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• The content and main components of epicuticular waxes in wild and agronomically important Agave species were analyzed. • A correlation between the epicuticular wax content, the ploidy level and the type habitat in which they grow was observed. • This information contributes to better understand the tolerance of agaves to different types of stress. Agaves are cultivated in Mexico as a source of industrial products such as fibers, nutritional supplements and alcoholic beverages. A particularly important trait present in all agaves, which makes them economically viable crops for certain geographic regions, is their ability to grow under water limiting conditions. One of the anatomical characteristics that contributes to this adaptation, is the thick layer of epicuticular waxes deposited on their surface which reduces water loss by evapotranspiration. Still, to date, and in spite of their economic importance, there has been practically no effort to improve the genetics and productivity of agaves; this investigation focuses on the differences in the content and types of the epicuticular waxes present on the surface of leaves of wild and agronomically important Agave species with different ploidy level. The agaves analyzed were two diploids [ A. tequilana Weber and the hybrid H11648 (A. amaniensis Trel. & Nowell x A. angustifolia Haw. back crossed to A. amaniensis)]; two pentaploids (A. fourcroydes var. Sac ki and A. fourcroydes var. Yaax ki) and a hexaploid (A. angustifolia var. Chelem ki) The epicuticular waxes were obtained by hexane extraction and their chemical composition was established by capillary gas chromatography–mass spectrometry (GC/MS). The amount of epicuticular wax varied significantly between the different types (4.40–35.63 μg cm−2), with A. angustifolia var. Chelem Ki (hexaploid) and A. tequilana (diploid) presenting the highest and lowest amounts, respectively. With the exception of A. tequilana , n-alkanes were the main components (63.32–92.13 % of total wax) in the epicuticular wax, with hentriacontane (C31) and tritriacontane (C33) as main compounds. Alternatively, in A. tequilana two aliphatic alcohols were the main components of the wax. These results suggest a correlation between the total epicuticular wax content, the chemical composition of the wax, the ploidy level and the type of habitat in which they grow. This information contributes to the understanding of the tolerance of agaves to different types of stress. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Steroids and triterpenoids of leaf cuticular waxes of Lonicera caerulea were investigated. • The significant differences of steroids and pentacyclic triterpenoids were observed. • Friedelin were reported exclusively in the leaf waxes of Jolanta and Wojtek cultivars. Abstract Lonicera caerulea , known as edible honeysuckle, honeyberry, blue honeysuckle, sweet berry honeysuckle, or haskap, is a perennial fruit-bearing plant belonging to the Caprifoliaceae family. Currently, the cultivation of this plant species is becoming increasingly popular due to its early fruit ripening, exceptional resistance to frost, pests, and diseases, as well as its potential health-promoting and therapeutic properties. GC–MS analysis of steroids and triterpenoids from leaf waxes of selected cultivars and genotypes of edible honeysuckle displayed significant difference in the qualitative and quantitative composition. The leaves of edible honeysuckle cultivars of Russian origin were characterized by common features: distinctively high content of steroids in relation to pentacyclic triterpenoids, with 24-methylenecycloartanol and α-amyrin as compounds dominating in respective classes; and the absence of friedelin. The Polish cultivars and genotypes analyzed in this study can be divided into two groups: Jolanta cultivar, genotypes T, and Nr 38, showing a certain degree of similarity with the Russian cultivars (e.g., the predominance of steroids), by contrast to Wojtek cultivar, genotypes Nr 30, and 44, characterized by the predominance of pentacyclic triterpenoids with α-amyrin. A special feature was the presence of friedelin, which was identified only in two cultivars (Jolanta and Wojtek) belonging to two different groups. [ABSTRACT FROM AUTHOR]

One of the oldest cereal crops, barley is thought to have been domesticated ∼ 8000 years ago, in the Fertile Crescent. In this study, we explored the overlooked contribution of cuticular lipid metabolism to barley domestication by comparatively characterizing wild and domesticated barley variants. We revealed substantial phenotypic variances in plants' overall morphology and in vegetative and reproductive tissues. Multiple microscopic approaches combined with gas chromatography-mass spectrometry (GC-MS) metabolite profiling indicated that wild barley leaves are more densely covered with epicuticular waxes compared to domesticated leaves with distinct compositions, but both variants contain a similar cuticle ultrastructure. Gene expression assays corroborated these observations showing higher transcript expression of key epicuticular wax biosynthetic genes in wild barley leaves, but similar expression patterns of cutin biosynthetic genes in leaves of both cultivars. Wild barley leaves also transpired water at higher rates apparently due to higher stomata density and conductance. Previous evidence claimed that barley leaf epicuticular waxes shape the interactions with Blumeria graminis f.sp. hordei (Bgh), the causal agent of powdery mildew in barely. However, in-vivo and in-vitro inoculation assays inferred that the disparate wax content and composition in wild and domesticated leaves had no apparent effect on Bgh pre-penetration processes. Altogether, our data provide novel insight into the compositional variances in cuticular lipids of wild and domesticated barley leaves and their impact on plant-environment interactions. • Wild and domesticated barley plants are morphologically different. • Wild and domesticated barley leaves form a similar cuticle ultrastructure. • Leaves of wild and domesticated barley differ in epicuticular wax coverage • Wild barely leaves transpire more water apparently due higher stomata densities • Pre-penetration of Blumeria graminis f.sp. hordei is similar in both varieties [ABSTRACT FROM AUTHOR]

