Morpho-ecological structure of oribatid mite (Acariformes, Oribatida) communities in the forest litter of recultivated areas

The study of morpho-ecological organization of oribatid mite communities (Acariformes, Oribatida) inhabiting forest litter of recultivated areas in steppe zone conditions of Ukraine was performed. The role of the forest and forest floor litter in optimization of the ecological situation on degraded lands was demonstrated. The function of environment creation by oribatids, as primary destructors of dead plant matter, supporting such ecosystem services as soil fertility improvement and nutrients turnover was highlighted. The research was performed within different stratigraphic types of bulk edaphotops in the recultivated plot of “Pavlogradskaya” colliery (Pavlograd, Dnipropetrovsk region, Ukraine) planted with red juniper (Juniperus virginiana L.). Withdrawal and collection of mites was performed with thermoeclector. For determination of the domination structure in the mite communities, the Engelmann scale was used. Adaptive (morpho-ecological) groups of oribatid mites were diagnosed by Krivolutsky. It was established that the number of species of oribatid mites in the forest litter of the studied red juniper plantation varied from 16 to 25. Average density of oribatid mites varied from 4,720 to 25,327 ind./m2. Among such morpho-ecological groups as soil surface inhabitants, small soil pore inhabitants, deep soil forms, floor litter inhabitants and unspecified forms, identified in the coniferous litter, the share of unspecified forms increased from loess-like loam type (21% of total amount) to Calcic Chernozem types with different stratigraphy (41.0%, 70.0% and 70.4% accordingly). Deep soil forms in the forest floor litter of the studied red juniper plots were not identified for any of recultivation types. The obtained results expand our understanding of the role of oribatid mites in the processes of ecological rehabilitation of disturbed ecosystems in the conditions of modern nature management

Modification of the epicuticular waxes of plant leaves due to increased sunlight intensity

Climatic changes observed around the world in recent years are associated with an increase in the solar radiation intensity and temperature and reduction in the humidity. Fluctuations of environmental factors significantly change the conditions for the existence of plants, which dictates the need for adaptive reactions of plant organisms at the different levels of their organization. Such dangerous processes as excessive heating of the surface of plant leaves and water loss can be prevented by the formation of a cuticle, which is a complex composition consisting of cutin and the soluble intracuticular and epicuticular waxes. We suggested that the structure, component composition and properties of the cuticle of trees undergo adaptive changes due to microclimatic conditions in different parts of the tree crown. The study was aimed at the identification and evaluation of light-induced differences in the accumulation and composition of leaf epicuticular waxes of Ulmus trees (native U. minor Mill. and alien U. pumila L.), and was conducted in 2018–2019 in Dnipro city located in the steppe zone of Ukraine. Analysis of the waxes’ chloroform extracts was carried out using GC Shimadzu 2010 PLUS equipped with a flame ionization detector and capillary column SP-2560. The highest amount of epicuticular waxes (12.23 ± 0.39 µg/cm2) was on the sunlit leaves of U. pumila, and wax deposits on the sunned leaves exceeded twice those on the shaded leaves in both U. minor and U. pumila. Long-chain hydrocarbons detected in the epicuticular waxes of both elm species were represented by free fatty acids, aldehydes, alcohols, and n-alkanes in various ratios. In the epicuticular waxes of U. minor, fatty acids dominated both on shaded and sunned leaves, while alkanes together with alcohols were the main components in U. pumila waxes, especially on the sunlit leaves. According to our results, local high illumination of leaves in the crown of both elm species caused increase in share of long-chain alkanes (1.2–1.9 times), but simultaneous reduction of the content of free fatty acids (1.5–16.8 times) in the epicuticular waxes’ composition. General patterns of the leaf epicuticular waxes’ modification due to increased solar radiation and air temperature can indicate the adaptive metabolic responses of woody plants to changing climatic conditions

Phytochemical profiles, antioxidant and antimicrobial activity of Actinidia polygama and A. arguta fruits and leaves

