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[Transfer of plasmid RP4 into some phytopathogenic bacteria and its relation to their virulence]
Abstract:
Plasmid RP4 were transferred from Escherichia coli into Pseudomonas solanacerum, Xanthomonas campestris pv. oryzae, X. campestris pv. campestris, and X. campestris pv. citri at the frequencies of 1.8 X 10(-6), 2.8 X 10(-6), 1.4 X 10(-2) and 2.0 X 10(-3), respectively. The frequencies of transfer depended on bacterial species and conjugation conditions. Treatment of bromide at the concentration of 2 micrograms/ml and acridine orange at 100 micrograms/ml for 32 hrs the plasmid RP4 could be cured from the transconjugant of P. solanacerum at the frequencies of 75% and 95%, respectively. When transconjugant of P. solanacearum was inoculated into tomato plants, the decrease in virulence was observed, furthermore, no plasmids were detected both in the wild-type strain and the cured transconjugant. It thus appears that the virulence may not be related to plasmids.
Insights
This study investigated plasmid transfer in bacteria and found that while plasmid RP4 could be transferred, curing it from Pseudomonas solanacearum did not affect virulence, suggesting plasmids may not be linked to this trait.
Area of Science:
- Microbiology
- Bacterial Genetics
- Plant Pathology
Background:
- Plasmids are extrachromosomal DNA elements that can confer various traits to bacteria.
- Understanding plasmid transfer and their role in bacterial virulence is crucial for disease management.
Purpose of the Study:
- To investigate the transfer efficiency of plasmid RP4 into different bacterial species.
- To determine if plasmid RP4 is essential for the virulence of Pseudomonas solanacearum in tomato plants.
Main Methods:
- Conjugation experiments were performed to transfer plasmid RP4 from Escherichia coli to Pseudomonas solanacearum, Xanthomonas campestris pv. oryzae, X. campestris pv. campestris, and X. campestris pv. citri.
- Plasmid curing was induced using bromide and acridine orange treatments.
- Virulence assays involved inoculating tomato plants with wild-type and cured strains of P. solanacearum.
Main Results:
- Plasmid RP4 transfer frequencies varied significantly among the tested bacterial species.
- Bromide and acridine orange treatments effectively cured plasmid RP4 from P. solanacearum transconjugants at high frequencies (75% and 95%, respectively).
- Transconjugants of P. solanacearum cured of plasmid RP4 showed a decrease in virulence, and plasmids were undetectable in both wild-type and cured strains.
Conclusions:
- The frequency of plasmid transfer is dependent on the bacterial species and conjugation conditions.
- Plasmid RP4 can be efficiently eliminated from P. solanacearum using chemical treatments.
- The study suggests that virulence in the tested P. solanacearum strain may not be directly related to the presence of plasmid RP4.