Distribution Of Trichomes Research Articles

Glandular trichomes of Ceratotheca triloba (Pedaliaceae): morphology, histochemistry and ultrastructure

This study was initiated to characterize the distribution, morphology, secretion mode, histochemistry and ultrastructure of the glandular trichomes of Ceratotheca triloba using light and electron microscopy. Its leaves bear two morphologically distinct glandular trichomes. The first type has long trichome with 8-12 basal cells of pedestal, 3-14 stalk cells, a neck cell and a head of four cells in one layer. The second type has short trichome comprising one or two basal epidermal cells, a unicellular or bicellular stalk and a multicellular head of two to eight cells. There is a marked circular area in the upper part of each head cell of the long trichome. This area is provided with micropores to exudate directly the secretory product onto the leaf surface by an eccrine pathway. The secretory product has copious amount of dark microbodies arising from plastids which are positive to Sudan tests and osmium tetroxide for unsaturated lipids. The secretion mode of short trichomes is granulocrine and involves two morphologically and histochemically distinct vesicle types: small Golgi-derived vesicles which are positive to Ruthenium Red test for mucilaginous polysaccharides; the second type is dark large microbodies similar to that of long trichomes with low quantity. These two types are stored in numerous peripheral vacuoles and discharge their contents accompanied by the formation of irregular invaginations of the plasmalemma inside the vacuoles via reverse pinocytosis. These two secretion modes of long and short trichomes are reported for the first time in the family Pedaliaceae. The long trichomes have more unsaturated lipids, while the short trichomes contain more mucilaginous polysaccharides.

A morphological and chemotaxonomic study of Teucrium arduini L. in Croatia, and Bosnia and Herzegovina

A study on the type and distribution of trichomes, morphological traits of the calyx and content of antioxidant compounds was conducted on Teucrium arduini L. populations in Croatia and in Bosnia and Herzegovina. Non-glandular trichomes, peltate trichomes and small capitate trichomes with four secretory head cells were observed on leaves, stems and calyx, whereas long capitate trichomes with a unicellular head cell were observed exclusively on the calyx. Average calyx length was 5.23–6.51 mm, calyx tube length 2.92–3.68 mm, lower lip length 1.25–2.42 mm and upper lip length 1.89–2.99 mm. The concentration of antioxidant compounds in all populations was the highest in leaves: total polyphenols (TP): 8.43–13.55%; tannins (T): 1.79–7.33%; flavonoids (TF): 0.28–0.40%; phenolic acids (TPA): 2.90–5.07%. Inflorescences generally contained the smallest amount of TP (5.89–11.42%), T (0.87–6.50%) and TPA (1.66–2.27%), while the smallest content of TF was obtained for the majority of stem samples (0.06–0.12%). The researched populations did not differ with regard to the type and overall distribution of the trichomes, though the Bosnian populations have a shorter calyx tube and longer upper lip. Some variability was observed in the TP and T content between sampling sites, while quite high variability was noted in the TF and TPA content.

Micromorphological and Chemotaxonomical Traits of Micromeria croatica (Pers.) Schott

A study on the types and distribution of trichomes, pollen morphology, chemical composition of essential oil (analyzed by GC-FID and GC/MS), and the content of macroelements (Na, K, Ca, and Mg) and trace elements (B, Fe, Cu, Mn, Zn, Al, Pb, Cr, Cd, Ni, Hg, and As) analyzed by ICP-AES (=inductively coupled plasma atomic emission spectroscopy) was conducted on Micromeria croatica (Pers.) Schott. Non-glandular trichomes, peltate trichomes (typical hairs of Lamiaceae), small capitate trichomes (composed of one basal epidermal cell and one head cell), and larger capitate trichomes (composed of one basal epidermal cell, two to three stalk cells, and one head cell with subcuticular space) were observed on leaves, stems, the calyx, and corolla. Pollen of M. croatica had six apertures (hexacolpate) which were set in the equatorial pollen belt (zonocolpate) and showed medium reticulate ornamentation (hetrobrochate type). The essential oil contained from 27 to 39 constituents, the most representative of which were caryophyllene oxide and E-caryophyllene. Among the investigated macroelements, the content of K was highest (8730-10080 mg/kg). The content of trace elements ranged from 0.12 mg/kg (Cr) to 78.00 mg/kg (Fe), while the content of Cd, Ni, Hg, and As were lower than the limit of quantification.