Plants of two species of Actinidia genus grown in an adverse steppe climate were examined in terms of secondary metabolites’ accumulation, antioxidant potential, and antimicrobial ability. The aim of the work was to reveal whether the introduced plants A. arguta and A. polygama retain their well-known health benefits. Total content of polyphenols (549.2 and 428.1 mg GAE/100 g FW, respectively), flavonoids, and phenolic acids as well as total antioxidant activity and reducing power of the fruit isopropanol extracts were found to be equal or even higher than the reported data on kiwifruit varieties cultivated in China and other regions. Antioxidant potential and phenolic compounds’ content in the fruit peel of both species were higher when compared to pulp, while corresponding indices of leaves exceeded those of the fruit. Disc-diffusion assays showed low to moderate antibacterial activity of A. arguta and A. polygama fruit and leaf extracts against collection Gram-negative and Gram-positive strains. Clinical strains of P. aeruginosa and E. coli resistant to the action of ofloxacin were notably inhibited by A. arguta and A. polygama fruit and leaf crude extracts. Inhibiting effects of plant extracts on clinical strains of K. pneumoniae and A. baumannii were comparable with the effect of ofloxacin. GC-MS assays identified 23 and 36 chemical constituents, respectively in A. arguta and A. polygama fruit isopropanol extracts. The main compounds in both extracts were 2-propenoic acid, pentadecyl ester followed by squalene, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-dien-2,8-dione, octadecanoic acid, 2-oxo-methyl ester, ethyl-isoallocholate, and phytol having known bioactivities. Our findings confirmed the preservation of useful properties by the introduced plants and also indicated the rich health-promoting abilities and expedience of cultivating A. arguta and A. polygama in a steppe climate

Phytochemical profiles and antimicrobial activity of the inflorescences of Sorbus domestica, S. aucuparia, and S. torminalis

The genus Sorbus L. is known for its extremely complex taxonomical relationships and health-promoting phytochemicals included in the composition of its floral constituents. The inflorescences of three Sorbus species (rowans), characterized by distinct molecular-genetic traits, were studied in order to examine the possible chemotaxonomic and antimicrobial value of their metabolites. GC–MS profiling of the hexane extracts of S. domestica, S. aucuparia, and S. torminalis inflorescences identified a total of 87 components, which represented six chemical classes (hydrocarbons, alcohols, esters, fatty acid, aldehydes, and ketones) and miscellaneous minor floral constituents (1-methylinosine, 5-amino tetrazole, 1,4-dimethylbenzene, 3,5-bis(1,1-dimethylethyl)-phenol, 3-acetoxy-7,8-epoxylanostan-11-ol, cycloeucalenol acetate, etc.). Principal component analysis (PCA) of the qualitative and quantitative heterogeneity of the floral metabolites determined 1-hentetracontanol, nonacosane, pentadecyl acrylate, 1-methylhexacosane, cycloeucalenol acetate, butyl acetate, and urs-12-ene as the main components which contributed to the differences between S. domestica, S. aucuparia and S. torminalis and resulted in the distinction between the rowan species. Disc-diffusion assays showed variability in activity of inflorescence extracts against Gram-negative (Enterobacter dissolvens, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) and Gram-positive (Micrococcus lysodeikticus, Staphylococcus aureus, and S. epidermidis) bacterial and clinical fungal (Candida albicans) strains. The effect of S. torminalis was high against S. epidermidis and P. aeruginosa, while it was at its lowest against clinical C. albicans strains. Inflorescences of S. domestica showed the highest inhibition of P. aeruginosa, and moderate effects against S. epidermidis and C. albicans. Inflorescences of S. aucuparia caused low to moderate growth inhibition of both Gram-positive and Gram-negative bacterial strains, while it showed the highest effect on C. albicans. Antimicrobial properties of rowan inflorescences may be attributed to oleic, linoleic, arachidic, hexadecanoic, and pentadecanoic acids, 24-norursa-3,12-diene, hexahydrofarnesyl acetone, cycloeucalenol acetate, and other compounds which have known bioactivity. These findings indicated rowan inflorescences as a rich source of valuable secondary metabolites and allow us to assume an application of the floral constituents as chemotaxonomic markers of the genus Sorbus species

