Development of wheat (Triticum aestivum) pollen wall before and after effect of a gametocide

1990 ◽  
Vol 68 (11) ◽  
pp. 2509-2516 ◽  
Author(s):  
Gamal A. El-Ghazaly ◽  
William A. Jensen
Keyword(s):  
Electron Microscopy ◽  
Triticum Aestivum ◽  
Key Words ◽  
Light And Electron Microscopy ◽  
Pollen Grains ◽  
Pollen Wall ◽  
Seed Plants ◽  
Before And After ◽  
After Effect

Light and electron microscopy studies show that pollen wall development in plants treated with the gametocide RH0007 and untreated plants was similar until the stage at which sporopollenin is normally deposited on the wall. At this stage, the pollen wall of treated plants is 80% thinner than that of the control. Shortly after this stage, the pollen grains in the treated plants collapse and abort. We conclude that the gametocide clearly acts through the inhibition of sporopollenin formation, which results in pollen death. As sporopollenin is found only in the pollen wall of seed plants and the spores of nonseed plants, harm to other parts of the plant is not expected to occur. Key words: pollen wall development, Triticum aestivum, gametocide.

The development and zoospore ultrastructure of a polycentric chytridiomycete gut fungus, Orpinomyces joyonii comb.nov.

1991 ◽  
Vol 69 (3) ◽  
pp. 580-589 ◽  
Author(s):  
Jinliang Li ◽  
I. Brent Heath ◽  
K.-J. Cheng
Keyword(s):  
Electron Microscopy ◽  
Distribution Pattern ◽  
Key Words ◽  
Light And Electron Microscopy ◽  
General Morphology ◽  
Organelle Distribution ◽  
Central Nuclei

Orpinomyces bovis, a polycentric gut fungus isolated from a steer, was examined with both light and electron microscopy and renamed Orpinomyces joyonii comb.nov. on the basis of its general morphology and zoospore ultrastructure. The multinucleate rhizomycelium is extensively branched, and sporangia form exogenously on branched or unbranched sporangiophores. The organelles in the zoospores have a distribution pattern typical of other gut fungi, i.e., anterior ribosomal aggregates, central nuclei, and posterior presumptive hydrogenosomes. The perikinetosomal apparatus in O. joyonii is comparable to that in monocentric gut fungi but with minor variations. New details of the posterior dome are described. It contains highly ordered specialized lamellae, peripheral granules, and megatubules. Microtubules intersect the dome predominantly at approximately right angles to its surface; this differs from monocentric gut fungi, in which microtubules form a posterior fan running parallel to the dome. We suggest that both monocentric and polycentric gut fungi are monophyletic, since both have a similar, distinctive perikinetosomal apparatus, posterior dome, and organelle distribution pattern. Key words: Orpinomyces joyonii, gut fungi, ultrastructure, posterior dome, perikinetosomal apparatus.

Anatomy of the Unpollinated and Pollinated Watermelon Stigma

1982 ◽  
Vol 54 (1) ◽  
pp. 341-355
Author(s):  
M. SEDGLEY
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Freeze Fracture ◽  
Pollen Grain ◽  
Acidic Polysaccharides ◽  
Before And After ◽  
Em Autoradiography ◽  
Pollen Grain Wall ◽  
Stigma Secretion

The structure of the watermelon stigma before and after pollination was studied using light and electron microscopy, freeze-fracture and autoradiography. The wall thickenings of the papilla transfer cells contained callose and their presence prior to pollination was confirmed using EM-autoradiography, freeze-fracture and fixation. No further callose thickenings were produced following pollination. Pollination resulted in a rapid increase in aqueous stigma secretion and localized disruption of the cuticle, which appeared to remain on the surface of the secretion. Autolysis of the papilla cells, which had commenced prior to pollination, was accelerated and appeared to take place via cup-shaped vacuoles developed from distended endoplasmic reticulum. The reaction was localized to the papilla cells adjacent to the pollen tube only. Both pollen-grain wall and stigma secretion contained proteins, carbohydrates, acidic polysaccharides, lipids and phenolics.

FIB-SEM: An Additional Technique for Investigating Internal Structure of Pollen Walls

2013 ◽  
Vol 19 (6) ◽  
pp. 1535-1541 ◽  
Author(s):  
Alisoun House ◽  
Kevin Balkwill
Keyword(s):  
Electron Microscopy ◽  
Internal Structure ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Pollen Grains ◽  
Grain Morphology ◽  
Pollen Grain ◽  
Pollen Wall ◽  
Scanning Electron

AbstractPollen grain morphology has been widely used in the classification of the Acanthaceae, where external pollen wall features have proved useful in determining relationships between taxa. Although detailed information has been accumulated using light microscopy, transmission electron microscopy and scanning electron microscopy (SEM) techniques, internal pollen wall features lack investigation and the techniques are cumbersome. A new technique involving precise cross sectioning or slicing of pollen grains at a selected position for examining wall ultrastructure, using a focused ion beam-scanning electron microscope (FIB-SEM), has been explored and promising results have been obtained. The FIB-SEM offers a good technique for reliable, high resolution, three-dimensional (3D) viewing of the internal structure of the pollen grain wall.

