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Light and electron microscope studies of host-parasite relations in a mycoparasite

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dc.contributor.author Golesorkhi, Roya. en_US
dc.date.accessioned 2009-07-09T18:38:51Z
dc.date.available 2009-07-09T18:38:51Z
dc.date.issued 1981-07-09T18:38:51Z
dc.identifier.uri http://hdl.handle.net/10464/1936
dc.description.abstract Light microscope studies of the mycoparasite Piptocephalis virginiana revealed that the cylindrical spores of the parasite became spherical upon germination and produced 1-4 germ tubes. Generally t"l.vO germ tubes were produced by each spore. When this parasite was inoculated on its potential hosts, Choanephora cucurbitarum and Phascolomyces articulosus, the germ tube nearest to the host hypha continued to grow and made contact with the host hypha. The tip of the parasite's germ tube became swollen to form a distinct appressorium. Up to this stage the behavior of the parasite was similar regardless of the nature of the host. In the compatible host-parasite combination, the parasite penetrated the host, established a nutritional relationship and continued to grow to cover the host completely with its buff colored spores in 3-4 days. In the incompatible host-parasite combination, the parasite penetrated the host but its further advance was arrested. As a result of failure to establish a nutritional relationship with the resistant host, the parasite made further attempts to penetrate the host at different sites producing multiple infections. In the absence of nutrition the parasite weakened and the host outgrew the parasite completely. In the presence of a non-host species, Linderina pennispora the parasite continued to grow across the non-host 1).yp_hae vlithout establishing an initial contact. Germination studies showed that the parasite germinated equally well in the presence of host and non-host species. Further electron microscope studies revealed that the host-parasite interaction between P. virginiana and its host, C. cucurbi tarum, was compatible when the host hyphae were young slender, with a thin cell wall of one layer. The parasite appeared to penetrate mechanically by pushing the host-cell wall inward. The host plasma membrane invaginated along the involuted cell wall. The older hyphae of C. cucurbitarum possessed two distinct layers of cell wall and-showed an incompatible interaction when challenged vlith the parasite. At the point of contact, the outer layer of the host-cell wall dissolved, probably by enzymatic digestion, and the inner layer became thickened and developed a papilla as a result of its response to the parasite. The haustoria of the parasite in the old hyphae were always surrounded by a thick, well developed sheath, whereas the haustoria of the same age in the young host mycelium were devoid of a sheath during early stages of infection. Instead, they were in direct contact with the host protoplast. The incompatible interaction between a resistant host, P. articulosus and the parasite showed similar results as with the old hyphae of C. cucurbitarum. The cell wall of P. articulosus appeared thick-with two or more layers even in the 18-22 h-old hyphae. No contact or interaction was established between the parasite and the non-host L. pennispora. The role of cell wall in the resistance mechanism is discussed. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Host-parasite relationships. en_US
dc.subject Parasites. en_US
dc.subject Microscopes. en_US
dc.subject Microscopy. en_US
dc.subject Electron microscopes. en_US
dc.title Light and electron microscope studies of host-parasite relations in a mycoparasite en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Biological Sciences en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Biological Sciences en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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