The Structure and Cytochemistry of the Pistil of Sternbergia lutea (Amaryllidaceae)

Studies were carried out on structural and cytochemical aspectsof the pistil of Sternbergia lutea (L.) KerGawl. The stigmais of the wet papillate type; the papillae are unicellular andare arranged densely around the rim of a funnel-shaped stigma.The stigma exudate is limited and is confined to the bases ofthe papillae and the inner lining of the stigma. The papillaeare smooth in the distal part and are covered with intact cuticle-pelliclelining. The cuticle is disrupted at places towards the baseof the papillae releasing the exudate. The exudate is rich inpectins and other polysaccharides but poor in proteins and lipids.The papillae show dense cytoplasmic profiles with extensiveendoplasmic reticulum (ER), abundant mitochondria, polyribosomesand active dictyosomes. The style is hollow. The stylar cavityis surrounded by two to four layers of glandular cells. In theyoung pistil the canal is lined with a continuous cuticle, butin the mature pistil the cuticle becomes disrupted and the canalis filled with the secretion produced by the cells of the surroundingglandular tissue. Ultrastructurally, the cells of the glandulartissue are very similar to the stigmatic papillae. The innertangential wall of the cells bordering the canal is uniformlythicker than other walls. The secretion in the stylar canal,as well as the intercellular spaces of the glandular tissue,stain intensely for pectins and polysaccharides but poorly forproteins and lipids. Pollen tubes grow through the stylar canal.Structural and cytochemical details of the pistil of Sternbergiaare compared with other hollow-styled systems. Pistil, Sternbergia lutea (L.) Ker-Gawl., stigma and style, structure and cytochemistry     

Development and Histochemistry of the Pistil of the Grape, Vitis vinifera

The development of the grape pistil is followed for a periodof 9 weeks from flower initiation to anthesis. Three phasesof pericarp differentiation are revealed: ring meristem formation;cell proliferation by anticlinal cell divisions; and a maturationphase characterized by periclinal cell division and differentiation.Both the stigma papillae and the transmitting tissue of thestyle originate by periclinal cell divisions. The receptivestigma is of the wet type and comprises many filamentous papillae,each composed of about 20 cells and covered by a loose cuticle.The stigma exudate shows similar cytochemical properties tothe material in the intercellular spaces of the transmittingtissue and is physically continuous with it. After pollinationand coincident with withering of the stigma, a single layerof stylar cells becomes suberized, forming a protective layerof cicatrix. Vitis vinifera, grape, pistil, development, histochemistry     

Pollen-pistil Interaction in a Non-pseudogamous Apomict,Commiphora wightii

Structural and cytochemical details of the pistil and the interactionof pollen and pistil were studied in a non-pseudogamous apomict,Commiphorawightii.The anthers in the male and bisexual flowers producefunctional pollen grains. The stigma is of the wet and papillatetype. The style is typically solid with two strands of transmittingtissue that traverse the entire length of the style. There isa marked reduction in the area occupied by the transmittingtissue from the stigma to the base of the style. The cells ofthe transmitting tissue are isodiametric in transverse as wellas longitudinal section and do not form longitudinal files ofelongated cells as reported for other taxa. Proteins could notbe localized in the intercellular matrix. Although pollen grainsgerminate on the stigma, pollen tubes do not grow beyond theproximal one third of the style. Changed orientation of thecells of the transmitting tissue and absence of proteins inthe intercellular matrix could account for the failure of thepistil to support pollen growth.Copyright 1998 Annals of BotanyCompany Guggul, pollen-pistil interaction, non-pseudogamous apomict,Commiphora wightii, transmitting tissue     

The transmitting tract in Trimezia fosteriana (Iridaceae). III. Pollen tube growth in the stigma, style and ovary

Trimezia fosteriana is a self-incompatible plant with an open style. The stigma was found to be receptive for approx. three hours. Pollen tube growth in the entire transmitting tract was followed with LM, SEM and TEM. The cuticle that covers the mature papillae is continuous but in the rest of the transmitting tissue it is thin and ruptured. The pollen tubes grow in a mucilage mixed with cuticle remnants. In the style, however, larger parts of a cuticle film remains which gives the impression that pollen tube growth occurs under a cuticle. The secretion contains proteins and carbohydrates including pectic substances. The pollen tube growth rates were estimated to 2 mm/hour in the stigma, 1–2 mm/hour in the style and 0.5 mm/hour in the ovary.     

