Mucilage Cells Research Articles

Comparative floral structure and systematics in the sarracenioid clade (Actinidiaceae, Roridulaceae and Sarraceniaceae) of Ericales

In molecular phylogenetic studies, Actinidiaceae, Roridulaceae and Sarraceniaceae form a strongly supported clade, which is sister to the ericoid clade (Clethraceae, Cyrillaceae and Ericaceae). In pre-molecular classifications, the sarracenioid families were often not affiliated with other ericalean taxa or considered to be closely related with each other, as they differ conspicuously in their habit, mode of nutrient uptake and/or superficial floral structure. In order to interpret the findings of molecular phylogenetic analyses from a morphological point of view, a detailed comparative study of floral morphology, anatomy and histology of these three families is presented. In addition, earlier literature is reviewed. The three families share a series of general and, at the level of Ericales, most likely plesiomorphic floral features, including pentamery, actinomorphy and hypogyny. Other, more specialized features, such as polystemony, choripetaly and integument number, turn out to be homoplasious in the sarracenioid clade. A floral feature shared by the three families is late anther inversion, which, in Ericales, is restricted to the sarracenioids and ericoids. Potential synapomorphies for the sarracenioids include vesicles that appear to contain condensed tannins in floral tissue, proximally thick petals, ovules with a nucellar hypostase and the presence of iridoid compounds. For the subclade of Actinidiaceae and Roridulaceae, potential synapomorphies include the presence of raphides and mucilage cells in floral tissue, a secretory inner surface in the gynoecium and the absence of synlateral vasculature in the ovary. Floral features in the clade are discussed and compared with the other families of Ericales. Further structural studies in other clades of Ericales and a well-resolved molecular phylogeny of the order are needed to test the systematic value of these features further. Some features may turn out to be true synapomorphies, whereas others may turn out to be widespread in Ericales and therefore plesiomorphic for the order.

Leaf anatomical features of three Theobroma species (Malvaceae s.l.) native to the Brazilian Amazon

Theobroma species have economic importance due to their use in the cosmetic and food industries, mainly in the production of chocolate. However, the anatomy of their vegetative structures remains poorly studied. The goal of this study was to describe the anatomical features of Theobroma grandiflorum, T. speciosum and T. subincanum to contribute to the biological knowledge of these species, as well as provide support to the biotechnological studies of native fruit plants of the Amazon. Leaves at different developmental stages were collected and analyzed under light microscopy and scanning electron microscopy. Sessile and stalked stellate trichomes and digitiform glandular trichomes were observed in the expanded leaves of T. grandiflorum and T. subincanum. These species were also similar in the morphology of the midrib, the organization of the mesophyll and the presence of starch grains in the midrib pith cells. Claviform glandular trichomes and mucilage cells in the epidermis occurred only in the expanded leaves of T. speciosum. The presence of mucilage secretory trichomes in shoot apices (colleters) of all species is a new finding for the genus Theobroma.

Idioblastic mucilage cells in Teucrium polium leaf. Anatomy and histochemistry

In the mesophyll of Teucrium polium L. leaves, isolated or grouped idioblastic secretory cells occur in contact with the distal (adaxial) vessel elements of the vascular bundles. They appear to originate from one or more bundle sheath cells and their intracellular space is entirely occupied by the secretory material. The latter has a glycoproteinaceous constitution (mucilage), as histochemical tests showed. Idioblastic cells, therefore, correspond to typical mucilage cells. Mucilage seems to play a crucial role in the adaptation of the plant to unfavourable environmental conditions.

Effect of zinc on nectar secretion of Hibiscus rosa-sinensis L

Zinc toxicity in secretory cells caused a range of effects, mainly depending on metal concentration. Low concentrations activated nectary function increasing nectar secretion but secretion was greatly inhibited or stopped entirely by ongoing concentration. Water loss rate of zinc treated flower parts was significantly reduced whereas green sepals were dehydrated more rapidly in comparison to colored petals. The content of zinc, calcium, magnesium and manganese increased mainly in sepals under excess of zinc, but in the secreted nectar this metal was not evident. Morphological changes were observed in mucilage cells concerning the mucilage structure and appearance. The parenchymatic, subglandular cells displayed an early vacuolarization and cytoplasm condensation. Secretory hairs appeared to be thinner, the apical cell folded inwards and plasmolytic shrinkage became severe in all cells. The waxy cuticula showed an increased electron density. A plasmalemma detachment from the external cell walls was observed creating a gap between cell wall and plasmalemma. ER cisterns of all treated nectary hairs dominated the cytoplasm and electron dense deposits were seen within its profiles. A great number of other organelles were also present, showing electron dense deposits in their membranes as well. The vacuome was drastically reduced in all cells, except in the subglandular ones and electron dense membrane remnants were observed.

