Penetration of Zea mays by Helminthosporium carbonum

1975 ◽  
Vol 53 (23) ◽  
pp. 2872-2883 ◽  
Author(s):  
Gordon M. Murray ◽  
Douglas P. Maxwell
Keyword(s):  
Electron Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Epidermal Cells ◽  
Cell Cytoplasm ◽  
Mesophyll Cells ◽  
Fibrillar Material ◽  
Transmission Electron ◽  
Corn Plants ◽  
Resistant Genotypes

Light microscopy showed that on corn leaves, 81–93% of appressoria of Helminthosporium carbonum races I and II are formed over junctions of epidermal cells. During the early stages of penetration of corn plants resistant and susceptible to race I, 63–83% of appressoria have an epidermal cell nucleus within 10 μm. Transmission electron microscopy of race II on inbred W187R showed that appressoria are attached to the cuticle by fibrillar material. Vesicles are present in the appressorium at the site of cuticle penetration and initial cuticle penetration appears to be enzymic; subsequent rupture may be mechanical as the penetration peg widens. A septum forms between the appressorium and the subcuticular hyphae. Epidermal cell cytoplasm is thicker beneath penetration sites than elsewhere under the epidermal wall. Changes in epidermal cytoplasm were observed 8 h after inoculation; by 18 h epidermal cells beneath subcuticular hyphae have electron-opaque contents. Hyphae are mainly subcuticular up to 48 h after inoculation, and underlying epidermal and mesophyll cells are frequently collapsed. Results indicate that H. carbonum races I and II have similar initial reactions on susceptible and resistant genotypes and that penetration occurs by degradation of the cuticle and host cell walls.

Morphology of infection of onion leaves by Alternaria porri

1994 ◽  
Vol 72 (8) ◽  
pp. 1164-1170 ◽  
Author(s):  
Theresa A. S. Aveling ◽  
Heidi G. Snyman ◽  
F. H. J. Rijkenberg
Keyword(s):  
Electron Microscopy ◽  
Epidermal Cell ◽  
Leaf Surface ◽  
Infection Process ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Close Proximity ◽  
Alternaria Porri ◽  
Infected Cells ◽  
Germ Tubes

Conidial germination of Alternaria porri, formation of prepenetration structures, penetration of the onion leaf surface, and the postpenetration processes were studied using light, scanning electron, and transmission electron microscopy. Ninety-six percent of conidia germinated at 25 °C within 24 h of inoculation. Each conidium formed several germ tubes that grew in any direction across the leaf surface. Each germ tube usually terminated in a bulbous appressorium formed directly on the epidermal cell (52.4% of appressoria) or on a stoma (48.6% of appressoria). Following direct penetration of the outer epidermal cell wall or the stoma, bulbous primary hyphae developed below the appressoria. Secondary hyphae developed from the primary hyphae within 48 h after inoculation and grew within the intercellular spaces penetrating mesophyll cells. The changes in ultrastructure of cells in close proximity to hyphae and of infected cells are described. Key words: Allium cepa, electron microscopy, infection process, purple blotch.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

The development of the notochord in the chick embryo, studied by scanning and transmission electron microscopy

Development ◽  
1976 ◽  
Vol 35 (2) ◽  
pp. 383-401
Author(s):  
Mary Bancroft ◽  
Ruth Bellairs
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chick Embryo ◽  
Intercellular Spaces ◽  
Notochordal Cells ◽  
Fibrillar Material ◽  
Transmission Electron ◽  
Phases Of Development ◽  
Scanning Electron

The notochord of the chick embryo between stages 5 and 23 inclusive has been studied by scanning electron microscopy, supplemented by transmission electron microscopy. Three main phases of development are described, and these have been designated: bilaminar; rodlike, unvacuolated; rod-like and vacuolated. The change in shape of the organ from bilaminar to rod-like is accompanied by changes in the shape, orientation and position of the cells, an increase in the complexity of the cell contacts, and the laying down of a basal lamina. The change from the unvacuolated to the vacuolated phase is accompanied by increasing complexity within the cytoplasm. Most of the vacuoles are intracellular and appear empty though some contain a granular material. The notochordal sheath appears to be secreted by the notochordal cells and fine fibrillar material has been seen in the intercellular spaces. By stage 23, most of the notochordal cells have become so highly vacuolated that the cytoplasm has become closely packed around the nucleus.

scholarly journals Submicroscopical Features of Leaves of Xyris Species

2001 ◽  
Vol 44 (4) ◽  
pp. 405-410 ◽  
Author(s):  
Maria das Graças Sajo ◽  
Silvia Rodrigues Machado
Keyword(s):  
Electron Microscope ◽  
Cell Walls ◽  
Guard Cells ◽  
Leaf Ultrastructure ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Inner Surface ◽  
Stomatal Guard Cells ◽  
Adaptative Significance ◽  
Scanning Electron

The leaf ultrastructure of five Xyris species were examined using scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical methods. All studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. Such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. Pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. There were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.

