DIVERSITY OF RALSTONIA SOLANACEARUM POPULATIONS AFFECTING TOBACCO CROPS IN NORTH CAROLINA

Abstract

One hundred eighty four strains of Ralstonia solanacearum isolated in 2007 and 2008 from 11 tobacco fields in North Carolina were evaluated for genotypic diversity and aggressiveness. All strains were race 1, biovar 1, and belonged to phylotype II. Genetic diversity of the strains was assessed with the use of repetitive sequence–based polymerase chain reaction. DNA primers (REP, ERIC, and BOX) were used to generate genomic fingerprints. Both REP and BOX revealed 3 patterns: Ar, Cr, and Dr and Ab, Cb, and Db, respectively. Five patterns were identified with ERIC-PCR. Pattern Ae was found in 80% of the strains collected. Pattern Be was in 4%, pattern Ce in 13%, pattern De in 2%, and pattern Ee in 1% of the strains collected. Cluster analyses showed that the strains were 88% similar and constitute a rather homogeneous group. Aggressiveness of strains was evaluated on 3 tobacco cultivars with different levels of resistance to bacterial wilt. Overall, aggressiveness depended on the field from which the strains...