|YUEN, JEANNE M.|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2009
Publication Date: 3/5/2009
Citation: Norman, D.J., Zapata, M., Gabriel, D.W., Duan, Y., Yuen, J.F., Mangravita-Novo, A., Donahoo, R. 2009. Genetic diversity and host range variation of Ralstonia solanacearum strains entering the United States. Phytopathology. 99:1070-1077.
Technical Abstract: Each year, large volumes of plant propagative stock are imported into the United States; occasionally, Ralstonia solanacearum is found systemically infecting this plant material. In this study, 106 R. solanacearum strains were collected over a 10-year period from imported ornamental propagative stock and vegetable production. An additional, 32 control strains were added to this study. Strains were compared using rep-PCR primers BOX, ERIC, and REP. Additional strain comparisons were made using AFLP along with sequence analysis of the Endoglucanase and the Cytochrome b561 genes. Using rep-PCR primers, populations could be distinguished by biovar and, to an extent, country of origin and original host. Similarity coefficients were relatively low in many rep-PCR clusters. Low similarity coefficients are evidence of the heterogeneity of populations and indicate that disease outbreaks over time have been caused by different clonal populations. Similar population differentiations of R. solanacearum were obtained when comparing strain sequences using either the Endoglucanase or Cytochrome b561 genes. We found that most of the biovar 1 strains of R. solanacearum entering the United States are genetically distinct from the biovar 1 strains currently found infecting vegetable production. These introduced biovar 1 strains also have a broader host range and can infect not only tomato, tobacco, and potato; but also anthurium, pothos and cause symptoms on banana. All introductions into the US of Race 3, Biovar 2 strains in the last few years have been linked to geranium production. These biovar 2 strains are genetically similar although some banding differences could be detected using AFLP.