Fruit cuticle micromorphology of several cultivars of Olea europaea L. was described with the aim to individualize features of the epicarp and epicuticular waxes useful to technological processings. All olive cvs. analyzed in this paper showed only epicuticular waxes arranged in crystalloid structures (granules, platelets, plates and rodlets). The epicarp aspects examined in this work were: the entire thickness of epicarp from surface to the base of epidermal cell, the height of the epidermal cell, the thickness of the cuticular flange that is wedged between epidermal cells and the thickness of the cuticular membrane, the continuous layer on the top of the epidermal cell. The cuticular membrane was the most important parameter, being the only barrier up the epidermal cells. Gentile di Chieti and Dritta cvs. had the thickest cuticular membrane (17.04 and 16.05 μm for green olives, respectively), Castiglionese , Carboncella and Kalamata cvs. had a medium cuticular membrane while the cuticular membrane of Intosso cv. was very thin (8.46 μm for green olives). The epicarp thickness decreased during ripening of fruits in all examined cultivars. Multivariate approaches were also used to identify similarities and differences between cultivars. [ABSTRACT FROM AUTHOR]

Abstract: Fresh blueberries are highly perishable and must be preserved by either freezing or drying technologies. However, moisture impermeability of their skin is a barrier against the moisture diffusion slowing down the drying process. The aim of this study was to investigate the impact of liquid nitrogen pretreatments on osmotic dehydration kinetics of two blueberry species, Vaccinium corymbosum L. and Vaccinium angustifolium Ait, and on the physicochemical quality of dehydrated fruits. The number of immersions in liquid nitrogen was a determinant factor that accelerated water loss. Depending on the blueberry species, a reduction of dehydration time from 45% to 65% was obtained for liquid nitrogen treated samples when compared to control blueberries. Microscopic observations of the blueberry skin before and after the liquid nitrogen pretreatment revealed a decrease of the cuticle thickness, dewaxing of the skin surface and the presence of micro-fissures facilitating moisture and sugar transfer during the osmotic process. The dewaxing of the blueberry skin due to liquid nitrogen immersions was confirmed by wax quantification before and after the cryogenic pretreatments. Osmotic dehydration and liquid nitrogen pretreatments showed a slight decrease in the levels of phenolic compounds and anthocyanins compared to the fresh blueberries. [Copyright &y& Elsevier]

Abstract: The chemical composition of epicuticular waxes of Mandevilla guanabarica and Mandevilla moricandiana was comparatively analyzed by extraction in n-hexane and chloroform. The mean wax content per unit of leaf area in the n-hexane extract was about 13–30 μg cm−2 for M. guanabarica, containing 20–28% n-alkanes and 55–63% triterpenes; for M. mori-candiana, the mean content was 19 μg cm−2, containing 73% n-alkanes and 14% triterpenes. In the chloroform extract, the wax yield was 40–80 μg cm−2 for M. guanabarica, with about 9–11% n-alkanes and 75–82% triterpenes; while for M. moricandiana, the wax yield was 110 μg cm−2, with 52% n-alkanes and 14% triterpenes. The major compounds identified were lupeol, pentacyclic triterpenes of the α- and β-amyrin class, and n-alkanes such as nonacosane, hentriacontane and tritriacontane. These results indicate that the quantitative chemical profiles of epicuticular waxes of M. guanabarica and M. moricandiana are distinct and could be used as an additional feature in taxonomic identification. [Copyright &y& Elsevier]

