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.

Cytological observation of the infection process of Venturia carpophila on peach leaves

Plant Disease ◽  
2021 ◽  
Author(s):  
Yang Zhou ◽  
Lei Zhang ◽  
Chuan-Ya Ji ◽  
Chingchai Chaisiri ◽  
Liangfen Yin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Laser Scanning ◽  
Infection Process ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Post Inoculation ◽  
Transmission Electron ◽  
Leaf Surfaces ◽  
Germ Tubes

Peach scab caused by Venturia carpophila, is one of the most destructive fungal diseases of peach worldwide, which seriously affects the peach production. Up to date, the infection process and pathogenesis of V. carpophila on peach remain unclear. Here, we present the infection behaviour of V. carpophila at the ultrastructural and cytological levels in peach leaves with combined microscopic investigations (e.g., light microscopy, confocal laser scanning microscopy, scanning electron microscopy and transmission electron microscopy). V. carpophila germinated at the tip of conidia and produced short germ tubes on peach leaf surfaces at 2 days post-inoculation (dpi). At 3 dpi, swollen tips of germ tubes differentiated into appressoria. At 5 dpi, penetration pegs produced by appressoria broke through the cuticle layer, and then differentiated into thick sub-cuticular hyphae in the pectin layer of the epidermal cell walls. At 10 dpi, the sub-cuticular hyphae extensively colonized in the pectin layer. The primary hyphae ramified into secondary hyphae and proliferated along with the incubation. At 15 dpi, the sub-cuticular hyphae divided laterally to form stromata between the cuticle layer and the cellulose layer of the epidermal cells. At 30 dpi, conidiophores developed from the sub-cuticular stromata. Finally, abundant conidiophores and new conidia appeared on leaf surfaces at 40 dpi. These results provide useful information for further understanding the V. carpophila pathogenesis.

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.

Ultrastructure of eastern cottonwood clones susceptible or resistant to leaf rust

1987 ◽  
Vol 65 (8) ◽  
pp. 1586-1598 ◽  
Author(s):  
L. Shain ◽  
U. Järlfors
Keyword(s):  
Electron Microscopy ◽  
Leaf Rust ◽  
Light And Electron Microscopy ◽  
Infection Process ◽  
The Other ◽  
Host Cells ◽  
Eastern Cottonwood ◽  
Melampsora Medusae ◽  
Wall Appositions ◽  
Infected Cells

The infection process in four clones of eastern cottonwood susceptible or resistant to leaf rust caused by Melampsora medusae was studied by light and electron microscopy. Infection was initiated by stomatal rather than direct entry. Typical dikaryotic haustoria were observed in all clones within 1 day of inoculation. Some healthy-appearing haustoria were observed in susceptible clones throughout the duration of the study, which was terminated during the initiation of uredial production. Incompatibility was expressed differently in the two resistant clones. In clone St 75, most haustoria and invaded host cells that were observed appeared necrotic within 2 days of inoculation. Cell wall appositions appeared during this time in cells adjoining necrotic host cells. Some infected cells disintegrated within 4 days of inoculation. Affected host cells of clone St 92, on the other hand, plasmolyzed during the first 2 to 3 days after inoculation. Necrotic host cells were not observed in this clone until the 4th day after inoculation. Hyphal ramification and host plasmolysis were extensive at 6 days after inoculation.

scholarly journals Comparative Study of Leaf Surface Texture and Ability to Expand of Cured Tobacco

2001 ◽  
Vol 19 (7) ◽  
pp. 333-338
Author(s):  
R Rohr ◽  
A Eberhard ◽  
R Delon ◽  
JP Descombes ◽  
JM Demor
Keyword(s):  
Electron Microscopy ◽  
Leaf Surface ◽  
Point Of View ◽  
Relative Importance ◽  
Palisade Parenchyma ◽  
Adaxial Side ◽  
Objective Criterion ◽  
Transmission Electron ◽  
The Difference ◽  
Expansion Capacity

AbstractTobacco leaf texture, appreciated by the difference of surface roughness of cured leaves, is studies with light microscopy and scanning electron microscopy (SEM). The leaf texture is obviously determined by the presence or absence of conical cellular protuberances on the adaxial side of the leaf. Considering the anatomic point of view, the leaf thickness, always more important when the leaf texture is open, is the only objective criterion which could be associated to the texture. The ultra-structural study with SEM and transmission electron microscopy (TEM) demonstrates that the expansion capacity of tobacco doesn't rely on cytological factors such as cellular reserves or debris. The expansion capacity could be inversely proportional with the relative importance of the mesophyll comparing to palisade parenchyma. On the studied material, no direct relation between the leaf texture and the expansion capacity has been noticed.