Soluble cuticular wax composition and antimicrobial activity of the fruits of Chaenomeles species and an interspecific hybrid

Plants of the genus Chaenomeles Lindl. (Rosaceae) naturally grow in Southeast Asia and represent the richest resource of biologically active compounds with beneficial properties for humans. Plants of C. japonica (Thunb.) Lindl. and C. speciosa (Sweet) Nakai species, and interspecific hybrid C. × superba (Frahm) Rehder (C. japonica × C. speciosa, Superba group) have been successfully introduced in the steppe zone of Ukraine and bear fruits. In this study, we evaluated chemical composition of fruit cuticular waxes and antimicrobial activity of fruit extracts. The soluble waxes were characterized using gas chromatography-mass spectrometry (GC-MS), and 26–36 compounds, representing 91.7–96.6% of the total soluble cuticular waxes, were identified. Waxes of Chaenomeles fruits belonged to six classes, namely fatty acids, alcohols, aldehydes, esters, ethers and alkanes. Aldehydes 7-hexadecenal and heptacosanal, and alkanes hexatriacontane and tetrapentacontane were the main constituents in the soluble cuticular waxes of C. speciosa and C. × superba fruits, accounting for more than half of the total contents. However, alkane tetrapentacontane, alcohol 8,10-hexadecadien-1-ol and heptacosanal prevailed in C. japonica fruit waxes. Isopropanolic fruit extracts exhibited dose-dependent antimicrobial activity against four Gram-negative bacteria, five Gram-positive bacteria and one fungal strain in the disc diffusion assay. In general, extracts from the Chaenomeles fruits demonstrated higher activity against Gram+ bacteria than Gram- strains. The strongest inhibiting activity was shown against Staphylococcus epidermidis (by the fruit extracts of C. × superba and C. speciosa), Micrococcus lysodeikticus and Candida albicans (both by C. × superba fruit extract). Results of the study confirmed accumulation of the bioactive compounds in the fruit waxes of different Chaenomeles species and antimicrobial ability of Chaenomeles fruits as well. These findings revealed the bioactive compounds in fruit cuticular waxes and suggested health-promoting properties of introduced Chaenomeles species

Cuticular wax composition of mature leaves of species and hybrids of the genus Prunus differing in resistance to clasterosporium disease

The interaction of a host plant with pathogen implies an extremely complex process involving the outer waxy layer of the cuticle, cutin, cell membrane, and intracellular structures. However, the initial contact between plants and pathogens takes place in cuticular waxes covering the surface of leaves, stems and fruits. Despite many findings on the role of plant epicuticular waxes, there is a gap in the understanding of the relationship between individual compounds and their functions. The pathogenic fungus Clasterosporium carpohilum (Lev.) Aderh. parasitizes the tissues of many stone fruit trees, damaging leaf and fruit surface. The aim of this work was to find out if the quantity and composition of leaf epicuticular wax could be responsible for the resistance to clasterosporium disease. The study of differences of plants in fungal resistance was carried out on species and hybrids of the genus Prunus from the collection of the Botanical Garden of Oles Honchar Dnipro National University (Dnipro city, Ukraine). The chloroform extracts of epicuticular waxes from the surface of mature leaves were analyzed by gas chromatography connected to mass-spectrometry. GC/MS assay was performed using Shimadzu GCMS-QP 2020 El equipped with capillary column (5% diphenyl/95% dimethyl polysiloxane), and helium as a carrier gas. Mass Spectrum Library 2014 for GSMS was used to identify the separated compounds of the wax extracts. The maximum total wax amount on the adaxial and abaxial leaf surface of hybrid 2 was twice the minimum wax accumulation for hybrid 4. Overall, 20 individual compounds belonging to six hydrocarbon classes were identified. Leaf epicuticular wax composition both in Prunus persica (L.) Batsch and P. dulcis (Mill.) D. A. Webb, and hybrids was dominated by long-chain n-alkanes with even carbon number (77.6–90.9% of total sum). The alkenes’ class was represented only by 17-pentatriacontene detected in the wax of both Prunus species. Octadecanaldehyde was found in epicuticular wax of P. dulcis while absent in wax of the more resistant species P. persica. Prime alcohols 1-tetradecanol and 1-hexacosanol were detected in leaf waxes of hybrid 4 and P. dulcis respectively. The ester class contained seven compounds found in leaf epicuticular waxes of both plant species and all hybrid forms. The identification of phthalic acid esters in leaf wax extracts was unexpected, and the phthalates’ origin is discussed. Strong positive correlation between leaf damage and tetrapentacontane content in epicuticular waxes could presumably be the result of infection-induced metabolism reprogramming in epidermal cells of infected leaves

