COLEUS, A NEW HOST FOR RALSTONIA SOLANACEARUM RACE 1 BIOVAR 3 IN INDIA

Abstract

Ralstonia solanacearum was isolated from wilting coleus plants (Coleus forskohlii) in six commercial nurseries around Bangalore (south India). Colonies of all isolates were irregular with smooth margins, slimy dull white with pink to red centre on SMSA medium, Gramnegative, non-capsulated and non-spore forming. Bacterial identity was confirmed by PCR with species-specific 16S rDNA-based primers OLI1+Y2 and DAS-ELISA. The isolates could infect tomato, potato, and ginger, but failed to infect mulberry and banana. Six isolates were identified as race 1, based on pathogenicity tests, and as biovar 3, based on carbohydrate utilization.