The transmitting tract in Trimezia fosteriana (Iridaceae). 1. Ultrastructure in the stigma, style and ovary

An ultrastructural investigation of the entire transmitting tract in Trimezia fosteriana (Iridaceae) was undertaken. The transmitting tissue is secretory but transfer cells do not occur at any level. With exception for the stigma papillae, the cells are covered with large amounts of secretory products. The papillae have a thick and ridged cuticle. The cuticle in the rest of the transmitting tract is thin and detached from the cell wall by the secretory products. It is more or less ruptured in the secretory parts of the stigma and ovary. In the stylar canal the major part of the cuticle is continuous and covers the secretory products. The occurence of a large amount of vesicles in the stigma transmitting tissue cells is interpreted as a result of high dictyosome activity. An electron opaque material is produced in the dictyosomes and appears in vesicles and vacuoles but also between the plasma membrane and the cell walls in the stigma. A small amount of such material is present in the cell walls. Corresponding material is also present in the style and the ovary but declines basipetally. Plastids with strongly electron opaque plastoglobules are present at all levels in the transmitting tract.     

Structural and Cytochemical Characteristics of the Stigma and Style in Vitis vinifera L. var. Sangiovese (Vitaceae)

Studies were carried out on structural and cytochemical aspectsof the stigma and style ofVitis vinifera . The stigma is ofthe wet papillate type with a continuous cuticle and pellicle.During the development of the papillae, the cell walls increasein thickness and produce a secretion product constituted oflipids that pass through the wall forming the exudate. The styleis solid with a central core of transmitting tissue which hasconspicuous intercellular spaces that increase remarkably fromthe periphery to the centre where the cuticle is present. Theintercellular spaces, where the pollen tubes grow, contain amatrix that includes polysaccharides, pectic substances andscattered areas of lipidic nature. Cytochemistry; stigma; style; ultrastructure; Vitis vinifera     

Organization of the Stigma and Transmitting Tissue of Rice,Oryza sativa (L.)1

Abstract: The stigma of Oryza sativa (L.) is typically dry and plumose. The pistil is bifurcated just above the ovary. The distal parts of the two main branches are densely covered by multicellular, multiseriate papillae. The papillae are covered by a cuticle‐pellicle layer. The pecto‐cellulosic wall of the papillae is distinctly three‐layered. The transmitting tracts of the two main axes are not clearly demarcated, and are made up of several compactly arranged cell layers around the vascular bundle. The cells of the transmitting tissue are polygonal, narrow and elongated. They show plasmodesmata on the transverse, as well as longitudinal walls. The extracellular matrix in the transmitting tissue, containing polysaccharides and pectic substances, is restricted to the corners of the cells, forming long, narrow, linear canals along the axes.     

The structure and cytochemistry of the pistil of Hypericum calycinum: the style

Summary A typical style of Hypericum calycinum is solid with a core of transmitting tissue traversing the whole length of the style. This transmitting tissue consists of loosely arranged cells and large intercellular spaces filled with a secretion product. The secretion product is rich in lipids, but poor in proteins and polysaccharides. The intercellular spaces of the transmitting tissue originate partly by a separation of cells as a result of the decomposition of the middle lamella and partly by degeneration of some of the cells of the transmitting tissue. H. calycinum is self-compatible. Both self- and cross-pollinations result in profuse pollen germination on the stigma and pollen tube growth through the style. The data on Hypericum is discussed in relation to information available on other solidstyled systems.     