Stem fasciation in cacti and succulent species — tissue anatomy, protein pattern and RAPD polymorphisms

Fasciated and normal stem segments of Opuntia microdasys, Opuntia cylindrica, Huernia primulina and Euphorbia lactea were collected from the same plant and compared for their anatomy, water relations and genetic variations. Anatomical differences in terms of thickness of cuticle, vascular bundle, xylem and phloem were analyzed in both normal and fasciated stems. The mucilage cells were higher in the fasciated form of Opuntia microdasys than that in the normal form. Water status in terms of total water content (TWC), water deficit and relative water content (RWC) was influenced by fasciation. Genetic variations were tested in normal and fasciated stems using randomly amplified polymorphic DNA (RAPD) fingerprints and SDS-PAGE of soluble protein extracts. SDS-PAGE protein and RAPD analysis confirmed that normal and fasciated tissues were genetically different. Polymerase chain reaction (PCR) yielded different polymorphic banding patterns that were unique to each primer and distinguishable over all samples. The PCR results of normal and fasciated samples were significantly different in cases of primers P1, P2 and P3. These results indicate that occurrence of fasciation in Opuntia microdasys, Opuntia cylindrica, Huernia primulina and Euphorbia lactea is an epigenetic mutation of tissues.

Anatomical structure and histochemical localization about rhizomes of five species of Polygonatum

The microscopic structure and histochemical localization of the Polygonatum sibiricum, P. cytonema, P. filipes, P. zanlanscianense and P. odoratum was studied. Scanning electron microscope (SEM) and digital biological microscope (DBM) were applied in the research. Venation bundle showed in three types included collateral, amphivasal and incomplete amphivasal bundles. Morphological differences of venation bundles could be seen under the fluorescence microscope. Calcium oxalate existed in the mucilage cells looked similar to columnar crystals under SEM. In rhizome of Polygonatum, polysaccharides presented in mucilage cells, saponins and volatile oil were found in ground tissue. Microstructure difference of rhizomes would be used for identification of the Polygonatum plants. Polysaccharides and saponins are distributed in different cells of Polygonatum plants.

A SURVEY OF OIL CELLS IN THE DICOTYLEDONS WITH COMMENTS ON THEIR REPLACEMENT BY AND JOINT OCCURRENCE WITH MUCILAGE CELLS

ABSTRACT Anatomy, ultrastructure and development of mucilage and oil cells in the dicotyledons are reviewed, and a bibliography of the records for oil cells is given. In several families normally characterized by oil cells some of the species also have mucilage cells, or the oil cells seem to be “replaced” by mucilage cells. In other taxa intermediates between oil and mucilage cells have been reported in the literature. This poses the question of a possible homology of oil and mucilage cells, despite their very different attributes in the fully mature state. The taxonomic and phylogenetic significance of oil and mucilage cells is briefly discussed. The need for a comparative developmental, ultrastructural and biochemical study of critical taxa is stressed.

A SURVEY OF MUCILAGE CELLS IN VEGETATIVE ORGANS OF THE DICOTYLEDONS

ABSTRACT The distribution of mucilage cells in vegetative parts of the dicotyledons is reviewed on the basis of an extensive literature study. Mucilage or slime cells occur in 144 families, belonging to 47 orders as defined in Takhtajan's system of classification. Their systematic and diagnostic value at different levels of the taxonomic hierarchy is discussed. Although mucilage cells are generally diagnostic at the species level, variation within genera and families seriously limits the systematic significance in mostphylads. The core families of the Malvales, which are all mucilaginous, constitute an exception at the ordinal level, while in a number of genera, families, and orders the distribution of mucilage cells tends to be associated with natural groups. In most families and orders of the subclass Asteridae, mucilage cells are absent from the vegetative organs. Development, ultrastructure, histochemistry, and distribution of mucilage cells are briefly reviewed. In almost all well documented cases, m...

