Author:M. Anitha, V. Paranidharan and M. Karthikeyan
Ralstonia solanacearum (Smith) Yabuuchi et al. is one of the most severe pathogen of Solanaceous crops with a wide host range. Ralstonia solanacearum race 1 is responsible for causing bacterial wilt in brinjal. The pathogenic strains were isolated from wilted brinjal plants and isolated on triphenyl tetrazolium chloride (TTC) medium. The strains were confirmed by proving pathogenicity on brinjal plants. Phenotypic characterization revealed that out of five media tested TTC medium was an excellent source for growth and extracellular polysaccaride production (EPS) of R. solanacearum. Upon biochemical analysis the R. solanacearum strains showed positive reaction for catalase, KOH, citrate utilization and acid production while negative results were observed for Gram staining, starch hydrolysis and fluorescent pigment production. The biovar of the strain was identified by utilization of disaccharides (cellobiose, maltose and lactose) and sugar alcohols (dulcitol, mannitol and sorbitol). The strains of R. solanacearum were confirmed to belong to Race 1 based on symptom production on different hosts and hypersensitive response on tobacco plant. Therefore, it is confirmed that R. solanacearum race 1 causing bacterial wilt of brinjal belongs to biovar III. PCR amplification of ITS region of the strains of R. solanacearum was done and sequenced [MH481663 (ERY1) and MH481664 (VBN1)].
Key words : Brinjal, Ralstonia solanacearum, Race 1, Biovar III