Fluorescent Pseudomonas sp PF17 as an efficient plant growth regulator and biocontrol agent for sunflower crop under saline conditions

The plant growth promoting and biocontrol ability of a fluorescent pseudomonad bacterium isolated from a saline soil was evaluated. Isolate PF17 was identified as a Pseudomonas sp., and displayed high salinity tolerance. Indeed, a slight increase in salinity stimulated its growth. PF17 exhibited plant growth promoting and biocontrol potential up to 600 mM NaCl and produced a variety of metabolites including indole-3-acetic acid, siderophore, pyocyanin, hydrogen cyanide, chitinase, beta-1, 3 glucanase and an ability to solubilize phosphate. The plant growth promoting characters were maintained up to 200 mM NaCl, followed by a gradual reduction up to 600 mM NaCl. In vitro and in vivo studies, including field trials, were performed with sunflower under saline conditions. It was observed that PF17 showed plant growth promotion and significant biocontrol potential against the serious native phytopathogen, Macrophomina phaseolina, even under saline conditions.