Fusarium Wilt Suppression and Agglutinability of Pseudomonas putida

Mutants of Pseudomonas putida (Agg) that lack the ability to agglutinate with components present in washes of bean and cucumber roots showed limited potential to protect cucumber plants against Fusarium oxysporum f. sp. cucumerinum. However, a higher level of protection was observed against Fusarium wilt in cucumber plants coinoculated with the parental bacterium (Agg), which was agglutinable. The Agg mutants did not colonize the roots of cucumber plants as extensively as the Agg parental isolate did. In competition experiments involving bean roots inoculated with a mixture of Agg and Agg bacteria, the Agg strains colonized roots to a greater extent than the Agg cells did. These data suggest that the Agg phenotype provides additional interactions that aid in the beneficial character of P. putida.