This Article Full Text Full Text (PDF) Other Versions of this Article: AEM.01253-06v1 73/4/1225    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Castillo, J. A. Articles by Greenberg, J. T. Search for Related Content PubMed PubMed Citation Articles by Castillo, J. A. Articles by Greenberg, J. T. Agricola Articles by Castillo, J. A. Articles by Greenberg, J. T.

Evolutionary Dynamics of Ralstonia solanacearum

Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637,¹ PROINPA Foundation, Cochabamba, Bolivia²

Received 31 May 2006/ Accepted 11 December 2006

We investigated the genetic diversity, extent of recombination, natural selection, and population divergence of Ralstonia solanacearum samples obtained from sources worldwide. This plant pathogen causes bacterial wilt in many crops and constitutes a serious threat to agricultural production due to its very wide host range and aggressiveness. Five housekeeping genes, dispersed around the chromosome, and three virulence-related genes, located on the megaplasmid, were sequenced from 58 strains belonging to the four major phylogenetic clusters (phylotypes). Whereas genetic variation is high and consistent for all housekeeping loci studied, virulence-related gene sequences are more diverse. Phylogenetic and statistical analyses suggest that this organism is a highly diverse bacterial species containing four major, deeply separated evolutionary lineages (phylotypes I to IV) and a weaker subdivision of phylotype II into two subgroups. Analysis of molecular variations showed that the geographic isolation and spatial distance have been the significant determinants of genetic variation between phylotypes. R. solanacearum displays high clonality for housekeeping genes in all phylotypes (except phylotype III) and significant levels of recombination for the virulence-related egl and hrpB genes, which are limited mainly to phylotype strains III and IV. Finally, genes essential for species survival are under purifying selection, and those directly involved in pathogenesis might be under diversifying selection.

Published ahead of print on 22 December 2006.

This article has been cited by other articles:

• Yan, S., Liu, H., Mohr, T. J., Jenrette, J., Chiodini, R., Zaccardelli, M., Setubal, J. C., Vinatzer, B. A. (2008). Role of Recombination in the Evolution of the Model Plant Pathogen Pseudomonas syringae pv. tomato DC3000, a Very Atypical Tomato Strain. Appl. Environ. Microbiol. 74: 3171-3181 [Abstract] [Full Text]