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Poster: Epidemiology: Systematics/Evolution


Diversity and phylogeny of moko disease-causing Ralstonia solanacearum strains in Colombia
M. RAMIREZ (1), R. Jackson (2), V. Villegas-Escobar (3), J. Correa-Álvarez (3), C. Ramirez (1) (1) Universidad de Antioquia, Colombia; (2) Reading University, England; (3) Universidad Eafit, Colombia

Ralstonia solanacearum is a soilborne plant pathogen that causes bacterial wilt on a wide range of hosts of economic importance. This disease is particularly devastating in Musa spp., where it is known as Moko disease. A major challenge in controlling this disease is to understand the diversity of the pathogen and how it adapts over time. With such knowledge, it may be possible to identify drivers of adaptation and inform changes in management practices. We therefore sought to characterize the genotypic and phenotypic diversity of R. solanacearum isolates obtained from plantations of Musa spp. in Colombia, and infer their phylogenetic relationship. Sixty-six isolates were collected. The genetic diversity and phylogenetic relationship among all the isolates were assessed by multiplex PCR and sequence analyses (mutS, rplB, and egl). Multiplex PCR assigned all the strains to phylotype II/sequevars 4 and 6. Similarly, the phylogenetic analysis of the gene sequences confirmed the classification of the strains into phylotype II; but, in addition, identified three separate clusters: IIA/6 (banana), IIB/4 (banana), and IIB/4 (plantain). Pathogenicity tests showed symptoms of wilt on banana plants after one month, but only strains isolated from plantain infected tomato. This study shows that plantain and banana plantations in Colombia harbor genetically diverse strains of R. solanacearum, belonging to at least three separate clades, and with differences in pathogenicity.