Epicuticular Wax Composition Research Articles

Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface

Epidermal wax is strategically situated at the interface between plants and air; therefore, it plays a key role in plants’ interactions with their surroundings. It is also unstable and susceptible to light intensity. Hosta plants are shade-loving herbs with admirable flowers and leaves. Hosta ‘Halcyon’ and Hosta ensata F. Maek. are two species of Hosta with a glaucous and a glossy appearance, respectively. Light intensity can affect the composition of epicuticular wax on the leaf surface, which influences the leaf color phenotype and ornamental value. In this paper, the crystal micromorphology, content, and components of epicuticular wax on the leaves of two species of Hosta under different light conditions (10%-, 30%-, 50%-, 70%-, and 100%-intensity sunlight, relative light intensity (RLI)) have been studied using pot experiments. The results indicate that the epicuticular wax crystals of H. ‘Halcyon’ and H. ensata are tubular and platelet-like, respectively. The wax crystals of H. ‘Halcyon’ melted and formed a thick crust under 100% RLI, and those of H. ensata melted and formed a thick crust under 70% and 100% RLI conditions. The primary ingredients of the epicuticular wax of the two species of Hosta contained primary alcohols, alkanes, fatty acids, and esters; β-diketones were only detected in H. ‘Halcyon’. The quantity of epicuticular wax of H. ‘Halcyon’ reduced at first and then increased with an RLI increase, achieving its lowest value at 50% RLI, but that of H. ensata declined little by little. The amounts of C28 primary alcohols, C31 alkanes, and C18 fatty acids were significantly higher than those of other carbon atoms in the two genotypes of Hosta. The C31β-diketones content decreased with the increase in light intensity, which caused the white frost phenotype to gradually weaken in H. ‘Halcyon’.

Effect of light-induced changes in leaf anatomy on intercellular and cellular components of mesophyll resistance for CO2 in Fagus sylvatica.

Mesophyll resistance for CO2 diffusion (rm) is one of the main limitations for photosynthesis and plant growth. Breeding new varieties with lower rm requires knowledge of its distinct components. We tested new method for estimating the relative drawdowns of CO2 concentration (c) across hypostomatous leaves of Fagus sylvatica. This technique yields values of the ratio of the internal CO2 concentrations at the adaxial and abaxial leaf side, cd/cb, the drawdown in the intercellular air space (IAS), and intracellular drawdown between IAS and chloroplast stroma, cc/cbd. The method is based on carbon isotope composition of leaf dry matter and epicuticular wax isolated from upper and lower leaf sides. We investigated leaves from tree-canopy profile to analyse the effects of light and leaf anatomy on the drawdowns and partitioning of rm into its inter- (rIAS) and intracellular (rliq) components. Validity of the new method was tested by independent measurements of rm using conventional isotopic and gas exchange techniques. 73% of investigated leaves had adaxial epicuticular wax enriched in 13C compared to abaxial wax (by 0.50‰ on average), yielding 0.98 and 0.70 for average of cd/cb and cc/cbd, respectively. The rIAS to rliq proportion were 5.5:94.5% in sun-exposed and 14.8:85.2% in shaded leaves. cc dropped to less than half of the atmospheric value in the sunlit and to about two-thirds of it in shaded leaves. This method shows that rIAS is minor but not negligible part of rm and reflects leaf anatomy traits, i.e. leaf mass per area and thickness.

Phytochemistry and Micromorphology of Epicuticular Waxes in Four Juniper Species With Fragmented Distribution in the Balkans.

The cuticle is important in the interaction between the plant and its environment, especially in the dry areas. Four species of junipers from the section Sabina wild growing in the Balkans were selected to study leaf wax composition using GC/MS and GC-FID and its surface morphology under SEM to understand the correlation between the distribution and/or habitat of these species and their cuticles. SEM micrographs showed continuous, smooth epicuticular layers with crusts in all species but with a species-specific distribution of different 3D crystalloid types and different cuticle thickness. n-C33 alkane was the most abundant compound, followed by n-C29, n-C31, and n-C35, depending on the species and the site. The average chain length (N) was the lowest in J. phoenicea, but with the greatest dispersion around it. At the same time, the two most continental species (J. foetidissima and J. excelsa) show the N with the lowest dispersion around it. The statistical analyses confirmed the significance of climate on the evolution of the specific epicuticular wax composition in studied junipers.

