Structural investigation of the glandular trichomes of <Emphasis Type="Italic">Salvia argentea</Emphasis>

The morphology, anatomy and distribution of glandular trichomes on the aerial organs of Salvia argentea L. has been investigated. Two morphologically distinct types of glandular trichomes were determined. Capitate glandular trichomes forming a base 1–7 celled, a stalk 1–5 celled or no stalk and a head uni- or bicellular had various types. In capitate trichomes, the neck cell that has an important role especially for xeroformic 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. argentea. Peltate glandular trichomes had a large secretory head forming 1–5, 8 central and 8–10, 12, 14 peripheral cells. Peltate trichomes are present on all aerial organs, except petiole, being the most abundant on calyx and corolla. Results were shown by tables and photographs.     

线纹香茶菜叶上腺毛发育的细胞学研究

为进行中药溪黄草基原植物的品种鉴定,采用光镜和电镜对线纹香茶菜(原变种)[Isodon lophanthoides var.lophanthoides]叶上腺毛的发育进行细胞学研究。结果表明,线纹香茶菜具有头状腺毛和盾状腺毛2种类型。头状腺毛无色透明,由1个基细胞、1个柄细胞和1或2个头部分泌细胞构成;盾状腺毛为红色,由1或2个基细胞、1个柄细胞和4~8个分泌细胞构成头部。2种腺毛均由原表皮细胞经两次平周分裂形成,后因柄细胞和头部细胞所处的分化状态不同而形成两类腺毛。2种腺毛超微结构表明,质体、高尔基体和粗面内质网为主要分泌物产生和运输的细胞器。当盾状腺毛成熟时,角质层下间隙充满了分泌物,其分泌物的性质很可能决定了线纹香茶菜腺毛的颜色。     

Anatomy,trichome morphology and palynology of Salvia chrysophylla Stapf (Lamiaceae)

The anatomy, palynology, morphology and distribution of the trichomes on the aerial parts of Salvia chrysophylla Stapf, an endemic species in Turkey, were studied in order to understand the usefulness of these characteristics for systematic purposes. Some anatomical characters such as (1–)2–24-rowed pith rays in roots, dorsiventral leaves, obviously larger upper epidermal cells, and two to three large vascular bundles in the center and two to four small subsidiary bundles in the wings of petiole provide information of taxonomical significance. Three main types of trichomes were observed on the stem, inflorescence axis, leaf and calyx surfaces of S. chrysophylla. They are peltate, capitate glandular and non-glandular. Capitate glandular and non-glandular trichomes were further subdivided into several kinds. Glandular trichomes are present in abundance on the inflorescence axis and calyx, but non-glandular ones were mainly situated on the leaf and stem. Scanning Electron Microscopy (SEM) studies on the pollen grains have revealed that they are oblate-spheroidal and their exine ornamentation is bireticulate-perforate.     

冬凌草腺毛的形态学及组织化学研究

利用光学显微镜对药用植物冬凌草地上部分腺毛的形态、分布和组织化学进行了研究。结果表明:(1)冬凌草的叶表皮有3种形态显著不同的毛,即非腺毛、盾状腺毛和头状腺毛;盾状腺毛和头状腺毛均具1个基细胞、1个柄细胞和头部;成熟的盾状腺毛的头部一般由4个分泌细胞组成,而头状腺毛头部由2个分泌细胞组成。(2)组织化学鉴定结果显示:2种腺毛中均含有黄酮类成分,盾状腺毛中还含有单萜、倍半萜等萜类成分;冬凌草甲素可能只存在于盾状腺毛中,但需要更直接的证据证明。研究认为,高密度的盾状腺毛可以作为筛选冬凌草高甲素含量品种的一项重要依据。     

Sideritis syriaca ssp. syriaca: Glandular trichome structure and development in relation to systematics

Sideritis syriaca ssp. syriaca is a taxon with a low essential oil content. Its leaves bear glandular trichomes of two types: long hairs with a 4-celled head, a 4-celled stalk and a 4-celled foot (reported for the first time in Lamiaceae) and short hairs with a 4–celled head, a unicellular stalk and a unicellular foot. The second type is considered intermediate between the capitate and peltate hairs, common in Lamiaceae, but found in S. syriaca ssp. syriaca. The ontogeny of the trichome types is described. The possible significance of the glandular trichome structure to Lamiaceae systematics is further discussed.     

