Trichomes

The abaxial leaf surfaces of Anomozamites villosus sp. nov., a new species of bennettitalean foliage from the Middle Jurassic Daohugou beds of Inner Mongolia, China, are covered with soft, shaggy hairs that are loosely, but regularly distributed across the lamina. Selectively arranged, long, stiff or acerate hairs directed or bent towards the leaf apex, project on the abaxial side of the leaf from the rachis margins. Both types of hairs are interpreted predominantly as adaptations for passive defence against damage by arthropods (sap-sucking, leaf-chewing or oviposition) rather than being morphological responses to physical environmental parameters, e.g. xeromorphic features. As several of the leaves show evidence for high levels of leaf-margin feeding by phytophagous arthropods, these mechanisms have not been entirely effective and may have evolved to defend against only selected arthropods or behavioural strategies. These findings contribute to the reconstruction of ecological interactions in the exceptionally preserved Jurassic Daohugou biota of northern China, and provide a rare insight into the plant–arthropod co-evolutionary ‘arms race’.

The micromorphological structure of seedlings of Rhynchosia minima (L.) DC. is described, from a dry ruderalized site of Karachi, on the basis of optical (OM) and scanning electron microscopy (SEM). The seedling appeared to be " Phanerocotylar-Epigeal-foliaceous " type. Several types of trichomes from cotyledons and leaves and structure of the resin gland (Brown-orange bulky capitate, glandular trichome) are described. Cotyledons are amphitrichomic and amphistomatic with paracytic arrangement of subsidiary cell. R. minima leaflets were amphistomatic with much larger number of stomata on ventral surface (283.3 ± 4.39 stomata per mm 2 , N = 100, CV = 38.6%) as compared to the dorsal surface (48.06 ± 1.85 stomata per mm 2 , N = 100, CV = 38.6%). The diversity of foliar stomata included, paracytic, anisocytic, staurocytic and anomocytic types. The stomatal size on abaxial surface leaf averaged to 18.53 ± 0.36 x 13.17 ± 0.30 µm. The predominating class of stomatal width (pore + guard cells) was 10.1 – 16 µm. Stomata on adaxial surface were comparable in size (19.76 ± 0.22 x 11.19 ± 0.18 µm). Quantitative element analysis based on elements detector system (EDS) of energy dispersive X-ray spectroscopy (EDS) is described.

