Abstract: Plant growth-promoting rhizobacterium Pseudomonas aeruginosa strain IE-6S+ suppresses root-knot nematode (Meloidogyne spp) indirectly by enhancing defense mechanism leading to induced systemic resistance in tomato. However, which determinants are important in the induction of resistant reaction in plants against nematode by IE-6S+ is yet fully understood. Salicylic Acid (SA) production by bacteria acts as endogenous signal for the activation of certain plant defense responses. In a split root trial with tomato plant as a host and M. javanica as challenging pathogen, IE-6S+ induced systemic resistance in both wild type and NahG tomato seedlings. Moreover, the bacterial efficacy against nematode was not altered when soil chemical compositions was changed by the addition of iron. These results suggest that P. aeruginosa IE-6S+ suppress root-knot nematode indirectly via enhanced defense mechanism in plants, which is independent of SA accumulation in the host.