Colonization of Sphagnum cells by Lyophyllum palustre

1985 ◽  
Vol 63 (4) ◽  
pp. 757-761 ◽  
Author(s):  
E. Untiedt ◽  
K. Müller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Host Cell ◽  
Cell Walls ◽  
Transmission Electron ◽  
Scanning Electron

Lyophyllum palustre (Peck) Singer, a basidiomycete (Tricholomataceae) parasitizing Sphagnum, was examined for points of contact between hyphae and Sphagnum cells with the help of light microscopy, scanning electron microscopy, and transmission electron microscopy. Results indicate that the fungus attacks Sphagnum cells by penetrating cell walls and altering host cell protosplasm. In addition, the formation of additional partitioning cell walls in attacked living Sphagnum cells was observed.

Wilts caused by Verticillium species. A cytological survey of vascular alterations in leaves

1982 ◽  
Vol 60 (6) ◽  
pp. 825-837 ◽  
Author(s):  
Jane Robb ◽  
Alexandra Smith ◽  
Lloyd Busch
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Sem Analysis ◽  
Disease Symptoms ◽  
Vascular Tissues ◽  
Transmission Electron ◽  
Tem Method ◽  
Cytological Alterations ◽  
Host Parasite ◽  
Leaf Symptoms

Plants that are infected with fungi of the species Verticillium frequently develop foliar disease symptoms which may include one or more of the following: flaccidity, drying, chlorosis leading to necrosis, vascular browning, epinasty, and leaf abscission. A number of ultrastructural and chemical alterations occur in the vascular tissues of such leaves: deposition of brown pigments, coating of xylem vessel walls with abnormal material (i.e., lipid-rich coatings or fibrillar coatings), plugging of xylem vessels with gums, gels or tyloses, degeneration of parenchyma cells, and accumulation of abnormal electron dense materials in primary and secondary cell walls. Different host–parasite combinations exhibit different leaf symptoms and different cytological alterations. The purpose of the present survey was to determine whether the extent of any of the possible vascular alterations in leaves could be correlated with the wilting tendency of the host.Chrysanthemums, snapdragons, eggplants, sunflowers, potatoes, sycamore maples and hedge maples were infected with V. dahliae; alfalfa and hops were infected with V. albo-atrum. When leaf symptoms were well advanced, samples were taken from the major lateral leaf veins and were prepared for light (LM) and transmission electron microscopy (TEM) or scanning electron microscopy (SEM). The various types of alterations in the vascular tissues were identified by a correlated LM–TEM method and (or) SEM analysis and for each sample vein the proportion of vessels affected by each type of alteration was calculated. Four leaf samples, each from different plants, were analysed for each host. The visual symptoms, including vascular browning, were estimated subjectively. The degree of leaf flaccidity was correlated positively with the proportion of lipid-coated vessels and inversely with the degree of vascular browning. No other correlations were observed.

Light and transmission electron microscopy of English oak ectomycorrhizal short roots

1984 ◽  
Vol 62 (7) ◽  
pp. 1327-1335 ◽  
Author(s):  
H. H. Edwards ◽  
R. V. Gessner
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Quercus Robur ◽  
Lipid Droplets ◽  
Apical Meristem ◽  
Fungal Symbiont ◽  
Host Root ◽  
Transmission Electron ◽  
Cell Layers ◽  
English Oak

The incorporation of caffeine in standard transmission electron microscope fixation procedures has allowed good preservation and embedment of ectomycorrhizal short roots of English oak (Quercus robur L.). In the mantle the most conspicuous structures are cystidia which radiate outwards from the surface. These conically shaped cells have knobs at their tips and thickened cell walls. The cystidia and other outer mantle cells contain many cytoplasmic constituents, whereas the inner mantle cells are nearly devoid of cytoplasm. The mantle cells are held together by an intercellular slime network. The Hartig net cells are filled with cytoplasm and contain numerous lipid droplets. Typical dolipore septa separate the cells; however, these cells have irregularly branched shapes. The host root tissue appears little altered by the presence of the fungal symbiont. However, the root cap consists of only a few cell layers. The apical meristem is functional as evidenced by the presence of newly divided cells and microtubules lining enlarging cells.

