Submitted to: Bacterial Wilt, The Disease and Ralstonia Solanacearum Species Complex
Publication Type: Book / Chapter
Publication Acceptance Date: 6/20/2005
Publication Date: 7/15/2005
Citation: Robertson, A.E., Fortnum, B.A., Wechter, W.P., Denny, T.P., Kluepfel, D.A. 2005. Insertions in the avirulence gene avra alter the virulence of Ralstonia solanacearum on Nicotiana tabacum. In: Allen, C., Prior, P., and Hayward, A.C., eds. Bacterial Wilt and the Disease and Ralstonia solanacearum species Complex. St. Paul, MN: APS Press. p 359-364. Interpretive Summary: None.
Technical Abstract: Bacterial wilt is a major disease of tobacco in both North and South Carolina, but it rarely occurs on tobacco in Georgia and Florida, although it is common on tomato in tobacco-growing counties there. We examined the genetic diversity of R. solanacearum in the southeastern U.S. using REP-PCR. Neighbor-joining tree analysis showed that South Carolina isolates segregated from Georgia, North Carolina and Florida isolates. To further investigate this apparent diversity, the avirulence gene avrA was cloned and sequenced from selected R. solanacearum isolates from the Carolinas and Georgia. Avirulence genes determine race specificity of a pathogen by limiting the range of host cultivars or host species and genera that the pathogenic strain may attack. Therefore loss or inactivation of an avirulence gene often extends the host range of a pathogen to include plants that were previously resistant because they contained the corresponding resistance gene. Here we describe characteristics of avrA in the R. solanacearum populations of the southeastern US and their correlation with the differences in bacterial wilt incidence between the Carolinas and Georgia/ Florida.