Light-Independent Nitrogen Assimilation in Plant Leaves: Nitrate Incorporation into Glutamine, Glutamate, Aspartate, and Asparagine Traced by 15N

Although the nitrate assimilation into amino acids in photosynthetic leaf tissues is active under the light, the studies during 1950s and 1970s in the dark nitrate assimilation provided fragmental and variable activities, and the mechanism of reductant supply to nitrate assimilation in darkness remained unclear. ¹⁵N tracing experiments unraveled the assimilatory mechanism of nitrogen from nitrate into amino acids in the light and in darkness by the reactions of nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, aspartate aminotransferase, and asparagine synthetase. Nitrogen assimilation in illuminated leaves and non-photosynthetic roots occurs either in the redundant way or in the specific manner regarding the isoforms of nitrogen assimilatory enzymes in their cellular compartments. The electron supplying systems necessary to the enzymatic reactions share in part a similar electron donor system at the expense of carbohydrates in both leaves and roots, but also distinct reducing systems regarding the reactions of Fd-nitrite reductase and Fd-glutamate synthase in the photosynthetic and non-photosynthetic organs.

Evidence for an extinct lineage of angiosperms from the Early Cretaceous of Patagonia and implications for the early radiation of flowering plants

The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, but new evidence from cuticle structure suggests that it is an angiosperm. Here we document the morphology and cuticle anatomy of Mesodescolea and explore its significance for early angiosperm evolution. We observed macrofossils and cuticles of Mesodescolea with light, scanning electron and transmission electron microscopy, and used phylogenetic methods to test its relationships among extant angiosperms. Mesodescolea has chloranthoid teeth and tertiary veins forming elongate areoles. Its cuticular morphology and ultrastructure reject cycadalean affinities, whereas its guard cell shape and stomatal ledges are angiospermous. It shares variable stomatal complexes and epidermal oil cells with angiosperm leaves from the lower Potomac Group. Phylogenetic analyses and hypothesis testing support its placement within the basal ANITA grade, most likely in Austrobaileyales, but it diverges markedly in leaf form and venation. Although many Early Cretaceous angiosperms fall within the morphological range of extant taxa, Mesodescolea reveals unexpected early morphological and ecophysiological trends. Its similarity to other Early Cretaceous lobate leaves, many identified previously as eudicots but in some cases pre-dating the appearance of tricolpate pollen, may indicate that Mesodescolea is part of a larger extinct lineage of angiosperms.

Optimization of High-Pressure Extraction Process of Antioxidant Compounds from Feteasca regala Leaves Using Response Surface Methodology

Circular economy principles are based on the use of by-products from one operation as the raw materials in another. The aim of this work is to obtain extracts with high antioxidant capacity and resveratrol content for the superior capitalization of the biomass of Feteasca regala leaves obtained during vineyard horticultural operations in spring. In order to obtain a high-quality extract at an industrial level, an optimal extraction process is needed. Central composite design (CCD) was used for the experiment design, which contained three independent variables: the ratio of extraction solvent to solid matter, temperature (°C) and time (minutes). The evaluation of extracts was done by measuring the total antioxidant capacity of the extracts using photo-chemiluminescent techniques, and the resveratrol content using liquid chromatography. Process optimization was done using response surface methodology (RSM). Minitab software version 17.0 was used for the design of experiments and data analysis. Regression analysis showed that the model predicts 87.5% of the variation for resveratrol and 96% for total antioxidant capacity (TAC). The temperature had the biggest influence on the extraction yield. The optimal operational conditions for the extraction method applied had the following conditions: ratio e/m 2.92; 43.23 °C and 55.4 min. A maximum value of 34,623 µg ascorbic acid equivalent (AAE) /mL total antioxidant capacity and 182.4 µg/mL resveratrol content were obtained when the optimal extraction parameters where used. The values obtained in experiments proved that by using RSM an accurate model can be obtained for extraction of Feteasca regala leaves.

