First report of bacterial wilt of Gboma (Solanum macrocarpon) caused by Ralstonia solanacearum in Benin.
In March 2012, wilted plants of Gboma (Solanum macrocarpon; the major leafy vegetable cultivated in Benin) without foliar yellowing were observed at three locations (Dogbo, Lokossa, and Athiémé) in the southwestern districts. Longitudinal sections of most stems of Gboma showed brown vascular discoloration. The cut stems released whitish bacterial ooze in water. R. solanacearum was recovered from all symptomatic plants on modified SMSA medium. In 2014, a survey throughout the Abomey-Calavi area (Atlantic District) identified bacterial wilt of Gboma within all cultivated farms, with incidences ranging from 15 to 75.2%. Thirty newly collected bacterial isolates were identified as R. solanacearum using ImmunoStrip assays and diagnostic PCR. Alignment of R. solanacearum reference sequences confirmed that all strains from Abomey-Calavi and two from Dogbo belonged to one unique Sequence Type (ST) within Phylotype I (egl ST 43 (sequevar 31), mutS ST 22). This ST has also been reported to be widespread in the Ivory Coast and in South Africa, India, and Reunion Island. This is thought to be the first report of R. solanacearum causing bacterial wilt on Gboma in Benin.