotic stress for separating the dual function of carbohydrates in osmotic adjustments and cell metabolism.

The Role of Aquaporin Overexpression in the Modulation of Transcription of Heavy Metal Transporters under Cadmium Treatment in Poplar.

Populus alba 'Villafranca' clone is well-known for its tolerance to cadmium (Cd). To determine the mechanisms of Cd tolerance of this species, wild-type (wt) plants were compared with transgenic plants over-expressing an aquaporin (aqua1, GenBank GQ918138). Plants were maintained in hydroponic conditions with Hoagland's solution and treated with 10 µM of Cd, renewed every 5 d. The transcription levels of heavy metal transporter genes (PaHMA2, PaNRAMP1.3, PaNRAMP2, PaNRAMP3.1, PaNRAMP3.2, PaABCC9, and PaABCC13) were analyzed at 1, 7, and 60 d of treatment. Cd application did not induce visible toxicity symptoms in wt and aqua1 plants even after 2 months of treatment confirming the high tolerance of this poplar species to Cd. Most of the analyzed genes showed in wt plants a quick response in transcription at 1 d of treatment and an adaptation at 60 d. On the contrary, a lower transcriptional response was observed in aqua1 plants in concomitance with a higher Cd concentration in medial leaves. Moreover, PaHMA2 showed at 1 d an opposite trend within organs since it was up-regulated in root and stem of wt plants and in leaves of aqua1 plants. In summary, aqua1 overexpression in poplar improved Cd translocation suggesting a lower Cd sensitivity of aqua1 plants. This different response might be due to a different transcription of PaNRAMP3 genes that were more transcribed in wt line because of the importance of this gene in Cd compartmentalization.

Daily osmotic adjustments in stem may be good predictors of water stress intensity in poplar.

Drought events impair the carbon and water balances in plants. Climate changes highlight the importance to understand the limits of woody species to reallocate carbon in different processes and the mechanisms driving the osmotic adjustments during the day under stress. In this frame, the aim of this work was to investigate the plant capability to shift energy among competing sinks and preserve the osmotic balance during the day under severe short periods of water deficit. The role of carbohydrates as osmolytes as well as energy sources was investigated in poplar plants. Results highlighted that during water deficit soluble sugars, derived both from the new synthetised carbon and starch degradation, were principally convoyed in the bark. This increase in carbohydrates allowed the maintenance of a water reserve used during the day to prevent a water decrease within the xylem. The decrease of xylem sap osmotic potential during the night, driven by an increase of K, Ca, and fructose (+0.46, 0.52, and 0.26 mg ml-1 in water limited plants after 8 days of withholding water, respectively), probably further attracted water into the xylem. This response mechanism increased at higher water deficit intensity. The little variations in carbohydrates and mineral elements within the leaves highlighted the main role of sinks rather than sources in the early response to water deficit.

Effect of Preharvest Abiotic Stresses on the Accumulation of Bioactive Compounds in Horticultural Produce.

The quality of horticultural products is the result of the interaction of different factors, including grower's crop management ability, genotype, and environment. Sub-optimal environmental conditions during plant growth can induce abiotic stresses and reduce the crop performance with yield reduction and quality losses. However, abiotic stresses can induce several physiological, biochemical, and molecular responses in plants, aiming to cope with the stressful conditions. It is well known that these abiotic stresses are also elicitors of the biosynthesis of many metabolites in plants, including a wide range of bioactive compounds, which firstly serve as functional molecules for crop adaptation, but they have also a great interest for their beneficial effects on human health. Nowadays, the consumer is oriented to low-energy foods with low fat content, but at the same time, growing attention is paid to the presence of bioactive molecules, which are recognized as health-related compounds and concur to the nutraceutical value of plant-derived foods. In this context, fruit and vegetables play an important role as sources of bioactive ingredients in the diet. At the cultivation level, the understanding of crop responses to abiotic stresses and how they act in the biosynthesis/accumulation of these bioactive compounds is crucial. In fact, controlled abiotic stresses can be used as tools for improving the nutraceutical value of fruit and vegetables. This review focuses on the quality of vegetables and fruits as affected by preharvest abiotic stressors, with particular attention to the effect on the nutraceutical aspects.

Populus alba dioctyl phthalate uptake from contaminated water.

Phthalates are micro-pollutants of great concern due to their negative effects on ecosystem functioning and human health. Thanks to its capability in uptake and accumulation of organic pollutants, Populus alba L. "Villafranca" clone could be a good candidate for reducing the impacts derived by the persistence of such compounds in the environment. We investigated plant response and uptake of dioctyl phthalate (DOP) by poplar, grown in hydroponics condition, for 21 days with 0, 40, and 400 µg L-1 of d4-DOP. Treated plants, after 21 days of 400 µg L-1 d4-DOP, showed an increase in root dry biomass (+ 29%) at the expense of aerial parts (- 8%) compared with control. The root development could be sustained by the increase of Mg uptake by poplar. LC-MS/MS analysis demonstrated the uptake and accumulation in roots of d4-DOP starting from day one (3.5 ± 3.29 and 7.1 ± 3.28 in 40 and 400 µg L-1 d4-DOP respectively), despite volatilization of d4-DOP was observed from nutritive solution. The chemical interaction between d4-DOP and Zn occurred in roots of plants treated with the high d4-DOP concentration, without limiting the Zn concentration in leaves. Results confirm the high tolerance of "Villafranca" clone to xenobiotic and suggest the poplar capability in d4-DOP uptake and accumulation at root level.