Abstract: In this review, we provide an overview of the role of glucosinolates and other phytochemical compounds present in the Brassicaceae in relation to plant protection and human health. Current knowledge of the factors that influence phytochemical content and profile in the Brassicaceae is also summarized and multi-factorial approaches are briefly discussed. Variation in agronomic conditions (plant species, cultivar, developmental stage, plant organ, plant competition, fertilization, pH), season, climatic factors, water availability, light (intensity, quality, duration) and CO2 are known to significantly affect content and profile of phytochemicals. Phytochemicals such as the glucosinolates and leaf surface waxes play an important role in interactions with pests and pathogens. Factors that affect production of phytochemicals are important when designing plant protection strategies that exploit these compounds to minimize crop damage caused by plant pests and pathogens. Brassicaceous plants are consumed increasingly for possible health benefits, for example, glucosinolate-derived effects on degenerative diseases such as cancer, cardiovascular and neurodegenerative diseases. Thus, factors influencing phytochemical content and profile in the production of brassicaceous plants are worth considering both for plant and human health. Even though it is known that factors that influence phytochemical content and profile may interact, studies of plant compounds were, until recently, restricted by methods allowing only a reductionistic approach. It is now possible to design multi-factorial experiments that simulate their combined effects. This will provide important information to ecologists, plant breeders and agronomists. [Copyright &y& Elsevier]

We investigated foliar and litter responses of European aspen (Populus tremula L.) to urbanization, including factors such as increased temperature, moisture stress and nitrogen (N) deposition. Leaf samples were collected in 2006–2008 from three urban and three rural forest stands in the Helsinki Metropolitan Area, southern Finland, and reciprocal litter transplantations were established between urban and rural sites. Urban leaves exhibited a higher amount of epicuticular waxes and N concentration, and a lower C:N ratio than rural ones, but there was no difference in specific leaf area. Urban litter had a slightly higher N concentration, lower concentrations of lignin and total phenolics, and was more palatable to a macrofaunal decomposer. Moreover, litter decay was faster at the urban site and for urban litter. Urbanization thus resulted in foliar acclimatization in terms of increased amount of epicuticular waxes, as well as in accelerated decomposition of the N-richer leaf litter. [Copyright &y& Elsevier]

Abstract: 13C nuclear magnetic resonance spectroscopy (NMR) was applied to determine the different components of apolar and polar fractions which were isolated by column chromatography from the crude chloroform-soluble waxes of olive fruits (Olea europaea) Dritta cultivar. 13C NMR enabled the determination in the wax apolar fraction, of aliphatic aldehydes, and of benzyl, alkyl and glyceryl esters. In particular, the fatty acid composition of alkyl esters, comprising saturated and unsaturated oleic and linoleic acids, was determined. Acyl chain composition and the chain composition of 1,3- and 2-glycerol positions were also determined for triacylglycerols of olive fruit waxes. Oleanolic and maslinic acids were confirmed to be the major components of wax polar fraction. Complete assignments of 13C NMR chemical shifts of oleanolic and maslinic acids as a mixture were achieved by using homonuclear correlation spectroscopy with gradient (g-COSY), attached proton test (APT), inverse-detected heteronuclear single-quantum coherence with gradient (g-HSQC), high-resolution heteronuclear correlation spectroscopy (HETCOR) for C–H directly attached pairs and C–H long-range-coupled experiments. [Copyright &y& Elsevier]

Abstract: The distribution of n-alkanes of foliar epicuticular waxes of Psidium guajava (Myrtaceae) exposed to air pollutants was determined by GC-EIMS. Saplings were exposed for two periods of one year (July 2000–June 2001 and December 2000–November 2001) in two experimental sites: Pilões River Valley (PV), where the contamination of air pollutants is relatively low, and Mogi River Valley (MV), which is severely affected by pollutants released by chemical, fertilizer, ceramic, iron and steel industries. On average, total leaf waxes were higher for plants that were exposed initially in the rainy season (December). Leaf waxes showed different n-alkane composition comparing both sites, especially during the first period of exposure (July 2000–June 2001). The main n-alkane waxes in both areas were C25, C26 and C27. However, in both experimental periods, an increase of the relative amounts of homologous of shorter carbon chains (C18–C23) under pollutants influence was observed. While the total percents of such homologues were on average 9.5 and 10.2 at PV for the first and second experimental periods, the observed percents at MV were on average 15.6 and 13.7, respectively. The results of the present work are in agreement with previous findings that air pollutants affect the synthesis of surface waxes, leading to alterations of the distribution of wax constituents. [Copyright &y& Elsevier]

Abstract: The diamondback moth (DBM), Plutella xylostella (L.), is a destructive insect pest of cruciferous crops with a cosmopolitan distribution. Its genetic elasticity has enabled it to develop resistance to almost every insecticide applied in the field. Its natural host range is limited to cultivated and wild Brassicaceae that are characterized by having glucosinolates, sulfur-containing secondary plant compounds. Adults utilize an integrated suite of chemical and morphological cues for host plant location and recognition. Certain glucosinolates, cardenolides, plant volatiles, waxes, as well as host plant nutritional quality, leaf morphology and leaf color, or a combination of these factors, may trigger reproductive and feeding activities of DBM. Host plant resistance forms an important component of integrated pest management programs. In this review, we synthesize information on certain plant biochemical and morphological characteristics that have been investigated to promote DBM resistance to its host plants. The efficacies of transgenic crucifers and the potential role of trap cropping for the management of DBM are also discussed. [Copyright &y& Elsevier]

