scholarly journals Secretory Structures of Pogostemon auricularius: Morphology, Development, and Histochemistry

Symmetry ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 13 ◽  
Author(s):  
Jiansheng Guo ◽  
Cheng Zhou

Pogostemon auricularius, an aromatic plant in Lamiaceae, has wide application in pharmaceutical preparations. However, little is known about the secretory structures that contain the medicinal compounds. In this study, two kinds of glandular trichome types, including peltate glandular trichomes and short-stalked capitate trichomes, were identified in the leaves and stems by cryo-scanning electron microscope. Oil secretion from the glands contained lipids, flavones, and terpenes, and the progresses of secretion were different in the two glands types. The investigation by transmission electron microscope indicated that the endoplasmic reticulum system and plastids were involved in the biosynthesis of oils in the two glandular trichomes. The vacuoles showed a new role in the oil preparations and storage. The synthesized oil could be transported from the head cell to the sub-cuticular space by different way in the two glands. Comparative analysis of the development, distribution, histochemistry and ultrastructures of the secretory structures in Pogostemon auricularius led us to propose that the two glands may make different contribution to the collection of medicinal compounds. Furthermore, the characteristics of two glands in the secretory stage probably indicated the synthesizing site of metabolite.

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Peina Zhou ◽  
Mengjiao Yin ◽  
Shilin Dai ◽  
Ke Bao ◽  
Chenglin Song ◽  
...  

Abstract Background Perilla frutescens (L.) Britt is a medicinal and edible plant widely cultivated in Asia. Terpenoids, flavonoids and phenolic acids are the primary source of medicinal ingredients. Glandular trichomes with multicellular structures are known as biochemical cell factories which synthesized specialized metabolites. However, there is currently limited information regarding the site and mechanism of biosynthesis of these constituents in P. frutescens. Herein, we studied morphological features of glandular trichomes, metabolic profiling and transcriptomes through different tissues. Results Observation of light microscopy and scanning electron microscopy indicated the presence of three distinct glandular trichome types based on their morphological features: peltate, capitate, and digitiform glandular trichomes. The oil of peltate glandular trichomes, collected by custom-made micropipettes and analyzed by LC–MS and GC–MS, contained perillaketone, isoegomaketone, and egomaketone as the major constituents which are consistent with the components of leaves. Metabolomics and transcriptomics were applied to explore the bioactive constituent biosynthesis in the leaves, stem, and root of P. frutescens. Transcriptome sequencing profiles revealed differential regulation of genes related to terpenoids, flavonoids, and phenylpropanoid biosynthesis, respectively with most genes expressed highly in leaves. The genes affecting the development of trichomes were preliminarily predicted and discussed. Conclusions The current study established the morphological and chemical characteristics of glandular trichome types of P. frutescens implying the bioactive constituents were mainly synthesized in peltate glandular trichomes. The genes related to bioactive constituents biosynthesis were explored via transcriptomes, which provided the basis for unraveling the biosynthesis of bioactive constituents in this popular medicinal plant.


2004 ◽  
Vol 31 (3) ◽  
pp. 267 ◽  
Author(s):  
James L. Smith II ◽  
J. Daniel Hare

Plant trichomes commonly serve a role in mechanical and chemical defence against herbivores, but may also have the potential to alter physiology by reducing the amount of light absorbed by leaves, lowering temperatures, and reducing water loss. Populations of Datura wrightii Regel in southern California produce 'sticky' plants with glandular trichomes and 'velvety' plants bearing non-glandular trichomes. Because stickiness is inherited as a dominant Mendelian trait, and the proportions of sticky plants vary among populations with the moisture availability of their environment, there may be some ecophysiological differences between trichome types that contribute to their ability to survive in a particular geographic location. To examine the possible physiological significance of trichome variation, we measured the spectral properties, midday gas-exchange rates, and water potentials of D. wrightii leaves from sticky and velvety plants growing in a field experiment. The differences in leaf reflectance (0.9%) and absorptance (1.3%) of photosynthetically active radiation (PAR) between trichome types are too small to have any direct physiologically significant effect. Simulations of leaf temperatures based on the difference in leaf absorptances reveal that leaf temperature would be no more than 1°C lower in velvety compared to sticky plants. Gas-exchange measurements revealed no significant difference between types in their transpiration rates or stomatal conductances. In this case, trichome variation may be more important to plant defenses than to physiology.


