Eggplant accessions show stable resistance to <i>Ralstonia pseudosolanacearum</i>

Abstract Bacterial wilt of eggplant, caused by Ralstonia pseudosolanacearum , is one of the most destructive diseases affecting this crop. The most effective control is the use of resistant varieties. Therefore, the aim of this study was to evaluate the reaction of eggplant genotypes to R. pseudosolanacearum , to analyse the stability of resistance of eggplant accessions to different strains of the bacterium and to morphologically characterize the resistant accessions. Four experiments were carried out in a completely randomized experimental design. In the first, the aggressiveness of 50 strains of the pathogen was evaluated, with five replicates and 250 plots. The second consisted of evaluating the resistance of 20 eggplant genotypes, with four replicates and 80 plots. In the third trial, four resistant accessions were inoculated with strains of different aggressiveness in a factorial design (4 × 3), with four replicates and 48 plots. In the fourth trial, a morphological characterization of the four resistant eggplant accessions was carried out. The most aggressive isolate identified was CCRMRs 81, from which four resistant accessions were selected: CNPH 67, CNPH 84, CNPH 100 and CNPH 109. When tested with strains CCRMRs 81, CCRMRs 134 and CCRMRs 217, these accessions maintained a highly resistant phenotype. Although they have non-commercial morphological characteristics, they can be used as sources of resistance in eggplant breeding programmes or as rootstock varieties. Significance of the Study What is already known on this topic? Bacterial wilt, caused by Ralstonia pseudosolanacearum , is one of the most destructive diseases affecting eggplant ( Solanum melongena L.), leading to severe yield losses in several producing regions. The use of resistant cultivars is considered the most effective and environmentally sustainable management strategy. However, resistance levels may vary among genotypes and are often influenced by pathogen diversity and environmental conditions. Despite the importance of this disease, studies assessing the stability of resistance in eggplant genotypes under different conditions are still scarce, which limits the progress of breeding programmes. What are the new findings? This study evaluated the reaction of 20 eggplant genotypes to R. pseudosolanacearum and analysed the stability of resistance across different experiments. Significant variability in genotype response was observed, with some showing high resistance while others were highly susceptible. The identification of the most resistant and stable genotypes provides essential candidates for breeding programs. Furthermore, this work highlights the differential performance among materials, emphasizing the importance of combining phenotypic evaluation with resistance stability analysis for more efficient selection. What are the expected impacts on horticulture? The results provide strategic information for breeding programmes aimed at developing eggplant cultivars resistant to bacterial wilt. The identification of genotypes with stable resistance contributes to reducing yield losses and decreasing reliance on chemical control measures. In the long term, these findings can foster the sustainability of horticulture, enhance food security and strengthen the competitiveness of eggplant production, particularly in regions severely affected by the disease.