Evaluation of Solanum peruvianum (sensu lato) germplasm to a standard Ralstonia solanacearum race 1/biovar 1 isolate and to a novel ‘Hawaii 7996’ resistance-overcoming race 3/biovar 2A isolate from Brazil

A major strategy to control the bacterial wilt (BW), caused by the Ralstonia species complex in tomato has been the employment of resistant cultivars and/or root-stocks. The tomato line ‘Hawaii 7996’ is a major source of stable and broad-spectrum resistance against BW. However, the detection of R. solanacearum isolates that overcome the ‘Hawaii 7996’ resistance in Brazil and elsewhere highlights the need for preemptive breeding actions. In the present work, 72 accessions of Solanum peruvianum (sensu lato) and other four wild species were evaluated against two R. solanacearum isolates: ‘CNPH-RS 488’ (race 3/biovar 2A/phylotype II/sequevar 1), virulent on ‘Hawaii 7996’, and ‘CNPH-RS 489’ (race 1/biovar 1/phylotype IIA/sequevar 50), a standard isolate that is avirulent on Hawaii 7996′. The responses to inoculation of the tested accessions were compared to that of ‘Hawaii 7996’ and ‘L390’ (BW-susceptible). The clear-cut differences in the responses among accessions to both isolates suggested the presence of distinct BW resistance mechanisms in this germplasm. Sixteen accessions displayed resistant reactions to ‘CNPH-RS 488’ and 31 to ‘CNPH-RS 489’. However, only seven accessions (predominantly of the species S. corneliomulleri) displayed resistance reactions to both isolates. These new sources of resistance to R. solanacearum may be useful for breeding programs aiming to anticipate potential problems with the further dissemination of bacterial populations with a virulence profile similar to that of R. solanacearum ‘CNPH-RS 488’.