The Chemical and Biological Profiles of Leaves from Commercial Blueberry Varieties

Blueberries have seen an ascending production line boosted by World Health Organization (WHO) approvals for their contributions to a healthy diet and the evidence that they act against different diseases. This increase resulted in significant amounts of discarded leaves, which could be a valuable source of bioactive compounds. In the present study, ultrasound-assisted extraction technology was used to determine and compare the chemical and biological profiles of leaves from six commercial blueberry (Vaccinium corymbosum L.) varieties. Feruloylquinic acid was the major compound identified, ranging from 19.23 ± 0.18 mg/g (at the lowest level, registered in the Spartan variety) to 49.62 ± 0.41 mg/g (at the highest level, registered in the Nelson variety). Rutin was the second major compound identified, for which Toro, Nelson, and Elliot leaves registered the highest values, with 35.77 ± 0.19 mg/g, 32.50 ± 0.20 mg/g, and 31.53 ± 0.1 mg/g, respectively. Even though analogous polyphenols were detected in the six cultivars, their concentrations and amounts were different. The leaf extracts of the cultivars Toro, Elliot, and Nelson appear to be good sources of antioxidants, registering high percentage inhibitions of DPPH radicals, of 70.41%, 68.42%, and 58.69%, respectively. The blueberry leaf extracts had a strong antibacterial activity and a low antifungal capacity, and a low-to-moderate antimutagenic capacity towards Salmonella typhimurium TA98 and TA100 strains, with Toro leaf being the best candidate. All of these biological activities indicate health-related benefits, recommending them as suitable candidates for medical and pharmaceutical applications. The present paper adds significant knowledge to the field of blueberry leaves via chemical and biological profiles, supporting the ultrasound-assisted extraction technique as a useful and green method to provide alternative sources of bioactive compounds.

Absorption and distribution of root, fruit, and foliar-applied 45 Ca in 'Clemenules' mandarin trees

BACKGROUND

The mechanisms of calcium (Ca) absorption and transport in plants are still poorly understood. This study focused on assessing the absorption and distribution of Ca in different plant organs after root (soil), foliar, or fruit application to 6-year-old 'Clemenules' mandarin trees, grown in pots, using ⁴⁵ Ca as a tracer.

RESULTS

The rate of ⁴⁵ Ca absorption and transportation in plant tissues varied according to the treatment method. The fruit and shoot Ca supply led to a rate of 97% to 98% ⁴⁵ Ca retention in such organs. In Ca-treated fruits, 22% of the applied ⁴⁵ Ca moved to the pulp and 78% remained in the flavedo and albedo. The fruit peel was examined by scanning electron microscopy and transmission electron microscopy (SEM and TEM) and variations were observed during fruit development. Following ⁴⁵ Ca soil treatment, approximately 56% of ⁴⁵ Ca activity was measured in the soil, with 19.5% determined in the roots, 14.6% in the trunks (90% in bark and sapwood and only 10% in heartwood), 9.6% in shoots, and 0.3% in fruits.

CONCLUSION

Calcium mobility in 'Clemenules' mandarin trees is limited and depends on the mode of Ca fertilizer application. The distribution of Ca to and within the fruits may be limited during development because of structural and functional constraints. © 2020 Society of Chemical Industry.

Sweet Immunity: The Effect of Exogenous Fructans on the Susceptibility of Apple (Malus × domestica Borkh.) to Venturia inaequalis

There is an urgent need for novel, efficient and environmentally friendly strategies to control apple scab (Venturia inaequalis), for the purpose of reducing overall pesticide use. Fructans are recently emerging as promising “priming” compounds, standing out for their safety and low production costs. The objective of this work was to test a fructan-triggered defense in the leaves of apple seedlings. It was demonstrated that exogenous leaf spraying can reduce the development of apple scab disease symptoms. When evaluated macroscopically and by V. inaequalis-specific qPCR, levan-treated leaves showed a significant reduction of sporulation and V. inaequalis DNA in comparison to mock- and inulin-treated leaves, comparable to the levels in fosetyl-aluminum-treated leaves. Furthermore, we observed a significant reduction of in vitro mycelial growth of V. inaequalis on plates supplemented with levans when compared to controls, indicating a direct inhibition of fungal growth. Variations in endogenous sugar contents in the leaves were followed during priming and subsequent infection, revealing complex dynamics as a function of time and leaf ontogeny. Our data are discussed in view of the present theories on sugar signaling and fructan-based immunity, identifying areas for future research and highlighting the potential use of fructans in apple scab management in orchards.

