scholarly journals Pathogenicity and Ultrastructural Studies of the Mode of Penetration by Phoma strasseri in Peppermint Stems and Rhizomes

2012 ◽  
Vol 61 (4) ◽  
pp. 273-279 ◽  
Author(s):  
BEATA ZIMOWSKA
Keyword(s):  
Host Tissue ◽  
Conidial Suspension ◽  
Time Intervals ◽  
Ultrastructural Studies ◽  
Mucilaginous Sheath ◽  
Transmission Electron ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Direct Placement

Pathogenicity and ultrastructural investigation of the inoculation of peppermint stems and rhizomes with Phoma strasseri conidia was undertaken using scanning and transmission electron microscopy to examine the host-parasite relationship. Pathogenicity experiments demonstrated that all tested P. strasseri isolates had infected the stems and rhizomes of peppermint. Of all inoculation methods, direct placement of colonized agar plugs on damaged epidermis and soaking stems and rhizomes in conidial suspension were the most effective. The behavior of the conidia deposited on the stems and rhizomes was investigated at different time intervals after inoculation: 6, 16, 24, 36 and 48 h. Conidia produced an appressorium directly at the end of a short germ tube. Appressoria were formed over the cuticle, but never over stomata. Direct penetration to host tissue through the cuticle was observed. The spore and hyphae were covered with a mucilaginous sheath.

scholarly journals Ultrastructural Studies of the Mode of Penetration by Phoma macdonaldii in Sunflower Seedlings

2000 ◽  
Vol 90 (8) ◽  
pp. 915-920 ◽  
Author(s):  
A. Roustaee ◽  
G. Dechamp-Guillaume ◽  
B. Gelie ◽  
C. Savy ◽  
R. Dargent ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Integrity ◽  
Time Intervals ◽  
Ultrastructural Studies ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Phoma Macdonaldii ◽  
Host Tissues

An ultrastructural investigation of the artificial inoculation of sunflower with Phoma macdonaldii conidia was undertaken using light, scanning, and transmission electron microscopy to elucidate the host-parasite relationship. The behavior of the conidia deposited on the cotyledon petiole was investigated at various time intervals after inoculation. Conidia adhesion and germination were observed first. The cotyledon petiole was invaded by the fungus directly through the cuticle and via stomata. Externally, the spore and germ tube were covered with a mucilaginous polysaccharide sheath of a cotton-like appearance and of variable thickness. At the time of penetration, the host cuticle was perforated mechanically. The cuticle was slightly depressed and no enzymatic alteration could be observed. The fungus did not form appressoria on the surface of the host tissues but developed an infection peg. As soon as the cuticle barrier was crossed, the fungus rapidly colonized the host parietal layer. In a first step, the plasmalemma of the host cell appeared to be stuck against the cell wall. As soon as the fungus passed through the epidermal cell wall to reach the host cytoplasm, the plasmalemma was disrupted, and the subsequent rapid breakdown of cell integrity favored the colonization of the tissues by the pathogen.

Host—parasite relationships of Blastocrithidia familiaris in Lygaeus pandurus Scop. (Hemiptera: Lygaeidae)

Parasitology ◽  
1986 ◽  
Vol 92 (1) ◽  
pp. 1-12 ◽  
Author(s):  
K. L. Tieszen ◽  
D. H. Molyneux ◽  
S. K. Abdel-Hafez
Keyword(s):  
Rectal Wall ◽  
Peritrophic Membrane ◽  
Unit Membrane ◽  
Ultrastructural Studies ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Relationship Of ◽  
The Relationship ◽  
Outer Unit

SUMMARYBlastocrithidia familiaris were found to be parasitic in the midgut, ileum and rectum of Lygaeus pandurus. The host—parasite relationship is described. Attachment of parasites in the midgut and ileum occurs by interdigitation of expanded flagella over and between the microvilli. No attachment to microvilli was observed where extracellular membranes form well-organized layers which lie parallel to the gut wall and completely separate the microvilli border from the lumen. The extracellular membranes originate from delamination of the outer unit membrane of microvilli which consists of a double plasma membrane. The function of the extracellular membrane layers and their possible role as a peritrophic membrane in preventing parasite attachment is discussed in relation to previous studies on midgut cells in Hemiptera with a similar apical coat on midgut microvilli. In the rectum, parasites attach to the cuticle of the gland cells and not to the rest of the rectal wall. Attachment to the cuticle occurs by the formation of hemidesmosomes. A comparison of the relationship of B. familiaris and its host to previous ultrastructural studies of associations between kinetoplastid flagellates and their respective hosts is discussed.

