Typescript (photocopy) / x, 100 leaves, [40] 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, Dept. of Plant Pathology and Agricultural Biochemistry, 1982

Thesis (Ph.D.)-- University of Adelaide, Dept. of Plant Pathology and Agricultural Biochemistry, 1982. / Typescript (photocopy).

Agrobacterium tumefaciens is a common soil bacterium that causes crown gall disease on many dicotyledonous plant species. It has been exploited for use in genetic engineering because it is able to promote transfer of any DNA segment to plant chromosomes. Many molecular factors in both the plant and bacterium contribute to successful infection and DNA transfer. Two bacterial factors were studied for this dissertation. The first was bacterial synthesis of cytokinins due to the induced expression of the gene tzs. Cytokinin production by some A. tumefaciens strains at the time of infection was hypothesized to enhance infection or influence host range. To test this hypothesis, heterologous strains engineered to express tzs and a native strain from which tzs was deleted were evaluated for tumor induction on a number of plant species. Major differences were seen when radish roots were infected with the tzs deletion strain. Morphological differences of the galls formed suggested a possible role for tzs in T-DNA transfer efficiency. β-glucuronidase assays with a mannopine synthase promoter-uidA fusion gene were used to study T-DNA transfer early in the infection process. No biological role for tzs was confirmed with either tumorigenesis or T-DNA transfer assays. However, optimized conditions for GUS fluorometric assays were established and the infection process was characterized. The second factor studied was a β-glucosidase gene in A. tumefaciens strain 83/73. This strain is highly infective on conifer hosts, whereas others are not. It is also able to hydrolyze the conifer phenolic compound, coniferin, to an active virulence gene inducer, coniferyl alcohol. This appears to be a major host range determining factor. As a first step in proving this role, the gene for the β-glucosidase enzyme responsible for hydrolysis of coniferin in strain B3/73 was cloned and sequenced. The deduced protein sequence has homology to other β-glucosidases, including a conserved active site. / Graduation date: 1991

Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Pathology, 1988. / Includes bibliographical references (leaves 113-130).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 190-199).

Thesis--Wisconsin. / Includes bibliographical references (leaves 90-98).

Diversas especies del género Agrobacterium producen tumores en gran cantidad de plantas cultivadas, causando la enfermedad conocida en inglés como "crown gall". En esta tesis se ha demostrado que cepas patógenas y no patógenas de las especies A. tumefaciens, A. rhizogenes y A. vitis son capaces de formar biopelículas tanto sobre superficies inertes como sobre raíces de tomate. Las cepas de A. tumefaciens y A. vitis se unieron a poliestireno y polipropileno, mientras que las de A. rhizogenes sólo se unieron a polipropileno. Se ha constatado que la formación de biopelículas in vitro sobre superficies abióticas en Agrobacterium spp. depende de la especie (biovar), la superficie y las condiciones de cultivo. Mediante microscopía electrónica de barrido y microscopía láser confocal, utilizando cepas marcadas con GFP, se demostró que las tres especies formaban estructuras complejas compuestas por numerosas células bacterianas dispuestas según alguno de los siguientes modelos: 1) tapices densos y continuos, 2) grandes agregados irregulares embebidos en material extracelular, o 3) en forma de setas globulares atravesadas internamente por canales. Los resultados sugieren que la formación de biopelículas puede estar asociada a la colonización y supervivencia de estas especies bacterianas en la rizosfera. Además, la capacidad del agente de biocontrol A. rhizogenes K84 de formar biopelículas durante su interacción con la planta podría ser una característica relevante para el control de la enfermedad. Con el propósito de ahondar y conocer genes implicados en la formación de biopelículas en este agente de biocontrol se han utilizado dos estrategias. Mediante genética clásica, se analizó una librería de mutantes al azar de la cepa K84 y se identificaron dos mutantes afectados en la formación de biopelículas. Uno fue incapaz de unirse y formar biopelículas sobre polipropileno, pero por el contrario se unió y formó biopelículas sobre ápices radiculares. El otro mutante produjo más biopelícula que la cepa K84, tanto en superficie abiótica como en ápices radiculares. / Abarca Grau, AM. (2011). Biopelículas en Agrobacterium spp [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/11670

Hohenheim, University, Diss., 2007.

Hohenheim, Univ., Diss., 2007.