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ANNUAL CONFERENCE :: Abstract Library
Abstract Library
2003 Conference Abstract
| Type of Submission |
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Submission Type: |
Poster Presentation |
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Subject Category: |
Environmental Microbiology |
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| Session Information |
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Presentation Date: |
May 27, 2003 |
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Abstract ID: |
B17 |
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Session: |
Poster 2 |
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Time: |
15:00 |
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| Presenting Author |
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| Other Authors |
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P.J. WILLSON, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8.
J.J. GERMIDA, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8.
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| Title |
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Phylogenetic analysis of pseudomonads associated with the roots of field-grown canola. |
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| Abstract Text |
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The ability of bacteria to exploit new environments and to respond to environmental stress is most easily explained by the acquisition of new genes. This study examined the relatedness of root-associated pseudomonads based on phylogeny and phenotypic properties, and the influence of plasmid DNA on this relatedness. Pseudomonads (N = 145) isolated from the rhizosphere and root-interior of four cultivars of field-grown canola (Melfort, SK) were clustered according to their 16S rRNA sequences and selected phenotypic properties (antibiotic resistances, enzyme production, and carbon substrate utilization). On the basis of 16S rRNA sequences, two major clusters were observed, namely the Pseudomonas fluorescens complex and the P. putida complex. Cluster analysis of their phenotypic properties exhibited little correlation with their phylogenetic relationships. In the majority of situations, the isolates grouped into a phenotypic cluster had less than 60% similarity among their phenotypic traits despite a close evolutionary relationship as determined by 16S rRNA sequencing (distance value < 0.1). Isolation of plasmid DNA from 66 isolates revealed that 71% (N = 47) harboured at least one large plasmid (>50kb), with 28% of these (N = 13) having more than one large plasmid. The results indicated that the genotype of fluorescent pseudomonads was not accurately reflected by their phenotype. Adaptation through mobile genetic elements could explain the discrepancy between the phylogenetic and the phenotypic positions of the bacteria. Further analysis into the genotype-phenotype dissimilarity will be conducted with an emphasis on the influence of mobile genetic elements on bacterial phenomes. |
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