Ralstonia solanacearum, one of the most important bacterial pathogen of tomato, is a constant threat to this crop. Plant–pathogen interactions are mediated by a complex network of molecular and cytological events that determine a range between susceptibility. Pusa ruby (susceptible) and Hawaii7996 (resistant) cultivar of tomato was treated with betabutyric acid (BABA) having three different concentration (@50µM) prior to inoculation of R. solanacearum at intervals of 6, 24, 48 and 96hpi using root drenching inoculation technique under control conditions. The role of defense-related enzymes in imparting resistance in tomato with chemical elicitor against R. solanacearum was investigated by quantifying enzymes activity and gene expression of three defense-related enzymes peroxidase (POD), catalase and superoxide dismutase (SOD). POD enzyme activity was noticed increased after inoculation with BABA (50 µm) + R. solanacearum upto 48hpi (3.76 min/mg protein) in Pusa Ruby and (5.36 min/mg protein) in Hawaii7996 whereas, kept decreased level at 96hpi as compared to control. The significant increase level of CAT activity was noticed in combination of BABA (50µM) + R. solanacearum in both Pusa Ruby (25.58 min/mg protein) and Hawaii7996 (31.58 min/mg protein) cultivars at 48hpi and decreased level of SOD enzyme was noticed at 96hpi (17.91 min/mg protein) Pusa Ruby and (29.91 min/mg protein) Hawaii7996 as compared to control. The relative expression was recorded significant (P<0.005) high 2.61 fold up-regulation after treated with pathogen in both cultivars as compared to control. Pusa Ruby cv. showed the significant highest values of gene expression with BABA+ R. solanacearum treatment in both POD and SOD genes at 96hpi as compared to resistant cultivar of tomato. The relative expression CAT gene was found highest in resistant cv. Hawaii7996 and was lowest in the susceptible cv. Pusa Ruby. Minimum wilt incidence 5.54 % was recorded in BABA (50µm) in resistant cv. Hawaii7996 followed by 9.14 % in Hawaii7996 without BABA treatment and susceptible cv Pusa Ruby (29.10%) after 28 days of inoculation of R. solanacearum. BABA also provided good health of plants of both the cultivars of tomato under glasshouse conditions.

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