Cuticular Layer Research Articles

Synergistic mechanism of insecticidal activity in basil and mandarin essential oils against the tobacco cutworm

Owing to the complexity in the chemical composition of plant essential oils, they often display enhanced insecticidal activity when applied as a mixture. Although the insecticidal activity of plant essential oils has been gaining more attention recently, understanding in the mechanism of synergy has not been studied as much. In the present study, insecticidal activity of 28 individual essential oils and their mixtures against the third instar larvae of Spodoptera litura was examined. Among the oils tested, basil oil exhibited the strongest contact toxicity, and mandarin oil displayed the greatest boosting effect when the remaining oils were mixed with basil oil. Estragole and linalool were determined as the major active constituents for the insecticidal activity of basil oil and limonene for mandarin oil from the chemical analyses and compound elimination assay. Based on the LD50 values, the binary mixture of basil and mandarin oils exhibited enhanced toxicity compared to the individual application of the two oils, showing synergy ratios of 1.3 and 1.4 from two statistical models. As for the major active compounds, synergistic interaction was found in tertiary mixture of estragole, linalool, and limonene in the blending ratio of 7:2:7, displaying the same insecticidal activity of the binary mixture of basil and mandarin oils. The synergistic effect was only observed in the tertiary mixture, indicating each compound play crucial roles of the overall contact toxicity. Increased penetration through cuticular layer and amplified neurophysiological response were proposed for the mechanism of synergistic effect.

Muscle and epidermal contributions of the structural protein \u03b2-spectrin promote hypergravity-induced motor neuron axon defects in C. elegans

Biology is adapted to Earth’s gravity force, and the long-term effects of varying gravity on the development of animals is unclear. Previously, we reported that high gravity, called hypergravity, increases defects in the development of motor neuron axons in the nematode Caenorhabditis elegans. Here, we show that a mutation in the unc-70 gene that encodes the cytoskeletal β-spectrin protein suppresses hypergravity-induced axon defects. UNC-70 expression is required in both muscle and epidermis to promote the axon defects in high gravity. We reveal that the location of axon defects is correlated to the size of the muscle cell that the axon traverses. We also show that mutations that compromise key proteins of hemidesmosomal structures suppress hypergravity-induced axon defects. These hemidesmosomal structures play a crucial role in coupling mechanical force between the muscle, epidermis and the external cuticle. We speculate a model in which the rigid organization of muscle, epidermal and cuticular layers under high gravity pressure compresses the narrow axon migration pathways in the extracellular matrix hindering proper axon pathfinding of motor neurons.

Leaf color as a morpho-physiological index for screening heat tolerance and improved water use efficiency in rabbiteye blueberry (Vaccinium virgatum Aiton)

The rabbiteye blueberry (Vaccinium virgatum Aiton) is a promising new fruit crop in the subtropical lowland. However, mid-day temporary wilting of young shoot tips often occurs in the high summer heat and strong irradiance, warranting breeding for heat tolerance. Differences in leaf color among rabbiteye blueberry genotypes are visually distinguishable. To test the hypothesis that leaf color can be a morpho-physiological index for early screening in heat tolerance breeding with lighter leaf color preferred, leaf color of selected ‘Blueshower’ open-pollinated siblings was quantified using CIE L*a*b* color space. Diurnal leaf to air temperature differences (ΔTleaf-air), chlorophyll content (Chl), mid-day gas exchange parameters and water use efficiency (WUE) were measured. The collected data were correlated with L*a*b* information. In hot sunny days, the genotypes with dark leaf color or low L* absorbed heat quicker than those with light leaf color or high L*, resulting in greater ΔTleaf-air in the morning hours. The differences in ΔTleaf-air were similar among the genotypes after mid-day, likely due to the negative correlation between L* and transpiration (E) that facilitates heat dissipation. Maximum leaf net CO2assimilation (An) was recorded at leaf temperature around 35°C in all genotypes and was positivly corrected with b*. a* was positively correlated with leaf Chl content but not with any gas exchange parameters, suggesting that the effect of Chl content on An was overpowered by the effect of leaf lightness derived from cuticular wax layers on leaf surface. Although increasing L* reduced E and thus improved WUE, the genotype with the highest L* value had the lowest mid-day stomatal conductance and intercellular CO2 concentration, resulting in a significantly low An than that in the genotypes with moderate L*. We concluded that leaf lightness is a feasible index for heat tolerance breeding. For hot and arid climates, genotypes with high L* are recommended for their outstanding WUE but in the expense of An. For the hot humid subtropical climate, genotypes with moderate L* and high b* will be better candidates for their high An in well-watered conditions.