PROTOPLASMA ◽  
2019 ◽  
Vol 257 (1) ◽  
pp. 299-317 ◽  
Author(s):  
Agata Konarska ◽  
Piotr Chmielewski

Abstract Orobanche picridis is an obligate root parasite devoid of chlorophyll in aboveground organs, which infects various Picris species. Given the high level of phenotypic variability of the species, the considerable limitation of the number of taxonomically relevant traits (mainly in terms of generative elements), and the low morphological variation between species, Orobanche is regarded as one of the taxonomically most problematic genera. This study aimed to analyse the taxonomic traits of O. picridis flowers with the use of stereoscopic and bright-field microscopy as well as fluorescence, scanning, and transmission electron microscopy. The micromorphology of sepals, petals, stamens, and pistils was described. For the first time, the anatomy of parasitic Orobanche nectaries and the ultrastructure of nectaries and glandular trichomes were presented. Special attention was paid to the distribution and types of glandular and non-glandular trichomes as well as the types of metabolites contained in these structures. It was demonstrated that the nectary gland was located at the base of the gynoecium and nectar was secreted through modified nectarostomata. The secretory parenchyma cells contained nuclei, large amyloplasts with starch granules, mitochondria, and high content of endoplasmic reticulum profiles. Nectar was transported via symplastic and apoplastic routes. The results of histochemical assays and fluorescence tests revealed the presence of four groups of metabolites, i.e. polyphenols (tannins, flavonoids), lipids (acidic and neutral lipids, essential oil, sesquiterpenes, steroids), polysaccharides (acidic and neutral polysaccharides), and alkaloids, in the trichomes located on perianth elements and stamens.


Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1666
Author(s):  
Dario Kremer ◽  
Edith Stabentheiner ◽  
Faruk Bogunić ◽  
Dalibor Ballian ◽  
Eleni Eleftheriadou ◽  
...  

A study of the trichomes types and distribution and pollen morphology was carried out in nine Micromeria taxa (M. cristata ssp. cristata, M. cristata ssp. kosaninii, M. croatica, M. graeca ssp. graeca, M. graeca ssp. fruticulosa, M. juliana, M. kerneri, M. longipedunculata and M. microphylla) and five closely related Clinopodium species (C. dalmaticum, C. frivaldszkyanum, C. pulegium, C. serpyllifolium and C. thymifolium) from the Lamiaceae family of the Balkan Peninsula. By scanning electron microscope, non-glandular trichomes, peltate and capitate trichomes were observed on the calyx, leaves and stem of the studied species. Two subtypes of capitate trichomes were observed in Micromeria species: subtype 1 (consisting of a basal epidermal cell and an elliptically shaped head cell) and subtype 2 (consisting of a basal epidermal cell, two to three stalk cells and a round head cell). In Clinopodium species, three types of capitate trichomes were observed: subtype 1, subtype 3 (consisting of a basal epidermal cell, a short peduncle cell, and a single round head cell), and subtype 4 (consisting of a basal epidermal cell, a stalk cell, and an elongated head cell). These results support the recent transfer of Micromeria species from the section Pseudomelissa to the genus Clinopodium.


2019 ◽  
Vol 18 (2) ◽  
pp. 53-69 ◽  
Author(s):  
Radosław Kowalski ◽  
Grażyna Kowalska ◽  
Monika Jankowska ◽  
Agnieszka Nawrocka ◽  
Klaudia Kałwa ◽  
...  