Fates of attached E. coli o157:h7 on intact leaf surfaces revealed leafy green susceptibility

Leafy greens, especially lettuce, are repeatedly linked to foodborne outbreaks. This paper studied the susceptibility of different leafy greens to human pathogens. Five commonly consumed leafy greens, including romaine lettuce, green-leaf lettuce, baby spinach, kale, and collard, were selected by their outbreak frequencies. The behavior of E. coli O157:H7 87-23 on intact leaf surfaces and in their lysates was investigated. Bacterial attachment was positively correlated with leaf surface roughness and affected by the epicuticular wax composition. At room temperature, E. coli O157:H7 had the best growth potentials on romaine and green-leaf lettuce surfaces. The bacterial growth was positively correlated with stomata size and affected by epicuticular wax compositions. At 37 °C, E. coli O157:H7 87-23 was largely inhibited by spinach and collard lysates, and it became undetectable in kale lysate after 24 h of incubation. Kale and collard lysates also delayed or partially inhibited the bacterial growth in TSB and lettuce lysate at 37 °C, and they sharply reduced the E. coli O157:H7 population on green leaf lettuce at 4 °C. In summary, the susceptibility of leafy greens to E. coli O157:H7 is determined by a produce-specific combination of physiochemical properties and temperature.

Fatty alcohols, a minor component of the tree tobacco surface wax, are associated with defence against caterpillar herbivory.

Despite decades of research resulting in a comprehensive understanding of epicuticular wax metabolism, the function of these almost ubiquitous metabolites in plant-herbivore interactions remains unresolved. In this study, we examined the effects of CRISPR-induced knockout mutations in four Nicotiana glauca (tree tobacco) wax metabolism genes. These mutations cause a wide range of changes in epicuticular wax composition, leading to altered interactions with insects and snails. Three interaction classes were examined: chewing herbivory by seven caterpillars and one snail species, phloem feeding by Myzus persicae (green peach aphid) and oviposition by Bemisia tabaci (whitefly). Although total wax load and alkane abundance did not affect caterpillar growth, a correlation across species, showed that fatty alcohols, a minor component of N. glauca surface waxes, negatively affected the growth of both a generalist caterpillar (Spodoptera littoralis) and a tobacco-feeding specialist (Manduca sexta). This negative correlation was overshadowed by the stronger effect of anabasine, a nicotine isomer, and was apparent when fatty alcohols were added to an artificial lepidopteran diet. By contrast, snails fed more on waxy leaves. Aphid reproduction and feeding activity were unaffected by wax composition but were potentially affected by altered cutin composition. Wax crystal morphology could explain the preference of B. tabaci to lay eggs on waxy wild-type plants relative to both alkane and fatty alcohol-deficient mutants. Together, our results suggest that the varied responses among herbivore classes and species are likely to be a consequence of the co-evolution that shaped the specific effects of different surface wax components in plant-herbivore interactions.

The R2R3-MYB transcription factor EVER controls the emission of petunia floral volatiles by regulating epicuticular wax biosynthesis in the petal epidermis.

The epidermal cells of petunia (Petunia × hybrida) flowers are the main site of volatile emission. However, the mechanisms underlying the release of volatiles into the environment are still being explored. Here, using cell-layer-specific transcriptomic analysis, reverse genetics by virus-induced gene silencing and clustered regularly interspaced short palindromic repeat (CRISPR), and metabolomics, we identified EPIDERMIS VOLATILE EMISSION REGULATOR (EVER)-a petal adaxial epidermis-specific MYB activator that affects the emission of volatiles. To generate ever knockout lines, we developed a viral-based CRISPR/Cas9 system for efficient gene editing in plants. These knockout lines, together with transient-suppression assays, revealed EVER's involvement in the repression of low-vapor-pressure volatiles. Internal pools and annotated scent-related genes involved in volatile production and emission were not affected by EVER. RNA-Seq analyses of petals of ever knockout lines and EVER-overexpressing flowers revealed enrichment in wax-related biosynthesis genes. Liquid chromatography/gas chromatography-MS analyses of petal epicuticular waxes revealed substantial reductions in wax loads in ever petals, particularly of monomers of fatty acids and wax esters. These results implicate EVER in the emission of volatiles by fine-tuning the composition of petal epicuticular waxes. We reveal a petunia MYB regulator that interlinks epicuticular wax composition and volatile emission, thus unraveling a regulatory layer in the scent-emission machinery in petunia flowers.

