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Poster: Epidemiology: Pathogen Dispersal


Genetic diversity of pathogenic Clavibacter michiganensis subsp. michiganensis strains from Central Chile
M. VALENZUELA (1), S. Fuentes (2), F. Claverias (2), X. Besoain (3), M. Seeger (4) (1) Centro de Biotecnología DAL, Universidad Tecnica Federico Santa Maria, Chile; (2) Centro de Biotecnología DAL, Universidad Técnica Federico Santa María, Chile; (3) Escu

The bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis (Cmm) is the most important bacterial disease in tomato.The genetic diversity of Cmm strains isolated during 20 years from tomato plants in different Chilean tomato regions was studied. Twenty five isolates were characterized by growth on different media, Gram staining and enzymatic activities. For bacterial identification PSA8/R PCR amplification and 16S rRNA gene sequencing were used. In addition, the housekeeping gyrB and kdpA genes and the pathogenicity tomA and chpC genes were sequenced. All genes were polymorphic in these isolates. The kdpA gene showed the highest variability. Except for the kdpA gene, Chilean isolates genes showed high identity with genes from reference strain NCPPB382. Phylogenetic trees of gyrB and pathogenicity genes showed close relationship between Chilean stains and those from New York and Serbia. Analyses of concatenated kdpA-gyrB genes yield 7 Chilean haplotypes. Geographical distribution of the isolates was analyzed. Most of the Chilean isolates clustered separately from the Serbian and New Yorker strains, suggesting that Chilean bacteria have a different origin. Additional housekeeping genes and a higher number of isolates will be studied.