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Title:Pathogenicity Genes of Pseudomonas Syringae Pv. Tabaci Br2
Author(s):Salch, Yangkyo Park
Department / Program:Plant Pathology
Discipline:Plant Pathology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Plant Pathology
Abstract:Pseudomonas syringae pv. tabaci BR2 produces tabtoxin and causes wildfire disease on tobacco and bean plants. Tn5 mutants of PTBR2.024 were generated by using pGS9::Tn5. The Tn5 mutants wre prototrophs, resistant to kanamycin, nalidixic acid, and streptomycin, but sensitive to chloramphenicol. Eight of 2,686 Tn5 mutants showed no symptoms and ten showed reduced symptoms when inoculated onto detached tobacco leaves of Nicotiana tabacum cv. Havana 38, but all showed typical wildfire symptoms on detached leaves of Phaseolus vulgaris cv. Top Crop. Two of the nonpathogenic mutants failed to produce tabtoxin. Southern hybridization analysis using ('32)P-labelled pGS9 indicated that Tn5 had inserted into different EcoRI and SalI restriction fragments in each of the eight nonpathogenic mutants. Hybridization to additional EcoRI and SalI bands in two mutants indicated a second insertion of IS50 or Tn5. The EcoRI fragment containing Tn5 from each of the eight nonpathogenic mutant genomic DNAs was cloned into vectors pTZ18R or pLAFR3.
A cosmid genomic library of the parent strain was constructed by using a cosmid vector pLAFR3. Five of the 1,750 clones contained DNA that hybridized to pTZ184.1 from mutant PTBR4.000. Six contiguous EcoRI fragments (57 kb in length) were present in three different clones. A 7.2 kb EcoRI fragment was present in all three clones. The 7.2 kb fragment was subcloned and the recombinant clone (pQS409) restored pathogenicity to the original mutant PTBR4.000. None of the six EcoRI fragments hybridized to the other seven mutants. The 7.2 kb fragment was conserved in P. syringae pvs. tabaci and angulata, but not in other pathovars or strains.
Issue Date:1987
Description:126 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.
Other Identifier(s):(UMI)AAI8711867
Date Available in IDEALS:2014-12-15
Date Deposited:1987

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