Leaf architecture and anatomy of eleven species of Mortoniodendron (Malvaceae s.l.)

The genus Mortoniodendron is distributed from southeastern Mexico to Colombia and contains about 18 species of trees and shrubs. The main goal of this study is to describe and compare the leaf architecture and the anatomy of 11 species of Mortoniodendron using cleared leaves and paradermal and transverse leaf sections. All of the species of Mortoniodendron share a simple lamina with an entire margin. The differences among the species include the venation pattern, the relative thickness and course of the secondary veins, the presence or absence of the intersecondary veins, the tertiary vein pattern, the number of branches in veinlets, and the marginal ultimate venation. The leaf anatomy is similar to other species of the Malvaceae s.l.: for example, mucilage cells are common in Mortoniodendron. There are unique attributes of the leaf architecture and anatomy, such as the eucamptodromous venation pattern of M. guatemalense, which facilitates the identification of the species. The species M. palaciosii, M. pentagonum, M. ruizii, M. uxpanapense, and M. sp. nov. share features that suggest that they are closely related.

Stem and root anatomy of two species of Echinopsis (Trichocereeae, Cactaceae)

This study characterizes and compares the stem and root anatomy of Echinopsis calochlora and E. rhodotricha (Cactaceae) occurring in the Central-Western Region of Brazil, in Mato Grosso do Sul State. Three individuals of each species were collected, fixed, stored and prepared following usual anatomy techniques, for subsequent observation in light and scanning electronic microscopy. Echinopsis calochlora revealed uniseriated epidermis, while E. rhodotricha had patches of bisseriated epidermis; all species showed thick cuticle, parallelocytic stomata at the epidermis level, and a well-developed hypodermis. Cortical and medullary bundles are present in the studied species, as well as mucilage cells in the cortex region. The secondary phloem is composed by sieve tube elements, companion cells, axial and radial parenchyma. Sclereids were found at the outer regions of phloem in the roots. The secondary xylem is non fibrous in the stems of E. calochlora, and fibrous in the stems of E. rhodotricha and in the roots of both species. Many of these characteristics are commonly found in Cactaceae, and represent important adaptations for survival in xeric environments.

Mucilage formation in selected taxa of the genusArtemisiaL. (Asteraceae, Anthemideae)

AbstractThe myxocarpic diaspores ofArtemisiataxa are characterized by the presence of mucilage cells in the achene coat, which differ between taxa and subgenera in shape and arrangement, and the ability to form a mucilage envelope after hydration. A detailed analysis of 38 taxa revealed three main achene behaviours related to achene coat structure and the modes of water retention after hydration. The most common achene coat possessed mucilage cells which formed a mucilage envelope after hydration; normally developed mucilage cells were able to produce mucilage after wetting. In taxa where the mucilage cells were not present in the achene coat, water was gathered under a loosely adhered achene coat or in the spaces between the covering trichomes. Myxocarpic diaspores were mostly observed in taxa occurring in dry habitats, whereas taxa devoid of the ability to produce mucilage grew predominately in mesotropic habitats. The ability to form a mucilage envelope was also related to the ploidy level. The shape and arrangement of the mucilage cells in the achene coat may differ between taxa and subgenera. InTridentatae, the mucilage cells were dispersed in groups, forming a characteristic pattern. The role of myxocarpy in the dispersal and distribution of theArtemisiataxa is discussed.

Comparative anatomy of selected rhizomatous and tuberous taxa of subfamilies Orchidoideae and Epidendroideae (Orchidaceae) as an aid to identification

