Molecular Studies on the Role of a Root Surface Agglutinin in Adherence and Colonization by Pseudomonas putida

Pseudomonas putida aggressively colonizes root surfaces and is agglutinated by a root surface glycoprotein. Mutants of P. putida derived chemically or by Tn5 insertion demonstrated enhanced or decreased agglutinability. Two nonagglutinable Tn5 mutants (Agg) and two mutants with enhanced agglutinability (Agg) possessed Tn5 in unique restriction sites. Agg mutants colonized root surfaces of seedlings grown from inoculated seeds, but at levels lower than those observed with the Agg parent. In short-term binding studies, Agg cells adhered at levels that were 20- to 30-fold less than those for Agg parental cells. These data suggest that the agglutination interaction plays a role in the attachment of P. putida to root surfaces.