Molecular Characterization and Epidemiology of Ralstonia solanacearum Race 3 biovar 2 Causing Brown Rot of Potato in Mauritius

Abstract

AbstractOutbreaks of brown rot disease caused by Ralstonia solanacearum Race 3 biovar 2 have resulted in losses of 291 t of potato, worth approximately USD 171 000 since 2005 over three growing seasons. The gradual spread of this quarantine disease in Mauritius has warranted a study of the population of the pathogen. The epidemiological and ecological groupings of R. solanacearum isolated from outbreaks in Mauritius from 2005 to 2008 were examined following a study of their genetic relatedness by PCR‐based marker amplified with REP and IS1112 PCR primers. The band‐based genomic fingerprint data clustered strains in two major groups B and C, and one minor group A. Group B comprised exclusively of strains that caused the outbreaks in 2008 and appeared to originate from a different clonal lineage from strains clustered in groups A and C. Nucleotide polymorphisms within each group and shared markers suggest that group B strains could represent a novel introduction of the pathogen compared to the initial population of strains responsible for the outbreaks in 2005 and 2006. The clustering of strains isolated from imported ware potatoes obtained from the local market support the hypothesis that this could be a source of entry of the pathogen in Mauritius.