Use of Pseudomonas fluorescens-based formulations for management of tomato spotted wilt virus (TSWV) and enhanced yield in tomato

Strains of Pseudomonas fluorescens were investigated for biocontrol efficacy against tomato spotted wilt virus ( TSWV) in tomato both alone and in mixtures. P. fluorescens strains applied to seed, soil and foliage or as a seedling dip significantly reduced TSWV, with a concomitant increase in growth promotion in both the glasshouse and field. Two native strains ( CoP-1 and CoT-1) and one foreign strain (CHAO) reduced TSWV. In P. fluorescens - treated tomato plants, increased activity of polyphenol oxidase, beta-1,3-glucanase and chitinase was observed, and induction of chitinase was confirmed by western blot analysis. Induction of new protein ( 18 kDa) detected by SDS - PAGE in P. fluorescens - treated tomato plants was not found in healthy and P. fluorescens - untreated virus inoculated control plants. Indirect ELISA clearly showed a reduction in viral antigen concentration in P. fluorescens - treated tomato plants corresponding to reduced disease ratings. All the P. fluorescens - treated tomato plants also showed enhanced growth and yield compared to control plants. Hence, plant growth promoting rhizobacteria ( PGPR) could play a major role in reducing TSWV and increasing yield in tomato plants.