Trichome micromorphology of Iranian Stachys (Lamiaceae) with emphasis on its systematic implication

Trichomes of 37 taxa of the genus Stachys and one species of Sideritis (S. montana) were examined using light and scanning electron microscopy. The indumentum shows considerable variability among different species, but is constant among different populations of one species, and therefore, affords valuable characters in delimitation of sections and species. The characters of taxonomic interest were presence of glandular and non-glandular trichomes, thickness of the cell walls, number of cells (unicellular or multi-cellular), presence of branched (dendroid) trichomes, presence of vermiform trichomes, orientation of trichomes in relation to the epidermal surface, curviness of trichomes, and presence of papillae on trichome surface. Two basic types of trichomes can be distinguished: glandular and non-glandular trichomes. The glandular trichomes can in turn be subdivided into subtypes: stalked, subsessile, or sessile. The stalks of the glandular trichomes can be uni- or multi-cellular. Simple unbranched and branched trichomes constitute two subtypes of non-glandular trichomes. Our data do not provide any support for separation of Sideritis from Stachys. The following evolutionary trends are suggested here for Stachys: vermiform trichomes with stellate base are primitive against vermiform trichomes with tuberculate base, long vermiform trichomes are primitive against the short simple trichomes, appressed trichomes are advanced against spreading ones, and loss of glandular trichomes is advanced against their presence. Overall, trichome micromorphology is more useful in separation of species within sections rather than characterizing large natural groups known as sections, except for few cases.     

甘草腺毛的形态发生和组织化学研究

利用扫描电镜及薄切片技术对甘草的腺毛形态发生和发育过程进行了观察,并对腺毛发育过程中黄酮类成分积累进行了组织化学定位研究。结果表明：甘草腺毛为多细胞构成的盾状腺毛,有长柄和短柄2种类型;前者主要分布在花萼片上,而后者主要分布于叶片上。组化鉴定结果显示：腺毛中存在着黄酮类成分、其他亲脂类和非纤维素多糖类成分;在腺毛的发育过程中,黄酮类物质是随腺毛的发育成熟,在头部盘状结构的分泌细胞及角质层下腔中积累。研究结果对进一步探讨甘草叶中黄酮类成分的合成及其作用提供科学依据。     

Glandular trichomes and essential oil constituents ofCalamintha menthifolia (Lamiaceae)

Plant material ofCalamintha menthifolia was collected from two populations grown in the Vikos-Aoos area (NW. Greece). The structure and ontogeny of the glandular trichomes and the chemical composition of the secreted essential oil were studied. The leaves ofC. menthifolia have numerous glandular trichomes of three morphological distinct types: 1) glandular scales with a unicellular foot and stalk, and a 12-celled head, 2) glandular hairs with a unicellular foot and stalk, and a unicellular pear-shaped head and 3) glandular hairs with a unicellular foot, a bicellular stalk and a unicellular elongated head. Qualitative and quantitative GC-MS analyses of the essential oils revealed piperitone oxide as the main constituent in both populations. In the light of these results the relationships beweenC. menthifolia and other members of theSatureja group as well as its taxonomy are discussed.     

A Study on the Morphology of Foliar Trichomes of Evergreen Oaks (Quercus) in China and Its Implication in Taxonomy

Most of the evergreen oaks (Quercus L.) are endemic to China and distributed in a large moutainous area of southwestern China at an altitude of 2600-4000m. The delimitation of sections and species in the group has not been satisfactorily solved. The foliar trichomes are very an important character in identifying species of oaks. As a result of observation on 17 species and 2 varieties of evergreen oaks in China under scanning electron microscope, ten types of foliar trichomes are recognized: Simpleuniseriate, Simple-branched, Bulbous, Rosulate, Solitary, Stipitate-fasciculate, Fasciculate, Multiradiate, Stellate and Fused-stellate. The first four types fall into glandular trichomes and the last six non-glandular trichomes. The taxa examined have a combination of various types of the trichomes. All the evergreen oaks have non-glandular trichomes on their foliar epidermis, but glandular trichomes occur solely in certain taxa. These two types of foliar trichomes are obviously different in structure and function, which represent different adular trichomes and the last six non-glandular en oaks are divided into two groups: the glandular group and the non-glandular group according to the types of foliar trichomes and it is reasonable to divide the evergreen oaks into two sections: Sect. Suber (Reichenb.) Spach and Sect. Englerianae (A. Camus) Hsu et Jen. Foliar trichomes of the evergreen oaks show a continuity in density from species predominately with glandular trichomes at a high altitude to species solely with non-glandular trichomes at a low elevation. The characters of branching of foliar trichomes, especially the number of branches, can imply to some extent the evolutionary position of a given evergreen species. Considering the types, density and branches of foliar trichomes combined the evolutionary relationships among the evergreen oaks in China are proposed. Q. gilliana is the startpoint, from where evolution took place in two directions: glandular and non-glandular. In the glandular direction envolved are Q. aquifolioides, Q. longispica and Q. guyavaefolia. Q. pannosa is a species with the most types and highest number of glandular trichomes. In non-glandular line aligned are Q. spinosa, Q. senescens, Q. senescens var. muliensis, Q. monimotricha with the reduction of glandular trichomes and increase of non-glandular trichomes. After Q. tungmaiensis no glandular trichomes appear and it solely depends on non-glandular trichomes to protect itself. Q. granchetii is the climax in the non-glandular line with the highest density and number of branches of foliar trichomes. And then some species, such as Q. engleriana, Q. phillyraeoides, have few or no trichomes. Q. dolicholepis, Q. baronii and Q. baronii var. capitata show the close re-lationships because they share fused-stellate trichomes.     