This article addresses the vegetative anatomy (leaves, stems, roots, root tubers and rhizomes) of 13 species of subfamily Orchidoideae (Orchidaceae), belonging to the genera Neottia Guettard, Cephalanthera L.C.M. Richard, Epipactis Zinn, Limodorum Boehmer, Spiranthes L.C.M. Richard, Platanthera L.C.M. Richard, Serapias L., Himantoglossum W.D. Koch and Anacamptis L.C.M. Richard, because anatomical studies have provided very useful criteria for orchid diagnosis. In the study three types of painting methods—Delafield’s hematoxylin and safranin, Alcian blue-periodic acid schiff, and alcoholic phloroglucinol + HCl—were employed, and identification tables were prepared. Anatomical results demonstrated the differences in the leaf anatomy of tuberous and rhizomatous orchids. In the stem anatomy, all the rhizomatous genera were found to be anatomically different, especially in regard to the collateral vascular bundles, the distribution of vascular bundles and xylem properties. In root anatomy, the central cylinder, pith, endodermis and/or pericycle properties are distinctive features in all studied taxa. For root tubers, velamen layering, wall outline mucilage cell patterns in ground tissue and arrangements of vascular arches can be used to label taxa. Regarding the rhizome anatomy of the studied taxa, vascular cylinder results in particular were very significant for the distinction of genera. Finally, we strongly emphasize the importance of this kind of detailed anatomical study to solve identification problems of orchid taxonomy.

Anatomical and micromorphological studies on Teucrium sect. Isotriodon (Lamiaceae) in Turkey with a taxonomic note

In this study, the anatomical features of the leaf and stem, besides the nutlet characteristics of some Teucrium sect. Isotriodon (Lamiaceae) taxa in Turkey, T. montbretii Betham subsp. montbretii, T. montbretii subsp. pamphylicum P. H. Davis, T. odontites Boiss. & Bal., T. cavernarum P. H. Davis, T. antitauricum T. Ekim, along with an isolated population of T. montbretii (T. montbretii subsp.) were investigated. The anatomical studies revealed that the taxa share generally similar anatomical characters, such as thicker upper leaf cuticles and larger upper leaf epidermal cells compared to lower ones and diacytic to anomocytic stomata on the leaves. However, the portion of the mesophyll occupied by palisade parenchyma and the occurrence of mucilage cells in leaf epidermis shows difference among the taxa. Furthermore, the studied taxa have general stem characteristics of the Lamiaceae family, except for having poorly developed collenchyma at the corners. With the amphistomatic leaves and developed sclerenchymatic tissue in the leaf median vein, T. cavernarum is seperated from the other taxa. Trichome types on the vegetative organs and nutlet shape and sculpturing are generally the same or similar in the studied taxa, but trichomes on the nutlets are different among them. Based on nutlet characteristics and some morphological ones, it was revealed that the isolated population of T. montbretii represent a new subspecies, T. monbretii subsp. yildirimlii M.DinA§ & S.DoAŸu subsp. nov.

Taxonomy of Wiborgiella (Crotalarieae, Fabaceae), a Genus Endemic to the Greater Cape Region of South Africa

Abstract A taxonomic revision of the recently described genus Wiborgiella is presented. Nine species are recognized within the genus, two of which are newly described, W. dahlgrenii and W. vlokii . The genus is endemic to the Cape region of South Africa and most species are highly localized and rare. Wiborgiella species can be distinguished from other genera in the tribe Crotalarieae by a combination of brown young branches (early formation of bark in the stems of the perennial species), laminar trifoliolate leaves, glabrous petals, a 4 + 6 anther arrangement, and oblong, wingless, inflated fruit. Anatomical studies revealed that all species of the genus have dorsiventral leaves (mesophyll differentiated into palisade parenchyma adaxially and spongy parenchyma abaxially) with mucilage cells in the epidermis which distinguishes Wiborgiella from other closely related genera, such as Calobota which has isobilateral leaves without mucilage cells. The fruits of Wiborgiella species are all thin-walled, have hig...

Diversity and evolution of floral structure among early diverging lineages in the Ericales.

This is a combination of review and original data on floral structure and diversity in the two earliest diverging lineages of the Ericales, i.e. the balsaminoids, comprising Balsaminaceae, Marcgraviaceae and Tetrameristaceae, and the polemonioids, comprising Fouquieriaceae and Polemoniaceae. Each clade is strongly supported in molecular studies, while structural synapomorphies have largely been lacking. For the balsaminoid families, we compare floral morphology, anatomy and histology among selected taxa and find that the entire clade is strongly supported by the shared presence of nectariferous tissue in the floral periphery, thread-like structures on anthers, truncate stigmas, secretion in the ovary, as well as mucilage cells, raphides and tannins in floral tissues. A possible sister group relationship between Balsaminaceae and Tetrameristaceae is supported by the shared presence of post-genital fusion of filaments and ovary and a star-shaped stylar canal. For polemonioids, we document unexpected diversity of floral features in Polemoniaceae, partly providing structural links to Fouquieriaceae. Features include cochlear and quincuncial corolla aestivation, connective protrusions, ventrifixed anthers and nectariferous tissue in the base of the ovary. In addition, we outline future directions for research on floral structure in the Ericales and briefly discuss the general importance of structural studies for our understanding of plant phylogeny and evolution.