Effect of heat shock on ultrastructure and calcium distribution in Lavandula pinnata L. glandular trichomes

The effects of heat shock (HS) on the ultrastructure and calcium distribution of Lavandula pinnata secretory trichomes are examined using transmission electron microscopy and potassium antimonate precipitation. After 48-h HS at 40°C, plastids become distorted and lack stroma and osmiophilic deposits, the cristae of the mitochondria become indistinct, the endoplasmic reticulum acquires a chain-like appearance with ribosomes prominently attached to the lamellae, and the plasma and organelle membranes become distorted. Heat shock is associated with a decrease in calcium precipitates in the trichomes, while the number of precipitates increases in the mesophyll cells. Prolonged exposure to elevated calcium levels may be toxic to the mesophyll cells, while the lack of calcium in the glands cell may deprive them of the normal protective advantages of elevated calcium levels. The inequality in calcium distribution may result not only from uptake from the transpiration stream, but also from redistribution of calcium from the trichomes to the mesophyll cells.

Morphological differentiation and distribution of non-glandular and glandular trichomes on Dracocephalum moldavicum L. shoots

The structure, micromorphology and distribution of trichomes on <i>Dracocephalum moldavicum</i> L. shots were investigated using light and scanning electron microscopy (SEM). There were distinguished 3 types of non-glandular trichomes, 3 types of glandular trichomes and papillae of the osmophore in the epidermis of the corolla. The highest density of non-glandular and glandular trichomes was found on the abaxial surface of the calyx, on bracts and in the upper part of the stem. Structural variations in the head and stalk of long glandular trichomes were demonstrated. The dimensions of particular types of trichomes are given in the present paper. Differences in the structure of the trichomes of this species are presented, compared to literature data. The micromorphology of particular trichome types is documented in numerous photographs showing the rich ornamentation of the cuticle of non-glandular trichomes.

The structure and distribution of glandular trichomes on the stems and leaves of drug eyebright (Euphrasia stricta D. Wolff ex J. F. Lehm.)

<i>Euphrasia stricta</i> is a medicinal plant being one of the ingredients of "Herba Euphrasiae". Many studies have been devoted to the identification of biologically active substances in the herb of eyebright, but much less research has been done on the constitution of glandular structures of this taxon. This paper relates to glandular trichomes located on the stems and leaves of <i>E. stricta</i>. The trichome structure was examined using light and scanning electron microscopy. It was shown that the stems of <i>E. stricta</i> were mainly covered by non-glandular trichomes, whereas glandular trichomes were rarely found on them. However, clusters of short capitate trichomes were found to occur in specific epidermal regions on both surfaces of the leaf blades and bracts. On the adaxial leaf surface, glandular trichomes grew only in the grooves above the vascular bundles, while on the abaxial surface in the depressions located in the expanded part of the teeth. The glandular hairs consisted of 1-2 cells of the stalk and a two-celled head. Trichomes with 3- or 4-celled heads were found sporadically. The glandular trichomes functioned non-synchronously, since they differed in head size and the colour of cell protoplasts. The presence of a light secretion was found on the surface and around the trichomes in both fresh and dry plant material.

Glandular trichomes as further differential characters between Stachys subgenus Betonica (L.) Bhattacharjee and Stachys subgenus Stachys

The genus Stachys L. has always presented great taxonomic and nomenclatural problems; the identification of two different genera, Betonica and Stachys, or of a single genus, Stachys, with the subgenera Betonica and Stachys, is still debated. In this work, different types of glandular trichomes (peltate and capitate) occurring in species belonging to both subgenera Betonica and Stachys are described. Observations were carried out on living plants growing in Italy, using scanning electron microscopy (SEM), to characterise trichome structure and distribution on vegetative and reproductive organs, and light microscopy (LM) to characterise their type of secretion, by means of histochemical methods. Stachys subgenus Betonica presents only peltate hairs, while Stachys subgenus Stachys has different types of large capitate hairs lacking in the subgenus Betonica. Furthermore, the peltate trichomes of the subgenus Betonica show an unusual secretion composed of flavonoids and essential oils. A thorough examination of numerous exsiccata belonging to subgenera Betonica and Stachys, stored in the Herbarium Centrale Italicum of Florence (FI), confirmed observations made on living material. The recorded characters allowed a clear distinction between the species of the subgenus Betonica and those of the subgenus Stachys. Consequently, a higher taxonomic rank than subgenus should be recommended for these taxa.