Heterostyly inPrimula. 1. Fine-structural and cytochemical features of the stigma and style inPrimula vulgaris huds

Summary The stigmas of the heterostylous genusPrimula are of the dry type without a free-flowing surface secretion. The papillae of the stigma surface cells of the two morphs, in pin (stigma exserted) and thrum (stamens exserted), bear a thin proteinaceous surface pellicle, overlying a discontinuous cuticle. The vacuoles of the papillate cells contain tannins, and tannin cells extend in files through the stigma heads and form a loose sheath surrounding the pollen-tube transmitting tract in the styles. The cells of the transmitting tissue in the stigma heads have a normal complement of organelles, and abundant ribosomal endoplasmic reticulum. The intercellular spaces contain an internal secretion which reacts cytochemically for both carbohydrate and protein. The transmitting tract in the styles forms a central core surrounded by several vascular strands. The cells are elongated, and the intercellular spaces here also have a carbohydrate-protein content. In a compatible pollination, thrum pollen tubes enter the stigma by penetrating the cuticle at the tip or on the flank of the pin papilla. Pin tubes on the thrum stigma enter between adjacent papillae, penetrating the thin cuticle at the base. The tubes grow through the transmitting tracts in the intercellular material.     

The Proteaceous Pistil: Morphological and Anatomical Aspects of the Pollen Presenter and Style of Eight Species Across Five Genera

The morphology and anatomy of pollen presenters, styles andpollen of species ofBanksia, Dryandra, Hakea, IsopogonandMacadamiawerestudied. Serial sections of pistils and SEM images of pollenwere quantified to determine whether the low fertility observedin the Proteaceae has a structural basis. Pollen access to thestigma was investigated. There were three types of stigmaticcavity. A groove in which the stigmatic papillae were enclosedwas present inDryandra, BanksiaandHakea. Macadamiahad a groovewith protruding papillae, andIsopogonhad a tube which enclosedthe papillae. Anatomical studies showed the pollen presenterto be structurally complex but overall to have similar internalanatomy across the species studied. The species could be groupedaccording to presence or absence of transfer tissue and presenceor absence of sclerenchyma, but these groups were not mutuallyexclusive. In the pistil there were three structural filtersto pollen tube passage. The first was at the stigma, where pollengrain access could be limited by the diameter or length of thestigmatic groove or the capacity of the pollination chamberin relation to pollen volume. The second and third related toa narrowing of the transmitting tissue tract within the pollenpresenter and in the lower style which could influence pollentube passage to the ovule.Copyright 1999 Annals of Botany Company Proteaceae,Banksia coccinea, Banksia ericifolia, Dryandra formosa, Dryandra nana, Dryandra quercifolia, Hakea bucculenta, Isopogon cuneatus, Macadamia integrifolia,stigmatic cavity, fertility, pollen presenter, structural limitation, stigma, pollen grain, image analysis, transfer tissue.     

Structural and Cytochemical Analysis of the Stigma and Style in Tibouchina semidecandra Cogn. (Melastomataceae)

Structural and cytochemical aspects of the pistil of Tibouchinasemidecandra Cogn. were studied. The stigma is of the wet-papillatetype and is structurally divisible into a papillar zone anda stigmatic zone. The papillar zone consists of loosely arrangedpapillae which are matchstick-shaped, unicellular, and producelipid droplets that remain entrapped below the thick cuticle.The bulk of cell volume is made up of large vacuoles rich intannin. The stigmatic zone consists of layers of secretory cellswith dense cytoplasm, actively secreting dictyosomes and numerousrough endoplasmic reticulum (RER) profiles. Free-flowing lipidexudate, produced by these cells, is initially stored in theintercellular spaces, and subsequently extruded out to coverthe surface. The style is solid with a core of transmittingtissue traversing its whole length. The transmitting tissueconsists of loosely arranged cells with numerous organellesand conspicuous intercellular substance rich in polysaccharidesand pectins. Ultrastructural details indicate that the intercellularsecretion is accompanied with fraying of the wall component.Both the transverse and longitudinal walls contain plasmodesmata.Copyright1995, 1999 Academic Press Cytochemistry, stigma and style, ultrastructure, Tibouchina semidecandra     

The Anatomy, Histochemistry and Ultrastructure of Stigmas and Styles in Commelinaceae

