The present study was undertaken to unravel the biocontrol potential of Pseudomonas fluorescens (Pf) against potato bacterial wilt caused by Ralstonia solanacearum and the possible augmentative effect of salicylic acid (SA) in this respect. Pathogen-inoculated and uninoculated plants were treated with either Pf, SA or both, and the effects of the treatments were tested on the pathogen prevalence, management and some pathogenesis-related biochemical constituents as well as on vegetative growth

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... rameters of the host. In addition, molecular analysis was performed to assess the antibiotic-producing ability of Pf. Results indicated that Pf harbors the phlD gene encoding the antibiotic 2, 4-diacetylphloroglucinol. Application of SA augmented the biocontrol effect of Pf hence, the suppressive effect of the combined treatment surpassed that of either Pf or SA alone. Besides the direct effect of the combined treatment on the pathogen, indirect effects manifested by increasing the accumulation of ascorbate, phenols, chlorophylls and carotenoids as well as by inducing activity of the antioxidant enzymes peroxidase and superoxide dismutase. Direct and indirect effects of the combined treatment were reflected in enhanced growth of Pf+SA-treated plants compared with untreated, pathogen-inoculated plants. It was concluded that SA could be utilized to boost the biocontrol action of Pf as an environment-friendly approach for controlling potato bacterial wilt disease.