The objective of the study was to perform micromorphological analyses of the secretory structures of leaves and stems of oil-bearing industrial plants from the Lamiaceae family such as lemon balm (Melissa officinalis L.), peppermint (Mentha × piperita L.), sage (Salvia officinalis L.), marjoram (Origanum majorana L., syn. Origanum dubium Boiss.), rosemary (Rosmarinus officinalis L.) and common thyme (Thymus vulgaris L.) using light microscope and scanning electron microscope. In addition, an estimation of the content of volatile substances in the plant species under study was performed using GC-MS, as well as the qualitative and quantitative analysis of essential oil, that is an important component in terms of the estimation of raw material applicability for use in the industry. In the epidermal cells of studied plants, 2 types of Lamiaceae-type glandular trichomes were identified: short- and long-stalked capitate glandular trichomes with single- and bicellular secretory capitulum, and peltate glandular trichomes with eight- and over a dozen-cell secretory capitulum. Capitate trichomes were densely distributed on the surface of the epidermis, while peltate trichomes were sparse, though regular, and were situated in depressions. Glandular trichomes were found more frequently on leaves than on stems. The cuticle of the abaxial of leaf was characterized in most cases by the occurrence of larger average diameter peltate trichomes compared to the cuticle of the adaxial side of leaf. Peppermint produced the largest structures accumulating essential oil on the leaves (average diameter of peltate trichomes – 78.48 µm on the adaxial side of leaf, up to 96.43 µm), while on the stem, the highest average diameter of the peltate trichomes was observed in sage (an average of 75.53 µm, up to 85.99 µm). The lemon balm was characterized by the presence of capitate and peltate trichomes with the smallest diameter (an average of 44.26 µm). Lemon balm was characterized by the greatest density of glandular trichomes compared to other plant species. Among the plants studied, the highest content of oil was noted in the case of thyme and peppermint (2.22% and 2.20% v/w, respectively), and the lowest in green parts of lemon balm (0.17% v/w). The isolated essential oils contained predominantly components from the groups of monoterpenes and sesquiterpenes, and it is the presence of those substances that determines the possibility of utilizing the plants studied for a variety of purposes.


2014 ◽  
Vol 67 (4) ◽  
pp. 13-24 ◽  
Author(s):  
Aneta Sulborska ◽  
Elżbieta Weryszko-Chmielewska

<p>Due to the presence of secondary metabolites exhibiting pharmacological activity, the flowers of <em>Rosa rugosa</em> Thunb. have found application in traditional and folk medicine. The essential oil obtained from them is also considered to be a phytoncide. The morphological and anatomical characters of glandular trichomes located on the sepals of <em>R. rugosa </em>were studied by light and scanning electron microscopy. Using histochemical tests, the type of secretion produced in the trichomes was determined and its contents were compared with the secretion produced by the papillae on the petals.</p><p>It was found that multicellular glandular trichomes, having the features of colleters, and non-glandular trichomes were located on the abaxial epidermis, while only non-glandular trichomes were situated on the adaxial epidermis. The stalk cells of the glandular trichomes are arranged in multiple rows, whereas the epidermal cells of the head are arranged radially. The capitate trichomes were classified into two types: short and long trichomes. The largest density of glandular trichomes was recorded in the basal abaxial epidermis and in the middle part of the sepals. During the initial stages of bud development, the glandular hairs were green colored, whereas in the next development stages they changed the color to red. The histochemical tests used allowed us to find that the trichomes on the sepals and the papille on the petals produced lipid substances, polyphenols, tannins, and flavonoids. Sesquiterpenes were found only in the secretion of the glandular hairs on the sepals.</p>


PROTOPLASMA ◽  
2019 ◽  
Vol 257 (1) ◽  
pp. 285-298 ◽  
Author(s):  
Weronika Haratym ◽  
Elżbieta Weryszko-Chmielewska ◽  
Agata Konarska