The Content of Phenolic Acids and Flavonols in the Leaves of Nine Varieties of Sweet Potatoes (Ipomoea batatas L.) Depending on Their Development, Grown in Central Europe

The aim of the study was the qualitative and quantitative analysis of the bioactive components present in the leaves of 9 sweet potato cultivars grown in the moderate climate in Poland, which were harvested at different growth stages according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale (14, 51, 89). It was found that sweet potato leaves contained 7 polyphenolic compounds, including 5 chlorogenic acids-neochlorogenic acid (5-CQA), chlorogenic acid (3-CQA), 4-cryptochlorogenic acid (4-CQA), 34-di-O-caffeoylqunic acid (3,4-CQA), 3,5-di-O-caffeoylqunic acid (3,5-CQA)-and 2 flavonoids, quercetin-3-O-galactoside (Q-3-GA) and quercetin-3-O-glucoside (Q-3-GL). Their content depended on the genotype of the examined cultivars and on the stage of leaf development. The mean content of the identified polyphenolic compounds in the examined cultivars ranged from 148.2 to 14.038.6 mg/100 g^-1 DM for the leaves harvested at growth stage 14 according to the BBCH scale. In the case of leaves harvested at BBCH stage 51, the concentration of polyphenolic compounds ranged from 144.76 to 5026.8 mg/100 g^-1 DM and at BBCH stage 89 from 4078.1 to 11.183.5 mg/100 g^-1 DM. The leaves of the Carmen Rubin cultivar collected at stage 14 contained the highest amount of polyphenolic compounds, while Okinava leaves had the highest amount of these compounds at stage 51. The highest content of polyphenolic compounds in leaves at BBCH growth stage 89 was found in the Radiosa variety. The highest concentration levels were found for 3-CQA at all stages of leaf development. Significant correlations between polyphenol content and antioxidant activity measured by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing/antioxidant power (FRAP) were found. The results of this experiment revealed that the growth stages and genetic properties of cultivars have a very significant influence on the content of phenolic acids and flavonols in sweet potato leaves. The results are innovative and can have a practical application, as the knowledge of the content of the substances under study makes it possible to determine the optimal management practice of sweet potato leaf harvest in order to obtain more top-quality raw material.

Aqueous extract of dry powder blend of seeds and leaves of Picralima nitida (Stapf) T. & H. Durand reduce pain and inflammation in animal models

OBJECTIVES

Blend of seeds and leaves of Picralima nitida herein referred to as West African Durand powder (WDP) was investigated for antinociceptive and anti-inflammatory properties.

METHODS

Acute toxic effect of the aqueous extract was evaluated in mice of both sexes. Antinociceptive effect of WDP (100-400 mg/kg) was evaluated in models of acetic acid-induced writhing and thermal nociception on hot plate in mice. Carrageenan-induced paw oedema and air pouch rat models were used to evaluate the anti-inflammatory activity of the extract.

RESULTS

WDP (2,000 mg/kg) showed no toxic effect in mice. WDP at 100, 200 and 400 mg/kg inhibited abdominal writhings by 59.9, 66.0 and 79.0%, respectively. There was a significant increase in reaction time on the hot plate tests in mice treated with WDP (400 mg/kg). The paw oedema was reduced by WDP (100, 200 and 400 mg/kg) 5 h post-carrageeenan. Exudate volume was significantly reduced to 39.8 and 44.8% by 200 and 400 mg/kg WDP, respectively. WDP reduced Leucocytes counts (23.3 and 57.1%, respectively) and neutrophil counts (28.1 and 60.0%, as well as reduced nitrites, malondialdehyde levels and increased glutathione concentrations in the air pouch.

CONCLUSIONS

These results suggest that aqueous extract of blend of seeds and leaves of P. nitida possesses antinociceptive and anti-inflammatory properties.

Traditionally Used Sideritis cypria Post.: Phytochemistry, Nutritional Content, Bioactive Compounds of Cultivated Populations