The leaves of Carissa macrocarpa (Eckl.) A. DC., collected from plants grown as hedge at Oud Metha, Dubai, were studied for their phenotypic traits, morphometric characteristics, leaf area estimation and surface micromorphological structure. Short phytography of the plant has been described. Leaves were variable in shape-ovate, oblong, orbicular or almost round. Leaf length (measured from umbo region to the apex) averaged to 4.18 ± 0.12 cm with a moderate degree of variation (1.4-7.5 cm, CV: 28.73%). The leaf width at the widest points on the margins averaged to 3.12 ± 0.098 cm varying around 31.33% (1.0-6.2 cm). Around 92% of the leaves showed leaf length ranging between 2.1 and 6.0 cm. Aspect ratio (Length / breadth) of leaves in C. macrocarpa, averaged to 1.373 ± 0.0268 (varying from 0.87 to 2.36 with moderate variation of 19.21%. Apex angle averaged to 97.04 ± 1.387 o varying around 14.3 %. It was lesser than 90 o in 25% of the leaves, 90 o in 11% of the leaves and greater than 90 o in 64% of the leaves (91-148 o). Leaf base angle averaged to 109.44 ± 1.095 o. It was ≤ 90 o in 5% leaves and larger than 90 o (91-143 o) in 95% of the leaves i.e., in most of the cases leaf base was obtuse. Base angle related with apex angle as, Base Angle = 55.234 + 0.559 Apex angle ± 7.780. Leaf base in umbo area embayed in sinus in some cases and gave rise to cordate type of leaf base otherwise cuneate. Apical leaf extension length (La; distance on a perpendicular from the distal most point of mid-vein to the distal most extension of the leaf tissue) averaged to 1.33 ± 0.118 (N = 9, 1.0-1.5mm) as found in only in nine leaves. La was zero (non-existent) in 91% of the leaves. Basal leaf extension length (Lb) was observed in 14 leaves only which had cordate leaf base and their umbo region embayed in sinus. Lb was zero (non-existent) in 86% of leaves. Lb averaged to 1.714 ± 0.276mm (N = 14, 0.5-4mm). Spines were bifurcate oppositely produced on node and quite variable in size-small to giant (c 10 cm). The value of mean arithmetic coefficient (k) for leaf area estimation was found to be 0.70980 ± 0.008128 varying from 0.51 to 1.0529 (CV: 11.45%) and concentrated around the mean value. Leaf area (LAM, cm 2) was found to relate to the multiplicative parameter, LL (cm) x LB (cm), as given by the equation: (LAM) = 0.702.(LL x LB) 1.002 ± 0.115, R 2 = 0.968). Leaf area per leaf, in a sample of 100 leaves, averaged to 9.884 ± 0.5427 cm 2 varying from 1.02 to 27.98 cm 2 (CV: 55.93. It was positively skewed and leptokurtic-asymmetrically distributed. In 85% of the leaves LAM varied from 12.6 to 15.0 cm 2. Under the given growth conditions, Leaf dry matter, in comparison to SLA, appeared to be a better parameter in C. macrocarpa. The leaves of C. macrocarpa were hypostomatic. Lower epidermis had stomata generally of anomocytic type but also anisocytic type of arrangement of subsidiaries was seen. Stomata were round or oval or wide elliptical measuring stomatal diameter c 33.5-35.0 µm and outer stomatal ledge aperture c. 15 µm. They were variable in size and orientation. Stomata with common subsidiary (ies) were present. Anticlinal walls of pavement epidermal cells were straight to curvy. Leaves were trichomatous when young. In a sample of 60 microscopic frames of vision, the stomtal density per mm 2 on the ventral surface of leaves averaged to 283.8 ± 5.41 stomata varying from 190.35 to 432.62, CV: 14.77%. Leaf cuticle appeared to be in form of sheet. There were, however, epicuticular crystalloids, probably waxy, in form of granules and platelets which appeared to fuse to form lumps of various shapes.

Trichome morphology on the leaves of the 17 plant species belonging to family Asteraceae was investigated by light and scanning electron microscopy. Our data revealed that both eglandular and glandular trichomes were present in the taxa. Out of 17 species, 6 species showed glandular trichomes viz. Pluchea arguta, Pluchea lanceolata, Pulicaria angustifolia, Tridax procumbens, Vernonia cinerascens and Pulicaria carnosa; while 11 species showed eglandular trichomes viz. Blainvillea latifolia, Blumea obliqua, Conyza bonariensis, Conyza canadensis, Dicoma schimperi, Dicoma tomentosa, Eclipta prostrata, Echinops echinatus, Erigeron Canadensis, Lactuca remotiflora and Vernonia cinerea. Mostly trichomes were multicellular. The trichomes were usually conical in shape with pointed tips and distinct trichome bases. In few species trichomes base was indistinct. Cylindrical shape trichomes were also observed.

Surface microstructure of Capparis cartilaginea Decaisne leaves collected from coastal hills of Paradise Point, Karachi (Pakistan) was investigated. The leaves had unicellular strap-like trichomes of around 300 µm. The leaves were amphistomatic and as per Prabhakar's (2004) scheme of stomatal classification, there were four types of stomata identified in hexane treated leaves – anisocytic (70.79%), tetracytic (20.65%), anomocytic (7.74%) and staurocytic (0.65%). The density of stomata was relatively higher on dorsal surface (80.60 ± 1.45 per mm2) than on the ventral surface (61.9 ± 1.41 per mm 2). Cuticular striation, in mature leaves untreated with hexane, was in form of long parallel ridges radiating from the peristomatal rim and running over periclinal surface of the subsidiaries and continuing over adjacent epidermal cells. This Cuticular feature was strikingly different from the pattern reported for intraspecific taxa of Capparis spinosa described by S. Fici (2004), particularly the taxon viz. C. spinosa var. galeata Hook. F. & Thompson, an African collection, which has been considered synonymous to C. cartilaginea Decaisne by Jafri (1973).