The isolated or combined effects of dynamic controlled atmosphere (DCA) and 1-MCP on the chemical composition of cuticular wax and metabolism of ‘Maxi Gala’ apples after long-term storage

Apples have a continuous hydrophobic layer that covers the surface of the fruit, which is called the cuticle. The effects of 1-methylcyclopropene (1-MCP) on the cuticular wax layer of apples were reported after cold storage, although the interaction between 1-MCP and dynamic controlled atmosphere (DCA) is not yet known. Therefore, this study aimed to analyze the effects of 1-MCP on the wax composition and metabolism of ‘Maxi Gala’ apples after storage in a controlled atmosphere (CA) and dynamic controlled atmosphere based on chlorophyll fluorescence (DCA-CF) and respiratory quotient (DCA-RQ; RQ = 1.3 and 1.5). The 1-MCP treatment effectively decreased ethylene production for CA and DCA-CF treatments, while in DCA-RQ treatments produced no effect. The average extracted cuticular wax content of ‘Maxi Gala’ apples was 16.65 g m−2 and no differences in storage conditions or 1-MCP application were observed. Alkanes, alcohols, fatty acids, aldehydes, and terpenoids were identified in the chemical composition of the cuticular waxes, being alkanes and fatty acids the predominant ones. Moreover, 1-MCP decreased fatty acid and 10-nonacosanol concentrations in the fruit. Fruit with the 1-MCP application and stored in DCA had lower α-farnesene concentrations. The wax compositions of the DCA-stored apples with and without 1-MCP were similar. However, 1-MCP treatment resulted in a greater mass loss in fruit stored in DCA.

High Concentrations of Very Long Chain Leaf Wax Alkanes of Thrips Susceptible Pepper Accessions (Capsicum spp)

The cuticular wax layer can be important for plant resistance to insects. Thrips (Frankliniella occidentalis) damage was assessed on 11 pepper accessions of Capsicum annuum and C. chinense in leaf disc and whole plant assays. Thrips damage differed among the accessions. We analyzed the composition of leaf cuticular waxes of these accessions by GC-MS. The leaf wax composition was different between the two Capsicum species. In C. annuum, 1-octacosanol (C28 alcohol) was the most abundant component, whereas in C. chinense 1-triacotanol (C30 alcohol) was the prominent. Thrips susceptible accessions had significantly higher concentrations of C25-C29n-alkanes and iso-alkanes compared to relatively resistant pepper accessions. The triterpenoids α- and ß-amyrin tended to be more abundant in resistant accessions. Our study suggests a role for very long chain wax alkanes in thrips susceptibility of pepper.

Monitoring of changes in 5-n-alkylresorcinols during wheat seedling development.

For seven days of wheat growth, caryopsis remained the main source of 5-n-alkylresorcinols with C19 and/or C21 homolog as a main compound. Shoot contained small amount of these phenolic lipids; their average content was 3.23% of level obtained in the whole seedling. Moreover, 41.38% of resorcinolic lipids of seven-day-old shoot was accumulated in part of leaf covered by coleoptile. Interestingly, a removal of 1.07% of the primary pool of kernel alkylresorcinols by short-term washing (10s) of wheat seed with acetone before planting decreased their level only in seed of seven-day old seedling. Compared to the respective controls, this treatment did not affect the amount of these lipids in the green part of seedling that proved that de novo synthesis of 5-n-alkylresorcinols takes place in shoots. The very similar homolog profiles of these lipids in four- and seven-day-old shoots turned out to be markedly less diversified than those found in respective seed samples. Compared to the mature wheat caryopsis, the rise in the content of very-long-chain homologs was observed only in the oldest shoot. Their increased accumulation was probably connected with formation of cuticular layer providing the defensive barrier against various phytopathogens.