Sideritis species are recognized as important medicinal plants and their commercial demand is continuously on the rise both in the European and in the global market. Consequently, the cultivation of Sideritis species has been occurred to successfully meet the need for mass production of high-quality plant material. The present study was undertaken in order to investigate the chemical composition of cultivated S. cypria. Infusions of flowers and leaves were prepared separately, according to the European Medicine Agency (EMA) monograph. The infusion of the flowers revealed the presence of four flavones, isoscutellarein-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)-β-D-glucopyranoside, its 4′-O-methyl-derivative, 4′-O-methyl-hypolaetin-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)-β-D-glucopyranoside, and isoscutellarein-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)]-6″-O-acetyl-β-D-glucopyranoside; four phenylethanoid glucosides, acteoside, leucosceptoside A, lamalboside, and leonoside A; one iridoid, melittoside, and one phenolic acid, chlorogenic acid, while the infusion of the leaves of the same population afforded the same first two flavones; five phenylethanoid glucosides, acteoside, leucosceptoside A, lavandulifolioside, leonoside A, and lamalboside; melittoside and chlorogenic acid. The structural elucidation of the isolated compounds was undertaken by high-field NMR spectroscopy. Moreover, the essential oils of the flowers and leaves were studied by GC-MS, separately. In addition, the mineral, bioactive compounds, protein and carbohydrate contents were evaluated for both plant materials.

Metabolic Insights into the Anion-Anion Antagonism in Sweet Basil: Effects of Different Nitrate/Chloride Ratios in the Nutrient Solution

Sweet basil (Ocimum basilicum L.) is a highly versatile and globally popular culinary herb, and a rich source of aromatic and bioactive compounds. Particularly for leafy vegetables, nutrient management allows a more efficient and sustainable improvement of crop yield and quality. In this work, we investigated the effects of balanced modulation of the concentration of two antagonist anions (nitrate and chlorine) in basil. Specifically, we evaluated the changes in yield and leaf metabolic profiles in response to four different NO3-:Cl- ratios in two consecutive harvests, using a full factorial design. Our work indicated that the variation of the nitrate-chloride ratio exerts a large effect on both metabolomic profile and yield in basil, which cannot be fully explained only by an anion-anion antagonist outcome. The metabolomic reprogramming involved different biochemical classes of compounds, with distinctive traits as a function of the different nutrient ratios. Such changes involved not only a response to nutrients availability, but also to redox imbalance and oxidative stress. A network of signaling compounds, including NO and phytohormones, underlined the modeling of metabolomic signatures. Our work highlighted the potential and the magnitude of the effect of nutrient solution management in basil and provided an advancement towards understanding the metabolic response to anion antagonism in plants.

Side Streams of Broccoli Leaves: A Climate Smart and Healthy Food Ingredient

Human consumption of fruits and vegetables are generally below recommended levels. Waste from the production, e.g., of un-used parts such as broccoli leaves and stem when producing broccoli florets for food, is a sustainability issue. In this study, broccoli leaves were analyzed for the content of various dietary fibre and phenolics, applying the Uppsala method and HPLC analyses, respectively. The results showed that broccoli leaves had comparable levels of dietary fibre (26%–32% of dry weight (DW)) and phenolic compounds (6.3–15.2 mg/g DW) to many other food and vegetables considered valuable in the human diet from a health perspective. A significant positive correlation was found among soluble dietary fibre and phenolic acids indicating possible bindings between these components. Seasonal variations affected mainly the content of conjugated phenolics, and the content of insoluble dietary fibre. This study verified the importance of the use of broccoli production side streams (leaves) as they may contribute with health promoting components to the human diet and also socio-economic and environmental benefits to the bioeconomic development in the society.

Excess Copper-Induced Alterations of Protein Profiles and Related Physiological Parameters in Citrus Leaves

This present study examined excess copper (Cu) effects on seedling growth, leaf Cu concentration, gas exchange, and protein profiles identified by a two-dimensional electrophoresis (2-DE) based mass spectrometry (MS) approach after Citrus sinensis and Citrus grandis seedlings were treated for six months with 0.5 (control), 200, 300, or 400 μM CuCl2. Forty-one and 37 differentially abundant protein (DAP) spots were identified in Cu-treated C. grandis and C. sinensis leaves, respectively, including some novel DAPs that were not reported in leaves and/or roots. Most of these DAPs were identified only in C. grandis or C. sinensis leaves. More DAPs increased in abundances than DAPs decreased in abundances were observed in Cu-treated C. grandis leaves, but the opposite was true in Cu-treated C. sinensis leaves. Over 50% of DAPs were associated with photosynthesis, carbohydrate, and energy metabolism. Cu-toxicity-induced reduction in leaf CO2 assimilation might be caused by decreased abundances of proteins related to photosynthetic electron transport chain (PETC) and CO2 assimilation. Cu-effects on PETC were more pronounced in C. sinensis leaves than in C. grandis leaves. DAPs related to antioxidation and detoxification, protein folding and assembly (viz., chaperones and folding catalysts), and signal transduction might be involved in Citrus Cu-toxicity and Cu-tolerance.