Nitrogen and Growth Stage Influence Epicuticular Wax Composition on Rice Leaf and Sheath

Epicuticular wax plays an important part in protecting plant aerial organs from biotic and abiotic stresses. Nitrogen is the key limiting nutrient for crops and influences metabolite synthesis. However, how nitrogen influences wax composition on rice leaf and sheath at different growth stages has not been systematically examined. In this study, a total of 19 wax compounds in rice leaf and sheath were detected by using gas chromatography–mass spectrometry. Permutational multivariate analysis of variance (PermANOVA) indicated a significant influence of both nitrogen and growth stage on rice leaf and sheath wax composition. Nitrogen influenced wax composition on leaf and sheath mainly at 70 and 110 d, while the growth stage significantly influenced wax composition under all nitrogen levels. Our study provides the first report that rice wax composition changes with nitrogen and growth stage. This may support exploring nitrogen application and the associated ecological effects.

Laguncularia racemosa leaves indicate the presence of potentially toxic elements in mangroves

Brazilian mangroves have been severely impacted by metallurgical, petrochemical, pyrometallurgical smelters and other industrial activities. In Rio de Janeiro, mangroves are part of the Atlantic Rainforest now under the stress of high levels of industrial waste. Therefore, this work aimed to detect potentially toxic elements (PTEs) by evaluating the leaves of Laguncularia racemosa (L.) Gaertn. f. collected from three mangroves with different levels of pollution. To gain further insight toward an accurate diagnosis of the effects of anthropogenic pollution on mangrove stands, we evaluated leaf epicuticular wax composition, as well as morphological and anatomical traits. Samples were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES), gas chromatography (GC) and microscopy. Results revealed variation in the contents of PTEs among the three mangroves from lowest to highest concentration, as follows: Al (0.30–0.73), Pb (0.095–0.325) and Zn (0.25–0.30) mg/kg. Zn was detected in sclerenchyma tissues. Leaf epicuticular wax contained more than 50% of triterpenes, in particular, the pentacyclic triterpenes lupeol (41.61–55.63%) and β-amyrin (8.81–16.35%). Such high concentrations promote the increase in leaf permeability to salts and PTEs. Micromorphology of leaf epicuticular wax in L. racemosa also varied among the three evaluated sites, especially around stomatal openings, but no harmful changes were noted. L. racemosa plays a key role in the rich diversity of mangrove ecosystems. As such, this species could, by the presence of PTEs in its leaves, be a suitable biomonitor of toxic substances in coastal environments of the world and used accordingly in strategies designed for eco-sustainable technologies.

Sugarcane Wax Metabolites and Their Toxicity to Silkworms

Sugarcane wax has the potential to be utilized as a novel natural insecticide, which could help to reduce the large yield losses caused by agricultural pests. By employing the gas chromatography-mass spectrometry (GC-MS) approach, we conducted a study to analyze the composition of epicuticular wax from the rind of the sugarcane variety YT71210. A total of 157 metabolites, categorized into 15 classes, were identified, with naphthalene, a metabolite with insect-resistant properties, being the most prevalent. The feeding trial experiment suggested that sugarcane wax is toxic to silkworms by impacting the internal organs. Intestinal microbial diversity analysis suggested that the abundance of Enterococcus genus was significantly increased in both ordure and gut of silkworm after wax treatment. The results indicated that the feeding of wax has an adverse effect on the gut microbial composition of silkworms. Our findings lay a foundation for the efficacy of sugarcane waxes as a valuable natural insecticide and for the prediction of promising sugarcane varieties with insect resistance.

