Effect of bacteriaphage and exopolysaccharide on root colonization and rhizosphere competence by Pseudomonas fluorescens

Abstract

Pseudomonas fluorescens TC222 is a biocontrol agent. In this study, we focused on the influence of bspA encoding bacteriophage signal peptide protein and epsB encoding a putative Mig-14 family protein on the rhizosphere colonization and competence. After inoculation with each of strains individually, the number of each mutated strain was much lower than that of the wild-type strain. Both mutants inoculated with the wild-type strain at a ratio of 1:1 were outcompeted by the wild-type strain. Furthermore, both mutants showed a reduced biocontrol activity to Rhizoctonia solani and Gaeumannomyces graminis. To our knowledge, this is the first report that bspA and epsB are involved in root colonization and rhizosphere competence by P. fluorescens. © Springer-Verlag and the University of Milan 2010.