Simple sequence repeats and compositional bias in the bipartite Ralstonia solanacearum GMI1000 genome.
BACKGROUND
Ralstonia solanacearum is an important plant pathogen. The genome of R. solananearum GMI1000 is organised into two replicons (a 3.7-Mb chromosome and a 2.1-Mb megaplasmid) and this bipartite genome structure is characteristic for most R. solanacearum strains. To determine whether the megaplasmid was acquired via recent horizontal gene transfer or is part of an ancestral single chromosome, we compared the abundance, distribution and composition of simple sequence repeats (SSRs) between both replicons and also compared the respective compositional biases.


RESULTS
Our data show that both replicons are very similar in respect to distribution and composition of SSRs and presence of compositional biases. Minor variations in SSR and compositional biases observed may be attributable to minor differences in gene expression and regulation of gene expression or can be attributed to the small sample numbers observed.


CONCLUSIONS
The observed similarities indicate that both replicons have shared a similar evolutionary history and thus suggest that the megaplasmid was not recently acquired from other organisms by lateral gene transfer but is a part of an ancestral R. solanacearum chromosome.
Coenye
Tom
T
Laboratorium voor Microbiologie, Ghent University,K,L, Ledeganckstraat 35, B-9000 Gent, Belgium. Tom.Coenye@rug.ac.be
Vandamme
Peter
P
D001482:Base Composition / Q000235:genetics*; D019117:Burkholderia / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D019143:Evolution, Molecular; D016680:Genome, Bacterial; D010957:Plasmids / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*
D004269:DNA, Bacterial