Effect of saline irrigation on physiological traits, fatty acid composition and desaturase genes expression in olive fruit mesocarp.

The effect of salinity on physiological traits, fatty acid composition and desaturase genes expression in fruit mesocarp of olive cultivar Leccino was investigated. Significant reduction of shoot elongation (-12%) during salt treatments (80 mM NaCl) was associated with the translocation of Na in the aerial part. After 75 days of treatment, fruits from each plant were subdivided into four maturation groups (MG0, MG1, MG2, MG3) according to ripening degrees. Na accumulation increased in each MG under salinity, reaching the highest values in MG1 fruits (2654 mg kg-1 DW). Salinity caused an acceleration of the ripening process, increased fruit number and decreased total fatty acids content in MG3. An increase in oleic acid at MG1 (53%) was detected, with consequent increase in the oleic/linoleic (41%) and decrease in the polyunsaturated/monounsaturated ratios (30%). Those variations could be explained by the synergic up-regulation of OeSAD1, together with the down-regulation of OeFAD6 transcript levels.

Zinc Excess Induces a Hypoxia-Like Response by Inhibiting Cysteine Oxidases in Poplar Roots.

Poplar (Populus spp.) is a tree species considered for the remediation of soil contaminated by metals, including zinc (Zn). To improve poplar's capacity for Zn assimilation and compartmentalization, it is necessary to understand the physiological and biochemical mechanisms that enable these features as well as their regulation at the molecular level. We observed that the molecular response of poplar roots to Zn excess overlapped with that activated by hypoxia. Therefore, we tested the effect of Zn excess on hypoxia-sensing components and investigated the consequence of root hypoxia on poplar fitness and Zn accumulation capacity. Our results suggest that high intracellular Zn concentrations mimic iron deficiency and inhibit the activity of the oxygen sensors Plant Cysteine Oxidases, leading to the stabilization and activation of ERF-VII transcription factors, which are key regulators of the molecular response to hypoxia. Remarkably, excess Zn and waterlogging similarly decreased poplar growth and development. Simultaneous excess Zn and waterlogging did not exacerbate these parameters, although Zn uptake was limited. This study unveils the contribution of the oxygen-sensing machinery to the Zn excess response in poplar, which may be exploited to improve Zn tolerance and increase Zn accumulation capacity in plants.

Effects of Extra Virgin Olive Oil and Apples Enriched-Dark Chocolate on Endothelial Progenitor Cells in Patients with Cardiovascular Risk Factors: A Randomized Cross-Over Trial.

BACKGROUND: Endothelial dysfunction has been associated to cardiovascular outcomes in patients with cardiovascular risk factors. Circulating endothelial progenitor cells (EPCs) play an important physiological role for their reparative potential of vascular integrity, but are numerically reduced and functionally impaired in patients with cardiovascular risks. This study assesses the effects of Extra Virgin Olive Oil (EVOO) and apple-enriched dark chocolate intake on the blood levels of EPCs. Methods: Thirty volunteers with cardiovascular risk factors, enrolled in a randomised, crossover, four-weeks trial, received a solid dark chocolate bar (40 g/day) containing 10% EVOO or 2.5% dry apples. Urine samples were analyzed for endogenous metabolites. Circulating EPCs levels, clinical data and anthropometric examinations were collected. RESULTS: 26 volunteers (M/F:14/12, 51 ± 9 years of age) completed the study. Comparison of pre-post intervention revealed a significant increase in EPCs levels associated with EVOO-dark chocolate consumption. Most biochemical parameters were not significantly modified by both chocolates. CONCLUSIONS: This study shows that a daily consumption of a non fattening dose of dark chocolate enriched with EVOO improves blood levels of EPCs, a well known surrogate biologic marker for endothelial function.

Removal of micro-pollutants from urban wastewater by constructed wetlands with Phragmites australis and Salix matsudana.

This study assessed the ability to remove micro-pollutants from wastewater using herbaceous species (Phragmites australis L.) and trees (Salix matsudana Koidz.) in constructed wetland (CW) systems. The targets of the study were as follows: (i) pharmaceuticals like diclofenac, ketoprofen, and atenolol; (ii) 4-n-NP (4-n-nonylphenol) and the ethoxylated derivatives monoethoxylated nonylphenol (NP1EO) and diethoxylated nonylphenol (NP2EO); (iii) triclosan, a bactericide used in personal care products. The 12 CW systems, filled with clay and gravel, were irrigated with wastewater from municipal area of Pagnana (Tuscany, Italy) and influent and effluent water samples analyzed periodically by gas chromatography-mass spectrometry (GC-MS/MS). The removal efficiency of CWs planted with willow and common red ranged from 8.4 up to 100%, with the higher removal efficiency for triclosan. On the contrary, the removal efficiency of NPs and NPEOs appears lower than pharmaceuticals. Data demonstrated that P. australis efficiently removed NP, diclofenac, and atenolol, while S. matsudana preferentially removed NP1EO, NP2EO, ketoprofene, and triclosan. A specific selection of plants used in CWs could be exploited for the removal of specific xenobiotics from wastewater.