The anatomy and micromorphology of eleven species of Eugenia found in the ‘restinga’ of Marica, Rio de Janeiro, Brazil, were studied and compared. The characteristics found to be of most use in distinguishing the species are: presence and types of trichomes persistent in the adult material, form and arrangement of overlying cells (epidermal cells over secretory cavities), pattern of anticlinal walls of epidermal cells (primary sculpturing), occurrence of epicuticular striae and folds (secondary sculpturing) and presence of peristomatal folds. An analytical key based on these characteristics is presented for the Eugenia species studied.

Background and aims: Although trichomes are typical features of the species-rich genus Croton, little is known about their development, anatomical structure and function. This study aims to characterize the anatomy of leaf trichomes of three Croton species restricted to Brazilian rock outcrops, and investigate their functional role in an environment with limited soil water availability. Methods: Samples of leaves at different stages of maturity were submitted to standard anatomical light and scanning electron microscopy techniques to perform a structural and developmental study. Atmospheric water uptake was investigated through the absorption of aqueous solutions of berberine hemisulfate and Indian ink. Key results: The so-called trichomes actually correspond to emergences because they originate from protodermal and ground meristem activity rather than from epidermal tissue. These emergences show a complex anatomy, are closely associated with the mesophyll sclereids and might be involved in leaf atmospheric water uptake. The outermost cells of the emergences are arranged radially and present non-lignified thick walls. We demonstrate that an aqueous solution can effectively penetrate through the leaf emergences, continuing through sclereids and reaching the vascular bundle or flowing across the mesophyll maximizing water distribution in the leaf tissue. Conclusions: The complex structure and hypothesized function of Croton trichome-like emergences represent a novel finding in Euphorbiaceae. In the three species studied, these leaf emergences might play a role in atmospheric water absorption and they may be one of the clues for the occurrence of Croton in habitats with limited soil water supply where this genus is usually species-rich and abundant.

Research on the analysis of the anatomy of the stomatal and trichomes of the medicinal plant Dandang Gendis Clinacanthus nutans (Burm.f.) Lindau in Makassar City. This study aims to determine the anatomical structure of the stomatal and trichomes of longitudinal cross-section of leaves that are used as herbal medicines. This research method was used to spread acetone to obtain stomatal prints on the leaf surface, the data were analyzed descriptively. The results of the analysis of the anatomy of the stomatal and trichomes of leaves of the medicinal plant Dandang Gendis Clinacanthus nutans (Burm.f.) Lindau was a diacytic type of stomatal, the spread of stomatal was only found on the surface of the abaxial leaf including the apple type. The number of abaxial stomatal was 160 stomatal/mm 2. The number of epidermal cells was 748 epidermis/mm 2 and abaxial 504 epidermis/mm 2 , stomatal index 23.95%, and stomatal size 159.26 µm. On the adaxial and abaxial surfaces of the leaves of Dandang Gendis Clinacanthus nutans (Burm.f.) Lindau, glandular and lithocyst trichomes were encountered. Kata kunci: Stomatal, trichomes, medicinal plants PENDAHULUAN Tanaman Dandang Gendis Clinacanthus nutans (Burm.f.) Lindau merupakan salah satu jenis tanaman herbal, di Indonesia masyarakat dapat memanfaatkan jenis tanaman ini untuk pengobatan tradisional, sebagai tindakan pencegahan maupun pengobatan terhadap berbagai jenis penyakit. Pada permukaan daun tanaman terdapat stomata yang merupakan derivat epidermis. Stomata dalam fisiologi tumbuhan berperan sangat penting pada proses fotosintesis, transpirasi dan respirasi (Tambaru, 2015; Larcher, 1995). Stomata merupakan tempat pertukaran gas karbon dioksida (CO2) dari luar ke dalam jaringan daun dan oksigen (O2) dari jaringan tanaman ke atmosfir (Kumekawa et al. 2013). Selain stomata pada permukaan daun juga terdapat trikoma dan lithocyst merupakan derivat dari epidermis yang berfungsi melindungi tumbuhan dari kerusakan mekanis pada jaringan daun (Mulyani, 2006; Pandey dan Chadha, 1996). Hasil metabolisme sekunder yang dihasilkan dari proses fotosintesis tanaman berupa senyawa kimia seperti: alkaloid, terpenoid dan fenolik (Salisbury dan Ross, 1992). Hasil Jurnal Ilmu Alam dan Lingkungan 10 (1), (2019). 35-42 Jurnal Ilmu Alam dan Lingkungan