Formation of Escherichia coli O157:H7 Persister Cells in the Lettuce Phyllosphere and Application of Differential Equation Models To Predict Their Prevalence on Lettuce Plants in the Field

Escherichia coli O157:H7 (EcO157) infections have been recurrently associated with produce. The physiological state of EcO157 cells surviving the many stresses encountered on plants is poorly understood. EcO157 populations on plants in the field generally follow a biphasic decay in which small subpopulations survive over longer periods of time. We hypothesized that these subpopulations include persister cells, known as cells in a transient dormant state that arise through phenotypic variation in a clonal population. Using three experimental regimes (with growing, stationary at carrying capacity, and decaying populations), we measured the persister cell fractions in culturable EcO157 populations after inoculation onto lettuce plants in the laboratory. The greatest average persister cell fractions on the leaves within each regime were 0.015, 0.095, and 0.221%, respectively. The declining EcO157 populations on plants incubated under dry conditions showed the largest increase in the persister fraction (46.9-fold). Differential equation models were built to describe the average temporal dynamics of EcO157 normal and persister cell populations after inoculation onto plants maintained under low relative humidity, resulting in switch rates from a normal cell to a persister cell of 7.7 × 10-6 to 2.8 × 10-5 h-1 Applying our model equations from the decay regime, we estimated model parameters for four published field trials of EcO157 survival on lettuce and obtained switch rates similar to those obtained in our study. Hence, our model has relevance to the survival of this human pathogen on lettuce plants in the field. Given the low metabolic state of persister cells, which may protect them from sanitization treatments, these cells are important to consider in the microbial decontamination of produce.IMPORTANCE Despite causing outbreaks of foodborne illness linked to lettuce consumption, E. coli O157:H7 (EcO157) declines rapidly when applied onto plants in the field, and few cells survive over prolonged periods of time. We hypothesized that these cells are persisters, which are in a dormant state and which arise naturally in bacterial populations. When lettuce plants were inoculated with EcO157 in the laboratory, the greatest persister fraction in the population was observed during population decline on dry leaf surfaces. Using mathematical modeling, we calculated the switch rate from an EcO157 normal to persister cell on dry lettuce plants based on our laboratory data. The model was applied to published studies in which lettuce was inoculated with EcO157 in the field, and switch rates similar to those obtained in our study were obtained. Our results contribute important new knowledge about the physiology of this virulent pathogen on plants to be considered to enhance produce safety.

Phenolic Antioxidants in Aerial Parts of Wild Vaccinium Species: Towards Pharmaceutical and Biological Properties

Phenolic compounds are a widespread group of secondary metabolites found in all plants, representing the most desirable antioxidants due to their potential to be used as additives in the food industry (inhibition of lipid oxidation), and in cosmetology and medicine (protection against oxidative stress). In recent years, demand for the identification of edible sources rich in phenolic antioxidants, as well as the development of new natural plant products to be used as dietary supplements or pharmaceuticals, has been a great preoccupation. At present, from the "circular economy" perspective, there is an increased interest to use agricultural waste resources to produce high-value compounds. Vaccinium leaves and stems are considered essentially an agro-waste of the berry industry. Scientific studies have shown that phenolic compounds were found in a markedly higher content in the leaves and stems of Vaccinium plants than in the fruits, in agreement with the strongest biological and antioxidant activities displayed by these aerial parts compared to fruits. This paper aims to review the current state of the art regarding the phenolic antioxidants from leaves and stems of two wild Vaccinium species, bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.), as promising natural resources with pharmaceutical and biological activity.

THz Water Transmittance and Leaf Surface Area: An Effective Nondestructive Method for Determining Leaf Water Content