Modeling the invasiveness of Ulmus pumila in urban ecosystems in conditions of climate change

Climatic change can influence the boundaries of the natural and alien plant species distribution. Fluctuations in air temperature, relative humidity and other factors can become a stimulus to initiation and / or intensification of the invasive nature of some adventive plant species, especially in areas with a high degree of anthropogenic transformation. This paper presents an analysis of the current state and a forecast of the invasiveness of the alien species Ulmus pumila L. (Asiatic elm) in the Northern Steppe Dnieper under conditions of climatic change. Two local U. pumila populations consisting of young different age trees were found during a route survey in the territory of the large industrial city Dnipro (48°28′00″ N, 35°01′05″ E) in its left-bank and right-bank parts.The seed origin of both local populations of Asiatic elm is confirmed by the fact that the young plants were spaced at a distance of 50 to 120 m from adult trees, which could potentially be parent plants. Both the left-bank and right-bank populations of U. pumila were located on abandoned construction sites, where there were numerous reinforced concrete slabs, piles and abundant construction debris. In both U. pumila local populations, 100 different-aged trees were randomly selected throughout the site, and their age and the morphometric parameters were measured to simulate the development process of the detected populations, provided the current trends of climate change continue. Analytical dependence of the number of trees in the left-bank local U. pumila population on development time was described by a polynomial model with a determination coefficient of 98.3%. The graphic representation of this model had a sinusoidal character, and a similar dynamic of left-bank population growth in the subsequent years was suggested. The dynamic of the number of trees in the right-bank local Asiatic elm population was described by an exponential model with a determination coefficient of 84.4%, and its graphical representation was exponential. According to the forecast, by 2020, the number of plants in the right-bank local population of U. pumila can increase 4-fold in comparison with 2015 while maintaining the current dynamic of population development. Thus, the created mathematical models adequately described the dynamics of development of both local populations during the last 15 years and predicted their subsequent intensive growth, confirming the initiation and intensification of the invasive nature of the alien species U. pumila by climatic change in the Steppe Dnieper

Interspecific differences of antioxidant ability of introduced Chaenomeles species with respect to adaptation to the steppe zone conditions

