Diversity of Ralstonia solanacearum in tomato rhizosphere soil

The diversity of Ralstonia solanacearum (Rs) isolated from tomato rhizosphere soil using rep-PCR analysis was examined. Before planting tomato, Rs in the test field was about 2x10(2) cfu per gram dry weight (gdw) of soil. Forty isolates were all identified as race 1/biovar 3. These isolates gave 5 polymorphic patterns on rep-PCR analysis with primer sets REP and BOX. After 2 months, the susceptible tomato cultivar Odoriko planted in this field had wilted and died. On the other hand, all plants of resistant rootstock cultivar LS-89 survived. The population of Rs in the Odoriko field rose to over 8x10(5) cfu/gdw and 40 isolates showed only 2 polymorphic patterns. In the LS-89 field Rs was repressed to below 5x10(3) cfu/gdw and 40 isolates showed 4 polymorphic patterns, 2 of which were newly detected.