Systematics of the Eupatorium album Complex (Asteraceae) from Eastern North America

Abstract Analysis of ITS sequence data showed unexpected complexity for Eupatorium album and E. petaloideum, a closely related species pair from eastern North America that has been considered to form a single species. The two species consistently differed in ITS sequence by seven to eight bp as well as a one bp indel, and detailed analysis revealed little intraspecific variation. The ITS sequences of other samples that had similar but slightly differing morphology and were pollen sterile gave several patterns involving bp or indel polymorphisms that indicated that they were of hybrid derivation. Based on differences in leaf and phyllary shape and glandular trichome distribution it was possible to delimit the individual hybrid combinations from one another and from their progenitor species. Material previously called E. album from the western part of its range is of hybrid origin from E. album and E. lancifolium, and is described here as Eupatorium sullivaniae. Material from the northeastern part of the ra...

Finding the most appropriate IR technique for plant species identification

Quality control of herbal medicinal products is of extreme importance. Procedures for identification of plant species, such as biochemical analysis or macroscopic and microscopic examination of morphological and anatomical properties are time consuming and expensive[1]. A good alternative is infrared spectroscopy since it is rapid, easy to use, nondestructive and low-cost. Identification of species from dried whole leaf samples of pharmaceutically important Epilobium and Hypericum genera were investigated. To determine which infrared spectroscopy mode gives most informative spectra for plant species identification different modes of infrared spectroscopy were applied. These were diffuse reflectance, attenuated total reflectance (ATR), direct transmission of whole leaves, and KBr tablet transmission with comminuted leaves. First the informative wavenumbers were chosen by one-way analysis of variance. Afterwards the colinearity was reduced with principal component analysis. At last the species identification was determined with discriminant analysis. Best results were obtained with ATR and KBr tablet transmission. Still there were important differences between genera. ATR proved to be appropriate for discrimination among Epilobium species (accuracy of plant species identification was 98%), Epilobium species differ in distribution and morphology of trichomes on the surface of the leaves[2]. While for Hypericum species KBr tablet transmission proved to give best results (accuracy of plant species identification was 97%). Hypericum species differ in secondary metabolites that are acumulated in the interior of the leaves[3,4]. Results show that morphological properties of plant material should be taken into consideration when developing an infrared spectroscopy based method for identification of plant species.

Caracterização morfológica e classificação da superfície foliar de pimentas quanto à presença de tricomas e domácias

O conhecimento das características morfológicas das plantas é de grande relevância para o estudo das interações entre plantas, herbívoros e inimigos naturais. Variações nessas características são determinantes na ocorrência, abundância e diversidade de organismos que exploram esse habitat. Caracterizou-se a superfície foliar de quatro espécies de pimentas do gênero Capsicum e elaborou-se uma proposta de classificação das folhas com base nos critérios de presença ou ausência, densidade e distribuição de tricomas para domácias, visando a utilização dessas informações em estudos de resistência de plantas a artrópodes. A contagem dos tricomas foi feita em uma área de 5 cm²,no terço médio das folhas, sendo contabilizados os tricomas do limbo, das nervuras e das domácias. As espécies de pimenta diferiram significativamente quanto à densidade de domácias e tricomas presentes na nervura e no limbo de suas folhas. Também foi observada diferença significativa na densidade total de tricomas/cm² e no número de tricomas por domácia. Das quatro espécies de pimenta avaliadas, apenas C. baccatum var. pendulum (pimenta com ardume variedade dedo-de-moça) não possui domácias nem tricomas em qualquer região de suas folhas. A maior densidade de domácias foi observada em C. baccatum var. praetermissum, espécie em que se observou as maiores densidades de tricomas em todas as regiões da folha e a única com densidade significativa de tricomas no limbo. As variações quanto à presença, distribuição e densidade de tricomas e domácias podem ser determinantes na ocorrência de ácaros predadores e fitófagos nas plantas. Com base na caracterização efetuada foi proposta uma escala de classificação da superfície foliar das plantas, variando de 1 a 5, em função do número e da densidade de tricomas e domácias observados.

