Rhizosphere competence describes the ability of an organism to colonize, thrive and compete with other organisms in the rhizosphere. Different bacterial traits, including motility, chemotaxis and colonization determine which population will thrive and dominate certain rhizospheres. In this study we aim to understand what genes lead to the dominance of Pseudomonas in wheat rhizosphere by manipulation of genes suspected to be involved in determining rhizosphere competence. Several Pseudomonas isolates from wheat rhizosphere, were characterized and clustered into groups. Base on their characterization and root colonization results we selected three representative isolates: two belonging to P. stutzeri (124.a and 128.b) and one to P. fluorescens (133.c). Isolate 124.a showed the highest results in biofilm and motility assays and was the best root colonizer. The root environment has high diversity of bacteria, many of which are competing over nutrients secreted by the root. Rhizosphere competent bacteria need to reach the root in high numbers and to win the competition with their neighbors for nutrients and for niches on the root. Co-colonization of isolates 124.a and 133.c (expressing GFP and mCherry respectively) showed that each isolate occupy specific niche on the root. Similarities and differences of the genomes of the three isolates will be discussed in correlation with root competence traits. This will allow to identify genes and genetic networks that enable Pseudomonas species to dominate the wheat root environment.