scholarly journals Surface and Ultrastructural Feeding Injury to Strawberry Leaves by the Twospotted Spider Mite

HortScience ◽  
1990 ◽  
Vol 25 (8) ◽  
pp. 948-951 ◽  
Author(s):  
Richard J. Campbell ◽  
Randolph L. Grayson ◽  
Richard P. Marini
Keyword(s):  
Spider Mite ◽  
Leaf Surface ◽  
Twospotted Spider Mite ◽  
Fragaria Ananassa ◽  
Lower Leaf Surface ◽  
Palisade Parenchyma ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Vascular Elements ◽  
Twospotted Spider

Scanning and transmission electron microscopy were used to investigate damage to strawberry (Fragaria ×ananassa Duch.) leaves caused by twospotted spider mite (Tetranychus urticae Koch.). Mites damaged epidermal cells on the lower leaf surface, but did not damage major vascular elements of the leaf. Mite-damaged spongy and palisade parenchyma cells had coagulated protoplasts, with some cells devoid of cellular contents. Mesophyll cells adjacent to damaged regions showed no ultrastructural distortion or disruption of chloroplasts.

Plasmodium falciparum: regional differences in lectin and cationized ferritin binding to the surface of the malaria-infected human erythrocyte

Parasitology ◽  
1986 ◽  
Vol 93 (1) ◽  
pp. 17-32 ◽  
Author(s):  
I. W. Sherman ◽  
Jane R. T. Greenan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plasmodium Falciparum ◽  
Uniform Distribution ◽  
Lectin Binding ◽  
Red Cells ◽  
Cationized Ferritin ◽  
Transmission Electron ◽  
Erythrocyte Surface ◽  
Infected Cells

SUMMARYThe distribution of anionic residues on the surface of erythrocytes infected withPlasmodium falciparumwas studied using cationized ferritin (CF) and transmission electron microscopy. CF staining of uninfected erythrocytes or erythrocytes infected with a knobless variant resulted in a dense and uniform distribution of ferritin particles; however, when red cells infected with a knob-inducing variant were exposed to CF, aggregates of ferritin particles were observed in the region of membrane elevation. Lectin binding to the erythrocyte surface was visualized by transmission electron microscopy using ferritin-conjugated lectins and lectin-fetuin-gold. No differences were observed in the lectin-binding patterns of malaria-infected or uninfected erythrocytes using WGA (wheat-germ agglutinin), RCA (ricin), andLimax flavuslectin. In distinct contrast to the uniform distribution of ferritin particles seen with these lectins was the appearance of clusters of ferritin-ConA over the knobby regions. Localized aggregates of ConA were not seen in knob-free areas or on the surface of red cells infected with a knobless variant. No significant differences were found in the agglutination reactions of normal and infected cells with theCancer antennariuslectin specific forO-acylated sialic acids.

scholarly journals Effects of miltefosine treatment in fibroblast cell cultures and in mice experimentally infected withNeospora caninumtachyzoites

Parasitology ◽  
2012 ◽  
Vol 139 (7) ◽  
pp. 934-944 ◽  
Author(s):  
KARIM DEBACHE ◽  
ANDREW HEMPHILL
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Treatment Group ◽  
Neospora Caninum ◽  
Fibroblast Cell ◽  
Time Span ◽  
Human Foreskin Fibroblasts ◽  
Transmission Electron ◽  
Infected Cells

SUMMARYMiltefosine was investigated for its activity againstNeospora caninumtachyzoitesin vitro,and was shown to inhibit the proliferation ofN. caninumtachyzoites cultured in human foreskin fibroblasts (HFF) with an IC50of 5·2μM. Treatment of infected cells with 25μM miltefosine for a period of 10 h had only a parasitostatic effect, while after 20 h of treatment parasiticidal effects were observed. This was confirmed by transmission electron microscopy ofN. caninum-infected and miltefosine-treated HFF. Administration of miltefosine toN. caninum-infected Balb/c female mice at 40 mg/kg/day for 14 days resulted in 6 out of 10 mice exhibiting weight loss, ruffled coat and apathy between days 7 and 13 post-infection. In the group that received placebo, only 2 out of 8 mice succumbed to infection, but the cerebral burden was significantly higher compared to the miltefosine treatment group. In a second experiment, the time-span of treatment was reduced to 5 days, and mice were maintained without further treatment for 4 weeks. Only 2 out of 9 mice in the miltefosine treatment group exhibited signs of disease, while 8 out of 10 mice succumbed to infection in the placebo group. These results showed that miltefosine hampered the dissemination of parasites into the CNS during experimentalN. caninuminfection in mice.

