Studies on Ralstonia solanacearum Bacteriophages

青枯病菌バクテリオファージに関する研究

2015-03-25

2015-03-25

Ralstonia solanacearum is a soil-borne gram-negative bacterium that causes bacterial wilt disease in many important crops. Bacteriophages are viruses infectious to bacteria, and some virulent bacteriophages can lyze bacteria. The use of virulent bacteriophages may have great potential for protecting plant from R. solanacearum infection. In this study, new bacteriophages infectious to R. solanacearum were isolated and characterized. Three kinds of R. solanacearum bacteriophages, φRS138, φRS611, and φRS603 were isolated from the soil of a tomato field, and the host specificity and growth curve of them were analyzed. Based on their morphology, φRS138 was classified into the Siphoviridae family. φRS611 and φRS603 were characterized as an Ff-type phage belonging to the Inoviridae family. Further, the whole genome sequences of the three phages were determined. The φRS611 genome showed high similarity to those of Ralstonia phages RSS0 and RSS1 which have been reported by other group. However, approximately 900-nucleotide deletions were found, indicating that φRS611 is a deletion mutant of them. The φRS603 genome showed high similarity to those of Ralstonia phages φRSM1 and φRSM3 reported by Askora et al. However, φRS603 genome was unique, because its genome lost some open reading frames (ORFs) including integrase of φRSM3. In stead, φRS603 had ORF 11 that was homologous to other Ralstonia phages φRSS0 and φRSS1, indicating that φRS603 is an evolutional intermediate between RSS phages and RSM phages. In order to reveal integration mechanism, integration site of φRS603 genome in the genome of R. solanaceaum was analyzed. The φRS138 genome was composed of 41,941 base pairs in lengths of double-stranded DNA with a G + C content of 65.1% and putative 56 ORFs. The φRS138 genome could be divided into three regions homologous to prophage gene in R. solanaceaum K60-1, Pseudomonas aeruginosa phages of the Siphoviridae family, and genomes of other R. solanacearum strains. This is the first report for the complete genome sequence of R. solanaceaum phage of Siphoviridae family. The three phages isolated from the same soil of tomato field were different and unique, and may be useful for understanding molecular basis of infection to bacteria and as a biopesticide for controlling bacterial wilt disease.

博士（学術）

京都工芸繊維大学

New bacteriophages infectious to R. solanacearum were isolated and characterized.

14303甲第735号

http://hdl.handle.net/10212/2266

en

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Thesis or Dissertation

Thesis