An investigation of the foliar trichomes of Tetradenia riparia (Hochst.) Codd [Lamiaceae]: An important medicinal plant of Southern Africa

The morphology and distribution of leaf trichomes of Tetradenia riparia were studied using light and scanning microscopy. Three morphologically distinct types of trichomes were observed on T. riparia leaf surfaces: glandular capitate (short and long stalked), peltate and non-glandular. The glandular and non-glandular trichomes were present in abundance on both the adaxial and abaxial surfaces. Young leaves were densely covered with trichomes; however, the density of trichomes decreases progressively with leaf maturity. This suggests that the trichomes are established early in leaf differentiation and their density decreases with leaf development and age.     

The trichomes of pericarp in Juglans (Juglandaceae): scanning microscopy, fluorescent microscopy amd histochemistry

Four types of glandular and non-glandular trichomes of pericarp in four Juglans species (J. ailanthifolia, J. cordiformis, J. mandshurica and J. regia) from Juglandaceae were studied by scanning electron microscopy, fluorescent light microscopy and histochemistry. The capitate trichomes on short stalk, the capitate trichomes on long stalk and the peltate trichomes belong to glandular trichomes; the simple hairs concern to non-glandular trichomes. The investigated species differ one from another in dimensions and distribution oftrichomes as well as the chemical content and the mechanism of secretion. The fluorescent markers and histochemical tests show the presence of flavonoids, tannins and polyphenols in trichomes on short and long stalk. In peltate trichomes the flavonoids and tannins were found in lesser quantity and the polyphenols are absent. In simple hairs the phenolic substances have not been recognized. It has been come out with the suggestion about a functional role of each type of trichomes.     

Light, conventional and environmental scanning electron microscopy of the trichomes of Cucurbita pepo subsp. pepo var. styriaca and histochemistry of glandular secretory products

BACKGROUND AND AIMS: In the present study, the differences between glandular and non-glandular trichomes, the secretory process and the method of secretion were studied. Previous studies on leaves of Styrian oil pumpkin (Cucurbia pepo var. styriaca) plants have shown that four morphologically and ontogenetically independent glandular and non-glandular trichome types and one bristle hair type can be distinguished. The four types of trichomes can be categorized into three glandular trichome types: type I, a short-stalked trichome with four head cells including a 'middle-cell', two stalk cells and one basal cell; type II, a long-stalked trichome with two head cells, a 'neck-cell' region and a long stalk area; type IV, a 'stipitate-capitate' trichome with a mesophyll cell basement, a short stalk and a multicellular head; type III, a non-glandular 'columnar-digit' trichome, which consists of two head cells continuous with three-celled stalk, and the basal cell. METHODS: The histochemical studies (the main classes of metabolite in secreted material of glandular trichomes) were conducted in fresh and fixed hand sections, using the following tests: Sudan black B, Nile blue A, osmium tetroxide, neutral red, Naturstoffreagent A, FSA (fuchsin-safranin-astra blue), NADI (naphthol + dimethylparaphenylenediamine) and ruthenium red. Each suggested differences in the intercalations during the ontogenetical development of each trichome during the development stage. KEY RESULTS: The histochemical reactions revealed the main components of the materials secreted by all types of trichomes, which include lipids, flavones and terpenes and the different cell wall compositions. Glandular secretions were observed during environmental scanning electron microscopy (ESEM) and the trichomes compared with those seen by conventional scanning electron microscopy (CSEM). CONCLUSIONS: Scanning electron microscopy and histochemical analysis demonstrated that each of the trichomes studied produced and released secretory products in a characteristic way.     

