Characterization of Ralstonia solanacearum strains from Brazil using molecular methods and pathogenicity tests

Abstract

Forty one Brazilian strains of Ralstonia solanacearum from ornamental plants (Begonia sp., Fuchsia sp., Oxalis sp., Pelargonium x hortorum and Tagetes sp.), eucalyptus (Eucalyptus sp.), Solanaceae (Nicotiana tabacum, Solanum jilo, S. lycopersicum, S. melongena, S. tuberosum), banana (Musa sp.) and heliconia (Heliconia sp.), belonging to three different races and five biovars, were characterized by ERIC and BOX-PCR and classified in phylotypes by sequence analysis of the endoglucanase (Egl) and MutS genes. The virulence of 22 strains was evaluated on tomato cv. Petomech VF, potato cv. Agata and tobacco var. Burley. In the ERIC and BOX-PCR analysis, strains were separated into two main clusters showing high genetic diversity among them, with no correlation concerning race, biovar or geographical origin. Phylogenetic analysis based on sequences of part of the Egl and MutS genes revealed the predominance of phylotype II in Brazil. With exception of strains belonging to race 2, which were not included in the experiments, pathogenicity tests carried out with different strains of R. solanacearum showed high virulence on tomato and potato, and lower virulence on tobacco, showing no relationship with race, biovar or host plant from which the tested strain were originally isolated.