Abstract
Five of fifty bacteria isolated from Saharan weeds (Xanthium spinosum, Desmazeria rigida and Anacyclus clavatus) growing in the south of Tunisia showed in vitro antagonistic activity against Verticillium dahliae, thus were further evaluated for their ability to suppress Verticillium wilt of young olives. Three of the isolates, related to known members of the genera Pseudomonas and Achromobacter, induced a significant decrease in the rate at which the disease occurred in V dahliae-inoculated plants. The active compounds of the isolates were further investigated in terms of their inhibitory effects on the growth pattern of pathogenic fungi. The active compound produced by Pseudomonas sp. and Achromobacter xylosoxidans was not a protein. Overall, the findings presented in the current study indicate that the three bacterial strains isolated from the root of Saharan weeds hold promising potential for future application as biocontrol agents for the mitigation and prevention of Verticillium wilt of olive trees.