The anatomy and ultrastructure of stigmas in 37 species of 13genera of Commelinaceae are described. The stigmas are papillate,papillae forming a dense fringe of cells around the mouth ofthe stylar canal in most species. The papillar cell wall iscovered by an unstructured cuticle of variable thickness andis of variable thickness because of small wall ingrowths. Thecuticle and the external surface of the papillar cell wall arevariably disrupted, particularly in the mid and basal regionsof the cell. This was not found in species of the genus Aploleiaor Callisia. The cell cytoplasm possesses all major organellesexcept chloroplasts and each cell is vacuolate. In all species except Aploleia mulitiflora the style comprisesan epidermis, a cortex and a hollow, tripartite canal whichis continuous into the ovary cavity. The three vascular strandsare positioned at the apex of each canal lobe. The canal cellsare elongate and tabular and the wall abutting the canal hasingrowths. The style in Aploleia is solid and the transmittingtissue comprises cells whose walls are electron opaque. Thecytoplasms of both types of cell are similar in content althoughthere is a single, large vacuole in canal cells and many smallvacuoles in transmitting tissue. The morphology, position and histochemistry of stigmatic andstylar exudate was similar in all ‘wet’ stigmas.Most of the exudate originates from the stylar canal althoughsignificant contributions are made by the papillae in stigmasof Coleotrype, Dichorisandra and Thyrsanthemum. There is no apparent relationship between stigma structure andthe presence of self-incompatibility. Stigma papillae, stylar canal, transmitting tissue, Commelinaceae     

The Structure and Cytochemistry of the Stigma-style Complex ofCorylus avellanaL. 'Tonda Gentile delle Langhe' (Corylaceae)

Structural and cytochemical aspects of the stigma-style complexofCorylus avellanawere studied. In cross section the stigmaticstyle consists of papillae, one or two layers of sub-epidermalcells and a central transmitting tissue. The papillae coverthe style for about 80% of its length, are unicellular and arecoated with a cuticle-pellicle. During development, the cellwalls of the papillae increase in thickness and between them,below the cuticle, lipid bodies are observed. The sub-epidermalcells are similar in cell content to the papillae. The centraltransmitting tissue consists of highly vacuolated cells andthe intercellular spaces are filled with a proteic and polysaccharidicsubstance. Both the transverse and longitudinal walls containplasmodesmata.Copyright 1998 Annals of Botany Company cytochemistry, stigma and style, ultrastructure,Corylus avellana     

STIGMA,STYLE, AND OBTURATOR OF ORNITHOGALUM CAUDATUM (LILIACEAE) AND THEIR FUNCTION IN THE REPRODUCTIVE PROCESS

Transmitting tissue in Ornithogalum is divided into three regions corresponding to classical divisions of the gynoecium: stigma, style, and ovary. The stigma differentiates from epidermal cells of the stylar apex. These cells form the stigmal papillae and have dense cytoplasm with abundant ER and lipid bodies. Papillae have walls with small transfer-ingrowths. At floral receptivity, papillae secrete a small amount of surface exudate. Epidermal cells of the style contain numerous spherosomes and have thin filaments of cytoplasm traversing the central vacuole. The stylar cortex is composed of 3-6 layers of parenchyma cells which contain numerous spherosomes and often have secondary vacuoles. Vascular tissue in the style consists of one collateral bundle in each lobe. Cells of the epidermal layer lining the stylar canal are secretory. They are initially vacuolate but fill progressively with dense cytoplasm as their secretory activity increases. Secretory activity occurs in three phases, each characterized by a particular organelle population and secretory product. At anthesis, the canal is filled with an exudate consisting of carbohydrate, protein, and lipid. In the ovary, the obturator differentiates from cells at the base of the funiculus and the tip of the carpel margins. It forms a pad of tissue which covers most of the former placenta. The obturator is secretory and produces a surface exudate. We believe our observations on Ornithogalum support the hypothesis that all transmitting tissue is of the same morphological origin and that it provides nutritive and chemotropic factors for pollen tube growth.     