Plants of the genus Chaenomeles are traditionally used in the countries of South-East Asia, due to their high nutritional and health-promoting properties. However, the successful introduction of species promising for gardening from geographically remote areas requires the study of plant ontogeny under the conditions of new habitat. This is a very substantial problem for the steppe zone, where the continental climate has features of aridity and complicates the process of increasing the diversity of fruit crops by introducing the desired species. The present study aims to assess the effectiveness of the protective enzymatic system of different Chaenomeles genotypes subject to a steppe climate as well as the accumulation of the biologically active compounds with high antioxidant capacity. The study was performed on the basis of the introduced horticultural plants collection in the Botanical Garden of the DNU, and the Chaenomeles fruits, leaves, and the seeds were examined. The highest activity of catalase, benzidine-peroxidase and guaiacol-peroxidase, and the greatest enzymes activation during vegetation were found in leaves of Ch. cathayensis and Ch. speciosa, while the lowest activity was in leaves of both Japanese species. The biggest total phenolic content in the isopropanolic plant extracts, determined by Folin–Ciocalteau assay, was found in leaves of Ch. × superba, Ch. × californica and Ch. cathayensis (44.8, 52.8, and 43.6 mg GAE/g WW); a less high level was found in leaves of Ch. japonica and Ch. japonica var. maulei (43.1 and 40.2 mg GAE/g), while the lowest was in leaves of Ch. speciosa (29.3 mg GAE/g). The total flavonoids content determined using the aluminum chloride method, did not differ by variety or species in the plant leaves, being in the range of 2.6–2.9 mg of RE per g WW (accordingly, in leaves of Ch. japonica var. maulei and Ch. × californica). The high total reducing power determined by potassium ferricyanide assay was found in leaves of both hybridogenic species and Ch. cathayensis (respectively, 11.6, 14.1, and 11.4 AAE/g WW); leaves of both Japanese species had slightly lower values and the lowest was in leaves of Ch. speciosa (7.7 AAE/g). In the Chaenomeles fruits, the total phenolic content was the lowest in Ch. speciosa (17.8 mg GAE/g), average in both Japanese species (28.7 and 27.8 mg GAE/g), and the highest (33.3 mg GAE/g) was in Ch. cathayensis. The flavonoid accumulation was highest in the fruits of Ch. cathayensis and Ch. japonica var. maulei (0.67 and 0.63 mg RE/g), intermediate in both hybridogenic species and Ch. japonica (accordingly, 0.57, 0.42 and 0.38 mg RE/g), and the lowest in Ch. speciosa (0.30 mg RE/g). The total reducing power of Chaenomeles fruit was lower as compared to leaves, and decreased from 11.2 to 5.7 mg AAE/g in the series Ch. cathayensis > Ch. × californica > Ch. japonica > Ch. japonica var. maulei > Ch. × superba > Ch. speciosa. High correlation coefficients between total reducing power and total phenols content in the Chaenomeles leaves and fruits (respectively, r = 0.96 and r = 0.95, P < 0.05) confirm the significant contribution of phenolic compounds to the antioxidant capacity. The study results indicate a high antioxidant capacity of the Chaenomeles species in the conditions of the steppe climate due to the antioxidant enzymes activity and the accumulation of a significant amount of phenolic metabolites in leaves and fruits

Dengue Virus Capsid Protein Usurps Lipid Droplets for Viral Particle Formation

Dengue virus is responsible for the highest rates of disease and mortality among the members of the Flavivirus genus. Dengue epidemics are still occurring around the world, indicating an urgent need of prophylactic vaccines and antivirals. In recent years, a great deal has been learned about the mechanisms of dengue virus genome amplification. However, little is known about the process by which the capsid protein recruits the viral genome during encapsidation. Here, we found that the mature capsid protein in the cytoplasm of dengue virus infected cells accumulates on the surface of ER-derived organelles named lipid droplets. Mutagenesis analysis using infectious dengue virus clones has identified specific hydrophobic amino acids, located in the center of the capsid protein, as key elements for lipid droplet association. Substitutions of amino acid L50 or L54 in the capsid protein disrupted lipid droplet targeting and impaired viral particle formation. We also report that dengue virus infection increases the number of lipid droplets per cell, suggesting a link between lipid droplet metabolism and viral replication. In this regard, we found that pharmacological manipulation of the amount of lipid droplets in the cell can be a means to control dengue virus replication. In addition, we developed a novel genetic system to dissociate cis-acting RNA replication elements from the capsid coding sequence. Using this system, we found that mislocalization of a mutated capsid protein decreased viral RNA amplification. We propose that lipid droplets play multiple roles during the viral life cycle; they could sequester the viral capsid protein early during infection and provide a scaffold for genome encapsidation