Leaf epidermal characters of Solanum sect. polytrichum (Solanaceae) as taxonomic evidence

The morphological similarities among the species of Solanum are remarkable, and are often very difficult one clear distinction between them. This paper presents a comparative anatomical study of the leaf epidermis of five Brazilian species of Solanum sect. Polytrichum, carried out using light and scanning electron microscopy. The leaf epidermis surfaces were investigated to evaluate their taxonomic significance to be used for separation and delimitation of the species of the section. As results, some micro-morphological characters of the leaf epidermis, such as density, distribution and type of stellate trichomes, and the anticlinal walls of epidermal cells, and also the type and distribution of stomata proved to be the most useful and distinctive characters for the separation and delimitation of the species, and also may contribute as an additional support to the interspecific taxonomy and systematic of Solanum sect. Polytrichum.

Differences Among Epilobium and Hypericum Species Revealed by four IR Spectroscopy Modes: Transmission, KBr Tablet, Diffuse Reflectance and ATR

Quality control of dried plant material in assessments of suitability of herbal medicinal products is of extreme importance. Commonly used procedures for identification of species are time consuming and expensive. The development of multivariate statistical methods has enabled application of vibrational spectroscopy for establishing plant species membership. To determine which infrared spectroscopy mode gives most informative spectra for plant species identification. Different modes of infrared spectroscopy were applied for investigation of differences among Epilobium and Hypericum species: diffuse reflectance (DR), attenuated total reflectance (ATR), direct transmission of whole leaves and KBr tablet transmission with comminuted leaves. The same chemometrical methods were applied to all spectra. The informative wave numbers were chosen by one-way analysis of variance. Afterwards the colinearity was reduced with principal component analysis. In the final step the species identification was determined with discriminant analysis. Transmission and diffuse reflectance mode did not give satisfactory results. Best results for discrimination among Epilobium species were obtained with ATR mode (98%), while best results for Hypericum species were obtained with KBr transmission mode (97%). This might be explained by the morphological properties of the two genera. Epilobium species differ in distribution and morphology of trichomes on the surface of the leaves. Hypericum species differ in structures and secondary metabolites in the interior of the leaves. For best results in using infrared spectroscopy for plant species identification in quality control, the morphological properties of plant material should be taken into consideration.

Chemical Differences in Volatiles between Melittis melissophyllum L. subsp. melissophyllum and subsp. albida (Guss) P. W. Ball (Lamiaceae) Determined by Solid‐Phase Microextraction (SPME) Coupled with GC/FID and GC/MS

Melittis melissophyllum (Lamiaceae) is a perennial herb, typical of woody places, occurring in Italy with two subspecies, i.e., melissophyllum and albida. So far, the classification of these two taxa was only based on morphology, i.e., the presence of glandular trichomes, the dimension of the leaves, and the number of teeth on each side as the main discriminant characters. To find marker compounds to chemically discriminate the subsp. melissophyllum with respect to the subsp. albida, a solid-phase microextraction SPME analysis coupled with GC/FID (=flame ionization detector) and GC/MS was carried out. SPME proved to be a chemotaxonomically useful technique that permitted a clearly differentiation of the two subspecies at headspace level. The subsp. melissophyllum was characterized by high amount of the mushroom alcohol oct-1-en-3-ol and the phenolic coumarin, whilst the subsp. albida exhibited a high content in monoterpenes and sesquiterpenes, α-pinene, sabinene, and (E)-caryophyllene being the major compounds. Multivariate chemometric techniques, such as cluster analysis (CA) and principal-component analysis (PCA), were used to support chemical data and characterize the population according to the taxonomy. In addition, the micromorphology and distribution of glandular trichomes of both subspecies were studied by scanning electron microscopy (SEM).

