Sossou, B. E., Sikirou, R., Chen, Jaw-rong., Ayenan, A. T. M., Chang, H., Ezin, V. E., Maxwell, L., Schafleitner, R. and Achigan-Dako, E. G. (2026). Identification, Spatial Distribution and Genetic Diversity of Ralstonia solanacearum Species Complex Isolates from Gboma (Solanum macrocarpon) in Benin. Plant Pathology, 2026; 0:e70165. https://doi.org/10.1111/ppa.70165
Gboma (African eggplant, Solanum macrocarpon), a leafy vegetable in Benin, is susceptible to bacterial wilt (BW) caused by Ralstonia solanacearum species complex, which is increasingly leading to significant yield losses in many production areas. In this study, the incidence of BW and its distribution were evaluated using 140 samples of wilted plants from 572 gboma fields across seven agroecological zones. Ralstonia species were detected using the IpxC genomic region with the specific primer pair 759/760. Genetic diversity and phylogeny of isolates were assessed in 59 positive samples using the 16S–23S rDNA internal transcribed spacer region and the endoglucanase (egl) gene sequence. Findings revealed that plant infection incidence ranged from 0.09% to 18.5%, with an average of 2% per field. Genetic diversity and phylogeny of Ralstonia solanacearum species complex isolates revealed that most samples matched exotic phylotype I and clustered with reference strains corresponding to four sequevars (14, 17, 46 and 31). A plant from Bembereke had a putative co-infection of phylotype I and II strains. Sequevar 17-related strains were commonly found in non-coastal regions, and strains clustering with sequevars 31, 46 and 14 were present in coastal regions. Isolates from seven samples inoculated into Sika and Kombara, two cultivated commercial varieties of gboma, induced pathogenicity; three isolates induced a hypersensitive response (HR) on gboma. This study is a first step towards the development of intra- and extraregional quarantine measures to minimise the spread of new strains and implement other BW control strategies, including breeding research for BW-resistant cultivars.