Cuticular Chemistry of the Queensland Fruit Fly Bactrocera tryoni (Froggatt).

The cuticular layer of the insect exoskeleton contains diverse compounds that serve important biological functions, including the maintenance of homeostasis by protecting against water loss, protection from injury, pathogens and insecticides, and communication. Bactrocera tryoni (Froggatt) is the most destructive pest of fruit production in Australia, yet there are no published accounts of this species’ cuticular chemistry. We here provide a comprehensive description of B. tryoni cuticular chemistry. We used gas chromatography-mass spectrometry to identify and characterize compounds in hexane extracts of B. tryoni adults reared from larvae in naturally infested fruits. The compounds found included spiroacetals, aliphatic amides, saturated/unsaturated and methyl branched C12 to C20 chain esters and C29 to C33 normal and methyl-branched alkanes. The spiroacetals and esters were found to be specific to mature females, while the amides were found in both sexes. Normal and methyl-branched alkanes were qualitatively the same in all age and sex groups but some of the alkanes differed in amounts (as estimated from internal standard-normalized peak areas) between mature males and females, as well as between mature and immature flies. This study provides essential foundations for studies investigating the functions of cuticular chemistry in this economically important species.

Chemical Composition of Cuticular Waxes and Pigments and Morphology of Leaves of Quercus suber Trees of Different Provenance.

The chemical composition of cuticular waxes and pigments and the morphological features of cork oak (Quercus suber) leaves were determined for six samples with seeds of different geographical origins covering the natural distribution of the species. The leaves of all samples exhibited a hard texture and oval shape with a dark green colour on the hairless adaxial surface, while the abaxial surface was lighter, with numerous stomata and densely covered with trichomes in the form of stellate multicellular hairs. The results suggest an adaptive role of leaf features among samples of different provenance and the potential role of such variability in dealing with varying temperatures and rainfall regimes through local adaptation and phenotypic plasticity, as was seen in the trial site, since no significant differences in leaf traits among the various specimens were found, for example, specific leaf area 55.6–67.8 cm2/g, leaf size 4.6–6.8 cm2 and photosynthetic pigment (total chlorophyll, 31.8–40.4 µg/cm2). The leaves showed a substantial cuticular wax layer (154.3–235.1 µg/cm2) composed predominantly of triterpenes and aliphatic compounds (61–72% and 17–23% of the identified compounds, respectively) that contributed to forming a nearly impermeable membrane that helps the plant cope with drought conditions. These characteristics are related to the species and did not differ among trees of different seed origin. The major identified compound was lupeol, indicating that cork oak leaves may be considered as a potential source of this bioactive compound.

Mechanical creep of tea leaves.

Tea processing involves fermentation, withering, steaming or pan-firing, rolling, baking, and drying. Some of these steps are performed at a high temperatures. At such temperatures the creep of the tea leaves plays an important role in the quality of tea. In materials science, creep is the tendency of a tea leaf to move slowly or defom permanently under a constant load. There has been much research on the mechanical properties of the outmost cuticular layer of leaves but there are few reports addressing the mechanical properties of whole leaves. We cut tea leaf into specimen of dog-bone shape and measure the time-dependent creep deformation using a dynamic mechnical analyzer. Three different tea leaves grown in Taiwan were examined. The nonlinear Burgers model is proposed to describe the creep deformation of the tea leaves. The creep of the tea leaves consists of primary and steady states, and the creep deformation is accurately described by the Kelvin representation of the nonlinear Burgers model. The viscosities in the primary stages satisfied the Arrhenius equation, and the activation energies were determined. The stress exponents for the creep of the tea leaves were less than unity. The Maxwell representation of the Burgers model is mathematically equivalent to the Kelvin representation of the Burgers model and can also be used to explain the creep of tea leaves. © 2020 Society of Chemical Industry.