Water availability is a major limiting factor in plant productivity and plays a key role in plant species distribution over a given area. New technologies, such as terahertz quantum cascade lasers (THz-QCLs) have proven to be non-invasive, effective, and accurate tools for measuring and monitoring leaf water content. This study explores the feasibility of using an advanced THz-QCL device for measuring the absolute leaf water content in Corylus avellana L., Laurus nobilis L., Ostrya carpinifolia Scop., Quercus ilex L., Quercus suber L., and Vitis vinifera L. (cv. Sangiovese). A recently proposed, simple spectroscopic technique was used, consisting in determining the transmission of the THz light beam through the leaf combined with a photographic measurement of the leaf area. A significant correlation was found between the product of the leaf optical depth (τ) and the leaf surface area (LA) with the leaf water mass (Mw) for all the studied species (Pearson's r test, p ≤ 0.05). In all cases, the best fit regression line, in the graphs of τLA as a function of Mw, displayed R2 values always greater than 0.85. The method proposed can be combined with water stress indices of plants in order to gain a better understanding of the leaf water management processes or to indirectly monitor the kinetics of leaf invasion by pathogenic bacteria, possibly leading to the development of specific models to study and fight them.

Plasticity of phenotype and heteroblasty in contrasting populations of Acacia koa

BACKGROUND AND AIMS

Heteroblastic plant species, whose morphology or growth habit changes suddenly during development, offer unique opportunities to investigate the role of selection in canalizing development or increasing the adaptive importance of plasticity. Leaf forms of the Hawaiian tree Acacia koa (koa) change morphologically and physiologically during the first year of growth, providing time to study abiotic factors influencing transition rates relative to other Acacia species.

METHODS

The roles of light and water availability in triggering transition to the mature leaf form in contrasting (wet/dry) ecotypes of koa were investigated using a novel modelling technique to distinguish between chronological and ontogenetic controls in triggering transition. A light quality treatment was included to test interactions of heterophylly (the presence of multiple leaf forms) with heteroblastic processes on the resulting phenotype at transition.

KEY RESULTS

Increased light intensity increased transition rates, but reduced red to far-red light (R:FR) ratios did not affect transition rates, solidifying the current paradigm of heteroblasty. However, evidence was found for earlier transition ontogenetically under water stress, which is not part of the current paradigm and could differentiate the role of heteroblasty in some Acacia species versus other heteroblastic species. Ecotypic responses also indicate that plasticity of development could vary across koa's range and the adaptive significance of heteroblasty could be marginalized or amplified dependent on the disparate selective pressures present across koa's range.

CONCLUSIONS

The use of novel survival functions and a species with an elongated transition time helped to elucidate abiotic modifiers of ontogenetic trajectories. Differences in ontogenetic trajectories between contrasting ecotypes suggest that ongoing climate and land use change will have non-uniform effects on koa regeneration and establishment dynamics across its range.

Flower and Leaf Extracts of Sambucus nigra L.: Application of Membrane Processes to Obtain Fractions with Antioxidant and Antityrosinase Properties

This study aimed at evaluating and comparing the chemical profile as well as the antityrosinase and antioxidant activities of ethanol (EtOH) and methanol (MeOH) extracts of Sambucus nigra L. (Adoxaceae) flowers and leaves in order to discover new candidates for food additives and cosmetic and pharmaceutical products. For this purpose, a novel lower-melting-point ethylene-chlorotrifluoroethylene (LMP ECTFE) nanofiltration (NF) membrane was employed in order to produce the concentrated fractions of S. nigra. Floral extracts were richer in phytochemicals in comparison to the leaf extracts. The High-performance liquid chromatography (HPLC) profile revealed rutin, quercetin, protocateuchic acid, 3,5-dicaffeoylquinic acid, and neochlorogenic acid as the most abundant compounds. Ferric reducing antioxidant power (FRAP), 2,2’-diphenil-1-picrylhydrazil (DPPH) radical scavenging, and 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) tests were used to investigate the antioxidant properties. NF retentate fractions of floral ethanol extracts exerted the highest tyrosinase inhibitory activity with an IC₅₀ of 53.9 µg/mL and the highest ABTS radical scavenging activity (IC₅₀ of 46.4 µg/mL). In conclusion, the present investigation revealed the potential benefits of NF application in S. nigra extracts processing, suggesting the use of retentate fractions as a promising source for antioxidant and tyrosinase inhibitory compounds which could pave the way for future applications.