Pharmacognostical and physicochemical evaluation of Agasti leaf

Sesbania grandiflora (L.) Pers., commonly known as Agasti, is widely used in Ayurveda for the treatment of diseases and for processing of various formulations in Rasashastra. It is used for its astringent, antihistaminic, anxiolytic, anticonvulsive and febrifugal activities. Moreover, because of its edible nature, the leaves and pods are used as flavoring items in the cuisine of South India. A detailed investigation of fresh and powder of leaves of Agasti was carried out. The diagnostic characters of this plant include stomatal characters, presence of resins, oil globules, appressed epidermal hair and mucilage cells. Physicochemical studies revealed loss on drying (0.6%), total ash (10.75%), acid insoluble ash (0.045%), alcohol-soluble extractive (21.7%), and water-soluble extractive (30.72%). Preliminary analysis for the presence of various functional groups revealed the presence of alkaloids, saponins, phenols and proteins. Thin layer chromatographic study of the alcoholic extract showed the presence of five, six and seven spots in short UV, long UV and after spraying developing reagent, respectively. The information generated by this particular study will provide relevant pharmacognostical and physicochemical data needed for proper identification and authentication of leaves of this particular species.

Vegetative anatomy of some Ophrys, Orchis and Dactylorhiza (Orchidaceae) taxa in Trakya region of Turkey

The anatomical properties of leaves, stems, roots and root tubers of 27 taxa belonging to three orchid genera ( Ophrys, Orchis and Dactylorhiza) were investigated to determine their diagnostic characteristics and assess interspecific and intergeneric relationships by means of cladistic analyses. Anatomical sections were done using different staining methods, such as Sartur, Phloroglucin–HCl, Delafield's Hematoxylin–Safranin, and Alcian Blue–Periodic Acid–Schiff. Additionally, lengths of raphides (in all the organs), cuticle thickness, cell size and stomata dimensions (in the leaf epidermes), as well as dimensions of starch granules (only in root tubers) were measured and statistically compared. During root tuber investigations, for every taxon the types of meristele were outlined and diagrammed. All morphometric data except starch grain dimensions, are generally not significantly different between the investigated taxa. The anatomical sections showed the following basic anatomical characteristics: Leaf surface was glabrous, stomata were abaxially located and mostly anomocytic. Cuticle was mostly striate. The chlorenchyma was homogeneous. The stem had a uniseriate epidermis with several rows of thick- or thin-walled, sclerenchymatous (or collenchymatous) cortical parenchyms, a pericycle, collateral vascular bundles within a central ground tissue. Orchis purpurea lacks a pericycle. The roots generally had a uniseriate epidermis, an exodermis, a parenchymatous cortex with occasional inclusions of fungal pelotons and hyphae, an endodermis bearing casparian strips, pericycle, and vascular cylinders. Root tubers, from the outside to the centre, had orderly velamen, exodermis, and ground tissue, which were scattered with meristeles, mucilage cells and assimilatory cells bearing cruciate starch grains. Based on the anatomical results, tables were created based on the important primary (species-specific) and secondary (common-specific, used only in some taxa) descriptive characteristics. Some of the primary descriptive characters include the following: Leaf-epidermal wall properties (thin/thick), chlorenchyma cell shape, chloroplast distribution, presence or absence of large lacunae; stem-presence/absence of pericycle, cortical thickness; root-cell shape of exodermis, presence/absence of tilosome passage cells, shapes of endodermal and/or pericycle cells, structures and distributions of archs; root tuber forms of starch grains and mucilage cells and meristele types. In general, leaf chlorenchyma and stem pericycle were found to be thicker and mucilage-water storage cells were more frequent in the Orchis and Dactylorhiza taxa. Cladistically analysed anatomical data support the hypothesis that Ophrys and Dactylorhiza are monophyletic, but contrast the triphyletic states of Orchis, which is very likely to be the reason for uncovering the other Orchis taxa. Finally, we strongly emphasize the importance of this kind of detailed anatomical study to solve identification problems of orchid taxonomy, which have wrongly been disregarded in recent works.