Deciphering the Novel Role of AtMIN7 in Cuticle Formation and Defense against the Bacterial Pathogen Infection.

The cuticle is the outermost layer of plant aerial tissue that interacts with the environment and protects plants against water loss and various biotic and abiotic stresses. ADP ribosylation factor guanine nucleotide exchange factor proteins (ARF-GEFs) are key components of the vesicle trafficking system. Our study discovers that AtMIN7, an Arabidopsis ARF-GEF, is critical for cuticle formation and related leaf surface defense against the bacterial pathogen Pseudomonas syringae pathovar tomato (Pto). Our transmission electron microscopy and scanning electron microscopy studies indicate that the atmin7 mutant leaves have a thinner cuticular layer, defective stomata structure, and impaired cuticle ledge of stomata compared to the leaves of wild type plants. GC–MS analysis further revealed that the amount of cutin monomers was significantly reduced in atmin7 mutant plants. Furthermore, the exogenous application of either of three plant hormones—salicylic acid, jasmonic acid, or abscisic acid—enhanced the cuticle formation in atmin7 mutant leaves and the related defense responses to the bacterial Pto infection. Thus, transport of cutin-related components by AtMIN7 may contribute to its impact on cuticle formation and related defense function.

Adpression of medullosan prepollen-producing organs, their prepollen and cuticles (Westphalian, Intrasudetic Basin, Czech Republic)

The adpression fossil record from the Westphalian of the Intrasudetic Basin (Czech Republic) contains diversified medullosan prepollen organs. Langsettian bell-shaped prepollen organs were found in the Lampertice Member in the Žacléř area: Whittleseya elegans Newberry, W. delphinae Stockmans et Willière, W. silesiaca Pacyna et Zdebska and Givesia media (Stockmans) Stockmans et Willière. These fructifications may have been produced by plants with fronds of the fossil-genera Neuralethopteris Cremer and Alethopteris Sternberg. Parent plants of small Langsettian Aulacotheca sp. are uncertain. Duckmantian medullosan male fructifications from the Malé Svatoňovice area are elongated capsules described as Aulacotheca idae Šimůnek sp. nov. and were produced by plants with Alethopteris idae Šimůnek fronds. The prepollen grains and cuticles were isolated from Whittleseya elegans, W. delphinae, Givesia media and Aulacotheca idae. All prepollen grains are oval with two longitudinal grooves and a monolete suture, and are classified as Monoletes ovatus Schopf. There is great overlap in the dimensions of the prepollen of Whittleseya elegans, W. delphinae and Givesia media – 155–230 μm long and 100–180 μm wide. Prepollen of Aulacotheca idae are much bigger – 330–375 μm long and 190–245 μm wide. The inner cuticular layer is gently cutinised with polygonal cells. Cuticles from the prepollen organ surface has elongated cells in Whittleseya elegans (with stomata) and Givesia media (with trichome bases), and has polygonal cells in Whittleseya delphinae (with periclinal cell wall thickenings) and Aulacotheca idae (with hollow papillae on periclinal cell walls). The question, as to whether Whittleseya elegans and W. delphinae are conspecific is discussed.

Epigenetic Activation of Enoyl-CoA Reductase By An Acetyltransferase Complex Triggers Wheat Wax Biosynthesis.

The epidermal surface of bread wheat (Triticum aestivum) is coated with a hydrophobic cuticular wax layer that protects plant tissues against environmental stresses. However, the regulatory mechanism of cuticular wax biosynthesis remains to be uncovered in bread wheat. Here, we identified wheat Enoyl-CoA Reductase (TaECR) as a core component responsible for biosynthesis of wheat cuticular wax. Silencing of TaECR in bread wheat resulted in a reduced cuticular wax load and attenuated conidia germination of the adapted fungal pathogen powdery mildew (Blumeria graminis f.sp. tritici). Furthermore, we established that TaECR genes are direct targets of TaECR promoter-binding MYB transcription factor1 (TaEPBM1), which could interact with the adapter protein Alteration/Deficiency in Activation2 (TaADA2) and recruit the histone acetyltransferase General Control Nonderepressible5 (TaGCN5) to TaECR promoters. Most importantly, we demonstrated that the TaEPBM1-TaADA2-TaGCN5 ternary protein complex activates TaECR transcription by potentiating histone acetylation and enhancing RNA polymerase II enrichment at TaECR genes, thereby contributing to the wheat cuticular wax biosynthesis. Finally, we identified very-long-chain aldehydes as the wax signals provided by the TaECR-TaEPBM1-TaADA2-TaGCN5 circuit for triggering B graminis f.sp. tritici conidia germination. These results demonstrate that specific transcription factors recruit the TaADA2-TaGCN5 histone acetyltransferase complex to epigenetically regulate biosynthesis of wheat cuticular wax, which is required for triggering germination of the adapted powdery mildew pathogen.