Abstract Centaurea cyanus L. is a valuable source of many different bioactive substances. It is used in herbal medicine, but the structure of its organs used as raw material and secretory tissues has been insufficiently examined. The aim of this paper was to investigate the microstructure of C. cyanus flowers, bracts, stems and leaves with particular emphasis on secretory structures. Moreover, the main classes of secondary metabolites present in the secretion were identified and the taxonomic value of some micromorphological and anatomical features was analysed. Histochemical, micromorphological and ultrastructural analyses of aboveground organs of C. cyanus were carried out using light, fluorescence, scanning and transmission electron microscopy. The analyses revealed the presence of petal papillae and a characteristic cuticular pattern on the petals, stamens and stylar hairs. There were four types of non-glandular trichomes on the bracts, leaves and stem surfaces. The epidermal cells of the bracts contained prismatic calcium oxalate crystals. Two kinds of secretory structures, i.e. glandular trichomes and ducts, were observed in the C. cyanus organs. The glandular trichomes were located on the bract and stem surfaces, and the ducts were detected in the leaves and stems. Ultrastructural analyses of the epithelium of the ducts showed the presence of strongly osmiophilic insoluble phenolic material in vacuoles as well as moderately osmiophilic insoluble lipidic material in elaioplasts and vesicles. The results of histochemical assays showed a heterogeneous nature of the duct secretion, which contained essential oil, lipids, flavonoids, tannins and terpenes containing steroids.


Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1267
Author(s):  
Tatiana A. Feodorova ◽  
Oleg S. Alexandrov

Poplars from Aigeiros Duby section are very widespread in the world. A range of morphological characters were studied in such species of this section as Populus deltoides Bartram ex Marshall, P. nigra L. and their hybrid P. × canadensis Moench. However, there is little information about micromorphological characters of their leaves. The aim of this work was to study these characters and understand their species-specific potential. Thus, the morphological features, density and distribution of non-glandular trichoms, marginal glandular trichomes (salicoid teeth or coleters), epiglandular trichomes and basilaminar nectaries-glands were ontogenetically examined by both light and scanning electron microscopy in the certified by molecular markers P. deltoides, P. nigra and P. × canadensis samples. Non-glandular trichomes belong to the uni-, multicellular, uniseriate category. Marginal glandular trichomes can be classified as coleter types. Other morphological and anatomical trichome features are discussed with regard to their possible function. In summary, some variations in leaf morphology may be useful for the P. nigra, P. deltoides and their hybrid P. × canadensis species identification. These species differ in shape and number of basilaminar glands, as well as non-glandular trichome types and their distribution on the leaf.


Botany ◽  
2015 ◽  
Vol 93 (5) ◽  
pp. 297-306 ◽  
Author(s):  
Luiz Ricardo dos Santos Tozin ◽  
Shelly Favorito Carvalho ◽  
Silvia Rodrigues Machado ◽  
Tatiane Maria Rodrigues

Despite the ecological and medicinal importance of glandular trichomes in Verbenaceae, information on their structure, mainly at the subcellular level, is sparse. We analyzed the morphology and histochemistry of glandular trichomes in Lippia origanoides Kunth and Lippia stachyoides Cham., using conventional methods in anatomy, histochemistry, scanning and transmission electron microscopy, and ultracytochemical techniques. Five morphotypes (I–V) of glandular trichomes were identified in L. origanoides, and four morphotypes (I, III–V) in L. stachyoides. Morphotype I is the most abundant in both species. Lipids were detected in all morphotypes except IV; terpenes in I, II, and V; phenolic compounds in all morphotypes except V; neutral polysaccharides and protein in all morphotypes; mucilage exclusively in IV; alkaloids only in III. Each glandular morphotype showed ultrastructural peculiarities compatible with the chemical compounds produced. An association between glandular morphotype, secretion composition, and ultrastructural features in Lippia species was revealed, suggesting functions specific to each glandular morphotype.


Author(s):  
R. A. Waugh ◽  
J. R. Sommer

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.


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