Pollination and Pollen-pistil Interaction in Oil Palm, Elaeis guineensis

Structural and cytochemical aspects of the pistil and detailsof pollination and pollen-pistil interaction were investigatedin the African oil palm (Elaeis guineensis Jacq.), an importantperennial oil crop. The stigma is trilobed, wet and papillate.The branched papillae are confined to a narrow linear zone oneach stigmatic lobe. Each stigmatic lobe harbours a deep stigmaticgroove, which runs adaxially along the surface. The stigmaticgroove is bordered by a well-defined layer of glandular cells,each of which has a pectinaceous cap on the inner tangentialwall. The style is hollow. The canal cells show thickeningson the inner tangential wall. The stigmatic groove and stylarcanal contain an extracellular matrix secreted by the canalcells which is rich in proteins, acidic polysaccharides andpectins. The canal cells at the base of the style are papillateand loosely fill the stylar canal. The stigma becomes receptivewhen the stigmatic lobes separate, and remains so for 24 h.Pollination is mediated by weevils as well as by the wind. Undernatural conditions the pollination efficiency was 100%. Pollinationinduces additional secretion in the stigmatic groove and stylarcanal. During post-pollination secretion, the pectinaceous capsof the cells lining the stigmatic groove are degraded. Pollengrains germinate on the stigmatic papillae and tubes grow onthe surface of the papillae, entering the stigmatic groove andadvancing along it into the stylar canal to eventually gainaccess to the locules. Pollen tubes are seen in the ovules 18–20h after pollination. Copyright 2001 Annals of Botany Company Arecaceae, Elaeis guineensis, African oil palm, pollination, stigmatic grove, stylar canal, Tenera hybrid, weevil     

The Pollen-stigma Interaction: Pollen-tube Penetration in Crocus

In a compatible pollination in Crocus, pollen tube tips enterthe stigma papillae after the enzymic erosion of the cuticle,and the tubes continue downward growth towards the ovary betweenthe cuticle and the underlying pectocellulosic wall. The cuticleof the receptive zone of the stigma papilla is chambered, thechambers containing a secretion accumulated during the maturationof the stigma. Pollen exudates contain various acid hydrolases,but are incapable alone of eroding stigma cutin. Furthermore,there is no penetration when the proteins of the wall-held stigmasecretions are degraded enzymically. These facts are taken toindicate that the pollen contributes a ‘cutinase’precursor which is activated by a factor or factors held inthe stigma secretion. Pollens of certain Cruciferae producetubes capable of penetrating the Crocus stigma cuticle, suggestingthat notwithstanding the taxonomic remoteness of Cruciferaeand Iridaceae the enzyme activation systems are quite similar.     

Mechanism of Pollination in Gladiolus: Roles of the Stigma and Pollen-tube Guide

Gladiolus has a dry type of stigma. Compatible pollen grainsalight and germinate on the receptive surface of the papillae,penetrate the cuticle and grow towards the style through a sub-cuticularpollen-tube guide of mucilage. This is secreted from epidermalcells of the stylodium and style canal. The cuticle, which coversthe pollen tube guide mucilage, is continuous through the stylecanal to the ovary. The wet stigma of Lilium also has cuticulartissue running through the style canal, covering the mucilage.     

Pistil Receptivity and Pollen Tube Growth in Relation to the Breeding System of Eucalyptus woodwardii (Symphyomyrtus: Myrtaceae)

Pistil structure, stigma receptivity and pollen tube growthwere investigated in relation to seed set of Eucalyptus woodwardii.Self-pollination resulted in reduced capsule retention and seeddevelopment as compared with cross-pollination. The pistil consistedof an ovary with five locules, a long style with a canal extendingfor two-thirds of its length, and a papillate stigma. Therewas no change in style length with time after anthesis, butboth stigma secretion and ability to support pollen germinationand tube growth increased to reach a peak at 7 d. Pollen germinatedon the stigma surface and in the stylar canal, but most tubegrowth occurred intercellularly in the transmitting tissue surroundingthe canal. At the base of the style the pollen tubes split intofive groups following the transmitting tissue strands to theovary. Each group grew through a septum dividing two loculesand entered the placenta. The tubes then emerged from the placentato penetrate the ovules at between 10 and 20 d after pollination.Fewer ovules were penetrated following self- than cross-pollination. Eucalyptus woodwardii Maiden, Lemon-flowered gum, Pistil receptivity, Pollen tube growth, Breeding system, Self-incompatibility