Structure and composition of the tunic in the sea pineapple Halocynthia roretzi: A complex cellulosic composite biomaterial

Biological organisms produce high-performance composite materials, such as bone, wood and insect cuticle, which provide inspiration for the design of novel materials. Ascidians (sea squirts) produce an organic exoskeleton, known as a tunic, which has been studied quite extensively in several species. However, currently, there are still gaps in our knowledge about the detailed structure and composition of this cellulosic biocomposite. Here, we investigate the composition and hierarchical structure of the tough tunic from the species Halocynthia roretzi, through a cross-disciplinary approach combining traditional histology, immunohistochemistry, vibrational spectroscopy, X-ray diffraction, and atomic force and electron microscopies. The picture emerging is that the tunic of H. roretzi is a hierarchically-structured composite of cellulose and proteins with several compositionally and structurally distinct zones. At the surface is a thin sclerotized cuticular layer with elevated composition of protein containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised primarily of helicoidally-ordered crystalline cellulose fibres with a lower protein content. The subcuticular zone directly beneath the surface contains much less organized cellulose fibres. Given current efforts to utilize biorenewable cellulose sources for the sustainable production of bio-inspired composites, these insights establish the tunic of H. roretzi as an exciting new archetype for extracting relevant design principles. Statement of SignificanceTunicates are the only animals able to produce cellulose. They use this structural polysaccharide to build an exoskeleton called a tunic. Here, we investigate the composition and hierarchical structure of the tough tunic from the sea pineapple Halocynthia roretzi through a multiscale cross-disciplinary approach. The tunic of this species is a composite of cellulose and proteins with two distinct layers. At the surface is a thin sclerotized cuticular layer with a higher protein content containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised of well-ordered cellulose fibres with a lower protein content. Given current efforts to utilize cellulose to produce advanced materials, the tunic of the sea pineapple provides a striking model for the design of bio-inspired cellulosic composites.

Comparison of the suitability of plant species for greenbelt construction based on particulate matter capture capacity, air pollution tolerance index, and antioxidant system

Particulate matter (PM) pollution is an urgent urban environmental problem. However, plants can mitigate this pollution by filtering the air. Combining the PM capture capacity with the air pollution tolerance could be better evaluate the suitability of greenbelt plants. We selected nine dominant roadside plants growing at two sites in Beijing, and compared their PM capture capacity, morphological characteristics, biochemical characteristics, and air pollution tolerance index (APTI). Sophora japonica had the highest PM capture capacity (362.98 μg cm−2), and its wax layers could trap large amounts of PM2.5; this high efficiency is important for successful phytoremediation. Sophora japonica. Sabina chinensis, Ulmus pumila, and Euonymus japonicus also showed relatively high PM capture capacity. This is due to their complex cuticular wax layers, short petioles, rough surfaces, high stomata density, and dense canopy structures which reduce the possibility of resuspension of captured PM. Amount of PM captured per unit leaf area had a significant positive effect on the degree of membrane lipid peroxidation, indicating that species with high PM capture capacity suffered higher oxidative stresses. Air pollution showed the strongest negative effect size on chlorophyll contents of E. japonicas. While, S. japonica, S. chinensis, and U. pumila could prevent chlorophyll content decline under severe oxidative stress. Sophora japonica also had the highest APTI at both sites, indicating this species had the greatest tolerance to air pollution. Our findings suggest that S. japonica would be the most suitable species for greenbelt construction in Beijing, followed by S. chinensis, E. japonicus, and U. pumila.

