Thesis (M.S.)--University of Wisconsin--Madison, 1986. / Typescript. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 42-45.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 139-150).

Marburg, University, Diss., 2001.

Marburg, University, Diss., 2001.

A pathogenicity locus of Pseudomonas syringae pv. syringae identified by Tn5 mutagenesis was investigated. The mutant strain PS9024 is attenuated for disease expression in its host, Phaseolus vulgaris, but produces the hypersensitive reaction (HR) in the nonhost, tobacco (Nicotina tabacum). A cosmid clone carrying 16 kilobases (kb) of contiguous genomic DNA partially complements this mutant. Altered growth of the mutant in planta was also partially restored. Marker exchange mutagenesis with Tn3- HoHo1 at two other sites within this locus results in mutants with attenuated and severely reduced pathogenicity. The locus is complex and contains repetitive DNA sequences. Northern analysis reveals that this locus is expressed in planta, but is not expressed in a rich growth medium, and the transcript is larger than 10 kb, suggesting that the locus is transcribed as a polycistronic mRNA. Comparison of total cellular protein profiles of R32 and PS9024 using SDS-PAGE analysis further reveals that at least nine protein bands ranging from approximately 100 kD or above in size are present in the wild type strain R32, but absent from the mutant. Additionally, a protein of approximately 45 kD is absent from the mutant. The site of Tn5 insertion has been partially sequenced. The initial search of the data banks suggested a gene or genes related to the ornithine biosynthetic pathway map to this locus. Further study strongly suggest a gene that encodes a membranceassociated protein and under the control of a promoter identical to appA gene promoter maps at this site and it is involved in the process of pathogenesis. / Graduation date: 1991

Würzburg, Univ., Diss., 2008. / Zsfassung in engl. Sprache.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1956. / Typescript. Abstracted in Dissertation abstracts, v. 16 (1956) no. 11, p. 1991. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 34-37).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Jan. 13, 2009). PDF text: 227 p. : ill. (some col.) ; 2 Mb. UMI publication number: AAT 3323493. Includes bibliographical references. Also available in microfilm and microfiche formats.

No description available.

The aim of this study was to increase understanding of amino acid utilisation and amino acid permease (aa_permease) genes in the plant pathogen Pseudomonas syringae, which inhabits the nutrient-limited environment of the plant surface and intracellular apoplast. aa_permease genes are significantly reduced in P. syringae genomes compared to non plant-pathogenic Pseudomonas. Accordingly, this work demonstrates that P. syringae can utilise a restricted number of amino acids for growth compared to non plant-pathogenic Pseudomonas. The remaining aa_permease genes in Pseudomonas syringae pv. tomato are annotated as transporting GABA, ethanolamine, proline and aromatic amino acids. Sequence analyses, phylogenetic analyses, chemotaxis assays and gene expression analyses supported the functional annotations of the GABA, ethanolamine and aromatic aa_permeases, but showed that expression of the proline permease was specifically induced by histidine, which suggests that this encodes a histidine transporter. Expression of the GABA and histidine permeases was also induced in the presence of tomato apoplast, indicating that these amino acids may be assimilated during apoplast colonisation. P. syringae pv. tomato exhibited chemotaxis towards tomato apoplast and several constituent amino acids, which may be important for invasion of the apoplast from the plant surface. Uptake of several amino acids including GABA and histidine appeared to be negatively affected in alkaline media. The aa_permeases use electrochemical potential energy to transport substrates and this mechanism may be affected by pH. The plant apoplast becomes increasingly alkaline during infection and this may select against the retention of particular transporters in P. syringae. As GABA is an abundant amino acid in the apoplast and can be used by P. syringae strains for growth, the growth of P. syringae pv. tabaci was monitored in transgenic tobacco plants with increased GABA. Although growth was similar in all plants, significantly fewer symptoms and more callose deposition was observed upon infection.