Uptake, transport and toxicity of engineered nanomaterials (ENMs) into plant cells are complex processes that are currently still not well understood. Parts of this problem are the multifaceted plant anatomy, and analytical challenges to visualize and quantify ENMs in plants. We critically reviewed the currently known ENM uptake, translocation, and accumulation processes in plants. A vast number of studies showed uptake, clogging, or translocation in the apoplast of plants, most notably of nanoparticles with diameters much larger than the commonly assumed size exclusion limit of the cell walls of ∼5-20 nm. Plants that tended to translocate less ENMs were those with low transpiration, drought-tolerance, tough cell wall architecture, and tall growth. In the absence of toxicity, accumulation was often linearly proportional to exposure concentration. Further important factors strongly affecting ENM internalization are the cell wall composition, mucilage, symbiotic microorganisms (mycorr...

Trichomes of twenty two taxa of the genus Solanum, Withania, Petunia, Capsicum, Atropa, Lycopersicon, Cestrum, Hyoscyamus, Datura, Physalis and Nicotiana were examined by using light microscope and photomicroscope. The indumentums shows considerable variations among different species, and therefore, useable characters in de-limitation of species. The study revealed the characters of anatomic interest of leaf and stem epidermal features that have not been previously reported before and has been conducted first time. Size, shape and types of trichomes were measured with considerable variability and the presence of glandular and non-glandular trichomes were observed. Distribution of foliar trichomes emerged as a supportive taxonomic and anatomic tool, which are present in the species mostly are unicellular, bicellular and non-glandular, glandular with bulbous base.

Etiolated growth in darkness or the irreversible transition to photomorphogenesis in the light engages alternative developmental programs operating across all organs of a plant seedling. Dark-grown Arabidopsis de-etiolated by zinc (dez) mutants exhibit morphological, cellular, metabolic, and transcriptional characteristics of light-grown seedlings. We identify the causal mutation in TRICHOME BIREFRINGENCE encoding a putative acyl transferase. Pectin acetylation is decreased in dez, as previously found in the reduced wall acetylation2-3 mutant, shown here to phenocopy dez. Moreover, pectin of dez is excessively methylesterified. The addition of very short fragments of homogalacturonan, tri-galacturonate, and tetra-galacturonate, restores skotomorphogenesis in dark-grown dez and similar mutants, suggesting that the mutants are unable to generate these de-methylesterified pectin fragments. In combination with genetic data, we propose a model of spatiotemporally separated photoreceptive...

The micromorphological structure of seedlings of Rhynchosia minima (L.) DC. is described, from a dry ruderalized site of Karachi, on the basis of optical (OM) and scanning electron microscopy (SEM). The seedling appeared to be " Phanerocotylar-Epigeal-foliaceous " type. Several types of trichomes from cotyledons and leaves and structure of the resin gland (Brown-orange bulky capitate, glandular trichome) are described. Cotyledons are amphitrichomic and amphistomatic with paracytic arrangement of subsidiary cell. R. minima leaflets were amphistomatic with much larger number of stomata on ventral surface (283.3 ± 4.39 stomata per mm 2 , N = 100, CV = 38.6%) as compared to the dorsal surface (48.06 ± 1.85 stomata per mm 2 , N = 100, CV = 38.6%). The diversity of foliar stomata included, paracytic, anisocytic, staurocytic and anomocytic types. The stomatal size on abaxial surface leaf averaged to 18.53 ± 0.36 x 13.17 ± 0.30 µm. The predominating class of stomatal width (pore + guard cells) was 10.1 – 16 µm. Stomata on adaxial surface were comparable in size (19.76 ± 0.22 x 11.19 ± 0.18 µm). Quantitative element analysis based on elements detector system (EDS) of energy dispersive X-ray spectroscopy (EDS) is described.