Abstract: Changes of cuticular wax morphology, chemistry, and wettability of Brassica oleracea (Brassicaceae), Eucalyptus gunnii (Myrtaceae) and Tropaeolum majus (Tropaeolaceae), with different types of surface waxes, cultivated at three levels of relative air humidities (RH) (a: 20–30%, b: 40–75% and c: 98% RH) have been investigated. Wax chemistry was investigated by gas chromatography (GC) and mass spectroscopy (MS), micro morphology by scanning electron microscopy (SEM) and surface wettability by measuring the contact angle. Grown at 98% RH, all species showed decreased total wax mass and wax crystal density but significantly increased leaf surface wettability. In contrast cultivation at 20–30% RH led to increased total amounts of wax and reduced surface wettability. SEM investigations and GC/MS analysis revealed that wax crystal morphology and qualitative wax composition of Brassica were altered after cultivation at 98% RH, whereas chemical composition and morphology of wax crystals in Tropaeolum and Eucalyptus remained unchanged. [Copyright &y& Elsevier]

The essential oils from the oleoresin, leaf and fruit of Protium icicariba (Burseraceae), collected in the Atlantic forest were extracted by steam distillation and analysed by HRGC-MS. The resin oil was found to be entirely monoterpenoid and characterised by the predominance of p-cymene, followed by α-pinene, α-terpinolene and limonene. Monoterpenes, particularly of the terpinolene-type, predominate in the fruit oil, and germacrene-type sesquiterpenes, followed by α-copaene, γ-elemene and δ-cadinene make the greater part of the leaf oil. The leaf epicuticular wax of this species was also chemically characterised by HRGC-MS, indicating the major presence of n-nonacosane (C-29) and n-hentriacontane (C-31) together with some triterpenes. Histological sections of leaf, fruit and stem were carried out, in order to establish the microstructure present in these organs. [Copyright &y& Elsevier]

The waxy surfaces of three carnivorous plants, Nepenthes ventrata (Nepenthaceae), Brocchinia reducta and Catopsis berteroniana (Bromeliaceae), were compared using scanning electron microscopy (SEM). Their effects on attachment and locomotion of the fly Calliphora vomitoria were studied. The waxy surface of N. ventrata is comprised of a heterogeneous layer from which only platelet-shaped crystalloids could be detached by brushing. In the two bromeliads, the crystalloids are thread-shaped and form a homogenous dense network, which was entirely removable from the epidermis. Experimental data showed that none of the flies was able to walk across any of the waxy surfaces and only a few were able to take off from those surfaces. Both the absence of sites for claw anchorage, especially in N. ventrata, and the wax itself were shown to contribute to the trapping ability of the plants. Only half of the flies quickly recovered their locomotion ability on a glass surface after 20 min of being tested on waxy plant surfaces. SEM observations revealed that the wax of C. berteroniana formed a powder of broken crystals on the tenent setae of the flies'' pulvilli. In contrast, the waxes of B. reducta and N. ventrata appeared to have lost their crystal structure in contact with the tenent setae and formed an amorphous substance that adhered setae together. We hypothesize that wax interacts with adhesive fluids secreted by the fly pad and thereby prevents the tenent setae from functioning effectively. [Copyright &y& Elsevier]

• Isophyllous leaves of Mexican Selaginella are described. • Abaxial surface with two rows of lateral papillate cells aside of the middle region. • Epicuticular waxes as thin films, crusts or folds on the epidermal cells. • Mesophyll with two rows of sclerenchyma. • Xerophytic adaptations. The morphology and anatomy of vegetative leaves and sporophylls of six isophyllous species of Mexican Selaginella (subgen. Rupestrae): S. arsenei , S. extensa , S. peruviana , S. rupincola , S. sellowii and S. wrightii are described. The six species show small size of vegetative leaves (1.82–3.22 mm long × 0.32–0.62 mm wide), and lanceolate shape. The sporophylls are ovate (1.77–2.30 mm long × 0.63–0.84 mm wide). All species have hypostomatic leaves, with a central longitudinal stomatal groove on the abaxial surface. The central area is longitudinally flanked by long epidermal cells, and these by two rows of papillate cells. Epicuticular waxes as thin films, crusts or folds are present on the abaxial epidermal cells. The mesophyll has two longitudinal rows of sclerenchyma beneath the abaxial epidermis. Thickened epidermal cell walls are also present. These features are consistent with the climatic characteristics of the xeric environments these species live in, and can be considered xeric adaptations. [ABSTRACT FROM AUTHOR]