The Ultrastructure of the Glandular Trichomes of Solanum tuberosum

The potato plant has two types of glandular trichomes whichwere investigated by electron microscopy. One type has a eight celled globular head on a neck cell anda stalk cell Each glandular cell has many rather large vacuoles,a large nucleus, many ribosomes and mitochondria, a few Golgibodies, and darkly coloured, often irregular plastids (chloroplasts).The plastids are mostly located near the axial cell wall borderinga large central intercellular space filled with secretion materialThe plastids are assumed to participate in the formation ofthe secretion material, which reacts positively to esterasetests. The outer wall is covered by a thin cuticle. The other type has a club-shaped multicellular head on a singlestalk cell. The cytoplasmic features in the cells are similarto those of the globular-headed trichome, except that they possesslarge central vacuoles and randomly distributed plastids. Centricendoplasmic reticulum has been observed in young cells. Intercellularspaces develop between the cells and into the outer wall, whichis thus split into two. Whereas the older glandular cells reactpositively to tests for esterase, the secretion material itselfis pectinaceous and reacts negatively. The outer wall is cutinizedand covered by a cuticle. Solanum tuberosum L., potato, glandular trichomes, ultrastructure     

The taxonomic value of leaf anatomy and trichome morphology of the genus Cyclotrichium (Lamiaceae) in Turkey

The genus Cyclotrichium (Boiss.) Manden. & Scheng. is represented by six species in Turkey: C. glabrescens, C. leucotrichum, C. longiflorum, C. niveum, C. origanifolium and C. stamineum. They are aromatic perennial subshrubs used as spices or herbal teas in traditional Turkish medicine. The leaf anatomy and tomentum morphology of leaves and calyces of Cyclotrichium species in Turkey was investigated by scanning electron microscopy (SEM) and light microscopy (LM). The investigated species have equifacial (C. niveum, C. origanifolium) or bifacial leaves (C. glabressens, C. leucotrichum, C. longiflorum, C. stamineum). All species have peltate and capitate glandular, and simple (all species) or branched (C. niveum) eglandular trichomes and diacytic stomata. Peltate trichomes consist of a basal cell embedded in the epidermis, a stalk cell, and a broad 12 (–13)‐celled secretory head arranged in two concentric circles. The capitate trichomes observed in Cyclotrichium can be grouped into five types, differing in structure and size. They consist of either a pear‐shaped or globose unicellular head and uni‐or bicellular stalk, or a bicellular head and bicellular stalk. The density of peltate, capitate and eglandular trichomes differs between species. Peltate trichomes are densely spaced only on the calyx and on the leaf surface of C. niveum and C. origanifolium and on the abaxial leaf surface of C. longiflorum and C. stamineum. The significance of trichome architecture for taxonomy in Cyclotrichium and Lamiaceae in general is discussed.     

四棱草属比较形态及其分类系统位置的研究──Ⅳ．四棱草属及其近缘属叶表皮结构特征

四棱草属Ｓｃｈｎａｂｅｌｉａ及其近缘属筋骨草属Ａｊｕｇａ,香科科属Ｔｅｕｃｒｉｕｍ（唇形科Ｌａｂｉａｔａｅ）,获属Ｃａｒｙｏｐｔｅｒｉｓ,大青属Ｃｌｅｒｏｄｅｎｄｒｕｍ（马鞭草科Ｖｅｒｂｅｒｎａｃｅａｅ）５属,６种代表植物的叶表皮细胞形状、气孔类型和毛状体类型的比较研究结果是：（１）叶上表皮细胞形状是深波纹状不规则形,浅波纹状不规则形和浅波纹状四边形;（２）气孔类型是不规则型,平列型,横列型和等位横列型。（３）毛状体类型属单毛和鳞片毛二种类型。根据上述特征及其分布规律,作者认为四棱草属在唇形科与马鞭草科系统演化的框架里,是处于中间过渡类型的位置。     

Glandular trichomes of Humulus lupulus var. Brewer's Gold: Ontogeny and histochemical characterization of the secretion

Leaves of Humulus lupulus possess two types of glandular trichomes: - peltate (lupulin) and bulbous.
Peltate trichomes are formed from a protodermal cell by two anticlinal divisions in perpendicular planes, followed by two periclinal ones that give rise to the initials of the head cells, the basal and the stalk cells. Head cells divide successively in radial and irregular planes. Fully developed peltate trichomes are built of a glandular head consisting of 30 to 72 cells, four stalk cells and four basal cells.
Bulbous trichomes are also formed from a protodermal cell by an anticlinal division followed by two periclinal ones that produce the initials of the glandular head cells, and the basal and stalk cells. Fully developed bulbous trichomes consist of four (occasionally eight) head glandular cells, two stalk cells and two basal cells.
The density of peltate trichomes decreases with the expansion of the leaves.
Both peltate and bulbous trichomes secrete essential oils. Peltate trichomes are the preferential site for the synthesis of bitter resins. Tannic acids could not be detected histochemically either in peltate or in bulbous trichomes. Both types of trichomes produce secretion that accumulates in the subcuticular space, being released, in the case of bulbous trichomes, by rupture of the cuticle.     

