Vita. / Digitized by Kansas Correctional Industries

No description available.

Bibliography: leaves 169-185.

Also available as microfiche. / Header title of microfiche :"The study of the molecular level of the NZ isolate of LTSV and its satellite RNA" / Bibliography: leaves 102-125. / iv, 126 leaves, [30] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1994

" August 2002." / Bibliography: leaves 218-235. / viii, 235 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The pathogenicity of Phomopsis taxon 1 is examined in relation to symptom expression and bud loss on grapevines. Phomopsis taxon 1-specific DNA probe, pT1P180, and taxon 2-specific probe, pT1P25, were used to detect Phomopsis taxon 1 and Phomopsis taxon 2 in infected buds, canes and shoots in glasshouse and field experiments. Experiments confirm the isolates of taxon 1 examined did not cause leaf or shoot symptoms associated with Phomopsis cane and leaf spot, and that taxon 2 is more virulent than taxon 1. Suggests that taxon 1 (Diaporthe) is an endophyte which does not cause harm to the grapevine and that chemical control is not warranted for control of taxon 1 on grapevine. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2002

Bibliography: leaves 102-125.

Tan spot of wheat is an economically significant disease caused by the fungal pathogen, Pyrenophora tritici-repentis. Certain races of the fungus secrete Ptr ToxA (ToxA), a 13.2 kDa proteinaceous host-selective toxin that is responsible and sufficient to cause disease in susceptible wheat varieties. Disease symptoms develop only when the ToxA gene in the fungus and a single gene in the wheat host are expressed. The understanding of this gene-for-gene interaction could be instrumental towards control of the disease and is also being developed as a model system for understanding host-pathogen interactions. Here, this effort is given a solid structural foundation through crystallographic analysis of the ToxA structure. The ToxA structure was solved at 1.65 Å resolution using the anomalous signal from inherently present sulfur atoms. The monomeric toxin adopts a β-sandwich fold of two anti-parallel β-sheets composed of four strands each. The mapping of existing mutation data onto the structure reveals that a sequence of Arg- Gly-Asp(RGD) and surrounding residues required for activity are present on a solvent-exposed loop thereby making them potential candidates for recognition events that are required for ToxA activity. Unexpectedly, after a simple circular permutation, the ToxA structure is topologically identical to the classic mammalian RGD containing fibronectin type III (FnIII) domain, and furthermore the RGD residues are topologically equivalent. These results support the hypothesis that ToxA, like FnIII, interacts with an integrin-like receptor on the host plant cell surface. There has been a renewed interest in the method of using the anomalous signal from sulfur atoms to solve protein structures. As a spin-off of the structure solution work, the data were systematically analyzed to study the effects of crystal decay, resolution and data redundancy on the ability to locate the sulfur positions and subsequent phasing of the protein. The analyses show that the choices made about data redundancy and resolution limits may be crucial for the structure determination and that anomalous correlation coefficients are helpful indicators in making these choices. / Graduation date: 2006

A necrosis at the tip of cones was observed on hop (Humulus lupulus), cultivar "Nugget", grown in Oregon in the early 1990's. Fusarium sambucinum and F. avenaceum were recovered from symptomatic cones in 1998 and preliminary inoculation experiments suggested both Fusarium species could cause hop cone necrosis. Studies were carried out to (1) examine pathogenicity and demonstrate Koch's postulates for hop cone tip blight using isolates of F. avenaceum and F. sambucinum obtained from hop cones; (2) examine isolates of F. avenaceum and F. sambucinum derived from other diseased plant hosts, and other Fusarium species derived from hop cones, for ability to cause cone necrosis; and (3) survey commercial fields to determine Fusarium populations on 'Nugget' cone parts. Isolates ofF. avenaceum and F. sambucinum recovered from diseased hop cones were used for pathogenicity experiments. In addition, cone inoculations were done with single isolates of F. avenaceum and F. sambucinum from diseased sweet corn roots, one isolate of F. sambucinum recovered from a diseased potato tuber, individual isolates of F. equiseti and F. oxysporum from hop cones. Cones of two hop cultivars, 'Nugget' and 'Willamette', were collected from three different farms on three sampling dates and inoculated with spore suspensions of hop-derived F. avenaceum and F. sambucinum at concentrations of 10��, 1O���, and 10��� conidia/ml to examine dosage effects. Necrosis was evaluated 2, 4, 6, and 8 days after inoculation. Percent cone necrosis decreased as inoculum concentration of either F. avenaceum or F. sambucinum decreased, and was lowest on water-treated cones, for all three sampling dates. The respective Fusarium species were recovered from symptomatic cones. Cone necrosis developed following cone inoculation with F. avenaceum or F. sambucinum from potato or corn. Hop cones inoculated with F. equiseti or F. oxysporum also developed necrosis, but at relatively lower levels compared to the other Fusarium species used for inoculations. For the surveys in commercial hop fields, burr and cone material were collected on five different dates. Fusarium sambucinum was recovered most frequently, but F. avenaceum was also found. Both Fusarium species were recovered from asymptomatic burr and cone materials throughout the growing season. In general, Fusarium species, F. equiseti, F. oxysporum, F. culmorum, F. solani, plus F. avenaceum and F. sambucinum were found more frequently early in the season on stigmatic tissue, and Fusarium recovery decreased as the season progressed. Fusarium prolferatum and F. monilforme were recovered rarely. / Graduation date: 2004

Thesis (M.Sc.)(Microbiology)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.