An ultrastructural study of Nosema polyvora blunck infecting the malpighian tubules of Pieris canidia larva

1994 ◽  
Vol 52 ◽  
pp. 258-259
Author(s):  
W. W. K. Cheung ◽  
J. B. Wang
Keyword(s):  
Osmium Tetroxide ◽  
Insect Pests ◽  
Uranyl Acetate ◽  
Malpighian Tubules ◽  
Ultrastructural Studies ◽  
Microbial Insecticide ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Phosphate Buffered Saline

Microsporidian protozoans of Nosema spp. are common pathogens of insects in the orders Lepidoptera, Hymenoptera and Orthoptera. They are chronic pathogens that can be transmitted horizontally as well as vertically in susceptible insects. Thus they have the potential of being a microbial insecticide for suppressing insect pests populations. During the course of ultrastructural studies of the malpighian tubules of Pieris canidia we have found that Nosema polyvora Blunck commonly infects the tubules. It is worthwhile to investigate into the ultrastructure of this protozoan in order to better understand the host-parasite relationship.Fourth instar larvae of P. candidia were dissected in phosphate buffered saline and malpighian tubules were isolated for fixation in 2.5% glutaraldehyde in 0.2M phosphate, pH 7.2, for 1 hr. Subsequently, tissues were post-fixed in 1% osmium tetroxide in phosphate buffer and were dehydrated in alcohol/acetone series. Tissues were finally embedded in spurr resin and were cut with a Reichart ultrotome. Sections were stained with uranyl acetate and lead citrate for observation under a Zeiss EM 9S-2 or JEOL JEM CX-II electron microscope.

scholarly journals The infection process of Colletotrichum fuscum on oregano leaves and stems

2021 ◽  
Vol 20 (5) ◽  
pp. 97-106
Author(s):  
Beata Zimowska ◽  
Ewa Dorota Król
Keyword(s):  
Infection Process ◽  
Host Tissue ◽  
Conidial Suspension ◽  
Origanum Vulgare ◽  
Time Intervals ◽  
Necrotic Spots ◽  
Stems And Leaves ◽  
Germ Tubes ◽  
Scanning Electron ◽  
Direct Placement

Anthracnose, caused by Colletotrichum fuscum, produces regular necrotic spots on oregano leaves and stems, causing severe crop losses. In this study, Koch’s postulates were fulfilled and infection process was investigated using scanning electron microscopy. Leaves and stems of Origanum vulgare were inoculated and incubated at 24°C in wet chambers under high relative humidity. Pathogenicity experiments demonstrated that all tested C. fuscum isolates had infected stems and leaves of oregano. Of all inoculation methods, direct placement of colonized agar plugs on injured epidermis and soaking plant organs in conidial suspension were the most effective. The behavior of the conidia deposited on the oregano leaves was investigated at different time intervals after inoculation: at 12, 18, 32, 48, 67 and 98 h. Conidia produced an appressoria of varying shapes which has been formed at the end of germ tubes of different lengths. Penetration to host tissue through stomata was observed. Acervuli formed on the leaves surface after 98 h after inoculation, typically with sharp pointed setoses.

Susceptibilities of Various Snail Intermediate Hosts of Schistosoma mansoni to Different Strains of the Parasite

1965 ◽  
Vol 39 (4) ◽  
pp. 363-376 ◽  
Author(s):  
M.F.A. Saoud
Keyword(s):  
Puerto Rico ◽  
Schistosoma Mansoni ◽  
Intermediate Hosts ◽  
Considerable Evidence ◽  
The Past ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Different Strains ◽  
Host Parasite ◽  
Comprehensive Studies

In the past two decades, considerable evidence has accumulated in the literature about the differences in the susceptibility of various intermediate hosts of Schistosoma mansoni to different strains of the parasite. Comprehensive studies on this aspect of host-parasite relationship have been published by Files & Cram (1949), Abdel-Malek (1950) and Files (1951). The results of more recent studies have been reported by Wright (1962) and Saoud (1964).In the present paper, the writer has studied the susceptibility of four intermediate hosts of S. mansoni from Brazil, Puerto Rico, Egypt and Tanganyika to some strains of the parasite.

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