Variegation in Selaginella martensii f. albovariegata. II. Plastid structure in mature leaves

1982 ◽  
Vol 60 (11) ◽  
pp. 2384-2393 ◽  
Author(s):  
James A. Tanno ◽  
Terry R. Webster
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Chloroplast Ultrastructure ◽  
Structural Defects ◽  
Seed Plants ◽  
Wild Type ◽  
Membrane Systems ◽  
High Susceptibility ◽  
Paraffin Sections ◽  
Mature Leaves

Mature green, variegated, and white leaves of Selaginella martensii f. albovariegata were examined by light and electron microscopy. Paraffin sections show the anatomy of all three leaf types to be comparable with that reported for wild type S. martensii. With the light microscope, chloroplasts in green cells appear identical with those of the wild type, while plastids in white cells are smaller and less regular in shape. Chloroplast ultrastructure in green cells is comparable with that described for S. martensii and other members of the genus and quite similar to that typical of seed plants. Plastids of white cells display many structural defects. Large portions of the plastid volume are occupied by vacuoles. In variegated leaves these plastids possess sparse internal membrane systems consisting primarily of irregular vesicles distributed throughout the stroma. In white leaves single lamellae and sets of aligned lamellae are associated with many of the plastid vacuoles. The plastid defects suggest a high susceptibility to photooxidative bleaching.

Pollen morphology of Lagotis (Scrophulariaceae)

1995 ◽  
Vol 73 (5) ◽  
pp. 701-709 ◽  
Author(s):  
Charles L. Argue
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
As Species ◽  
Close Relationship ◽  
Scanning Electron

The pollen grains of 18 species of Lagotis have been examined using light microscopy and scanning electron microscopy of whole and fractured pollen. The grains are characterized by tricolporate apertures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large exinous processes over the endoaperture; and columellate, semitectate, reticulate to microreticulate exines with or without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded, differentially sculptured colpus border is absent. Lagotis pollen is distinct from that of the Selagineae and Globularia and indistinct from that of some Veroniceae; however, the characters shared with the latter are of wide occurrence in the Scrophulariaceae. Pollen morphology supports the distinction between L. brachystachya and L. stolonifera. It is consistent with the postulated close relationship between L. micrantha and L. integra, and provides no evidence to support the reestablishment of L. cashmeriana, L. minor, L. pallasii, or L. kunawurensis as species distinct from L. glauca. Key words: pollen morphology, Lagotis, Globularia, Selagineae, Veroniceae.

Pollen Wall Proteins: Pollen-Stigma Interactions in Ragweed and Cosmos (Compositae)

1973 ◽  
Vol 12 (2) ◽  
pp. 421-443 ◽  
Author(s):  
R. B. KNOX
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Pollen Wall ◽  
Stigma Surface ◽  
Cosmos Bipinnatus ◽  
Stigmatic Papillae ◽  
Scanning Electron

The release of wall-held materials from the pollen of ragweed (Ambrosia tenuifolia) and Cosmos bipinnatus on to the stigma surface has been followed. When fresh stigmas were viewed by scanning electron microscopy, a fluid material was observed coating pollen grains, pollen tubes and adjacent stigmatic papillae. This fluid contained pollen-wall antigens, including the allergen Antigen E, detected by immunofluorescence, and proteins, lipids and carbohydrates detected by cytochemical methods. In Cosmos, the fate of the antigens was much the same after both compatible and incompatible matings. In incompatible matings, pollen tubes were blocked with a polysaccharide considered to be callose. Callose particles appeared on neighbouring stigmatic papillae, and adjacent stigmatic hairs accumulated callose internally. This reaction may be an important one for the incompatibility response.