Uptake, transport and toxicity of engineered nanomaterials (ENMs) into plant cells are complex processes that are currently still not well understood. Parts of this problem are the multifaceted plant anatomy, and analytical challenges to visualize and quantify ENMs in plants. We critically reviewed the currently known ENM uptake, translocation, and accumulation processes in plants. A vast number of studies showed uptake, clogging, or translocation in the apoplast of plants, most notably of nanoparticles with diameters much larger than the commonly assumed size exclusion limit of the cell walls of 5–20 nm. Plants that tended to translocate less ENMs were those with low transpiration, drought-tolerance, tough cell wall architecture, and tall growth. In the absence of toxicity, accumulation was often linearly proportional to exposure concentration. Further important factors strongly affecting ENM internalization are the cell wall composition, mucilage, symbiotic microorganisms (mycorrhiza), the absence of a cuticle (submerged plants) and stomata aperture. Mostly unexplored are the roles of root hairs, leaf repellency, pit membrane porosity, xylem segmentation, wounding, lateral roots, nodes, the Casparian band, hydathodes, lenticels and trichomes. The next steps towards a realistic risk assessment of nanoparticles in plants are to measure ENM uptake rates, the size exclusion limit of the apoplast and to unravel plant physiological features favoring uptake.

The chemical composition of the essential oils and the anatomical structures of the aerial parts from Baccharis anomala, B. megapotamica and B. ochracea growing in Brazil were studied. The volatile constituents isolated by hydrodistillation were analyzed by gas chromatograph coupled to a mass spectrometer detector (GC-MSD) and gas chromatograph coupled to a flame ionization detector (GC-FID). The botanical material was fixed, sectioned and prepared according to light and scanning microtechniques. The essential oil from B. anomala yielded 0.18% and showed α-acorenol (16.0%), spathulenol (13.3%) and caryophyllene oxide (12.1%) as the main components. Spathulenol (28.0% and 37.1%) and caryophyllene oxide (20.4% and 30.8%) represented the major constituents of the essential oils from B. megapotamica (yield = 0.17%) and B. ochracea (yield = 0.18%), respectively. The leaves and stems of these Baccharis species showed non-glandular trichomes and secretory ducts. Glandular trichomes were also found on the vegetative aerial parts of B. megapotamica

This study describes the anatomy and analyzes the histochemistry of the vegetative organs of Priva lappulacea (L.) Pers. Freehanded transversal and paradermal sections of fresh and fixed material were used for the anatomical and histochemical analyses, using optical microscopy. The anatomical characters are common to those described for the family, being able to be used to diagnosis in its identification. The leaves are highlighted by the presence of glandular and non-glandular trichomes, anomocytic stomata on both faces of the epidermis and dorsiventral mesophyll. The expansions in the petiole are added to the diagnosis of this species. The phytochemical study carried out with aerial organs showed the presence of triterpene (ursolic acid) and steroid (β-sitosterol), iridoids (ipolamide and catalpol), reducing sugar (glucose), flavonoid (luteolin) and fenilpropanoid (verbascosides). In the roots only glucose was found and two iridoids are present in stem and leaves. Alkaloids, saponins, cumarines, cinamic acid derivates, condensed proantocianidines and leucoantocianidines were not checked in the analyzed parts. The anatomical description and the histochemical tests are unpublished for P. lappulacea.

A small group of F-box proteins consisting of a conserved F-box domain linked to a domain homologous to the glycan-binding protein has been identified within the genome of Arabidopsis thaliana. Previously, the so-called F-box-Nictaba protein, encoded by the gene At2g02360, was shown to be a functional lectin which binds N-acetyllactosamine structures. Here, we present a detailed qRT-PCR expression analysis of F-box-Nictaba in Arabidopsis plants upon different stresses and hormone treatments. Expression of the F-box-Nictaba gene was enhanced after plant treatment with salicylic acid and after plant infection with the virulent Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000). β-glucuronidase histochemical staining of transgenic Arabidopsis plants displayed preferential activity of the At2g02360 promoter in trichomes present on young rosette leaves. qRT-PCR analyses confirmed high expression of F-box-Nictaba in leaf trichomes. A. thaliana plants overexpressing the gene showed...