The leaves of Anabarella Abramova (Pinopsida) from the Cretaceous ofthe north of East Siberia (Russia)

The paper documents in detail the morphology, epidermal features and cuticle ultrastructure of the leaves of the Mesozoic conifer genus Anabarella Abramova 1984. For the first time, the leaf epidermal and cuticle structures of the type species Anabarella kryshtofovichii Abramova from the Albian–Cenomanian (Cretaceous) of the Anabar river basin (East Siberia, Arctic Russia) were studied with the scanning electron (SEM) and the transmission electron (TEM) microscopes. Emended diagnosis for the genus Anabarella and the diagnosis for the species A. kryshtofovichii are provided, since only a description of this species was given in the original publication. Because the holotype has been lost, a lectotype is selected. The cuticular membrane of Anabarella leaves belongs to the type 1 of the cuticle classification of Holloway 1982: it is made up of the cuticle proper A (composed of an outer polylamellate A1 layer and an inner homogeneous A2 layer) and a cuticular fibrillate layer B1. The leaves of Anabarella kryshtofovichii differ from other fossil conifers by a very thick cuticle membrane consisting predominantly of a cuticle proper A; the cuticular layer B1 is less than 1% from the total thickness of cuticular membrane in the ordinary epidermal cells. The studied leaves have both xeromorphic (thick cuticle and sunken stomata) and mesomorphic (amphistomatic leaves, unprotected stomata) features. The mesomorphic features of the Anabarella leaves, as well as the deciduousness, were probably an adaptation to the humid conditions of the mid-Cretaceous Arctic climate with warm and dark winters.

Postharvest antimicrobial treatments with organic acids to improve the shelf life of fresh blueberries

Fresh highbush blueberries (Vaccinium corymbosum L.) are one of the most popular soft fruits characterized by attractive sensorial attributes and high antioxidant potential. They are highly perishable as they are susceptible to various microbial infections, both pre- and postharvest. The present research was conducted to investigate the effects of postharvest treatments with citric (2%), benzoic (0.2%) and sorbic (0.2%) acids on physicochemical, biochemical and microbiological evolution of fresh blueberries under cold storage conditions. Samples were evaluated initially and at 7-day interval for dry matter, total soluble solids, titratable acidity, total phenolic content, total flavonoid content, antioxidant activity and surface microbial load for six weeks storage time. Chemical treatments significantly reduced the microbial growth on the fruit surface throughout the storage period as compared to the control samples, but they caused a significant increase in moisture loss (sorbic acid > benzoic acid > citric acid > water), probably due to the partial damage of the natural cuticular wax layer covering the fruit. Antimicrobial effects of chemical treatments were more noticeable than their biochemical effects. Total phenolic, total flavonoid content and antioxidant activity showed similar variation pattern during storage in treated and control samples. However, at the end of the storage period, antioxidant activity was significantly higher in samples treated with citric acid and benzoic acid as compared with control samples.

Sequestration of Exogenous Volatiles by Plant Cuticular Waxes as a Mechanism of Passive Associational Resistance: A Proof of Concept.

Numerous plant-derived volatile organic compounds (VOCs) induce the expression of resistance-related genes and thereby cause an “associational resistance” in neighbouring plants. However, VOCs can also be sequestered by plant cuticular waxes. In case that they maintain their biological activity, such sequestered VOCs could generate a “passive” associational resistance that is independent of any gene expression in the receiver. As a proof of concept, we used major components of the cuticular wax layers of the tree, Parkinsonia praecox, and conidia of Colletotrichum lindemuthianum, a fungal pathogen that has not been reported to infect P. praecox. Wax layers were re-constituted on glass slides and exposed to each of 20 pure VOCs for 1 d and then to ambient air for 1 d or 15 d. Gas chromatography-mass spectrometry (GC-MS) analyses showed that all 20 VOCs were sequestered by the re-constituted wax layers. Exposure to 18 of the VOCs significantly inhibited the germination of C. lindemuthianum conidia on these wax layers after 1 day of exposure to ambient air. Four of the VOCs: 4Z-heptenol, farnesene, limonene, and 2E-decenal, inhibited germination rates to less than 25% of the controls. After 15 d, all VOCs were still detectable, although at strongly reduced concentrations, and no significant inhibition of conidial germination could be detected anymore. Exogenous VOCs can be sequestered by the components of plant cuticular waxes and maintain their biological activity, at least over a certain time span: an effect that could generate a transient “passive associational resistance” to pathogens.

