Evaluation of Resistance to Race 3, Biovar 2 of Ralstonia solanacearum in Tomato Germplasm

Sources of resistance to tropical race 1 strains of Ralstonia solanacearum, the causative agent of bacterial wilt, have been identified in the tomato germplasm. Till now, no experimental data are available on Lycopersicon spp. (now Solanum spp.) sources for resistance to temperate race 3, biovar 2 strains. Eighty-two accessions belonging to different Lycopersicon spp. were evaluated for resistance to a race 3 strain endemic to Re´union Island. Evaluation was conducted in growth chambers, and included the Lycopersicon esculentum cv. Roma as susceptible control. No immunity or complete resistance was observed in any accession tested under our experimental conditions. Therefore, race 3 strain was demonstrated to be highly pathogenic on all the Lycopersicon accessions tested. Partial resistance was significantly detected in only one accession belonging to the species Lycopersicon peruvianum, and one L. esculentum var. cerasiforme tomato line. Five other genotypes from the species L. esculentum, Lycopersicon hirsutum and L. peruvianum were noteworthy. The Hawaii 7996 line represented the best source of partial resistance to race 3 with 52% of wilting. It can therefore be used as a starting point for introducing resistance to bacterial wilt caused by R. solanacearum race 3 in tomato and studying its genetic control.