The effect of the floral repressorFLCon the timing and progression of vegetative phase change inArabidopsis

Plants undergo two major post-embryonic developmental transitions--the juvenile-to-adult vegetative transition (vegetative phase change) and the adult-to-reproductive transition (flowering). In woody plants, these transitions can be separated by years, but in herbaceous species they are often very close together, making it difficult to differentiate the effects of vegetative phase change and floral induction on vegetative development. To distinguish between these factors, we have compared the vegetative morphology of plants highly expressing the floral repressor FLC (FRI;FLC) with plants mutant for this gene (FRI;flc-3) under both photoinductive (long day, LD and night interruption, NI) and non-photoinductive (short day, SD) conditions. We show that the onset of abaxial trichome production is insensitive to floral induction, but the distribution and overall number of abaxial trichomes, as well as several other leaf traits associated with vegetative change, are strongly influenced by flowering. Most of the major differences in leaf morphology between FRI;FLC and FRI;flc-3 plants grown in LD can be attributed to the early flowering phenotype of FRI;flc-3, because these differences are not apparent in plants grown in SD. These include differences in leaf size, hydathode number and the distribution of abaxial trichomes along the length of the leaf. Leaf shape and the total number of abaxial trichomes are affected by FLC independently of its effect on flowering. Our results demonstrate that the onset and the progression of vegetative phase change are regulated by different combinations of endogenous and environmental factors, and reveal a role for FLC in vegetative development.

Structure and distribution of floral trichomes in Lycaste and Sudamerlycaste (Orchidaceae: Maxillariinae s.l.)

Phylogenetic analysis indicates that Lycastinae should be incorporated into a more broadly defined Maxillariinae. This is supported by several anatomical features, including the presence of sunken, glandular trichomes in both Lycastinae and Maxillariinae s.s. Until recently, these were known only from vegetative organs, but have since been reported from flowers of Maxillaria dichroma. One character currently used to distinguish between Lycaste and Sudamerlycaste is the distribution of floral trichomes. In this article, we test the reliability of this character, describe the floral micromorphology of Lycaste and Sudamerlycaste and investigate whether their flowers bear sunken hairs. Their floral micromorphology is compared with that of other genera currently assigned to Maxillariinae s.l. Flowers of Lycaste and Sudamerlycaste bear conical or obpyriform papillae and unbranched and unequally branched multicellular trichomes. Contrary to previous reports that trichomes are confined to the column in Sudamerlycaste, they also occur in the tepal axils. Labellar trichomes, although often present in Lycaste, are lacking in Sudamerlycaste. In Lycaste sections Lycaste and Aromaticae, floral trichomes tend to be unbranched, whereas section Intermediae has both unbranched and branched hairs. Branched hairs are more common in Sudamerlycaste. Some hairs are tracheoidal, pitted and lignified. These mainly occur in section Lycaste and, to a degree, in section Intermediae, but are absent from section Aromaticae and most species of Sudamerlycaste. Branched column hairs, present in Sudamerlycaste, are absent from all sections of Lycaste, and tracheoidal column hairs occur only in Sudamerlycaste. Sunken floral hairs are absent from both genera. Trichome structure and distribution may prove useful in distinguishing between these taxa and in elucidating the intergeneric relationships of Maxillariinae s.l.

An investigation of the glandular and non-glandular foliar trichomes of Orthosiphon labiatus N.E.Br. [Lamiaceae

Using a combination of light (stereo and compound) and scaning electron microscopy, this study investigates the distribution and morphology of foliar trichomes of Orthosiphon labiatus (Lamiaceae) at different stages of leaf development. Three types of trichomes were observed: two glandular types (large peltate and small capitate) and one non-glandular type. Results revealed that the development of peltate trichomes was initiated in the early stages of leaf development. However, a higher number of developed peltate trichomes was observed in mature leaves, indicating an increase with age. Capitate trichomes are, by contrast, rare and sparsely distributed on both leaf surfaces. The highest density of non-glandular trichomes was observed on the abaxial leaf surface, especially along the veins, with the density decreasing with leaf maturity. This paper contributes towards the body of knowledge being assembled on the family Lamiaceae as it manifests in southern Africa.