Plant defense to herbivore: role of leaf epicuticular wax composition of citrus cultivars in citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) larval density

Aiming to assess the role of leaf waxy cuticle and its chemical composition on citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae) larval feeding, six citrus cultivars were selected. Our findings showed that the larval density was higher at 59.5% on Mayer lime followed by 53.6% on Kinnow and the least activity of CLM was found (19.3-38.4%) on Musambi. The cuticular wax layer was found greater (67.6 µg/cm2) in Tangerine (Fairchild) followed by 59.6 µg/cm2 in Succari and 56.0 µg/cm2 in Musambi. The results showed that the epicuticular wax layer had negative and significant (P < 0.05) relation with the larval density. Other chemical compounds; aldehyde, alcohol, fatty acid, and hydrocarbon showed non-significant relation with the CLM larval density. Multiple regression analysis showed a 33.5% role of epicuticular wax with CLM larval density. The cultivars such as Succari and Musambi with a greater amount of leaf wax showed a lower density of CLM larvae. The study provides important information on wax related compounds involved in citrus-CLM interaction, which can help in developing an efficient control strategy for this destructive pest.

Leaf Epicuticular Wax Chemical Composition of Morettia phillaeana (Del.) DC. From Sudan

Morettia phillaeana was analyzed for its chemical composition of surface epicuticular wax. The constituents were extracted from the leaves by using n-hexane solvent, and were identified by using Gas chromatography-mass spectroscopy (GC/MS). The major components were hydrocarbons (74.15%), fatty acids, methyl ester (15.73%). and phytosterol (5.47%). Twelve components out of 29 were characterized representing 90.98% of total components. The most abundant compounds were tetracontane (57.74%), Octacosane (6.58%), β-sitoterol (5.47%), Hexadecanoic acid, methyl ester (3.81%), pentacosane (3.77%) and 2-methylhexacosane (3.43%).

Classification of sugarcane genotypes susceptible and resistant to the initial attack of sugarcane borer Diatraea saccharalis using epicuticular wax composition

Identifying compounds present in the sugarcane epicuticular wax and using these compounds to classify the genotypes susceptible and resistant to the initial attack of sugarcane borer (Diatraea saccharalis) was the aim of this study. A greenhouse experiment was performed in a factorial scheme with and without borer infestation using genotypes previously characterized as resistant or susceptible in field-based experiments. Sugarcane whorls of six-month-old plants were collected before (BI) and after (AI) 72 h of sugarcane borer infestation. The sugarcane epicuticular wax was extracted in both times, i.e., BI and AI and its chemical composition was assessed by gas chromatography coupled to mass spectrometry (GC-MS). Twenty-five compounds were identified for both BI and AI. Classification models were built using partial least squares for discriminant analysis (PLS-DA) and linear discriminant analysis (LDA). Variable selection methods were used to improve the classification models. Ordered predictors selection for discriminant analysis (OPSDA) selected compounds that correctly classified all the test samples before borer infestation (Error = 0.000), and exhibited the most suitable classification parameters for the test set after borer infestation (Error = 0.111). The C30 pentacyclic triterpene friedelin and a high alcohol/aldehyde ratio were associated with the classification of resistant genotypes. Our findings have applicability in developing a screening methodology for breeding programs interested in identifying genotypes resistant to the initial feeding of sugarcane borer.

Leaf surface traits related to differential particle adsorption – A case study of two tropical legumes

We aimed to test a set of epidermal traits in two legume species with contrasting chemical, physical, and micromorphological leaf-surface features to assess which ones would determine higher PM retention. For that, we performed a biomonitoring study in southeastern Brazil at the Steel Valley Metropolitan Region, where there is predominance of steel industry and one of the largest vehicle fleets in the country. A reference station was installed at a neighboring park. We evaluated leaf-surface roughness at two hierarchical levels, leaf wettability, epidermal-cell anticlinal-wall undulation, epidermal-cell perimeter, and the micromorphology and chemical composition of epicuticular waxes. Particle retention was significantly higher in Paubrasilia echinata than in Libidibia ferrea var. leiostachya, the former of which has lower roughness given by both the epidermal tissue (macro-roughness; 0.6 vs 2.6 μm) and epicuticular waxes (micro-roughness; 68 vs 220 nm), higher leaf wettability (82° vs 143°), lower epidermal-cell undulation index (1.2 vs 1.8), lower epidermal-cell perimeter (93 vs 146 μm), wax deposition in the form of a smooth layer (as opposed to densely aggregated rosettes of vertical platelets), and more polar wax chemical constitution (68% vs 47% of polar compounds). While all of the assessed traits contributed to particle retention, canonical loadings revealed that macro-roughness was the trait that contributed the most to the retention of PM2.5 (ca = 1.47; r = −0.56), PM10 (ca = 1.08; r = −0.61), PM100 (ca = −4.95; r = −0.39) and TSP (ca = 0.98; r = −0.62), although this trait was shown by factor analysis to be secondary in distinguishing between species (0.92 contribution to the second axis). Our findings shed new light on the criteria that should be considered when selecting species for green infrastructure aiming to reduce urban air pollution, as well as on novel possibilities for PM biomonitoring in the tropics.

