Antagonistic potential of fluorescent Pseudomonas and its impact on growth of tomato challenged with phtopathogens

Abstract

This study focused on the antagonistic potential of fluorescent Pseudomonas in vitro, and its inoculation effect on growth performance of Lycopersicon esculentum in Fusarium oxysporum and Rhizoctonia solani infested soil. Biochemical characteristics of fluorescent Pseudomonas showed that all ten isolates were positive to catalase, amylase, gelatinase and siderophore production. While three isolates (Pf5, Pf6 and Pf9) were oxidase positive, nine isolates (Pf1, Pf2, Pf3, Pf4, Pf6, Pf7, Pf8, Pf9, and Pf10) were tolerant to 6.5% NaCl. Isolates Pf5 and Pf6 were resistant to all the test antibiotics; in contrast, the remaining eight isolates responded differently to different antibiotics. Isolates Pf5 and Pf6 were antagonistic against 14 bacterial species, and two pathogenic fungi (F. oxysporum and R. solani). Inoculation with fulorescent Pseudomonas Pf5 induced a significant increase in root and shoot length, and dry weight. Treatment of plants with either F. oxysporum or R. solani drastically reduced the root and shoot length and dry weight of the plant. However, in the presence of fluorescent Pseudomonas the adverse effect of the pathogens on growth of L. esculentum was alleviated.

Key Words: Amylase, gelatinase, Lycopersicon esculentum, phytopathogens