Naturally pre-designed biomaterials: Spider molting cuticle as a functional crude oil sorbent

Diverse fields of modern environmental technology are nowadays focused on the discovery and development of new sources for oil spill removal. An especially interesting type of sorbents is those of natural origin—biosorbents—as ready-to-use constructs with biodegradable, nontoxic, renewable and cost-efficient properties. Moreover, the growing problem of microplastic-related contamination in the oceans further encourages the use of biosorbents. Here, for the first time, naturally pre-designed molting cuticles of the Theraphosidae spider Avicularia sp. “Peru purple”, as part of constituting a large-scale spider origin waste material, were used for efficient sorption of crude oil. Compared with currently used materials, the proposed biosorbent of spider cuticular origin demonstrates excellent ability to remain on the water surface for a long time. In this study the morphology and hydrophobic features of Theraphosidae cuticle are investigated for the first time. The unique surface morphology and very low surface free energy (4.47 ± 0.08 mN/m) give the cuticle-based, tube-like, porous biosorbent excellent oleophilic–hydrophobic properties. The crude oil sorption capacities of A. sp. “Peru purple” molt structures in sea water, distilled water and fresh water were measured at 12.6 g/g, 15.8 g/g and 16.6 g/g respectively. These results indicate that this biomaterial is more efficient than such currently used fibrous sorbents as human hairs or chicken feathers. Four cycles of desorption were performed and confirmed the reusability of the proposed biosorbent. We suggest that the oil adsorption mechanism is related to the brush-like and microporous structure of the tubular spider molting cuticles and may also involve interaction between the cuticular wax layers and crude oil.

Epicuticular wax variability of Juniperus deltoides R.P. Adams from the central Balkan – Ecology and chemophenetics

Juniperus deltoides R.P.Adams is a prickly, evergreen shrub that grows in the East Mediterranean on dry hills and mountains. Needle-like leaves have a thick cuticular layer on the surface, which serves as the ultimate barrier for prevention of water loss. n-Alkanes comprise the biggest part of this hydrophobic wax mixture. These compounds are studied as chemophenetic characters due to their chemical and physiological stability, and strong genetic control. Six central Balkan populations were studied and compared to one eastern and one western. Fifteen n-alkanes were identified, with C33 being dominant in all samples. Univariate and multivariate statistical analyses separated western population from all central Balkan populations, while the eastern Balkan population showed high similarity with the central ones. Climatic, orographic and pedological characteristics of the studied localities were also taken into account.

Suaeda vermiculata Forssk. ex J.F. Gmel.: Structural Characteristics and Adaptations to Salinity and Drought: A Review

The aim of the present study is to review the structural characteristics possessed and the adaptations implemented by Suaeda vermiculata; a partially succulent habitat-indifferent desert halophyte, to cope with salinity and drought stresses and gaining insight into its tolerance mechanisms. These characteristics include succulence, leaf burns, leaf shedding, stunted growth habit, change in colour of the leaves, thick cuticular layers and sunken stomata. Deep rooting system and high root/shoot ratio are two more drought adaptations that may also be incorporated as tolerance mechanisms, but no previous studies were encountered for S. vermiculata. These adaptations allowed S. vermiculata to tolerate broad distribution in arid and semi-arid regions and variable habitats including salinity. The presence of small glossy seeds devoid of structures enhancing dispersal, limit its range of spatial dispersal and may be regarded as an inherent limit to tolerance mechanisms.