The Combination of Abscisic Acid (ABA) and Water Stress Regulates the Epicuticular Wax Metabolism and Cuticle Properties of Detached Citrus Fruit.

The phytohormone abscisic acid (ABA) is a major regulator of fruit response to water stress, and may influence cuticle properties and wax layer composition during fruit ripening. This study investigates the effects of ABA on epicuticular wax metabolism regulation in a citrus fruit cultivar with low ABA levels, called Pinalate (Citrus sinensis L. Osbeck), and how this relationship is influenced by water stress after detachment. Harvested ABA-treated fruit were exposed to water stress by storing them at low (30–35%) relative humidity. The total epicuticular wax load rose after fruit detachment, which ABA application decreased earlier and more markedly during fruit-dehydrating storage. ABA treatment changed the abundance of the separated wax fractions and the contents of most individual components, which reveals dependence on the exposure to postharvest water stress and different trends depending on storage duration. A correlation analysis supported these responses, which mostly fitted the expression patterns of the key genes involved in wax biosynthesis and transport. A cluster analysis indicated that storage duration is an important factor for the exogenous ABA influence and the postharvest environment on epicuticular wax composition, cuticle properties and fruit physiology. Dynamic ABA-mediated reconfiguration of wax metabolism is influenced by fruit exposure to water stress conditions.

Correlation between leaf epicuticular wax composition and structure, physio-biochemical traits and drought resistance in glaucous and non-glaucous near-isogenic lines of rye.

SUMMARYThe objective of this research was to investigate the differences between glaucous and non‐glaucous near‐isogenic lines (NILs) of winter rye (Secale cereale L.) in terms of epicuticular wax layer properties (weight, composition, and crystal morphology), selected physiological and biochemical responses, yield components, above‐ground biomass, and plant height under soil drought stress. An important aspect of this analysis was to examine the correlation between the above characteristics. Two different NIL pairs were tested, each consisting of a typical glaucous line and a non‐glaucous line with a recessive mutation. The drought experiment was conducted twice (2015–2016). Our study showed that wax accumulation during drought was not correlated with higher leaf hydration and glaucousness. Environmental factors had a large impact on the response of the lines to drought in individual years, both in terms of physiological and biochemical reactions, and the composition of epicuticular leaf wax. The analysed pairs displayed significantly different responses to drought. Demonstration of the correlation between the components of rye leaf wax and the physiological and biochemical parameters of rye NILs is a significant achievement of this work. Interestingly, the study showed a correlation between the wax components and the content of photosynthetic pigments and tocopherols, whose biosynthesis, similarly to the biosynthesis of wax precursors, is mainly located in chloroplasts. This suggests a relationship between wax biosynthesis and plant response to various environmental conditions and drought stress.

"Wax On, Wax Off": In Vivo Imaging of Plant Physiology and Disease with Fourier Transform Infrared Reflectance Microspectroscopy.

Analysis of the epicuticular wax layer on the surface of plant leaves can provide a unique window into plant physiology and responses to environmental stimuli. Well‐established analytical methodologies can quantify epicuticular wax composition, yet few methods are capable of imaging wax distribution in situ or in vivo. Here, the first report of Fourier transform infrared (FTIR) reflectance spectroscopic imaging as a non‐destructive, in situ, method to investigate variation in epicuticular wax distribution at 25 µm spatial resolution is presented. The authors demonstrate in vivo imaging of alterations in epicuticular waxes during leaf development and in situ imaging during plant disease or exposure to environmental stressors. It is envisaged that this new analytical capability will enable in vivo studies of plants to provide insights into how the physiology of plants and crops respond to environmental stresses such as disease, soil contamination, drought, soil acidity, and climate change.