Scanning Electron Microscopy of Murine Oncornavirus Infected Cells

1974 ◽  
Vol 32 ◽  
pp. 252-253 ◽  
Author(s):  
S. Panem ◽  
P.S.D. Lin ◽  
A. V. Crewe ◽  
W. H. Kirsten
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscopic ◽  
Viral Budding ◽  
Transmission Electron ◽  
Virion Structure ◽  
Microscopic Studies ◽  
Infected Cells ◽  
Viral Morphogenesis ◽  
Scanning Electron

Although oncornaviruses have been the subject of numerous transmission electron microscopic studies, questions concerning virion structure and the maturation of virus at the infected cell membrane remain unanswered. We have begun to study viral morphogenesis with particular emphasis on the distribution of viral budding sites and the appearance of virus during maturation using scanning electron microscopy.

Maize Necrotic Lesion Virus Particles and Associated Cellular Inclusions

1988 ◽  
Vol 46 ◽  
pp. 296-297
Author(s):  
O. E. Bradfute ◽  
Raymond Louie
Keyword(s):  
Zea Mays L ◽  
Necrotic Lesion ◽  
Mesophyll Cells ◽  
Thin Sections ◽  
Virus Particles ◽  
Cellular Inclusions ◽  
Maize Roots ◽  
Close Proximity ◽  
Infested Field ◽  
Infected Cells

Maize necrotic lesion virus (MNLV), a newly found soil-borne virus, is apparently one of a complex of viruses infecting roots of maize (Zea mays L.) in northern Ohio (1). Maize roots become infected when plants are grown in infested, field soil that has undergone air-dry storage or in autoclaved, greenhouse soil infested with diseased roots. Symptoms on leaves of rub-inoculated maize and other monocot seedlings first appear as chlorotic local lesions that become necrotic after 24-36 hr.Numerous isometric virus particles of two sizes, ca. 17 and 29 nm in diameter, were observed in crude extracts from MNLV lesions negatively stained in phosphotungstic acid, pH 4.8 (Fig. 1). At pH 6.9 the larger virus particles were frequently stain-penetrated and clumped together or embedded in an amorphous matrix (Fig. 2). MNLV-infected cells were also examined in thin sections cut from fixed and embedded chlorotic lesions (Fig. 3-4). In the cytoplasm of some mesophyll cells, numerous isometric virus particles of both sizes were clearly recognized in close proximity to each other and to masses of electron-dense, amorphous inclusions.

Changes in the plastid ultrastructure during greening in cultured soybean cells

1989 ◽  
Vol 47 ◽  
pp. 1010-1011
Author(s):  
M.A. Gillott ◽  
G. Erdös ◽  
D. E. Buetow
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gene Regulation ◽  
Uranyl Acetate ◽  
Total Darkness ◽  
Ultrastructural Changes ◽  
Ethanol Dehydration ◽  
Mesophyll Cells ◽  
Plastid Ultrastructure ◽  
Transmission Electron

Mesophyll cells isolated from soybeans (Glycine max, L. Merr. var. Corsoy) can be grown photoautotrophically in suspension culture. The SB-P cell line can be bleached by maintaining them in total darkness in sucrose supplemented media for several weeks, and will regain photosynthetic competency when returned to the light. This system is ideally suited for the study of gene regulation and the biochemical and ultrastructural changes which occur during the greening process.Cells were fixed for electron microscopy after 8 weeks of growth in total darkness and at intervals of 1 h to 12 d after transfer to the light. Chlorophyll measurements were determined for each sample. For transmission electron microscopy, the cells were fixed for 1-2 h in 4% glutaraldehyde in 0.1M Pipes buffer, pH 7.4, washed in the same buffer, then postfixed for 1 h in 1% OsO4 in Pipes, pH 6.8. Following a graded ethanol dehydration series the cells were transferred into propylene oxide and embedded in Epon. Sections were stained with uranyl acetate and observed on a JEOL 100C TEM operated at 80 kV.

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