| Abstract: | Pathogenesis-related (PR) proteins are one of the major and preliminary proteins accumulated as a defense against biotic stress. This defense response can be induced by using beneficial rhizobacteria, which has been studied in various host-pathogen interactions. In the present study, eleven Pseudomonas isolates were assessed for their potential to ferment sorbitol, reduce nitrate, and produce mycolytic enzymes, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, phenazine antibiotics, and N-acyl homoserine lactones (AHLs). All isolates were tested against the host-specific pathogen Fusarium oxysporum MTCC1755 in tomato under greenhouse conditions, and shortlisted isolates were tested for their rhizosphere competence. In-vitro test results showed that the isolates were able to produce mycolytic enzymes, including protease, lipase, chitinase, cellulase, and amylase, and the antibiotic phenazine and were negative for pyoluteorin. All the isolates except two were positive for ACC deaminase production. Greenhouse results showed that the isolates M80, M96, and T109 significantly reduced symptoms of Fusarium wilt. Extended greenhouse tests under autoclaved and unautoclaved soil conditions showed that M80, M96, and T109 were excellent rhizosphere competitors and were identified as Pseudomonas putida. In brief, the defense-specific biochemical variations in the host could describe the improved defense against Fusarium wilt occurring in the primed plants. These three Pseudomonas strains could be used as potential biocontrol agents, along with their rhizosphere competence. |