Abscisic Acid Deficiency Alters Epicuticular Wax Metabolism and Morphology That Leads to Increased Cuticle Permeability During Sweet Orange (Citrus sinensis) Fruit Ripening.

Citrus fruit ripening is coupled with the synthesis and deposition of epicuticular waxes, which reduces water loss during fruit postharvest storage. Although abscisic acid (ABA) is a major regulator of citrus fruit ripening, whether ABA mediates epicuticular wax formation during this process remains poorly understood. We investigated the implication of ABA in cuticle properties and epicuticular wax metabolism, composition, and morphology by comparing the Navelate orange [Citrus sinensis (L.) Osbeck] and its ABA biosynthesis-impaired mutant Pinalate in four ripening stages. ABA deficiency had minor effects on cuticle thickness and epicuticular wax load, but correlated with cuticle permeability. ABA content aligned with mostly fatty acids accumulation in both cultivars, and also with specific alkane, terpenoid, and aldehyde constituents in the parental fruit. In turn, cuticle permeability correlated with the fatty acid profile during fruit ripening in the Navelate and Pinalate, and with primary alcohols, terpenoids, and aldehydes, but only in the mutant fruit. Low ABA levels increased the susceptibility of waxes to crack and were lost from the epicuticular layer. The RNA-seq analysis highlighted the differential regulation of a list of 87 cuticle-related genes between genotypes and ripening stages. Changes in the gene expression of the selected genes in both cultivars were consistent with the content of the aliphatics and terpenoid fractions during ripening. The results suggest a role for ABA in the regulation of fatty acid content and primary alcohol composition, and point out the importance of alkane and triterpenoid for controlling water permeance through fruit cuticles.

The chemical composition and potential role of epicuticular and intracuticular wax in four cultivars of table grapes

Abstract Plant cuticular wax is the first barrier to resist biotic and abiotic stress. However, little is known about the compositional differences between the epicuticular and intracuticular wax in grape berry. The compositional, morphological and functional features of cuticular wax in grape berries of Vitis vinifera cv. ‘Kyoho’, ‘Muscat Hamburg’, ‘Redglobe’, and ‘Zuijinxiang’ were investigated. The total and epicuticular wax of four berries were mainly composed of terpenoids, hydrocarbons, alcohols, fatty acids and esters. Oleanolic acid was the most abundant terpenoid among the four cultivars. Scanning electron microscopy revealed the crystalline flakes structure of the cuticular wax. Additionally, the removal of epicuticular wax accelerated the weight loss, browning, and softening of grape berries, indicating the plastic-wrap-like effect of the cuticular wax on postharvest quality. This study provided the theoretical basis for further application of the fruit wax or waxy analogue.

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.

Foliar Micromorphology and Anatomy of Five Mediterranean Enclaves in Artvin (Turkey)

Aim of study: We aimed to investigate leaf micromorphology including venation types, and petiole and leaf blade anatomical characteristics of five woody/scrubs Mediterranean enclaves (Cotinus coggygria Scop., Rhus coriaria L., Arbutus andrachne L., Punica granatum L. and Jasminum fruticans L.) in this study. Area of study: Artvin Province has three distinct climate types. The species studied were collected from natural habitats in Artvin, where Mediterranean climate type occurs. Material and methods: Leaves of five species were evaluated micromorphologically and anatomically by using stereomicroscopy, light microscopy and scanning electron microscopy. Main results: Two species have imparipinnately compound leaves, while three have simple ones. Four venation types were determined in the species. C. coggygria has channeled anticlinal walls of adaxial epidermal cells and A. andrachne has striate cuticular ornamentation in the abaxial surfaces. Differently from others, R. coriaria and J. fruticans have glandular trichomes, and P. granatum has bicollateral vascular bundle. Secretory canals and druses crystals were detected in some investigated species. Most of the species have hypostomatic leaf type, but J. fruticans has amphistomatic one. The highest stomata number and indices per mm2 were observed in P. granatum, while the lowest values were found in J. fruticans. Research highlights: Among the species examined, Punica granatum with the highest stomatal number and indices per mm2, narrowed and deciduous leaf with epicuticular wax composition has probably distinctive adaptive strategies to water deficiency and xerophytic habitats