Glandular Trichomes on Vegetative and Reproductive Organs of Leonotis leonurus (Lamiaceae)

The types of glandular trichomes, their ontogeny and patternof distribution on the vegetative and reproductive organs ofLeonotis leonurus at different stages of development, are studiedby light and scanning electron microscopy. Two morphologicallydistinct types of glandular trichomes (peltate and capitate)are described. Peltate trichomes, at the time of secretion,are characterized by a short stalk, which is connected witha large spherical head composed of eight cells in a single layer.Capitate trichomes can be divided into various types. Generally,they consist of a four-celled head supported by one or threestalk cells. The two kinds of trichomes differ in the secretionprocess. In the peltate trichomes, the secretory product seemsto remain accumulated in a subcuticular space, unless an externalfactor damages it. In the capitate trichomes, this product probablybecomes released through micropores. On the leaves peltate andcapitate trichomes are abundant, while on the flowers only thepeltate trichomes are numerous and the capitate are rare orabsent.Copyright 1995, 1999 Academic Press Leonotis leonurus R. Br., lion's ear, lion's tail, Lamiaceæ, glandular trichomes, morphology, ontogeny     

Glandular trichomes on aerial and underground organs in Chrysolaena species (Vernonieae – Asteraceae): Structure,ultrastructure and chemical composition

Although the occurrence of glandular trichomes is frequently reported for aerial vegetative organs, many questions still remain opened about the presence of such trichomes in underground systems. Here, we present, for the first time, a comparative study concerning the structure, ultrastructure and chemical aspects of both, the aerial and underground glandular trichomes of two different Chrysolaena species, C. obovata and C. platensis. Glandular trichomes (GTs) were examined using LM, SEM, and TEM and also analyzed by GC–MS and HPLC coupled to UV/DAD and HR-ESI-MS (HPLC–UV–MS). In both aerial (leaf and bud) and underground (rhizophore) organs, the GTs are multicellular, biseriate and formed by five pairs of cells: a pair of support cells, a pair of basal cells, and three pairs of secreting cells. These secreting cells have, at the beginning of secretory process, abundance of smooth ER. The same classes of secondary metabolites are biosynthesized and stored in both aerial and underground GTs of C. platensis and C. obovata. These GTs from aerial and underground organs have similar cellular and sub-cellular anatomy, however the belowground trichomes show a higher diversity of compounds when compared to those from the leaves. We also demonstrate by means of HPLC–UV–DAD that the sesquiterpene lactones are located inside the trichomes and that hirsutinolides are not artifacts.     

Characteristic Trichomes and Indumentum Specialization in African and European Parasitic Scrophulariaceae

Trichomes and their distribution patterns have been observed in the aerial parts of plants of the genera Striga, Buchnera, Rhamphicarpa, Euphrasia, Melampyrum and Rhinanthus, using both light (LM) and scanning electron microscopy (SEM). All trichomes belong to the multicellular, uniseriate category and can be classified as glandular and nonglandular types. On nearly all organs, the two types can be observed side by side. Apart from a large group of ubiquitous trichomes, some characteristic trichome types are reported; they are restricted either to chlorophyllous organs (foliage leaves, bracts, calyx and stem) or to the corolla. In some nonglandular trichomes mineral deposits have been found. Other morphological and anatomical trichome features are discussed with regard to their possible function.     

Promoters of AaGL2 and AaMIXTA-Like1 genes of Artemisia annua direct reporter gene expression in glandular and non-glandular trichomes

Herein, we report cloning and analysis of promoters of GLABRA2 (AaGL2) homolog and a MIXTA-Like (AaMIXTA-Like1) gene from Artemisia annua. The upstream regulatory regions of AaGL2 and AaMIXTA-Like1 showed the presence of several crucial cis-acting elements. Arabidopsis and A. annua seedlings were transiently transfected with the promoter-GUS constructs using a robust agro-infiltration method. Both AaGL2 and AaMIXTA-Like1 promoters showed GUS expression preferentially in Arabidopsis single-celled trichomes and glandular as well as T-shaped trichomes of A. annua. Transgenic Arabidopsis harboring constructs in which AaGL2 or AaMIXTA-Like1 promoters would control GFP expression, showed fluorescence emanating specifically from trichome cells. Our study provides a fast and efficient method to study trichome-specific expression, and 2 promoters that have potential for targeted metabolic engineering in plants.