A methodical and taxonomic study of dispersed oak pollen (Fagaceae) from the Holocene of Rolla, Missouri, USA

Phytotaxa ◽  
2016 ◽  
Vol 288 (3) ◽  
pp. 227
Author(s):  
MARIA V. TEKLEVA ◽  
ROBERT D. HASELWANDER
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Pollen Grains ◽  
Good Prospect ◽  
Long Distance ◽  
Forest Density ◽  
Oak Pollen ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Oak pollen has great potential to be used in reconstructing paleovegetation and paleoclimate. Pollen grains from Holocene sediments of Rolla, Missouri, USA were studied. The goal of this study was to evaluate the morphology of dispersed oak pollen using light and electron microscopy. Three types of oak pollen were recognized: Group 1, Group 2, and Group 3. They occurred in the sample in the following approximate percentage: 52, 32 and 16% respectively. Pollen of Group 1 corresponds to that of white oaks, pollen of Group 2 to that of red oaks. Pollen of Group 3 differs from oak pollen known for the studied region. While electron microscopy shows a good prospect for a detailed interpretation of dispersed oak pollen, many factors should be taken into account when assessing past vegetation: the paleo-forest density, location of sampling, apparent wind direction during pollination, and the “resolving ability” of pollen morphology for different oak species. The intensity of flowering and direction of the pollen transport can significantly influence the quantity of pollen of a particular species in the spectrum. The possibility of medium or long-distance transport of a small quantity of oak pollen from other regions should also be considered in the interpretations of fossil spectra.

Light and Electron Microscopy Studies in Psoriasis Before and After Treatment with Retinoids (Ro 10-9359)

Retinoids ◽  
1981 ◽  
pp. 457-466 ◽  
Author(s):  
H. Kamino-Kamino ◽  
S. Gómez-Estrella ◽  
V. Tsutsumi ◽  
M. T. Hojyo-Tomoka ◽  
L. Domínguez-Soto
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Before And After

Microscopic Examination of Chilling Injury Symptoms in Ethanol-treated Cucumber Seedling Roots

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 454e-454
Author(s):  
Windy A. Boyd ◽  
Paul H. Jennings
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Chilling Injury ◽  
Light And Electron Microscopy ◽  
Ethanol Solution ◽  
Root Tip ◽  
Cucumber Seedling ◽  
Cortical Cells ◽  
Before And After ◽  
Seedling Roots

Cucumber seedlings were germinated for 24 h at 25 °C and half were immersed in a 500 mM ethanol solution for 2 h. After rinsing, seedlings were chilled for 96 h at 2 °C. Control and ethanol-treated samples were taken for light and electron microscopy immediately before and after chilling, and after re-warming for 24 and 72 h. Preliminary experiments revealed visual chilling symptoms such as pinching of the root in a region just above the root tip. This region was excised under a microscope, fixed, and mounted for microscopic observations. The cortical cells of ethanol-treated seedlings before chilling appeared to be irregular in shape with irregular edges, and some epidermal damage was evident. Chilling caused much more epidermal damage in the control seedlings when compared to the ethanol-treated seedlings. After chilling, cortical cells in the control seedlings were observed to be irregularly shaped while those treated with ethanol had round cells. Upon re-warming, control seedlings exhibited increasing epidermal damage with broken cell walls, while ethanol-treated seedlings exhibited more differentiation in the stele.

Piromyces mae and Piromyces dumbonica, two new species of uniflagellate anaerobic chytridiomycete fungi from the hindgut of the horse and elephant

1990 ◽  
Vol 68 (5) ◽  
pp. 1021-1033 ◽  
Author(s):  
Jinliang Li ◽  
I. Brent Heath ◽  
Tom Bauchop
Keyword(s):  
Electron Microscopy ◽  
New Species ◽  
Key Words ◽  
General Model ◽  
Light And Electron Microscopy ◽  
Limited Range ◽  
Organelle Distribution ◽  
Two New Species

Vegetative thalli, developing sporangia, and zoospores of two new uniflagellate anaerobic chytridiomycete gut fungi, Piromyces mae sp. nov. and Piromyces dumbonica sp.nov., isolated from manure derived from the hindgut of the horse and elephant, respectively, were examined by light and electron microscopy. Piromyces mae differs from Piromyces communis by having papillae-like structures on the sporangium. Piromyces dumbonica differs from P. communis by its C-shaped elongated circumflagellar ring and characteristic organelle distribution in the zoospores. The circumflagellar rings in both new species are tilted at about 10° towards the spur in both prereleased and free zoospores. Three struts in both species connect the circumflagellar ring to the skirt and connective (a newly described perikinetosomal structure) surrounding the kinetosome opposite to the skirt. The connective interconnects the strut, skirt, scoop, kinetosome, and spur. A general model of the kinetosome and perikinetosomal apparatus is proposed for the gut fungi. This model attempts to unify and clarify previous descriptions of the apparatus in these fungi and shows the limited range of variations reported. Key words: gut fungi, Chytridiomycetes, kinetosomes, perikinetosomal apparatus.

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