Various morphological components of Millingtonia hortensis Linn. f. (cultivated in Dubai as roadside ornament) were studied for their surface micromorphology. The surface of this plant presented three important structures-much distributed trichomes on the surface of all organs of this plant, stomata present on leaf, pedicel, petals and fruit and tracheoidal system making the wing surface. The leaf was characterized with peculiar cuticular striation running parallel to each other and occasionally twined as the rope. Striations were generally confined within the perimeter of an epidermal cell but sometimes passing over several cells. Thirteen types of glandular and non-glandular trichomes are described in toto in this study-many of which were already described from this species but some of the trichomes were probably not observed in earlier studies e.g., 1) Branched moniliform trichomes on petals imparting velvet touch to the petal, 2) Multicellular uniseriate conical and stiff NGT with curved apical cell on peduncle, 3) Unicellular soft non-glandular trichome on petal, 4) Glandular trichomes present in pit and attached laterally with epidermis of the leaf and 5) Club shaped glandular trichomes on pedicel. Stomata were anomocytic type, raised above epidermis and with well-defined rim around. Guard cells outer ledges were very prominent. Contiguous stomata were frequent. Occasionally, triplet stomata were also present. Seed wing was thin and papery and composed of tracheoids running all over the seed surface in a fan like manner. Seed wing was porous with air spaces of varying sizes, well-suited for dispersal of seeds. The large air spaces showed tracheoidal ingrowths forming knot-like structures of various shapes and sizes, possibly for mechanical support to the wing. The findings are discussed in the light of available literature.

In contrast with the abundance of anatomical studies of secretory structures on aerial vegetative organs of Asteraceae species, the information about secretory structures on thickened subterranean organs is sparse. The aim of this study was to investigate the occurrence of secretory structures on thickened and nonthickened subterranean organs of seven Asteraceae species from three tribes: Eupatorieae (Chromolaena squalida and Gyptis lanigera), Vernonieae (Chresta sphaerocephala, Lessingianthus bardanoides, L. glabratus and Orthopappus angustifolius), and Plucheeae (Pterocaulon angustifolium). The specimens were collected in areas of cerrado from the State of São Paulo, Brazil. All species of the tribe Vernonieae studied exhibited endodermic cells, other than the epithelial cells of the canal, with secretory activity in the roots. In C. sphaerocephala roots, two types of endodermic cell were found, but only one had secretory activity. Secretory canals were found in the tuberous and nontuberous roots of all studied species. These data agree with the results from the literature for Asteraceae species. Here, we describe for the first time in Asteraceae the presence of secretory idioblasts in C. sphaerocephala. Secretory trichomes are present in the Orthopappus angustifolius rhizophore. Histochemical tests have shown that all types of secretory structure possess substances containing lipids. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 789–796.

Many angiosperms produce nectar that entices pollinator visits. Each floral nectary tends to embody a singular form, such as the receptacular ring arising beneath the ovary in mint flowers (Lamiaceae). Exceptionally, the annular floral nectary in Salvia farinacea possesses modified stomata plus secretory trichomes. This first study of nectary ultrastructure within the largest genus of Lamiaceae examined this unusual condition. Nectary anatomy, histochemistry, and ultrastructure were investigated from fresh and fixed material using light microscopy and scanning electron and transmission electron microscopy. The annular nectary encircled the ovary plus extended ventrally as a projection. Modified stomata occurred only in the projection's abaxial epidermis. Conversely, peltate trichomes with a basal cell, a stalk cell, and 4-7 head cells were interspersed among the ovary lobes and covered the projection's adaxial surface. Phloem and xylem supplied the nectary interior, where pa...

The aim of this study was to investigate whether gluconeogenesis catalysed by phosphoenolpyruvate carboxykinase (PEPCK) occurs during leaf senescence. This was addressed by determining changes in the abundance and intercellular location of enzymes necessary for gluconeogenesis during the senescence of barley leaves and cucumber cotyledons. PEPCK was never present in barley leaves, despite the presence of large amounts of isocitrate lyase (ICL), a key enzyme of the glyoxylate cycle, and of its product, glyoxylate. Although PEPCK was present in non-senescent cucumber cotyledons, its abundance declined during senescence. Throughout senescence, PEPCK was only present in the trichomes and vasculature, whereas ICL was located in mesophyll cells. Pyruvate,Pi dikinase (PPDK) which, in concert with NAD(P)-malic enzyme, is also capable of catalysing gluconeogenesis, was present in non-senescent barley leaves and cucumber cotyledons, but in both plants its abundance decreased greatly during se...