Foliage motion under wind, from leaf flutter to branch buffeting

The wind-induced motion of the foliage in a tree is an important phenomenon both for biological issues (photosynthesis, pathogens development or herbivory) and for more subtle effects such as on wi-fi transmission or animal communication. Such foliage motion results from a combination of the motion of the branches that support the leaves, and of the motion of the leaves relative to the branches. Individual leaf dynamics relative to the branch, and branch dynamics have usually been studied separately. Here, in an experimental study on a whole tree in a large-scale wind tunnel, we present the first empirical evidence that foliage motion is actually dominated by individual leaf flutter at low wind velocities, and by branch turbulence buffeting responses at higher velocities. The transition between the two regimes is related to a weak dependence of leaf flutter on wind velocity, while branch turbulent buffeting is strongly dependent on it. Quantitative comparisons with existing engineering-based models of leaf and branch motion confirm the prevalence of these two mechanisms. Simultaneous measurements of the wind-induced drag on the tree and of the light interception by the foliage show the role of an additional mechanism, reconfiguration, whereby leaves bend and overlap, limiting individual leaf flutter. We then discuss the consequences of these findings on the role of wind-mediated phenomena.

Morphological Analysis of Size and Shape (MASS): An integrative software program for morphometric analyses of leaves

PREMISE

Morphometric analysis is a common approach for comparing and categorizing botanical samples; however, completing a suite of analyses using existing tools may require a multi-stage, multi-program process. To facilitate streamlined analysis within a single program, Morphological Analysis of Size and Shape (MASS) for leaves was developed. Its utility is demonstrated using exemplar leaf samples from Acer saccharum, Malus domestica, and Lithospermum.

METHODS

Exemplar samples were obtained from across a single tree (Acer saccharum), three trees in the same species (Malus domestica), and online, digitized herbarium specimens (Lithospermum). MASS was used to complete simple geometric measurements of samples, such as length and area, as well as geometric morphological analyses including elliptical Fourier and Procrustes analyses. Principal component analysis (PCA) of data was also completed within the same program.

RESULTS

MASS is capable of making desired measurements and analyzing traditional morphometric data as well as landmark and outline data.

DISCUSSION

Using MASS, differences were observed among leaves of the three studied taxa, but only in Malus domestica were differences statistically significant or correlated with other morphological features. In the future, MASS could be applied for analysis of other two-dimensional organs and structures. MASS is available for download at https://github.com/gillianlynnryan/MASS.

Occurrence, Distribution and Risk Assessment of Mercury in Multimedia of Soil-Dust-Plants in Shanghai, China

The urban environment is a complex ecosystem influenced by strong human disturbances in multi-environmental media, so it is necessary to analyze urban environmental pollutants through the comprehensive analysis of different media. Soil, road dust, foliar dust, and camphor leaves from 32 sample sites in Shanghai were collected for the analysis of mercury contamination in soil–road dust–leaves–foliar dust systems. Mercury concentrations in surface soils in Shanghai were the highest, followed by road dust, foliar dust, and leaves, successively. The spatial distribution of mercury in the four environmental media presented different distribution patterns. Except for the significant correlation between mercury concentrations in road dust and mercury concentrations in leaves (r = 0.56, p < 0.001), there was no significant correlation between the other groups in the four media. Besides this, there was no significant correlation between mercury concentrations and land types. The LUR (Land use regression) model was used to assess the impact of urbanization factors on mercury distribution in the environment. The results showed that soil mercury was affected by factories and residential areas. Foliar dust mercury was affected by road density and power plants. Leaf mercury was affected by power plants and road dust mercury was affected by public service areas. The highest average HI (Hazard index) value of mercury in Shanghai was found in road dust, followed by surface soil and foliar dust. The HI values for children were much higher than those for adults. However, the HI values of mercury exposure in all sampling sites were less than one, suggesting a lower health risk level. The microscopic mechanism of mercury in different environmental media was suggested to be studied further in order to learn the quantitative effects of urbanization factors on mercury concentrations.