Leaf epidermal characteristics of Cissampelos L. (Menispermaceae) species from Northeastern Brazil

The morphological similarities among the species of Cissampelos are remarkable and the difficult to distinguish them as well. This article presents a comparative anatomical study of the leaves of common Northeastern Brazilian species of Cissampelos, carried out using light and scanning electron microscopy. The leaf epidermal was studied to obtain data on epidermal characteristics and to evaluate their taxonomic significance. As results, some micromorphological characters on the leaf epidermal like the cuticular waxes, the presence of papillae in epidermis and nonglandular trichomes, the anticlinal walls epidermal cells, the distribution, density and type of trichomes, and also the type and distribution of epicuticular wax proved to be the most useful characteristics to distinguish the species in taxonomic studies.

Temporal Control of Trichome Distribution by MicroRNA156-TargetedSPLGenes inArabidopsis thaliana

The production and distribution of plant trichomes is temporally and spatially regulated. After entering into the flowering stage, Arabidopsis thaliana plants have progressively reduced numbers of trichomes on the inflorescence stem, and the floral organs are nearly glabrous. We show here that SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) genes, which define an endogenous flowering pathway and are targeted by microRNA 156 (miR156), temporally control the trichome distribution during flowering. Plants overexpressing miR156 developed ectopic trichomes on the stem and floral organs. By contrast, plants with elevated levels of SPLs produced fewer trichomes. During plant development, the increase in SPL transcript levels is coordinated with the gradual loss of trichome cells on the stem. The MYB transcription factor genes TRICHOMELESS1 (TCL1) and TRIPTYCHON (TRY) are negative regulators of trichome development. We show that SPL9 directly activates TCL1 and TRY expression through binding to their promoters and that this activation is independent of GLABROUS1 (GL1). The phytohormones cytokinin and gibberellin were reported to induce trichome formation on the stem and inflorescence via the C2H2 transcription factors GIS, GIS2, and ZFP8, which promote GL1 expression. We show that the GIS-dependent pathway does not affect the regulation of TCL1 and TRY by miR156-targeted SPLs, represented by SPL9. These results demonstrate that the miR156-regulated SPLs establish a direct link between developmental programming and trichome distribution.

The foliar trichomes of Plectranthus laxiflorus Benth [Lamiaceae]: an important medicinal plant

Plectranthus laxiflorus (family Lamiaceae), is an important medicinal plant, distributed east of the southern continental escarpment from Humansdorp in the Eastern Cape province of South Africa. The distribution and morphology of leaf trichomes of P. laxiflorus were investigated using a combination of light and scanning electron microscopy. The leaves of P. laxiflorus bear both glandular (peltate and capitate) and non-glandular trichomes which are distributed on both the adaxial and abaxial surfaces. Capitate types of trichomes were fewer and more sparsely distributed than the peltate type. Initiations of both glandular and non-glandular trichomes were observed at various stages of leaf development. However, the proportion of mature to immature trichomes increased with leaf maturity, with immature trichomes being exceedingly rare on fully mature leaves.

Structural investigation of the glandular trichomes of endemic Salvia smyrnea L.

The morphology, anatomy and distribution of glandular trichomes on the aerial organs of Salvia smyrnea L. endemic to Turkey have been investigated with light microscopy (LM) and scanning electron microscopy (SEM). This species is evaluated in endangered (EN) category. Two morphologically distinct types of glandular trichomes were determined. Various types of capitate glandular trichomes consist of a 1–4 celled base, a 1–8 stalk celled or no stalk and a uni- or bicellular head. In capitate trichomes the neck cell that has an important role especially for xeromorfic plants, acting to prevent the backflow of secreted substance through the apoplast, has been distinctively observed in the investigated species. The capitate trichomes were present abundantly on all aerial organs of S. smyrnea. Peltate glandular trichomes had a large secretory head comprising 1–2 central and 4,6, 8–10 peripheral cells. This study pointed out that S. smyrnea was of rich glandular trichomes in point of diversity and quantity.