Ontogeny of Alnus rubra – Alpova diplophloeus ectomycorrhizae. II. Transmission electron microscopy

1989 ◽  
Vol 67 (1) ◽  
pp. 201-210 ◽  
Author(s):  
H. B. Massicotte ◽  
C. A. Ackerley ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Epidermal Cells ◽  
Root Cap ◽  
Alnus Rubra ◽  
Golgi Bodies ◽  
Hartig Net ◽  
Transmission Electron ◽  
Meristem Zone ◽  
Basal Portion ◽  
Branching System

Ultrastructural features of the two symbionts in ectomycorrhizae formed between Alnus rubra and Alpova diplophloeus change with developmental stage. In the root cap – meristem zone, hyphae penetrate between vacuolated root cap cells and become appressed to epidermal cells containing small vacuoles, plastids with starch, numerous Golgi bodies, mitochondria, and endoplasmic reticulum cisternae. In the young Hartig net zone, hyphae with few vacuoles penetrate between vacuolated epidermal cells that still contain numerous Golgi bodies but now have plastids with small starch grains. Hartig net hyphae begin to branch and eventually form a complex branching system in the mature Hartig net zone. Hartig net hyphae in the basal portion of the ectomycorrhizae synthesize lipid and finally become vacuolated.

Histopathological and ultrastructural comparison of Stemphylium sarcinaeforme and S. botryosum on red clover foliage

1978 ◽  
Vol 56 (17) ◽  
pp. 2097-2108 ◽  
Author(s):  
Verna J. Higgins ◽  
G. L. Lazarovits
Keyword(s):  
Cell Walls ◽  
Light And Electron Microscopy ◽  
Red Clover ◽  
Epidermal Cells ◽  
Blue Staining ◽  
Mesophyll Cells ◽  
Toluidine Blue Staining ◽  
Different Types ◽  
Wall Appositions ◽  
Palisade Cells

As part of a continuing study of non-host resistance, red clover leaves inoculated with the clover pathogen Stemphylium sarcinaeforme, or the closely related alfalfa pathogen S. botryosum, were examined by light and electron microscopy to compare the events occurring in the initial stages of infection. Stemphylium botryosum penetrated leaves primarily via the stomata with resultant death of the guard cells and with varying effects on adjacent epidermal cells. Appressoria were frequently formed, and although they rarely resulted in successful penetrations, the contacted epidermal cells were often markedly affected as judged by toluidine blue staining. Growth of hyphae was intercellular but very limited in its extent. At some infection sites, one to several mesophyll cells underwent extensive plasmolysis and cytoplasmic disruption. Less severely affected mesophyll cells contained large lipid bodies, abundant rough endoplasmic reticulum, and Golgi vesicles and had wall appositions at points of contact with necrotic cells or with hyphae. Stemphylium sarcinaeforme generally penetrated between or directly through the epidermal cells, causing death of the contacted cells. Hyphae grew intercellularly or intracellularly in the palisade tissue and hyphal elongation was considerably more rapid than that of S. botryosum. Palisade cells adjacent to, or containing, the hyphae underwent several different types of cytoplasmic deterioration. Mesophyll cells surrounding these areas showed the same features as comparable cells in tissue infected by S. botryosum. In tissue infected by either fungus, the exterior of host cell walls was coated with a layer of extracellular material.

Immunolocalization of a proteinase of the sap-staining fungus Ophiostoma piceae using antibodies to proteinase K

1995 ◽  
Vol 73 (10) ◽  
pp. 1604-1610 ◽  
Author(s):  
C. Hoffert ◽  
S. Gharibian ◽  
C. Breuil ◽  
D. L. Brown
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Walls ◽  
Polyclonal Antibodies ◽  
Immunogold Labelling ◽  
Proteinase K ◽  
Igg Antibodies ◽  
Extracellular Proteinase ◽  
Ophiostoma Piceae ◽  
Transmission Electron

Polyclonal antibodies were raised against proteinase K and were used to immunolocalize the major extracellular proteinase of the sap-staining fungus Ophiostoma piceae (Münch) H. and P. Sydow. Immunodot blotting showed that the IgG antibodies recognized both enzymes but reacted more strongly with proteinase K than with the O. piceae proteinase. Immunogold labelling and transmission electron microscopy revealed that the O. piceae proteinase was localized in the cell walls of O. piceae grown either in liquid media or wood. Key words: Ophiostoma piceae, proteinase, immunogold labelling, transmission electron microscopy, antibody, proteinase K.

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