A seed coat-specific promoter for canola

The canola industry generates more than $11 billion of yearly income to the Canadian economy. One problem of meal quality is the dark polyphenolic pigments that accumulate in the seed coat. Seed coat-specific promoters are a pre-requisite to regulate the genes involved in seed coat development and metabolism. The beta-glucuronidase (GUS) reporter gene was used to test an Arabidopsis promoter in developing and mature seeds of canola (Brassica napus). The promoter tested is the regulatory region of the laccase gene (AtLAC15) from Arabidopsis thaliana. The AtLAC15 promoter::GUS construct was inserted into canola double haploid line DH12075 using Agrobacterium-mediated transformation. Southern blot analysis using a 536 bp GUS probe showed variation among the transformed plants in the T-DNA copy numbers and the position of the insertion in their genomes. Histochemical assay of the GUS enzyme in different tissues (roots, leaves, stem, pollen grains, flowers, siliques, embryos and seed coats) showed ascending GUS activity only in the seed coat from 10 days after pollination (DAP) to the fully mature stage (35 DAP). GUS stain was observed in the mucilage cell layer, in the outer integument layer of the seed coat but not in the inner integument. The AtLAC15 promoter exhibited a specificity and expression level that is useful as a seed coat-specific promoter for canola.

Anatomical variation in Cactaceae and relatives: Trait lability and evolutionary innovation

The cacti have undergone extensive specialization in their evolutionary history, providing an excellent system in which to address large-scale questions of morphological and physiological adaptation. Recent molecular phylogenetic studies suggest that (1) Pereskia, the leafy genus long interpreted as the sister group of all other cacti, is likely paraphyletic, and (2) Cactaceae are nested within a paraphyletic Portulacaceae as a member of the "ACPT" clade (Anacampseroteae, Cactaceae, Portulaca, and Talinum). We collected new data on the vegetative anatomy of the ACPT clade and relatives to evaluate whether patterns in the distributions of traits may provide insight into early events in the evolutionary transition to the cactus life form. Many traits had high levels of homoplasy and were mostly equivocal with regard to infraclade relationships of ACPT, although several characters do lend further support to a paraphyletic Pereskia. These include a thick stem cuticle, prominent stem mucilage cells, and hypodermal calcium oxalate druses, all of which are likely to be important traits for stem water storage and photosynthesis. We hypothesize that high lability of many putative "precursor" traits may have been critical in generating the organismal context necessary for the evolution of an efficient and integrated photosynthetic stem.

Comparative floral structure and systematics in Chrysobalanaceae s.l. (Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, Trigoniaceae; Malpighiales)

Chrysobalanaceae s.l., one of the few suprafamilial subclades of Malpighiales that is supported by molecular phylogenetic analyses, and containing Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, and Trigoniaceae, was comparatively studied with regard to floral structure. The subclade is well supported by floral structure. Potential synapomorphies for Chrysobalanaceae s.l. are the following shared features: floral cup; flowers obliquely monosymmetric; sepals congenitally united at base; sepals of unequal size (outer two shorter); fertile stamens concentrated on the anterior side of the flower and sometimes united into a strap; staminodes absent in the posteriormost antepetalous position; anthers extremely introrse, with thecae almost in one plane; endothecium continuous over the dorsal side of the connective; dorsal anther pit; gynoecium completely syncarpous up to the stigma; carpel flanks slightly bulged out transversely and thus carpels demarcated from each other by a longitudinal furrow; flowers with dense unicellular, non-lignified hairs, especially on the gynoecium; light-coloured, dense indumentum on young shoots and inflorescences. Potential synapomorphies for Chrysobalanaceae + Euphroniaceae include: spur in floral cup; clawed petals; lignified hairs on petals; nectary without lobes or scales and mostly annular. Potential synapomorphies for Dichapetalaceae + Trigoniaceae include: special mucilage cells in sepals in mesophyll (in addition to epidermis); anthers almost basifixed; gynoecium synascidiate up to lower style; nectary with lobes or scales and semi-annular.