Transcriptional Reprogramming of Pea Leaves at Early Reproductive Stages

Pea (Pisum sativum L.) is an important source of dietary proteins. Nutrient recycling from leaves contributes to the accumulation of seed proteins and is a pivotal determinant of protein yields in this grain legume. The aim of this study was to unveil the transcriptional regulations occurring in pea leaves before the sharp decrease in chlorophyll breakdown. As a prelude to this study, a time-series analysis of ¹⁵N translocation at the whole plant level was performed, which indicated that nitrogen recycling among organs was highly dynamic during this period and varied depending on nitrate availability. Leaves collected on vegetative and reproductive nodes were further analyzed by transcriptomics. The data revealed extensive transcriptome changes in leaves of reproductive nodes during early seed development (from flowering to 14 days after flowering), including an up-regulation of genes encoding transporters, and particularly of sulfate that might sustain sulfur metabolism in leaves of the reproductive part. This developmental period was also characterized by a down-regulation of cell wall-associated genes in leaves of both reproductive and vegetative nodes, reflecting a shift in cell wall structure. Later on, 27 days after flowering, genes potentially switching the metabolism of leaves toward senescence were pinpointed, some of which are related to ribosomal RNA processing, autophagy, or transport systems. Transcription factors differentially regulated in leaves between stages were identified and a gene co-expression network pointed out some of them as potential regulators of the above-mentioned biological processes. The same approach was conducted in Medicago truncatula to identify shared regulations with this wild legume species. Altogether the results give a global view of transcriptional events in leaves of legumes at early reproductive stages and provide a valuable resource of candidate genes that could be targeted by reverse genetics to improve nutrient remobilization and/or delay catabolic processes leading to senescence.

Growth and biomechanics of shoot organs

Plant organs arise through complex interactions between biological and physical factors that control morphogenesis. While there has been tremendous progress in the understanding of the genetics behind development, we know much less about how mechanical forces control growth in plants. In recent years, new multidisciplinary research combining genetics, live-imaging, physics, and computational modeling has begun to fill this gap by revealing the crucial role of biomechanics in the establishment of plant organs. In this review, we provide an overview of our current understanding of growth during initiation, patterning, and expansion of shoot lateral organs. We discuss how growth is controlled by physical forces, and how mechanical stresses generated during growth can control morphogenesis at the level of both cells and tissues. Understanding the mechanical basis of growth and morphogenesis in plants is in its early days, and many puzzling facts are yet to be deciphered.

Tremella saccharicola f.a., sp. nov., a novel tremellaceous yeast species isolated from tropical regions

Ten strains representing a single anamorphic novel yeast species were isolated from the external surface (DMKU-SP23 and DMKU-SP40) and tissue (DMKU-SE89, DMKU-SE99, DMKU-SE100 and DMKU-SE147) of sugarcane leaves in Thailand, and phylloplane (IMUFRJR 52034) and rhizoplane (IMUFRJ 52036 and 52037) of sugarcane and associated soil (IMUFRJ 52035) in Brazil. These strains showed zero to two nucleotide substitutions in the sequences of the D1/D2 region of the LSU rRNA gene and zero to three nucleotide substitutions in the internal transcribed spacer (ITS) region. Tremella globispora was the most closely related species, but with 1.7-2.1 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene, and 5.3-6.0 % nucleotide substitutions in the ITS region. Phylogenetic analysis based on the concatenated sequences of the ITS and the D1/D2 regions showed that these 10 strains represented a single species belonging to the genus Tremella (class Tremellomycetes, subphylum Agaricomycotina) that was distinct from related species. They therefore represented a novel species of the genus Tremella although the formation of basidia and basidiocarp were not observed. The name Tremella saccharicola f.a., sp. nov. is proposed. The type strain is DMKU-SP23^T (=NBRC 109698^T=BCC 61186^T).

Study and modeling of the distribution process of some phenolic compounds between the solid and liquid phases

The article presents the results related to the study of distribution of biologically active substances from the plant raw material between solid and liquid phases. The aim of this study is to develop theoretical bases of the extraction process in the equilibrium state by the example of study and modeling of the distribution process of biologically active substances from Eucalyptus viminalis leaves. In these studies, we used ground plant raw material of E. viminalis leaves with particle fraction of 0.1-0.5 mm; and ethanol with concentration 80% ±1% v/v was used as an extractant. Qualitative and quantitative analyses were carried out by reversed phase high-performance liquid chromatography with rutin, chlorogenic acid, and euglobal standards equivalent to spissum extract of chlorophyllipt of the State Pharmacopoeia of Ukraine. A hypothesis has been suggested that Henry's adsorption law and the law of conservation of matter play a fundamental role in this process. The experimental data are described well by the suggested equation with high value of determination coefficient R ² =0.99. At the same time, F-test and the significance of coefficients in equations satisfy the statistic condition, which means that the current hypothesis about the adsorption mechanism of distribution of biologically active substances in the extraction system is not refuted. The results of these studies demonstrate good agreement of experimental data and theoretical model based on Henry's adsorption law and mass balance. The numerical values of constants in the model suggested have been calculated.